JPH03121959A - Braking force holding device - Google Patents

Abstract

PURPOSE:To detect a braking force releasing point correctly by detecting the inflection point of oil pressure caused by the operation of a clutch pedal, and setting a point, obtained by adding the constant clutch stroke quantity to this detected inflection point, as a braking force releasing point. CONSTITUTION:When abrasion is generated on a clutch plate 22, clutch play P between the lever 24 of a clutch pressure plate 23 and an operating part 25 is reduced, but when the operating part 25 touches the lever 24 (that is to be a point A) or the plate 23 is separated from the clutch plate 22 (that is to be a point B) at the time of operating the stepping-in or return of a clutch pedal 4, the oil pressure of a clutch booster 13 is inflected, and the stroke quantities S1, S2 from these clutch stroke inflection points to a braking force releasing point C become always constant. Accordingly, a control unit 15, upon detecting the oil pressure inflection point of the booster 13 from the output of an oil pressure sensor 13a, sets a point, obtained by adding the constant clutch stroke quantity to the detected inflection point, as a braking force releasing point, generates braking force, and when the clutch stroke reaches the braking force releasing point, deenergizes a solenoid check valve.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a braking force holding device, and more particularly to a device for smoothly and safely releasing the braking force of a vehicle equipped with a taranochi booster.

[Conventional technology]

When starting a vehicle stopped on a road, in conventional vehicles, the driver uses the parking brake (handbrake) with one hand to apply braking force to the vehicle and keep it at a stop, while gradually engaging the clutch. Depress the accelerator pedal. During this time, the parking brake is gradually loosened.

However, since complicated operations are required while coordinating the brake and accelerator, skill is required to perform a smooth start, which may result in so-called engine stalling or the vehicle moving backwards.

Therefore, in Japanese Patent Application No. 58-117483 (Japanese Unexamined Patent Publication No. 60-11719), the present applicant provided an electromagnetic check valve for braking between a mask cylinder and a wheel cylinder that cooperate with the brake pedal and the accelerator pedal. In order to use this electromagnetic check valve to smoothly start from a stopped state on a road, we use sensors such as an accelerator pedal sensor, clutch stroke sensor, engine rotation sensor, brake pedal switch, gear position switch, select position switch, and vehicle speed sensor. The electronic control unit inputs the output signals of the gear to the electronic control unit (CPLI). From these input signals, the electronic control unit determines that ■ the gear select position is not neutral, and ■ the vehicle speed is “'0”.
”, ■The end of the gear shift, ■The idle state of the engine, ■Depressing the foot brake, ■The release of the accelerator, and ■The amount of engagement of the clutch is less than the half-clutch state (
clutch disengagement), and only when all of these conditions (1) to (2) are satisfied, the electromagnetic check valve is energized to maintain the braking force at the wheel cylinder.

In addition, the braking force at the wheel cylinder is released when ■ the engagement amount of the clutch becomes larger than the half-clutch state (clutch engagement), or ■ when the gear is in the neutral position, or when the [phase] vehicle speed is set to the set vehicle speed. The electronic control unit determines that the accelerator pedal is being depressed at the above times and deenergizes the electromagnetic check valve.

However, with this braking force retention device, the braking force is released too quickly at the time of starting due to wear of the clutch driven plate, changes over time, and variations during assembly, which may cause the vehicle to back up on the uphill road, or cause the vehicle to slow down. This causes the brakes to drag.

Therefore, in Japanese Patent Application No. 62-94042 (Japanese Unexamined Patent Publication No. 63-25824), the present applicant further provided a variable resistor as a clutch connection determination adjustment element in the braking force holding device described in ``2'', and this variable resistor The electronic control device compares the set value and the actual clutch stroke, and deenergizes the electromagnetic check valve to release the braking force only when the clutch plate returns to the point where the latter becomes smaller than the former. .

[Problems to be Solved by the Invention] As described above, in the braking force retention device of Japanese Patent Application No. 62-94042, the clutch plate is worn out, causing the clutch to be in the half-clutch position.
In other words, since the braking force release point changes, manual adjustment using a variable resistor must be performed each time.Furthermore, this adjustment operation has the problem that the sense of the braking force release point varies slightly depending on each driver. was there.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a braking force holding device that can accurately detect the point at which the braking force is released without using a manual adjustment element.

[Means to solve the problem]

As a means for solving the above problems, a braking force holding device according to the present invention includes an electromagnetic check valve, a clutch booster driven by a clutch pedal, a hydraulic pressure sensor of the booster, a clutch stroke sensor, and a clutch booster driven by a clutch pedal. The inflection point of the oil pressure due to pedal operation is detected, and the point where a certain clutch stroke amount is added to the inflection point is set as the braking force release point, and the check valve is activated under predetermined conditions to generate braking force. and control means for deenergizing the check valve when the clutch stroke is reached.

[For production]

In the braking force holding device of the present invention, in vehicles such as large trucks that use a clutch booster (clutch booster) driven by a clutch pedal, by detecting the pressure of the clutch booster, This was done by taking advantage of the fact that pressure is difficult to apply within the clutch play range.

To explain this with reference to FIG. 5, when the clutch plate becomes worn, the clutch play P between the lever 24 of the clutch pressure plate 23 and the actuating part 25 will change as shown in FIG.
As shown in a) and the same figure (b), when this actuating part 25 hits the lever 24 when the clutch pedal 4 is depressed and released (point A) or from the clutch plate 22 to the pressure plate 23 is released (point B), the oil pressure of the clutch booster 13 is inflected, and the stroke is1. S2 is always constant ((b) in the same figure).

Therefore, when the control means detects the inflection point of the hydraulic pressure of the clutch booster due to the depression or return operation of the clutch pedal from the output of the oil pressure sensor, the control means controls the point obtained by adding the above-mentioned constant clutch stroke amount to this inflection point. After energizing the electromagnetic check valve to generate a braking force under known predetermined conditions, the electromagnetic reverse occurs when the clutch stroke detected by the clutch stroke sensor reaches this braking force release point. The upper valve is deenergized to release the braking force.

Thereby, the braking force release point due to wear of the clutch plate or the like can be automatically adjusted without using a manual adjustment element.

〔Example〕

FIG. 1 is a diagram showing the hardware configuration of an embodiment of the braking force holding device according to the present invention, and 1 is an accelerator switch that is turned on (contact connection) when the accelerator pedal 2 is released and turned off when the pedal is detected to be depressed. , 3 is a variable resistance type clutch stroke sensor that detects the stroke amount when the clutch pedal 4 is depressed, 5 is a parking (hand)
Parking brake switch 7 is turned on when the brake 6 is pulled to perform a braking operation, and 7 is a foot brake (stomp lamp) that is turned on when the brake pedal 8 is depressed.
Switch 9 is a neutral switch that turns on when the gear/neutral state of the transmission (T/M) 10 is detected;
11 is a speed changer [a vehicle speed sensor that detects the speed of the vehicle from the rotation of the output shaft 12 in 10; 13 is a clutch booster];
3 a is a hydraulic pressure sensor that detects the hydraulic pressure of the clutch booster 13; 14 is the clutch booster 13 and the clutch pedal 4;
14a is an air pressure sensor for the air tank 14; 15 is the switch 1, 5, 7.9, and sensor 3, 11.13a;
, 14a as a control means for inputting the detection signals of the controller 1.
When the brake unit 16 is deenergized by the output signal from the control unit 15, the hydraulic pressure 1- ] 7 +
> The brake oil sent to the wheel brake 18 through route +7b is reversed to release the braking force, and when it is energized, the hydraulic route 1.7a,! :Both are electromagnetic check valves for braking that prevent backflow of control oil and maintain braking force. In addition, sensor 3. The output signals of +3a and 14a are once A/D converted at the entrance of the control unit 15, as in normal analog signal processing, and then used for control.

FIGS. 2 and 3 are flowcharts of programs stored in advance in the control unit 15, and the operation of the embodiment of the present invention will be described with reference to these flowcharts.

First, in the flowchart of FIG. 2, the control unit 15 checks whether the air pressure in the air tank 14 is at a normal pressure sufficient to drive the clutch booster 3 (step 521 in FIG. 2).

If the pressure is lower than the normal pressure, the clutch booster 3 will not operate normally, so proceed to the flowchart in Figure 3. If the pressure is normal, when the clutch pedal 4 is depressed, the hydraulic pressure in the master cylinder of the clutch booster 3 will be reduced. An inflection point A that suddenly changes greatly is detected by the taratch stroke sensor 3 (step 522). This corresponds to the play stroke P of the clutch as shown in FIG.

To explain this more specifically using FIG. 5, when the clutch pedal 4 is depressed, hydraulic oil 28 is sent to the clutch booster 13, and air pressure proportional to this hydraulic pressure is sent from the air tank 14 to the clutch booster J3. and redouble it,
The lever 26 operates the actuating portion 25 via the link mechanism 27 .

This actuating portion 25 moves to the right in the figure and comes into contact with the lever 24 after passing the clutch play P, but the inflection point at which the hydraulic fluid 28 changes at this time corresponds to point 8.

If the actuating portion 25 continues to move as it is, the clutch pressure plate 23 will no longer be completely connected to the clutch plate 22 and flywheel 21, resulting in a lack of engine power. This is inflection point B
is equivalent to

However, it is not appropriate to release the braking force at this inflection point B, and furthermore, as shown in Fig. 4, point C, which has moved from inflection point B to the clutch disengaged side by a certain stroke amount, reduces the engine power. It is preferable to release the braking force as the point at which the transmission starts.

Further, the stroke amount S2 between the braking force release point C and the inflection point B or A. Sl is always constant. Because,
This is because the amount of wear on the clutch has been absorbed by the reduction in clutch play P.

Therefore, the stroke amounts Sl, S are determined in advance through experiments or the like.
By calculating 2 and adding it to the stroke value SA or SR at the inflection point A or B calculated as above, the braking force release point C can be set (step 523).
.

Normally, when starting to drive a vehicle, the franchise pedal 4 is operated in a new manner, so the initial braking force release point C is unknown. S□□ can be effectively obtained after the clutch pedal 4 is connected.

After the above steps, the normal braking force holding/release control shown in FIG. 3J is executed. Note that this control can use the well-known control already disclosed in the above-mentioned publication, but in the present invention, as described below, steps S2 and S
The difference is that the stroke value 5T11 for releasing the braking force described above is used in ll.

In Figure 3, the control console I4 first checks whether the accelerator pedal 2 is not depressed and is released, and the accelerator switch (SW) I is in the on state. (Step Sl in Figure 3).

When it is determined that the clutch is on, the clutch operation is checked (step S2). That is, the stroke is determined by comparing the A/D converted value of the resistance value of the flange stroke sensor 3 that detects the stroke (■) of the clutch pedal 4 with the braking force release stroke value STI+ obtained in step S23 in FIG. The value of sensor 3 is the braking force release value S71. When it is larger than , it is determined that the clutch is in the "disengaged" state.

In this step S2, the gear may be in the neutral position regardless of the position of the clutch, and therefore the neutral switch 9 may be on.

When it is determined in step S2 that the vehicle is not driven, it is checked whether the brake pedal 8 is depressed and the foot brake switch 7 is turned on (step S3).

When the brake pedal is depressed, the parking brake 6 is pulled and the parking brake switch 5
It is preferable to check whether or not it is turned off (step 34). This is because the parking brake generates braking force using a completely different system, and when the driver pulls the parking brake halfway,
On the other hand, if the wheel brake is applied by the foot brake, there is a risk that the holding pressure will drop due to valve leakage of the check valve 14, and the braking state will collapse. Therefore, when the parking brake 6 is not applied and the parking brake switch 5 is off, the braking is permitted and the process proceeds to step S5.

In step S5, it is checked whether the vehicle speed signal (pulse signal) from the vehicle speed sensor 11 indicates a predetermined speed V or less (step S5).

In this case, the predetermined speed means that the vehicle speed sensor 11 is at a speed of °'0
Since it is not possible to detect "," a speed that can be or is close to "'0" is used.

When the vehicle speed approaches "0", that is, when the vehicle is almost at a standstill, it is preferable to check whether the vehicle speed has further fallen below a predetermined deceleration (step S6). ). This is because when the vehicle is running in rain or snow, if the brakes are applied, the tires will continue to slide, resulting in a boiling wheel condition, and it is dangerous to maintain this braked condition.

After this, it is diagnosed whether there is any abnormality in the vehicle speed sensor 11 (step S7). This is the H level (for example, 14■) and L level of the pulse signal normally generated by the vehicle speed sensor.
When a pulse other than the intermediate level (for example, 2V) is generated, it is determined that the sensor is abnormal.

When all of the braking permissible states in steps 31-37 are satisfied, it is preferable to check whether this state continues for a certain period of time (step S8 in the same step).
). This certain period of time means a common sense delay time (grace) in order to assume that the driver intends to maintain the braking force. Further, if this duration time is determined in step S5 by using another delay time in which the vehicle is considered to have stopped, a more accurate determination can be made.

After a certain period of time has elapsed in this way, the control unit yt□ 15 generates a signal for energizing the braking electromagnetic check valve 16 (step 39).

Through the processing up to this point, the braking force is applied and the vehicle comes to a stop.

Next, when starting the vehicle, the accelerator pedal 2 must be fully engaged and the engine must be able to drive the vehicle, so the accelerator pedal must be depressed. If the switch 1 is off, the process advances from step S1 to step Sll, where it is determined that the new I-ral switch 9 is not in the neutral position, and is therefore off, and the clutch pedal 4 is returned to switch to that shift II-
If it is detected that the brake force is smaller than the braking force release value 37M in step S23 in FIG. Checked the time 1- (same step 31)
0), after this duration elapses, the braking electromagnetic check valve 16
step 512) to de-energize and release the holding of the braking force.
Be prepared for 0 departures and 1 departure.

Even if the accelerator pedal 2 is not depressed, 2j, -
The tral switch 9 is not in the nib-1-ral position and is therefore off, and the clutch pedal 4 is returned so that the stroke amount becomes smaller than the braking force release value STH in step S23 in FIG. If it is detected that the vehicle is running, the check valve 1G is deenergized, the braking force is released, and the vehicle prepares for departure.

In this step as well, it is preferable to set a certain duration time (delay time when it is assumed that the transmission 10 is not in the neutral mode and a delay time when it is assumed that there is an intention to start) and make the determination. Step 510).

5 That is, at least the clutch stroke is equal to the braking force release value S
If the gear is not in the neutral state, the braking force will be released.

Finally, if the parking brake 6 is pulled in step S4 and the parking brake switch 5 is turned on, the process proceeds to step 310 as in the case of the accelerator switch 1, and it is assumed that the parking brake 6 has been applied. It is preferable to change the duration of the process.

〔Effect of the invention〕

As described above, the braking force retention device of the present invention detects the inflection point of the hydraulic pressure of the clutch booster due to the operation of the clutch and tire, and calculates the braking force by adding a certain amount of clutch and notch stroke to this inflection point. Since the check valve is deenergized when the clutch stroke reaches the release point, the braking force can be automatically released even if the clutch plate is worn out.

[Brief explanation of drawings]

FIG. 1 is a hardware configuration diagram showing one embodiment of the braking force holding device according to the present invention. FIG. 2 is a flowchart 1 of a program stored and executed in the control I-roll unit of the present invention. 1.1-Charts 1 to 4 of the program for normal braking force retention/release control stored in the control unit of the present invention and executed, FIG. 5 is a graph showing the relationship between the oil pressure of the clutch and the clutch stroke used in the present invention and the clutch stroke. FIG. 5 is a configuration diagram showing the relationship between the clutch booster and the clutch mechanism used in the present invention. In Fig. 1, 3 is a flanch stroke sensor;
13a is a clutch booster, 13a is an oil pressure sensor, I5 is a controller 1 to a roll unit, and 16 is an electromagnetic check valve for ff++]iJ+, respectively. In the figure, the same reference numerals indicate the same or opposite numbers.

Claims (1)

[Claims] An electromagnetic check valve, a clutch booster driven by a clutch pedal, a hydraulic pressure sensor of the booster, a clutch stroke sensor, detecting an inflection point of the hydraulic pressure due to operation of the clutch pedal, and detecting a constant pressure at the inflection point. a control means that sets a point where the clutch stroke amount is applied as a braking force release point, energizes the check valve under predetermined conditions to generate a braking force, and deenergizes the check valve when the clutch stroke is reached; ,
A braking force retention device characterized by comprising: