JPH0632217A - Brake boosting characteristic control device of vehicle loaded with automatic transmission - Google Patents

Abstract

PURPOSE:To obtain favorable brake feeling equal to that during the ordinary operation in the stopping state where large driving torque is generated in a brake boosting characteristic control device of a vehicle loaded with an automatic transmission including a torque converter. CONSTITUTION:A brake boosting characteristic control device comprises a brake booster (b), the brake boosting characteristic of which can be changed at least in two stages according to an instruction to an actuator (a), a car speed detecting means (c) for detecting the car speed, a driving torque detecting means for detecting the driving torque, and a brake boosting characteristic control means (e) for outputting an instruction for changing to the brake boosting characteristic having a higher liquid pressure increasing gain for the pedal effort than that of the ordinary operation when a vehicle is in the stopping to crawling speed region and designated driving torque is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake boosting characteristic control device for a vehicle equipped with an automatic transmission having a torque converter.

[0002]

2. Description of the Related Art Conventionally, as a negative pressure type tandem type brake booster, for example, one disclosed in Japanese Patent Laid-Open No. 1-212659 is known.

The above-mentioned conventional source shows a tandem brake booster which assists the pedaling force by utilizing the differential pressure between the intake negative pressure of the engine and the atmospheric pressure.

[0004]

However, in the above-mentioned conventional apparatus, even if the vehicle is in any operating state,
A unique brake boosting characteristic is given, and the brake boosting characteristic is set to a constant brake boosting characteristic with respect to an increase in pedal effort in order to obtain a good brake feeling during normal driving. Therefore, for example, in a vehicle equipped with an automatic transmission having a torque converter,
In the stop to very low speed range, when a large creep torque is generated in the torque converter due to engine idling rotation (when the engine speed increases, for example, when the engine is cold or when the cooler compressor is operating), it is particularly remarkable.
At the time of braking, a large pedal effort is required to counteract this drive torque, and the brake feel deteriorates.

The present invention has been made in view of the above problems. In a brake boosting characteristic control device for a vehicle equipped with an automatic transmission having a torque converter, the brake boosting characteristic control device is normally operated when a large driving torque is generated. The challenge is to obtain a good brake feeling that is equivalent to the time.

[0006]

In order to solve the above problems, a brake booster characteristic control device for a vehicle equipped with an automatic transmission according to the present invention uses a brake booster capable of changing the brake booster characteristic to generate a large driving torque. When the vehicle is in a stopped state, a means for changing to a brake boosting characteristic in which the hydraulic pressure increase gain is higher with respect to the pedal depression force than in the normal state.

That is, in the first invention, as shown in the claim correspondence diagram of FIG. 1, a brake booster b whose brake boosting characteristic can be changed in at least two steps by a command to the actuator a and a vehicle speed detecting means c for detecting the vehicle speed. And a brake boosting characteristic control means e for outputting to the actuator a command to change to a brake boosting characteristic having a higher hydraulic pressure increase gain with respect to the pedaling force than when the vehicle is stopped to a very low speed range. It is characterized by having.

Further, in the second invention, as shown in the claim correspondence diagram of FIG. 2, a brake booster b whose brake boosting characteristic can be changed in at least two steps by a command to the actuator a, and a vehicle speed detecting means for detecting the vehicle speed. c, drive torque detecting means d for detecting drive torque, and the vehicle is stopped
When a predetermined driving torque is detected in a very low speed range, a brake boosting characteristic control means (e) for outputting to the actuator a command for changing to a brake boosting characteristic having a higher hydraulic pressure increase gain with respect to the pedaling force than in a normal state is provided. It is characterized by

[0009]

When the vehicle speed detecting means c detects the stop of the vehicle to a slight speed, the brake boosting characteristic control means e
A command for changing to a brake boosting characteristic in which the hydraulic pressure increase gain is higher with respect to the pedal effort than usual is output to the actuator a.

On the other hand, creep torque is generated in the torque converter due to engine idling rotation, and this torque acts on the drive wheels.

In the first aspect of the present invention, when the brake operation is performed in this state, when the brake boosting characteristic is constant, a large pedal depression force is required by an amount corresponding to the increase of the driving torque due to the creep torque acting on the driving wheels. The increased driving torque is compensated by the increase in the braking torque due to the change in the brake boosted characteristic to the brake boosted characteristic having a high hydraulic pressure increase gain.

In the second aspect of the invention, for example, when the engine idling speed is increased and the engine is in a cold state, the vehicle speed detecting means c detects the stop of the vehicle to a very low speed, and the driving torque detecting means d detects a predetermined driving torque. Then, the brake boosting characteristic control means e outputs to the actuator a a command to change to a brake boosting characteristic in which the hydraulic pressure increase gain is higher with respect to the pedal depression force than in the normal state.

On the other hand, as the engine idling speed increases, the creep torque increases in the torque converter, and this torque acts on the drive wheels.

When the brake operation is performed in this state, if the brake boosting characteristic is constant, a large pedaling force is required for the driving torque increase due to the increase in idling speed acting on the drive wheels, but the brake boosting of the brake booster b is increased. The increased driving torque is compensated by the increase in the braking torque due to the change in the force characteristic to the brake boosting characteristic having a high hydraulic pressure increase gain.

Therefore, even when the idling speed is increased, the brake pedal can be depressed by the same pedal depression force as in the normal idling rotation, so that the brake can be activated and the vehicle can be stopped.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

First, the structure will be described.

FIG. 3 is an overall system diagram of a brake boosting characteristic control device for a vehicle equipped with an automatic transmission according to an embodiment of the present invention. The device of the embodiment is a torple type brake booster 1 (corresponding to a brake booster) and a vehicle speed sensor. It has (corresponding to vehicle speed detecting means) 2, an engine idling control unit 3, an inhibitor switch 4 (3 and 4 correspond to driving torque detecting means), and a control unit 5 (corresponding to brake boosting control means).

The torple type brake booster 1 has a first center plate 11 and a second center plate 12 inside a main body 10 formed of a first shell 6, a second shell 7, a third shell 8 and a fourth shell 9. It is divided into three parts.

The front chamber is a first chamber with a diaphragm 13.
A first negative pressure chamber 15 and a first atmosphere chamber 16 are defined by the power piston 14, and a second power piston 18 having a diaphragm 17 defines a middle chamber in the second negative pressure chamber 19 and a second atmosphere chamber 20. And the rear chamber is a diaphragm 2
The third power piston 22 provided with the third negative pressure chamber 2
3 and a third atmosphere chamber 24.

Further, the second shell 7 is provided with a negative pressure introducing pipe 25 for connecting a negative pressure source such as an intake manifold or a vacuum pump (not shown) to the second negative pressure chamber 19.

Reference numeral 26 is a valve body, to the tip of which an output shaft 27 is connected. The first, second, and third power pistons 14, 18, 22 are attached to the valve body 26, and the first and second center plates 11, 1 are attached.
2 is fitted to the valve body 26 via seal members 28 and 29.

A return spring 30 is interposed between the first shell 6 and the valve body 26, and the first, second and third power pistons 1 are connected via the valve body 26.
4, 18 and 22 are always biased rearward.

A plunger 31 is slidably fitted in the valve body 26, a reaction disc 32 is interposed between one end of the plunger 31 and the output shaft 27, and the other end of the plunger 31 is attached. The operation rod 33 is connected. A brake pedal (not shown) is connected to the operation rod 33.

Reference numeral 34 is an atmosphere valve, and when the atmosphere valve 34 is opened by advancing the operating rod 33 by depressing the brake pedal, the atmosphere is introduced into the third atmosphere chamber 24.

Reference numeral 35 denotes a vacuum valve, which is moved backward when the plunger 31 is released by depressing the brake pedal.
Is opened, the atmosphere chambers 16, 20, 24 communicate with the negative pressure chambers 15, 19, 23, and the return springs 30 cause the power pistons 14, 18, 22 to return to their original positions. ing.

The valve body 26 is formed with a passage 36 which communicates the inside of the valve body 26 with the third negative pressure chamber 23 and a passage 37 which communicates with the third atmosphere chamber 24.

Further, the valve body 26 has a passage 3 for connecting the second negative pressure chamber 19 to the first and third negative pressure chambers 15 and 23.
8, 39, and a passage 40 that connects the second atmosphere chamber 20 and the third atmosphere chamber 24 is formed.

The first atmosphere chamber 16 and the second atmosphere chamber 20 are provided with ports 41 and 42, respectively, and these ports 41 and 42 are connected by a control valve 43 so that they can communicate with each other and can be shut off. The control valve 43 corresponds to the actuator of the present invention.

The control unit 5 controls connection and disconnection of the control valve 43. When the engine idling control unit 3 outputs an engine idling up signal, the vehicle speed sensor 2 outputs a signal below a predetermined speed, and the inhibitor switch 4 outputs a signal other than the neutral range, the control unit 5 outputs the signal to the port 41. The control valve 43 sends a command to communicate with the port 42.
Configured to output to.

Next, the operation will be described.

FIG. 4 is a flow chart showing the flow of the brake boosting characteristic control operation performed by the control unit of the embodiment apparatus, and each step will be described below.

In step 101, it is judged whether the engine idling control unit 3 outputs an engine idling up signal.

In step 102, it is determined whether the vehicle speed V from the vehicle speed sensor 2 is less than or equal to a preset value V _O.

At step 103, it is judged if the select range position signal from the inhibitor switch 4 is a signal other than the neutral range signal.

At step 104, an ON command for connecting the ports 41 and 42 is output to the control valve 43.

In step 105, the control valve 4 is currently
It is determined whether the signal to 3 is ON.

At step 106, it is judged if the brake stop lamp switch 44 is ON indicating a brake operation.

In step 107, an OFF command for shutting off the ports 41 and 42 is output to the control valve 43.

(B) Normal engine idle-up is not performed When the vehicle is stopped or running, the process proceeds to step 101 → step 105 → step 107, and when the engine is idle-up, the vehicle speed is equal to or higher than the set value V _O. When traveling, the process proceeds from step 101 to step 102 to step 107, and the vehicle is stopped when the engine idling up.
When the automatic transmission is in the neutral range at a slight speed, the process proceeds to step 101 → step 102 → step 103 → step 107, and in any case, at step 107, the control unit 5 transfers to the control valve 43. The signal is turned off and the ports 41 and 42 are shut off.

At this normal time, before the brake is actuated,
Negative pressure from the intake manifold is introduced into the second negative pressure chamber 19 via the negative pressure introducing pipe 25, and this negative pressure is passed through the passage 3
It is also introduced into the first negative pressure chamber 15 and the third negative pressure chamber 23 via 8, 39, and the first, second, third negative pressure chambers 15, 19, 23 are in a negative pressure state.

Therefore, when a brake pedal (not shown) is depressed, the operating rod 32 advances and the atmosphere valve 34 opens, and the atmosphere is introduced into the third atmosphere chamber 24 through the passage 37, and this atmosphere further passes through the passage 40. Through the second atmosphere chamber 2
Introduced to zero.

As a result, a differential pressure is generated between the second negative pressure chamber 19 and the second atmospheric chamber 20, and between the third negative pressure chamber 23 and the third atmospheric chamber 24, and the second power piston 18 and the third power chamber Since the piston 22 moves forward, the valve body 26 can move forward with a large force, and the force is transmitted to the output shaft 27.

That is, the first power piston 14 does not operate, and the brake boosting characteristic of the torple type brake booster 1 is determined by the second and third power pistons 19 and 23 (solid line characteristic in FIG. 5). .

When the depression of the brake pedal is released, the vacuum valve 35 is opened by the backward movement of the plunger 31,
Each atmospheric chamber 16, 20, 24 and each negative pressure chamber 15, 19, 23
Are communicated with each other, and the return springs 30 return the power pistons 14, 18, 22 to their original positions.

(B) When the vehicle is stopped to idling up in a very low speed range When the engine idling speed increases due to cold engine operation or cooler compressor operation, etc., when the vehicle is stopped to a very low speed, step 101 → step 102 → step 103 → step 104 In step 104, the control valve 43 is turned on and the ports 41 and 42 are turned on.
A command that communicates with is output.

As a result, when the brake pedal (not shown) is depressed, the atmosphere in the second atmosphere chamber 20 is also introduced into the first atmosphere chamber 16, and the pressure difference between the first negative pressure chamber 15 and the first atmosphere chamber 16 is reduced. Occurs, the first power piston 14 moves forward in addition to the second and third power pistons 18 and 22, so that the valve body 26 can move forward with a larger force, and the brake boosting characteristic of the torple type brake booster 1 is increased. Is the first
It will be determined by the second and third power pistons (one-dot chain line characteristic in FIG. 5).

When the brake operation is performed in this state, if the brake boosting characteristic is constant, a large pedaling force is required for the drive torque increase due to idling up acting on the drive wheels, but the brake boosting of the triple type brake booster 1 is increased. The increased driving torque is compensated by the increase in the braking torque due to the change in the force characteristic to the brake boosting characteristic having a high hydraulic pressure increase gain.

Therefore, even when idling up, the vehicle can be stopped by operating the brake pedal by depressing the brake pedal with the same pedal depression force as during normal idling rotation.

Further, steps 101, 102 and 103 are start conditions for the high brake boosting characteristic changing control.
Even if the idling-up is completed, the control valve 43 goes to O
During braking operation in which the N signal is output, step 101 → step 105 → step 106 → step 1
In step 04, the high brake boosting characteristic changing control is maintained.

This is because the creep torque generated in the torque converter does not decrease immediately after the idling-up is finished, but remains as residual torque, so that the normal brake boosting characteristics are immediately returned after the idling-up is finished. In this case, if the pedal effort remains the same, the vehicle may jump out, and an operation of increasing the pedal effort is required to maintain the vehicle braking state.

Then, step 102 and step 10
When the condition of any one of step 3, step 105 and step 106 is not satisfied, the high brake boosting characteristic is returned to the normal brake boosting characteristic.

As described above, in the brake boosting characteristic control device for the vehicle equipped with the automatic transmission according to the embodiment, the following effects can be obtained.

(1) A triple type brake booster 1 capable of changing the brake boosting characteristic in two steps is used, and in a stop state in which a large driving torque is generated, a brake having a higher hydraulic pressure increase gain with respect to the pedal depression force than in the normal state. Since it is a device that changes to a boosting characteristic, it is possible to obtain a good brake feeling equivalent to that of a normal time when idling up in a stopped state where a large driving torque is generated.

(2) Based on the conventional tandem type brake booster, the triple type brake booster 1 has a simple structure and is used as a tandem type in normal times and as a triple type when changing brake boosting characteristics. Therefore, a brake booster capable of changing the brake boosting characteristic can be easily manufactured with a minimum design change.

(3) When the high brake boosting characteristic changing control is started, the high brake boosting characteristic changing control is performed during the brake operation in which the ON signal is output to the control valve 43 even if the idling-up is completed. Since it is maintained, it corresponds to the residual creep torque generated in the torque converter, and it is possible to prevent the vehicle from jumping out when returning to the normal brake boosting characteristic immediately after idling up, and to reduce the pedal effort. There is no need to raise it.

Although the embodiments have been described above with reference to the drawings, the specific configuration is not limited to the embodiments, and modifications and additions within the scope of the present invention are included in the present invention. Be done.

For example, in the embodiment, the brake booster is of negative pressure type, but may be of positive pressure type or hydraulic type.

In the embodiment, the brake booster can be changed in two stages by tandem and triple, but it may be changed in two stages by single and tandem.
Furthermore, it may be changeable in three or more steps, and
It may be steplessly changeable.

In the above embodiment, the idling control signal from the engine idling control unit is used to determine whether or not the engine is idle up. However, the vehicle speed is determined based only on the signal from the vehicle speed sensor. It is also included in the present invention that the brake control characteristic is uniquely changed depending on whether the set value is equal to or less than the set value V _O.

[0061]

As described above, according to the present invention, a brake booster characteristic control device for a vehicle equipped with an automatic transmission having a torque converter uses a brake booster capable of changing the brake boosting characteristic, and has a large size. In the stopped state where the driving torque is generated, the braking force is changed to a brake boosting characteristic in which the hydraulic pressure increase gain is higher with respect to the pedaling force than in the normal state. Therefore, in the stopped state, a good brake feeling equivalent to that in the normal state is obtained. The effect that can be obtained is obtained.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims of the first invention of the brake boosting characteristic control device for a vehicle equipped with an automatic transmission according to the present invention.

FIG. 2 is a diagram corresponding to the claims of the second invention of the brake boosting characteristic control device for a vehicle equipped with an automatic transmission according to the invention.

FIG. 3 is an overall system diagram showing a brake boosting characteristic control device for a vehicle equipped with an automatic transmission according to an embodiment of the present invention.

FIG. 4 is a flowchart showing a flow of a brake boosting characteristic control operation performed by the control unit of the device of the embodiment of the present invention.

FIG. 5 is a brake boosting characteristic diagram in the device of the present invention.

[Explanation of symbols]

 a actuator b brake booster c vehicle speed detecting means d driving torque detecting means e brake boosting characteristic control means

Claims (2)

[Claims] 1. A brake booster capable of changing a brake boosting characteristic in at least two steps in response to a command to an actuator, a vehicle speed detecting means for detecting a vehicle speed, and a pedal more than a normal pedal when a vehicle stop-low speed range is detected. A brake boosting characteristic of a vehicle equipped with an automatic transmission, comprising: a brake boosting characteristic control means for outputting to the actuator a command for changing to a brake boosting characteristic having a high hydraulic pressure increase gain with respect to pedaling force. Control device. 2. A brake booster capable of shifting a brake boosting characteristic in at least two stages by a command to an actuator, a vehicle speed detecting means for detecting a vehicle speed, a driving torque detecting means for detecting a driving torque, and a vehicle being stopped to a very low speed. When a predetermined drive torque is detected within the range, a boosting characteristic control means for outputting to the actuator a command for changing to a brake boosting characteristic having a higher hydraulic pressure increase gain with respect to a pedaling force than in a normal state, is provided. A brake boosting characteristic control device for an automatic transmission tower-mounted vehicle characterized by the above.