JPS62242859A - Judging device for fault of vehicle speed sensor - Google Patents

Abstract

PURPOSE:To securely judge the fault of a vehicle speed sensor at any time by deciding variation in the level of a vehicle speed signal in response to a run decision signal generated when it is decided that a vehicle is in a run state. CONSTITUTION:The vehicle is provided with a control means 1 consisting of the vehicle speed sensor 1a which detects the vehicle speed of the vehicle and generates the vehicle speed signal of frequency proportional to the detection result and a microcomputer which controls a controlled system mounted on the vehicle according to the vehicle speed signal. Then, the microcomputer further has a run state deciding means 2 and a fault deciding means 3. The run state deciding means 2 decides whether or not the vehicle is in the run state by receiving a signal from an automatic parking brake system, etc., and generates the run decision signal when deciding that the vehicle is in the run state. The fault deciding means 3, on the other hand, decides variation in the level of the vehicle speed signal in response to the run decision signal and generates a fault decision signal indicating the fault of the vehicle speed sensor 1a when it is decided continuously for a specific time that there is no level variation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicle speed sensor failure determination device that is used to determine failure of a vehicle speed sensor.

[Prior art]

Conventionally, in this type of vehicle speed sensor failure determination device, there is one that detects a disconnection when the vehicle speed sensor is disconnected, as disclosed in, for example, Japanese Utility Model Application Publication No. 59-54360.

[Means for solving problems]

However, in such a configuration, when detecting a disconnection of the vehicle speed sensor, a disconnection reference voltage that can be detected only when the disconnection occurs is applied to the output terminal of the vehicle speed sensor, and this disconnection reference voltage is detected when the disconnection occurs. Therefore, if the vehicle speed sensor fails due to a cause other than a disconnection, such as a short circuit or a mechanical factor, it cannot be detected.

Therefore, in order to cope with this problem, the present invention provides a vehicle speed sensor failure determination device that always reliably determines the failure of the vehicle speed sensor, regardless of the cause of the failure of the vehicle speed sensor. This is what I am trying to do.

[Means for solving problems]

In solving this problem, the structural features of the present invention are as follows:
As illustrated in FIG. 1, it has a vehicle speed sensor 1a that detects the vehicle speed and generates a vehicle speed signal at a frequency proportional to the detection result, and controls a controlled object mounted on the vehicle in accordance with the vehicle speed signal. In a vehicle equipped with a control means l for controlling, a driving state determining means 2 for determining whether or not the vehicle is in a driving state and generating a driving determination signal when it is determined that the vehicle is in a driving state, and responding to the driving determination signal. A failure determination means 3 is provided which determines the level change of the vehicle speed signal and generates a failure determination signal indicating a failure of the vehicle speed sensor 1a when the determination that there is no level change continues for a predetermined time.

[Effect]

By configuring the present invention in this way, when determining the running state of the vehicle, a state in which the level change of the vehicle speed signal should be repeated is identified as a normal state, and when determining the running state, the level of the vehicle speed signal is determined. The presence or absence of a change is monitored for a predetermined period of time, and when it is determined that there is no change in the level, the vehicle speed sensor 1a
This has been determined to be a malfunction. For this reason, the vehicle speed sensor la
Not only disconnection failures, but also all failures such as short-circuit failures and mechanical failures can always be determined in a timely and reliable manner, and as a result, necessary measures can be taken immediately after such failures are determined.

〔Example〕

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.
The figure shows an example in which the present invention is applied to an automatic parking brake system for a vehicle equipped with an automatic transmission (not shown). 10, and an electric control circuit 30 that controls the electric mechanism 20. The parking brake mechanism IO has a parking lever 11, and this parking lever 11 is
It is pivotably supported by a horizontal shaft 11a on a floor surface near the console box in the cabin of the vehicle so as to be tiltable in the vertical direction.

A horizontal shaft 11a is attached to the base end of the parking lever 11 so that the pulley 12 integrally interlocks with the parking lever 11.
On the other hand, a cylindrical handle 13 is fixed to the tip of the parking lever 11. The handle 13 has a knob 13a.
is pushed into the hollow part of the handle 13 against a coil spring (not shown) (provided in the hollow part of the handle 13) to move a release lever (not shown) rotatably attached to the parking lever 11. The bracket is separated from the engaging part (not shown) that is fixed to the floor surface. When the knob 13a is opened, it is urged outward by the coil spring to engage the release lever with the engaging portion of the bracket, thereby maintaining the parking lever 11 unrotatable in the control release direction.

The cable 14a is wound around the outer periphery of the pulley 12, and one end of the cable 14a is connected to a bolt 12b fitted inside the metal fitting 12a of the pulley 12, while the cable 14a is The other end of 14a is connected to the center of equalizer 15. Accordingly, the cable 14a moves the equalizer 15 to the left in FIG. 2 in response to the rotation of the pulley 12 in the clockwise direction in FIG. Accordingly, the equalizer 15 is allowed to move to the right. equalizer 15
connects both rear wheels Wl of the vehicle via respective rear cables 16a, 16b at both ends thereof.

It is connected to each brake shoe of Wr, and its left movement pulls both rear cables 16a, 16b to the left, while its right movement allows right movement of both rear cables 16a, 16b. Note that both rear wheels WJ and Wr are braked by the respective brake shoes in response to the leftward tensile force of both rear cables 16a and 16b.
The braking is released by each of the brake shoes when the leftward pulling force of 6a and 16b disappears. Further, in FIG. 2, the reference numeral 12c indicates a position adjustment nut for the pole 1-12b.

The electric mechanism 20 includes a rotary electric motor 21, a speed reducer 22, and a boot IJ23. And the forward rotation (or reverse rotation) of this worm
The pulley 23 is integrally and rotatably supported by a rotation shaft 22a of the worm wheel. A cable 14b extending from the equalizer 15 in the same direction as the cable 14a is wound around the outer periphery of the pulley 23 and connected to a part of the pulley 23 at its outer end.

Therefore, the pulley 23 rotates in the normal direction, causing the cable 14 to
b is wound and pulled to the left of the equalizer 15 in FIG.

The electric control circuit 30 includes a vehicle speed sensor 31, a shift switch 32, an accelerator switch 33, both brake switches 34 and 35, a release switch 36, a DC power source 81, an ignition switch 1G of the vehicle, and a vehicle speed sensor 31.
and a microcomputer 37 connected to each of the switches 32 to 36, and the ignition switch IG generates a closing signal when the ignition switch IG is closed. The vehicle speed sensor 31 is composed of a magnetic disc that rotates in conjunction with the output shaft of the automatic transmission, and a reed switch disposed near the magnetic disc. In this vehicle speed sensor 31, when the magnetic disk rotates, the reed switch magnetically detects each protrusion of the magnetic disk and closes them intermittently in proportion to the vehicle speed. generates a series of vehicle speed pulses with a frequency of The shift switch 7 32 closes and generates a shift signal in response to a shift operation of the automatic transmission to a drive range or a reverse range, and responds to a shift operation of the automatic transmission to a neutral range or a parking range. The shift signal is then opened and the shift signal disappears.

The accelerator switch 33 closes in response to depression of the accelerator pedal of the vehicle to generate an accelerator signal, and opens in response to release of the accelerator pedal to eliminate the accelerator signal. The brake switch 34 closes in response to depression of the foot brake pedal of the vehicle to generate a foot brake signal, and opens and disappears the foot brake signal in response to release of the foot brake pedal. The brake switch 35 closes when the parking lever 11 is tilted upward to generate a parking brake signal, and opens and eliminates this parking brake signal when the parking lever 11 completes the downward tilting.

The release switch 36 closes and generates a release signal when the braking by the electric mechanism 20 is released, and
When the braking force is generated based on the operation of 0, it opens and eliminates the release signal. Note that each of the switches 32 to 36 is of a normally open type.

The microcomputer 37 is constantly in operation by being supplied with power from the DC power supply B, and repeatedly executes a computer program stored therein in accordance with the flowchart shown in FIG. As stated above, various calculation processes are performed that are necessary to determine whether the vehicle speed sensor 31 is malfunctioning and to control the rotary electric motor 21 and the pilot lamp L. The pilot lamp L is controlled by the microcomputer 37. The failure (or non-failure) of the vehicle speed sensor 31 is indicated by blinking (or turning off).

In this embodiment configured as above, if the ignition switch IC is closed while the vehicle is stopped,
When the computer program whose execution has been started in step 40 proceeds to step 41 according to the flowchart in FIG. 3, the microcomputer 37 determines "YESJ" based on the closing signal from the ignition switch IG. When the driver shifts the automatic transmission to the drive range or the reverse range and depresses the accelerator pedal while repeating the "NO" determination, the microcomputer 37 causes the shift switch 32 to shift in step 42. rYEsJ is determined based on the shift signal generated from the accelerator switch 33 and the accelerator signal generated from the accelerator switch 33, and step 42
At step a, a reversal signal necessary to reverse the rotary electric motor 21 is generated. Then, during the repetition of the determination with rNOJ in step 43, the rotary electric motor 21 is reversed in response to the reverse rotation signal from the microcomputer 37, and the speed reducer 22 is accordingly reversed, and both cables 14a,
14b, equalizer 15 and both rear cables 16a, 1
6b is moved to the right by the elastic action of the coil springs of both brake shoes and releases the braking action on both rear wheels Wl and Wr. Then, when a release signal is generated from the release switch 36, the microcomputer 37 performs step 4.
At step 3, it is determined that rYEsJ is present, and at step 43a, the electric mechanism 20 is stopped when the reverse rotation signal disappears.

However, at this stage, [YESJ
Since both the foot brake signal from the brake switch 34 and the parking brake signal from the parking brake switch 35 disappear after this determination, the microcomputer 37 determines in step 44 that the vehicle is released from the braking state. Based on the judgment that “N
O”, and in step 45, the shift switch 32 is
Based on the shift signal from , it is determined that it is rYEsJ.

In such a state, if there is a level change in the vehicle speed pulse from the starting vehicle speed sensor 31 of the vehicle, the microcomputer 37 determines YESJ in step 46 based on the determination that a vehicle speed pulse has occurred. Thereafter, the cyclic calculations of steps 44, 45 and 46 are repeated, and the vehicle is placed in a running state.

In this state, if the foot brake pedal is depressed to stop the vehicle, the microcomputer 37 determines rYEsJ based on the foot brake signal generated from the brake switch 34 in step 44. Then, when the vehicle speed of the vehicle becomes equal to or less than the set vehicle speed value V during the repetition of the determination with rNOJ in step 47,
In step 47, the microcomputer 37 determines that rYEsJ is generated under the generation of the foot brake signal from the brake switch 34, and in step 47a, the microcomputer 37 outputs a normal rotation signal necessary for normal rotation of the rotating electric motor 21 for 11 seconds (for example,
1 second) occurs. Then, the rotation mll! 21 rotates in the normal direction for t1 seconds in response to the normal rotation signal from the microcomputer 37. In response, the reducer 22 rotates in the normal direction, the pulley 23 rotates in the normal direction, and the equalizer 15 and both rear cables 16a, 16b are connected by the cable 14b. To the left, both rear wheels W1
, Wr are placed in a braking state. Note that the set vehicle speed value ■ is determined by the microcomputer 37 as indicating that the vehicle is stopped.
is stored in advance in the ROM.

By the way, in the above-described operation, when the determination in step 46 is rNOJ, the microcomputer 37 determines "rYES" in step 48 based on the reset state of the timer in step 49a, and the microcomputer 37 determines "rYES" in step 48.
The timer is started at a. This causes the timer to start timing. However, in step 48, the symbol T represents the time value of the timer. Therefore, the microcomputer 37 determines "NO" in the next step 49 based on the fact that the timer has just started counting.

After that, the determination is "NO" in step 44, the determination is rYEsJ in step 45, the determination is "NO" in step 46, and the determination is "NO" in step 48.
” and rNOJ in step 49 are being repeated, if the timer value T exceeds the predetermined time value TO, the microcomputer 37 determines rYEsJ in step 49, In step 49a, the timer is reset, and in step 49b, a blinking signal necessary for repeating the blinking of the pilot lamp L is generated, and in response to this, the pilot lamp L repeats the blinking, provided that a predetermined time value TO corresponds to the permissible limit time (for example, 5 seconds) for which the level of the vehicle speed pulse remains unchanged for identifying an abnormality such as a short-circuit failure of the vehicle speed sensor 31, and is stored in the ROM of the microcomputer 37 in advance.

In other words, when both the determination as rNOJ in step 44 and the determination as rYEsJ in step 45 are established, the time value T of the timer reaches the predetermined time value TO after the first determination of "NO" in step 46. When the level of the vehicle speed pulse from the vehicle speed sensor 31 continues to remain unchanged until the vehicle speed exceeds the predetermined time value, it is determined in step 49 that it is rYEsJ. The pilot lamp L will blink when To elapses, and as a result,
The driver can recognize that an abnormality such as a short-circuit failure has occurred in the vehicle speed sensor 31. Further, after the flashing signal is generated in step 49b as described above, the microcomputer 37 repeats the determination as rYEsJ based on the closing signal from the ignition switch IC in step 49c, and then automatically controls the automatic parking brake system. make it impossible. This means that malfunction of the parking brake system after a failure of the vehicle speed sensor 31 is prevented.

Further, in the embodiment, in step 44, "
An example has been described in which the computer program proceeds to step 46 when both the determination "NO" and the determination rYESJ in step 45 are satisfied, but instead of this, the determination "NO" in step 44 and the determination "rYESJ" in step 45 are made. The computer program may be made to proceed to step 46 after determining whether the accelerator signal is rYESJ and whether or not the accelerator signal is generated from the accelerator switch 33.

Further, in the above embodiment, an example in which the present invention is applied to an automatic parking brake system for a vehicle equipped with an automatic transmission device has been described, but instead of this, an example in which the present invention is applied to an automatic parking brake system for a vehicle equipped with an automatic transmission device is described. The present invention may be modified to be applied to an automatic parking brake system. Therefore, in this modification, as shown in FIG. 4, a normally open shift switch 38 is adopted in place of the shift switch 32 in the above embodiment, and is closed when the manual transmission is shifted to the travel shift position. A normally open clutch signal notch 39 is provided on the clutch pedal of the vehicle and closes when the clutch pedal is released to generate a clutch signal, and the flowchart described in the above embodiment (See FIG. 3) is shown in the flowchart of FIG. 5 (partially changed).The other configurations are the same as those of the previous embodiment.

In this modified example configured in this way, after the determination from rYESJ in step 41 (see FIGS. 3 and 5), the determination from rNOJ is performed in step 42b (see FIG. 5), as in the case of the previous embodiment. During the repetition of
When the driver shifts the manual transmission to the travel shift position and depresses the accelerator pedal, the microcomputer 37 in step 42b outputs a shift signal generated from the shift switch 38 and the accelerator switch 3.
Based on the accelerator signal generated from 3, it is determined that it is rYESJ,
The computer program proceeds to step 42a (see FIGS. 3 and 5).

However, if the clutch signal is generated from the clutch switch 39 due to the release of the clutch pedal, the microcomputer 37 determines rYESJ in step 44a, and determines YESJ based on the shift signal from the shift switch 38 in step 45a. In this case, the computer program is advanced to step 46 and thereafter to achieve substantially the same effect as in the embodiment described above.In such a case, step 4
The discrimination from rYESJ in step 4a and the discrimination from rYEsJ in step 45a are the same as rNO in the above embodiment.
This corresponds to the determination with J and the determination with rYEsJ in step 45, respectively. Note that step 44b in FIG. 5 corresponds to step 44 in the embodiment described above.

In addition, in carrying out the present invention, the pilot lamp L
Instead, a voice synthesizer may be used instead of various indicators to indicate the failure of the vehicle speed sensor 31.

Further, in the embodiment and its modification examples, the vehicle speed sensor has been described as being composed of a magnetic disk and a reed switch, but instead of this, for example, the vehicle speed A sensor may also be configured.

Furthermore, in the above embodiments and variations thereof, the present invention is applied to an automatic parking brake system. The present invention may be applied to various control devices having the following embodiments.

[Brief explanation of drawings]

FIG. 1 is a diagram corresponding to the structure of the invention described in the claims, FIG. 2 is an overall configuration diagram showing an embodiment of the present invention, and FIG. 3 is a flowchart showing the operation of the microcomputer in FIG. 2. FIG. 4 is a block diagram of main parts showing a modification of the embodiment, and FIG. 5 is a flowchart showing the operation of the microcomputer in the modification. Explanation of symbols 10... Parking brake mechanism, 20... Drive mechanism, 21... Rotating electric motor, 3o... Electric control circuit,
31... Vehicle speed sensor, 32.38... Shift switch, 33... Accelerator switch, 34.35... Pre-kiss inch, 37... Microcomputer.

Claims (1)

[Claims] A vehicle comprising a vehicle speed sensor that detects the vehicle speed of the vehicle and generates a vehicle speed signal at a frequency proportional to the detection result, and a control means that controls a controlled object mounted on the vehicle in accordance with the vehicle speed signal, a driving state determining means for determining whether or not the vehicle is in a traveling state and generating a traveling determination signal when determining whether the vehicle is in a traveling state; and determining a level change of the vehicle speed signal in response to the traveling determination signal; A vehicle speed sensor failure determination device comprising: failure determination means for generating a failure determination signal indicating a failure of the vehicle speed sensor when the determination that there is no level change continues for a predetermined period of time.