CA1223069A

CA1223069A - Diagnostic processing system for automatic transmission of an automobile

Info

Publication number: CA1223069A
Application number: CA000456999A
Authority: CA
Inventors: Yasuyoshi Asagi; Noriaki Ogawa; Hitoshi Kasai; Toshihiro Hattori; Makoto Uriuhara; Shigeki Moride; Katsuya Shishido
Original assignee: Fujitsu Ltd; Isuzu Motors Ltd
Current assignee: Fujitsu Ltd; Isuzu Motors Ltd
Priority date: 1983-06-30
Filing date: 1984-06-20
Publication date: 1987-06-16
Also published as: US4642771A; EP0134646B1; EP0134646A1; KR880000074B1; KR850000320A; AU544230B2; AU2989184A; JPS6011765A; ES8601418A1; ES533840A0; DE3474849D1

Abstract

DIAGNOSTIC PROCESSING SYSTEM FOR AUTOMATIC
TRANSMISSION OF AN AUTOMOBILE

ABSTRACT OF THE DISCLOSURE:

A diagnostic processing system for the automatic transmission of an automobile to cooperate with the usual instruction element for producing an actuation signal for driving the transmission gears and clutch.
The system is chiefly comprised of a gear position sensor sensible to the gear position of the transmission gears and a diagnostic check element which determines, based on the gear position signal from the sensor and other information regarding the automobile running, the validity of the actuation signal.

Description

3L223~9 ,. -- 1 --DIAGNOSTIC PROCESSING SYSTEM FOR AUTOMATIC
TRANSMISSION OF AN AUTOMOBILE

BACKGROUND OF THE INVENTION
1. Field of the Invention he present invention relates to a diagnostic processing system for an automatic transmission in an 5 automobile.
The diagnostic processing system of the present invention cooperates with the automatic transmission of an automobile through the innovation of a gear position sensor. In particular, the gear position sensor is 10 useful for electric controlled automatic transmission, in that the tensor it used for detecting, among a plurality of gear position, which gear position is operable at any given moment. the present invention specifically refers to various factors to be checked through a diagnostic process, such as completion of a gear-out operation, completion of a gear-in operation, and completion of a gear change, etc.

2. Description of the Prior Art As is well known, in an automobile equipped with automatic transmission, awkward clutch operation is eliminated by automatically effecting suckle gear changes; enabling relatively trouble-free operation of the automobile for even an unskilled driver. Recently, the trend is toward the further realization of such a computer-assisted automatic transmission, namely an electronic controlled automatic transmission. Among the various types of electric controlled automatic transmission, the present invention refers to that wherein the automatic transmission is basically composed of members identical to those incorporated in usual manually operated transmissions, i.e., clutch and slidable-mesh gear transmissions, but in which these members are controlled by a microprocessor in response it -` 3L223~6~

to relevant data received, such as an accelerator position sign net, automobile speed signal, etc.
Automobile transmissions should operate with a high degree of reliability, and various systems have been proposed to attain this high reliability. However, none of these systems have yet attained the required reliability with respect to the aforementioned type of automatic transmission.
SUMMARY OF THE -INVENTION
Therefore, it is an object of the present invention to pro-vise a system which will attain a high reliability of the auto-matte transmission equipped in an automobile. Specifically, the present invention provides a diagnostic processing system for the automatic transmission of the type mentioned above.
Basically the above object is attained by employing a gear position sensor, in that signals output from the gear position sensor, and also other information signals, are received by the system which then determines whether or not the gear-out opera-lion is completed, the gear-in operation is completed, and if the sensor is operating normally. Further, if the sensor opera-lion is abnormal, the system instigates a support backup forth sensor.
In accordance with one particular embodiment of the pro-sent invention, there is provided a diagnostic processing system for an automatic transmission of an automobile, the auto-matte transmission is performed by transmission gears and clutch which are both activated by means of individual actual ions under the control of a control unit including therein an instruction element which produces an actuation signal for the actuators, with reference to a predetermined transmission map, in response to a variety of input data representing, at least, a rotation speed of an input-shaft, an automobile speed Ann on .
- pa -N/V ratio which is a ratio, predetermined for every transmission gear position, between the rotational input-shaft speed and the automobile speed, an accelerator pedal position, a clutch position, and an engine speed, the system is comprised of a gear position sensor cooperating with the transmission gears and a diagnostic check element formed, together with the instruction element, in the control unit, the diagnostic check element is operative to judge a gear position of the transmission gears based on the gear position signals output from the gear position sensor and determines whether or not each gear change is completed by analyzing the thus judged gear position and the input data of the rotation speed and the automobile speed I.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic block diagram of a known electronic controlled automatic transmission provided in a body of an automobile;
Fig. 2 is a schematic diagram of a map used for determining a suitable gear position for a predetermined automobile speed;
Fig. 3 is a schematic circuit diagram of a gear position sensor and its peripheral members;
Fig. 4 is an explanatory drawing of a table memory;
Fig. 5 illustrates a functional block diagram of a part of a control unit according to the present invention;
Fig. 6 is a flow chart revealing the diagnostic ~223~69 procedure performed in the diagnostic check element shown in Fig. 5;
Fig. 7 is a schematic and explanatory diagram representing the diagnostic check element of Fig. 5;
Fig. 8 is a functional block diagram of a part of a control unit according to the preserlt invention Figs. PA, 9B, and 9C are flow charts of the diagnostic procedure performed in the switch check and backup element shown in Fig. 8, and;
Fig 10 is a circuit diagram of an example of a mask treating circuit.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Before describing the preferred embodiments of the present invention, an explanation will be given of a known automatic transmission apparatus.
Figure 1 is a schematic block diagram of a known electronic controlled automatic transmission provided in a body of an automobile. The present invention is applied to an automobile having a construction as shown I in Fig, 1. That is, a usual clutch and sliding-mesh type transmission gears are actuated by respective actuators under the control of a control unit, in which a conventional torque-converter and auxiliary sub transmission are not used. In Fig. 1, reference numeral 1 represents an accelerator pedal, 2 a throttle actuator for adjusting a throttle valve 2', 3 an engine, 4 a clutch, 5 transmission gears, 6 solenoid valves for driving a clutch actuator 4' and a transmission actuator 5', 7 a drive wheel, 8 a mode selector provided with a select lever 8', for manually selecting a drive mode such as drive (D), neutral I and reverse (R), 9 a control unit, constituted by a microprocessor, for controlling the throttle actuator 2, the solenoid valves 6, and producing a hill start aid output (HA), and 10 an indicator for displaying the present gear position of the transmission 5.
The control unit 9 receives, at respective input 3L2~69 ports, a lever position signal PAL from the selector 8, an accelerator position signal PEA from the accelerator pedal 1, i.e., throttle angle signal, an engine speed indication signal IS from the output side of the engine 3, a clutch position signal SKYE from the clutch 4, a rotational input-shaft speed indication signal ITS , and an automobile speed indication signal IS , etc.
Note, the above-mentioned input signals PAL , PEA , SKYE ' IS , ITS , and so on (not shown) are detected by and produced from individual suitable sensors. These sensors are widely known per so.
The control unit 9 receives and processes the individual input signals from these sensors to produce output signals at the respective output ports, thereby controlling the engine speed through the throttle actuator 2, engagement or disengagement of the clutch through the clutch actuator I', and gear changes in the transmission 5 through the transmission actuator 5'.
Specifically, the engagement or disengagement of the clutch 4 is determined by an instruction element of the control unit 9 in response to the engine speed indication signal IS and the rotational input-shaft speed indication signal ITS. The gear change in the transmission is controlled in response to the accelerator position signal PEA , indicative of the throttle angle, and the engine speed indication signal IS , with reference to a transmission map (Fig. 2).
Figure 2 is a schematic diagram of a map used for determining a suitable gear position. The map determines a gear position best suited for the running of the automobile in accordance with the throttle angle THY in I, and the automobile speed AS in km/h.
A TO of 100% represents a state in which the throttle valve is fully opened, while a TO of 0% represents a state in which the throttle valve is closed. In the map of Fig. 2, numerals 1, 2, 3, 4, and 5 denote individual gear positions. The curves indicated by solid lines ~L~23~)6~

represent gear change borders during acceleration, while the curves indicated by broken lines represent gear change borders during deceleration. with reference to Fig. 1, when the condition of the running automobile is to be changed to another more suitable condition, through the accelerator position signal PEA and the automobile speed indication signal ITS by referring to the above-mentioned transmission map of Fig. 2, the clutch 4 is first disengaged my the clutch actuator 4' under control of the control unit 9. Then, when it is determined that the clutch 4 is completely disengaged, through the clutch position signal SKYE the trays-mission actuator 5' is activated to select a suitable gear position according to the transmission map. Thus, lo the related gear change operation is completed. The clutch actuator 4' is ken activated to reengage the clutch 4. From the viewpoint of high reliability ox the automatic transmission operation, it is important to fully ascertain whether or not the gear-out operation is correctly completed, and also, whether or not the gear-in operation is correctly completed, at least during the gear change operation. It is further important to ensure that the gear change operation as a whole is correctly completed, and that the gear position sensor (reference numeral 21 in Fig. 3) has not failed; and if such a failure condition does exit, to effect a particular backup treatment as soon as possible.
The system of the present invention operates to supervise the conditions of the clutch 4, transmission gears 5, and so on, as shown in Fig. 1, and to this end a gear position sensor 21 (Fig. 3) is introduced into the system. Figure 3 is a schematic circuit diagram of a gear position sensor and its peripheral members.
In Fig. 3, the gear position sensor is generally represented by reference numeral 21. The gear position sensor 21 is located in the transmission gears box 5 (Fig. 1) and constituted by gear position switches G12,

3~69 G34, GROW, G135, GNU and GROW. Data giving the on/off state of each gear position switch is stored in 8-bit buffer registers BFl and BF2.
Encircled reference numerals 1 through 5 of Fig. 3 5 denote first through fifth gear positions, respectively.
Encircled R denotes the reverse gear position. The gear position to be selected is determined by the gear position switches (G). These switches Go are classified as shift-side switches G135, GNU and GROW, and selection-10 side switches G12, G34j and GROW. Data giving the on/offstate of these switches is stored, as mentioned before, in the buffer registers BFl and BF2 both of which can be formed as an element of the microprocessor, i.e., the control unit 9 of Fig. 1. When one of the first, third 15 and fifth gear positions it selected, the switch G135 is turned on. In this case, the actuator of the switch G135, can be mechanically actuated by the selected transmission gear 5 (Fig. 1) (this also applies to switches GNU GROW). When the transmission is set at the 20 neutral gear position, the switch GUN is turned on. When one of the second and fourth gear positions and the reverse gear position is selected, the switch GROW is turned on.
For the selection side switches (G), when one of the first and second gear positions and the neutral gear position No is selected, the switch G12 is turned on.
In this case, the actuator of the switch G12 can be mechanically actuated by the selected transmission gear 5 (Fig. 1) (this also applies to switches G34 and GROW).
When one of the third and fourth gear positions and the neutral gear position No is selected, the switch G34 is turned on. When one of the fifth gear position the neutral gear position No, and the reverse gear position is selected, the switch GROW is turned on.
Thus, when one of the first, third, and fifth gear positions, the reverse and the neutral gear positions (No, No, I is selected, only one of the corresponding ~223~9 shift-side switches G135, GNU and GROW is turned on, and simultaneously, only one of the corresponding selection-side switches G12, G34, and GROW is turned on.
For example, if the gear position switch GROW at the shift-side is closed turned on) and, at the same time, the gear position G12 at the selection-side is closed, the microprocessor can determine that the second gear position is actually selected at that moment. In another example, if the gear position switch G135 at the shift-side is closed (turned on) and, at the same time, the gear position switch GROW at the selection-side is closed, the microprocessor can determine that the fifth gear position is actually selected at that moment.
The diagnostic processing system of the present invention will be now explained in detail. This explanation will first deal with the case where the aforesaid determination regarding the gear-out operation and gear-in operation is attained. That is, the determination is attained by analyzing the gear position signals PUGH and PAGE (shown in Fig. 3), the usual rotational input-shaft speed indication signal ITS (Fig. 1), and the usual automobile speed indication signal IS (Fig. 1).
us previously mentioned with reference to Fig. 3, for example, it is judged that the second gear position is to be selected if the gear position switches GROW
and G12 are both closed. Similarly, it is judged that the fifth gear position is to be selected if the gear position switches G135 and GROW are both closed. The abo~e-mentioned judgment is achieved in reference to a table of a table memory, as shown in Fig. 4.
Figure 4 is an explanatory drawing of a table memory. The table memory can be comprised of a read only memory (ROM) contained in a control unit (core-sponging to the control unit 9 of Fig. 1), which Willie explained with reference to Fig. 5 hereinafter.
In Fig. 4, the gear position signal PUGH and PAGE

~223~

(Fig. 3) are applied, as an input data Din and corresponding variables regarding the gear position are provided therefrom as an output data Dour , through a judgment process. In this table memory, at the left half column side, fogies "0" and "1" of the gear position signals PUGH and PAGE are shown. Each logic "1"
indicates that the corresponding gear position switch, such as G135, GUN --- GROW, is closed, while the logic "0"
indicates that it is open. Symbol "X" indicates a "don't care" status/ i.e., the logic may be "1" or "0" and either will do. The judgment is made in response to each combination of the fogies "1" and "0". For example, when the signals PUGH and PAGE assume fogies "100" as the shift-side and "010" as the selection-side, it is judged that the third (3) gear position is now selected.
In this way, the first (1) through fifth US) gear positions, the reverse OR) gear, and three neutral gear (No, No, No) positions can be determined in accordance with fogies "0" and "1" of the signals PUGH and PAGE.
Further, in the judgment column, *l denotes a shift-selection illegal state, where each of the signals PUGH and PAGE exhibits ll000" logic. *2 denotes a shift-illegal state, *3 a neutral-selection illegal state, and *4 a selection illegal state. Rows including *1 through *4 represent unidentified states which may be provided during the gear changes from one gear position to another gear position. The right side column indicates variables GEAR regarding the gear position. The variables GEAR are indicated in the form of machine words and express the conditions set in the transmission gear box (refer to 5 of Fig. 1). Each machine word is composed by 1 byte data, i.e., 8 bit data, wherein each lower 4 bits expresses a respective established gear position, i.e., 01, 03, 05 --- 06, while each upper 4 bits expresses auxiliary information.
Each symbol "+" represents information obtained by Owing with the corresponding lower 4 bit data of the gear ~2~3~;9 _ 9 _ position established immediately beforehand. Therefore, such information "+" can be utilized for executing a so-called retry operation. The retry operation is well known and is generally available in a manually operated 5 transmission to enable a smooth reset of a gear position even though the preceding gear change did not succeed in setting that same gear position. If, for example the gear position is set in the shift-illegal state I
during the retry operation, and if, for example, the 10 gear position established immediately beforehand is expressed as "02", then the variable GEAR should be expressed as "12'i, i.e., 10 + 02. The following table displays a sequence arbitrarily selecting one gear change, i.e., from the second gear position (2) to the 15 third gear position I

Table I 2 No No 3 II 02 I OX PA OX lo 03 The upper row represents each actual gear position, 25 which corresponds to the value in the column "JUDGE"
shown in Fig. 4, and the lower row represents each variable of the gears, which corresponds to the value in the column "VARIABLE" shown in Fig. 4.
Thus, according to the present invention, the 30 resultant judgment is obtained first in accordance with the signals PUGH and PAGE and then with reference to the table in the table memory of Fig. 4.
The corresponding N/V ratio is then read from an N/V
ratio table memory (mentioned hereinafter) in response 35 to the thus-obtained resultant judgment. This N/V
ratio can be defined as ~23~;9 N/V = F2 x TUG x 1000 wherein FOG denotes a final gear ratio, TUG a transmission gear ratio, and r a radius of the drive wheel (7 in Fig. lo. The obtained N/V ratio value, the rotation speed obtained from the rotational input-shaft speed indication signal IS , and the automobile speed obtained from the automobile speed indication signal IS are used to determine the gear position, in lo accordance with the following equation which derives a determination factor n.
n = pa - N/V x wherein the symbol y denotes a predetermined constant for compensation of error. The constant itself is not absolutely essential in the present invention, and may be any value, for example, ~500 rum.
Figure 5 is a functional block diagram of a part of a control unit according to the present invention. In Fig. 5, the control unit 39 receives, at least, the gear position signals PUG and PAGE (stored in the buffer registers BFl and BF2 of Figs. 3 and 7, but not shown in Fig. 5), the rotation speed output by the rotational input-shaft speed indication signal ITS , and the automobile speed output by the automobile speed US indication signal IS , and as a result, produces the actuation signal to be applied to the clutch actuator 4' and the transmission actuator 5', by means of the solenoid valve 6. The actuation signal is produced from the usual instruction element 36 (refer to Fig. 2), as in the control unit 9 of Fig. l. However, according to the present invention, the actuation signal is not produced until the diagnostic check element 35 allows the production of the same. The diagnostic check element 35 includes therein at least a judging element 31, a table referring element 32 (refer to the table memory of Fig. 4), a calculating element 33, and an determining element 34. The judging element 31 ~L2;~3~

produces the aforesaid N/V ratio data and sends it to the calculating element 33 by cooperating with the table referring element 32. The calculating element 33 executes the aforesaid arithmetic equation, i.e., 5 ¦ a - N/V x , and then produces the aforesaid determination factor n. The determining element 34 determines whether or not the gear-out operation is completed, and also, whether or not the gear-in operation is completed based on the thus given determination factor n. If the determination obtains a trouble-free response, the actuation signal from the element 36 becomes effective.
he operations achieved in the diagnostic check element 35 in Fig. 5 will be clarified as follows.
(1) Where the variable (GEAR) (refer to Fig. 4) is in a range of 01 through 06, a gear-in state it assumed, if the determination factor n sightsees n > 0, it is concluded, by the determining element 34, that the gear-in operation is not completed; while, if n < 0 stands, it is concluded that the gear-in operation is completed.
(2) Where the previous variable (GEAR) was in a range of 01 through 06 (which previous variable is held ; in a register 37 to be connected to an arithmetic logic unit (ALUM) of Fig. 5) and, at the same time, any one of the illegal states, i.e., *l through *4 of Fig. 4, exist, (a) if n > 0 stands, it is concluded that the gear-out operation is completed; while (b) if n < 0 stands, it is concluded that the gear-out operation is not completed.
Figure 6 is flow chart revealing the diagnostic procedure performed in the diagnostic check element 35 shown in Fig. 5. Referring to Fig. 6, in step a, the table memory (32) is accessed by the judging element 31, but initially a provisional variable GEAR Go is Aruba-trarily specified, in which Go is a value selected from 3~)6~

the right side column of Fig. 4. In step b, if Go < Of (expressed in hexadecimal notation) stands, a legal state is assumed, and therefore, in step c, the value Go is set for the variable GEAR as it is. If Go < Of does 5 not stand, an illegal state is assumed, and therefore, in step d, (GEAR AND OF) is added to Go to obtain a legal variable of the gear position.
Then an inherent diagnostic check is executed from step e. The variable GEAR G is judged, in step e, from lo the viewpoint of whether or not G = 01 06 stands.
If G - 01 06 stands (corresponding to the aforesaid condition (1)), a variable y is obtained through an equation ¦ a - NAG x I¦ based on the previously recited equation for the determination factor n. In 15 step g, if Y Y (r is the previously-mentioned constant for compensation used in the related equation) stands, the gear-ln operation is determined under the aforesaid condition Al), in step h, by the determining element 34 (Fig. 5), while if it does not stand, the gear-out 20 operation is determined under the aforesaid condition (2) in step Q.
Returning to step e, if G = 01 through 06 does not stand (corresponding to the aforesaid condition (2)), a logical addition of the variable GEAR, at its lower 25 4 bits, with the variable OF, at at its lower 4 bits, is executed, i.e., GEAR AND OF, so as to find a variable Go indicating a preceding gear position. In step j, whether or not Go is in a range of 01 through 06 is examined.
If the result is "No", the check is completed, since it 30 is concluded that the gear position is neutral. If the result of step j is "Yes", a similar equation to that of the step f is executed with respect to the variable Go.
Figure 7 is a schematic and explanatory diagram representing the diagnostic check element of Fig. 5.
35 In Fig 7, the variable GEAR from the table 32 is, on one hand, supplied to the usual instruction element 36, and, on the other hand, to the previously mentioned N/V

~L223069 ratio table memory 41, which receives the variable such as 01, 02 ..., and produces a corresponding value of the N/V ratio. The N/V ratio value is then given to a multiplier 42 to produce, with the automobile 5 speed I, the values shown in Fig. 6B as NAG x and N/V(G2) x I, at steps f and Jo In steps f and k, the rotation speed is subtracted by the thus multiplied value at a subtracter 43, to obtain the values - NAG x and - N/V(G2) x I. The absolute 10 values thereof can be obtained via an absolute value generating element 44 to produce each value of y to be obtained in these steps f and k. The thus generated absolute value y is applied to a comparator 45 having, as a threshold level, the aforesaid constant y for 15 compensation of error, so that steps g, b, and Q of Fig. 6 can be performed, When the output of the comparator 45 is logic "1", and if the aforementioned condition (1) stands, it is concluded that the gear-out operation is completed. While, when logic "0" is output from the comparator 45, and if the aforesaid condition 12) stands, it is concluded that the gear-in operation is completed. As a result, the determining element 34 of Fig. 5 allows the instruction element 36 to produce the actuation signal concerned.
As mentioned above, whether or not the gear change operation, i.e., gear-out and gear-in, is correctly completed can be determined according to the present invention, and, of course, the next operation, for example, engagement of the clutch 4, is not allowed to start until the gear change is confirmed to be completed:
if the clutch is engaged before the completion of the gear change, the transmission gears would be badly damaged. From this viewpoint, the above-mentioned diagnostic check by the diagnostic check element 35 of Fig. 5 is very important. In this case, it is also important to check whether or not the switches (G135, GNU GROW, G12j G34, GROW) of the gear position sensor 21 3~6 I

are operating normally. If a failure occurs in at least one of those switches, the validity of the diagnostic check for the gear change operation would be lost.
Therefore, it is preferable to also perform a diagnostic check for the switches of the sensor 21. It is further preferable that, if a failure occurs in one or more of the switches, a backup should be provide for the abnormal switch or switches. That is, even if such a failure occurs, the aforesaid diagnostic check on whether or not the gear change is completed still can be maintained.
Figure 8 illustrates a functional block diagram of a part of a control unit according to the present invention. The switch check and backup element 50 of Fig. 8 is incorporated into the diagnostic check element 35 shown in Fig. 5. In Fig. 8, a short-circuited switch recovering element 51 functions to find a short-circuited switch and then eject a mask operation thereto, thereby invalidating the switch. A mode discriminating element 52 follows the short-circuited switch element 51, and discrimates whether or not a running mode or a gear-changing mode is established.
The term running mode means that the output of the engine 3 (Fig. 1) is engaged with the drive wheel 7 fig. 1). A running mode determining element 53 functions to finally find the open-circuit switch, caused by a failure, with the aid of a part 55 mentioned later) in accordance with information received regarding the condition of the clutch and the condition of the transmission gear to be selected. A gear-changing mode determining element 54 functions to also finally find such an open-circuit switch caused by a failure, with the aid of the element 55 during a gear change operation, in accordance with information received regarding the condition of the clutch, the condition of the transmit-soon gear to be selected, and the rotation speed I. The above mentioned element 55 is a gear-change confirmation ~2~31)~9 element which functions to confirm whether or not the desired transmission gear-in operation is completed, and allows the element 36 to produce the actuation signal.
Also, if a switch failure exists, this element functions 5 to confirm whether or not the related gear change is completed, based on a judgment of whether or not the rotation of the input-shaft it normal. The operation of the switch check and backup element 50 will be explained below.
lo Figures PA, 9B, and 9C are flow charts revealing the diagnostic procedure performed in the switch check and backup element 50 shown in Fig. 8. The flow shown in Fig. PA is of the short-circuited failure of the switch dealt with by the element 51 of Fig. 8. In normal state two or more switches at the shift-side (Fig. 3) must not be closed simultaneously. Also, two or more switches at the selection-side must not be closed simultaneously. Ill however! it it determined that a short-circuited failure has occurred, in step a of Fig. PA, whether or not two or more switches have closed simultaneously is determined. If the result is "Yes", step b follows, but if "No", step e follows.
Step a and the following steps are executed for the shift-side switches and selection-side switches I separately and alternately.
In step b, i.e., when two or more switches are closed, whether or not each of the closed switches is masked is determined. If the result is "Yes" (this means that the switch was in a failure state) r step c follows, but if "No" (this means that the switch was normal), step d follows. The term "mask" is defined as a particular bit logic "1") for indicating that the on/off information of the corresponding switch is now invalid. The mask bit is variable, and therefore, if the failed switch is restored, the mask bit is reset to logic IlOli. In step c, the switch having the mask bit of logic lull i.e., a masked switch signal, is ~2~:3~

disregarded and treated as an open switch, i.e., the switch was in a failure state and is still in a failure state. This is followed by step e. On the other hand, in step d, the mask bit is newly given to the switches now in a failure state. In step e, the mask signal is canceled for the open switch or open switches. During steps a through d, if the result "Yes" in step b is produced continually for a predetermined term, an alarm signal ALMS is provided from the element 51 and given to the indicator 10 of Fig. l. This ALMS signal indicates that a permanent short-circuit failure has occurred in the switch, while the corresponding switch signal indicating "closed" is further treated as invalid.
Figure 10 is a circuit diagram of an example of a mask treating circuit. The mask treating circuit 60 receives an inherent gear position signal PUGH , as an input data, and then produces a mask processed signal MPSGH as an output data. The signal MPSGH is then supplied to the mode discriminating element 52 ox Fig. 8. Note, an identical circuit to the circuit 50 also exists for working with respect to the other signal PAGE and for producing the other mask processed signal MPSGH. Further, the function of the circuit 60 can also be achieved by predetermined programs as a software process. The circuit 60 is comprised of a plurality of AND gates, inventors, and flip-flops (OF), and an OR gate and NOR gate, as illustrated. The output A from the OR gate indicates, when logic lo that two or more switches are closed simultaneously.
The output B from the NOR gate indicates, when logic "l", that no masked switch signals exist. The inputs of this NOR gate represent mask command signals C. When the signal or signals C are logic "l", the corresponding switch signal or signals are masked. Once the core-sponging switch signal is changed to logic "0" loath short circuit failure is restored, the corresponding OF is reset.

~2~:3~3~9 The steps in Fig. 9B deal mainly with the flow of the operation of elements 52, 53, and 54 shown in Fig. 8.
In step f, if the mode discriminating element 52 (Fig. 8) determines that the running mode is now held, step Q
follows, while if it determines that the gear changing mode is now held, step g follows. In step g, i.e., when the gear change operation is executed, element 54 fig. 8) determines whether or not the clutch 4 (Fig. 1 is normal. If Lucy step h follows/ while if "Jo", step p follows. In step h, the element 54 determines whether or not the gear position switch selected immediately before is changed from a closed state to an open state. If the result at step h is "OFF", step i follows, while if "ON", step p follows. In step i, the element 54 determines whether or not the desired gear position is neutral or not. If the result it "Yes", step k follow, while it "No", step j follow. In step j, the element 54 determines whether or not the rotation speed of the input-shaft is reasonable in view of the N/V ratio value and the automobile speed I.
If the result is "Yes", step k follows, while if "No", step p follows.
In step k, the element 35 determines whether or not there exists a short-circuit failure at the gear position switch to be selected. If the result is "Yes", step p follows, while if "No", step o follows. If the result of step k is "No", i.e., when no short-circuit failure exists, then a diagnostic check for the switch is achieved by the element 55, from the standpoint of whether or not an open switch failure exists.
The steps Q, m, and n deal with the running mode determining element 53 (Fig. 8). In step Q, whether or not the clutch 4 (Fig. 1) is completely engaged is determined. If the result is "Yes", step m follows, while if "No", step p follows. In step m, it is determined whether or not the desired gear position is neutral. If the result is "Yes", step p follows while ~2~3~9 if "No", step n follows. In step n, it is determined whether or not the desired gear position switch is ON.
If the result is "Yes", step p follows, while if "No", the diagnostic check for the switch regarding an open-switch failure is started. If an open-switch failure exists, an alarm signal Ammo indicating a permanent open-circuit failure is generated and given to the indicator 10 fig. l), while the element 55 (Fig. 8) further carries out its operation regardless of the existence or nonexistence of these failure signals ARMS and Ammo. This shows the backup role of the element 55. The open-switch failure for the switch can be performed by detecting if the switch concerned is "OPEN" when it should be closed.
Steps p through u are dealt with chiefly by the gear change confirmation element 55 of Fig. 8. In step p, it is determined whether or not the desired gear position switch is closed. If the result is "Yes", it is confirmed, in step u, that the related gear change operation is completed. This allows the element 36 (Fig. 5) to produce the relevant activation signal.
If the result of step p is "No", it is determined, in step q, whether or not the desired gear position switch is in a failure state. If the result is "Yes", step r follows, while if "No", it is determined that the concerned gear change operation is not yet completed, and thoroughfare, the element 55 inhibits the element 36 from producing the activation signal. In step r, it is determined whether or not the desired gear position is neutral. If the result is "Yes", step u follows, while if "No", step s follows. In step s, it is determined whether or not the rotation speed a of the input-shaft is reasonable, taking into account the N/V ratio value and the automobile speed I. If the result is "Yes", step u follows, while if "No", step t follows.
As mentioned above in detail, the diagnostic processing system of the present invention can determine I

the completion of the gear change operation by utilizing the gear position sensor, and can also check the normality of the gear position sensor. Furthermore, even if a failure of the sensor occurs, the system can still oversee the completion of the gear change with a : high accuracy, to some extent.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A diagnostic processing system for an automatic trans-mission of an automobile, the automatic transmission is performed by transmission gears and a clutch which are both activated by means of individual actuators under the control of a control unit including therein an instruction element which produces an actuation signal for said actuators, with reference to a predetermined transmission map, in response to a variety of input data representing, at least, a rotation speed of .alpha. an input-shaft, an automobile speed .beta., an N/V ratio which is a ratio, predetermined for every transmission gear position, between the rotational input-shaft speed and the automobile speed, an accelerator pedal position, a clutch position, and an engine speed, the system is comprised of a gear position sensor cooper-ating with said transmission gears and a diagnostic check element formed, together with said instruction element, in said control unit, said diagnostic check element is operative to judge a gear position of said transmission gears based on the gear position signals output from said gear position sensor and determines whether or not each gear change is completed by analyzing the thus judged gear position and said input data of the rotation speed .alpha. and the automobile speed .beta..

2. A system as set forth in claim 1, wherein said gear position sensor is constituted by both shift-side switches, to produce shift-side gear position signals, and selection-side switches, arranged in an orthogonal manner to said shift-side switches, to produce selection-side gear position signals, both said shift side and said selection-side gear position signals composing said gear position signals.

3. A system as set forth in claim 2, wherein said judgement of the gear position is performed with the use of a table memory, mounted in said control unit, wherein the table memory defines a table which judges and produces variables of each gear position corresponding to said gear position signals.

4. A system as set forth in claim 3, wherein said diagnostic check element comprises: a table referring element containing therein said table memory; a judging element producing first said judged gear position via said table memory in the form of said variables and then producing said N/V ratio value specified, in response to each of said variables, by an N/V ratio table memory; a calculating part which produces a determination factor n through a predetermined procedure with said N/V ratio value from said N/V ratio table memory, said rotation speed .alpha. and said automobile speed .beta.; and an determining element which produces a determination result by analysing said determination factor n in the light of each condition defined by said variables, said determination result is an output of said diagnostic check element, which output allows said instruction element to make said actuation signal from said instruc-tion element effective.

5. A system as set forth in claim 4, wherein said calculating element produces said determination factor n through said procedure which is set up by a first step wherein said N/V ratio value is multiplied by said automobile speed .beta., i.e., mathematically expressed as N/V x .beta., a second step wherein said automobile speed .alpha.
is subtracted by the result of said first step, i.e., mathematically expressed as .alpha. - N/V x .beta., a third step wherein an absolute value thereof, is created, i.e., mathematically expressed as ¦.alpha. - N/V x .beta.¦, a fourth step wherein the thus created absolute value is subtracted by .gamma., i.e., mathematically expressed as ¦.alpha. - N/V x .beta.¦
- .gamma., to produce, as a result, said determination factor n, wherein .gamma. denotes a predetermined constant for compensation of error.

6. A system as set forth in claim 5, wherein said determining element produces said determination result to render said actuation signal effective, if it is determined that a gear-in state of said gear change is completed under conditions where n < 0 stands and said variable is in a legal state, i.e., one of said shift-side switches and one of said selection-side switches are both closed simultaneously, alternatively, if it is determined that a gear-out state of said gear change is completed under conditions where n ? 0 stands and said variable is in an illegal state, but the preceding variable was in said legal state, the illegal state is any one of shift-illegal, selection-illegal, neutral-selection-illegal and shift-selection-illegal states.

7. A system as set forth in claim 2, wherein said diagnostic check element further includes a switch check and backup element which is operative to check said normality of each of said shift-side and selection-side switches to ensure the validity of said determination result, i.e., the output of said diagnostic check element, and, in addition, if a failure occurs in the shift-side and selection-side switches, the switch check and backup element is operative to backup the failed switch so as to still support the function of the diagnostic check element.

8. A system as set forth in claim 7, wherein said switch check and backup element comprises: a short-circuit switch recovering element which receives said gear position signals and is operative to find a short-circuited switch and effect a mask operation to the failed gear position signal so as to make this failed gear position signal invalid with a mask bit and further is operative to reset the mask bit once the short-circuited switch is restored; a mode discriminating part which receives the output from said short-circuited switch recovering element and determines whether a running mode or a gear-changing mode is established; a gear-changing mode determining element which is activated by the output from said mode discriminating is operative to determine, at least, whether the clutch is normal, whether the preceding gear position switch is closed, and whether said rotation speed is reasonable; a running mode determining element which is activated by the output from said mode discriminating element and is operative to determine, at least, whether the clutch is completely engaged, whether the desired gear position is neutral, and whether the desired gear position switch is closed; and a gear change confirmation element which responds to the output of said running mode determining element and said gear-changing mode determining element and is operative to, first, find a open-circuit switch of said gear position sensor, if the gear-changing determining element determines that the following conditions stand, i.e., said clutch is normal, said preceding gear position switch is closed, said desired gear position is neutral and, if said rotation speed is reasonable, when the desired gear position it not neutral and if the desired switch position switch is not the short-circuited switch, and alternatively, the gear change confirmation element is also operative to find said open-circuit switch, if said running mode determining element determines that the following conditions stand, i.e., said clutch is completely engaged, the desired gear position is not neutral, and the desired gear position switch is not closed, and next the gear change confirmation element is operative to backup, if said short-circuit or open-circuit switch is found to exist, the failed switch to still determine the completion of the gear change if said backup part finds the following conditions, i.e., the desired gear position switch is not closed, the desired gear position switch is the failed switch, the desired gear position is not neutral, and the rotation speed .alpha. is reasonable and, alternatively, if said backup element finds one of the conditions, i.e., the desired gear position switch is closed, and the desired gear position is neutral.

9. A system as set forth in claim 8, wherein whether or not said rotation speed .alpha. is reasonable is determined by taking into account said N/V ratio value and said automobile speed .beta..

10. A system as set forth in claim 9, wherein said mask bit is raised when two or more switches of said shift-side switches are closed simultaneously or two or more switches of said selection-side switches are closed simultaneously.