JPH08324397A - On-slope starting auxiliary device - Google Patents

Abstract

PURPOSE: To correctly execute the release of braking force always corresponding to the timing of the start time without special adjustment or the like. CONSTITUTION: The braking torque F of a drum brake 1 is directly detected by a braking torque detecting means 8, and when the braking torque F is judged to be the specified value or less by a controller 9, that is, when forward torque is obtained enough to put a vehicle in a non-retreating state even if the operation of the drum brake 1 is released, an air pressure holding valve 10 is opened to release the braking action of the drum brake 1, and the release of braking force always corresponding to the timing of the start time is correctly executed without special adjustment or the like regardless of the change of the abrasion member of a clutch plate with the lapse of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slope start assisting device capable of smoothly releasing a braking force when starting a slope.

[0002]

2. Description of the Related Art In order to prevent the vehicle from moving backward when starting on a slope in an automobile, the clutch pedal is gradually released on the one hand while the brake pedal is released on the other hand, and at the same time, the accelerator pedal is appropriately depressed. ing.
When the side brake is pulled, the clutch pedal is gradually released on the one hand while the accelerator pedal is appropriately depressed on the other hand, and at the same time, the side brake is gradually released manually to prevent the vehicle from reversing when starting. I'm avoiding it. For this reason, starting a slope requires complicated operations,
This is an operation that requires skill. Also, in vehicles equipped with an automatic transmission (A / T vehicles), it is relatively easy to start a hill because there is no need to operate the clutch pedal, but when starting on a steep slope In addition, the side brake is operated to prevent the vehicle from moving backward when starting.

For this reason, conventionally, a hill-start assisting device has been used which holds a braking force until the vehicle starts when the hill starts. A conventional hill start assist device will be described with reference to FIG. FIG. 4 shows a schematic structure of a conventional hill start assist device.

As shown in the figure, the clutch pedal 21 is provided with a stroke sensor 22 for detecting the depression amount of the clutch pedal 21, and a signal from the stroke sensor 22 is inputted to a controller 23. On the other hand, air is supplied to the braking device 24 from an air tank 26 via an air pressure holding valve 25 that holds and releases the pressure of air for operating the braking device 24, and a braking force is obtained. The air pressure holding valve 25 is operated based on a command from the controller 23, and the braking force is obtained by the operation of the air pressure holding valve 25.

When a vehicle starts on a slope, the stroke sensor 22 detects the return stroke of the clutch pedal 21, which serves as the meet point of the clutch. When it is detected that the clutch pedal 21 has reached a predetermined return stroke, the controller 23 sends an opening command to the air pressure holding valve 25. When the air pressure to the braking device 24 is released, the braking by the braking device 24 is released and the vehicle can start. Therefore, the braking force of the braking device 24 is maintained until the clutch pedal 21 reaches a predetermined return stroke, and there is no risk of the vehicle retreating when starting on a slope.

[0006]

The conventional hill start assist device detects the start of the vehicle by detecting the stroke of the clutch pedal 21. For this reason, when the clutch plate is worn, the stepping allowance of the clutch pedal 21 at the meet point of the clutch changes, and correct start detection cannot be performed. If the detection at the time of starting cannot be performed correctly, there is a risk that the timing of releasing the air pressure to the braking device 24 may be shifted and the vehicle may move backward. Therefore, it is indispensable to adjust the stroke detection position of the clutch pedal 1 due to changes over time such as wear of the clutch.

On the other hand, there is known a device in which a torque sensor is provided on the clutch shaft to detect the output torque of the clutch and hold the braking force (see Japanese Patent Laid-Open No. 4-201770). By using this device to detect the start of the vehicle, the braking force of the vehicle can be maintained until the correct start of the vehicle regardless of wear of the clutch plate. However, since this device is provided with a sensor on the rotating clutch shaft, its practicality is extremely low, and even if it can be put to practical use, the reliability of the signal from the sensor will be low.

Further, even in the case of an A / T vehicle when starting on a steep slope, if the braking force of the vehicle can be maintained until the start, the slope can be started more easily. The auxiliary device could only be applied to vehicles equipped with a clutch pedal, and the A / T vehicle could not be applied to slope starting devices.

The present invention has been made in view of the above situation, and an object of the present invention is to provide a slope start assisting device capable of releasing the braking force always in synchronization with the start timing irrespective of changes over time. .

[0010]

The structure of the present invention for achieving the above object is a fluid pressure holding means for holding a fluid pressure supplied to a braking device for obtaining a braking force by a fluid pressure, and a braking device for the braking device. A braking torque detecting means for detecting the braking torque, and a fluid pressure holding means for holding the fluid pressure when the braking torque detected by the braking torque detecting means when the vehicle is stopped on an uphill becomes a predetermined value or less. It is characterized by comprising a control device for releasing.

Further, the braking device is a drum brake that obtains a braking force by bringing the brake shoe into contact with the drum by air pressure, and the fluid pressure holding means holds the pressure of air for operating the brake shoe. And an air pressure holding valve to be opened, for canceling the contact operation of the brake shoe with the drum when the braking torque is reduced to a predetermined value or less when starting uphill. And a function of opening the air pressure holding valve.

[0012]

When the vehicle is stopped uphill, the braking force is obtained by the fluid pressure holding means, the braking torque of the braking device acts in the backward rotation direction, and the braking torque is detected by the braking torque detecting means. . When the vehicle attempts to move forward when starting, the braking torque acting in the reverse rotation direction gradually decreases, and when the braking torque falls below a predetermined value, that is, sufficient forward rotation torque is obtained and the braking force disappears. However, when the vehicle does not move backward, the fluid pressure holding means releases the holding of the fluid pressure, and the braking force of the braking device disappears.

Further, when the vehicle is stopped on an uphill, the brake shoe comes into contact with the drum by the air pressure from the air pressure holding valve to obtain a braking force, so that the braking torque of the drum brake is changed in the reverse rotation direction. The braking torque is detected by the braking torque detecting means. When the vehicle tries to move forward at the time of starting, the rotational torque in the forward direction acts on the drum, and the braking torque acting in the backward rotating direction gradually decreases. When the braking torque becomes equal to or less than a predetermined value, that is, when the vehicle does not retreat even when the rotational force in the forward direction is sufficiently obtained and the braking force disappears, the air pressure retention valve is released and the brake shoe is applied to the drum. The contact operation is released and the braking force of the drum brake is lost.

[0014]

1 and 2 show a schematic structure of a hill start assisting device according to an embodiment of the present invention. FIG. 1 shows a situation at a stop and FIG. 2 shows a situation at a start. There is. Further, FIG. 3 shows a flowchart of start control. In the illustrated example, a drum brake is shown as the braking device for explanation, but the present invention is also applicable to a disc brake as the braking device.

As shown in FIGS. 1 and 2, a drum brake 1 as a braking device is mounted on a wheel 31 by pushing a pair of brake shoes 3 into contact with a drum 2 which rotates integrally with a wheel 31. Generates braking force. The pair of brake shoes 3 is spread by the cylinder 5 driven by the air supplied to the brake chamber 4. Air is supplied to the brake chamber 4 from an air tank 6 via an air pressure holding valve 10, and the air from the air tank 6 enters the brake chamber 4 via a brake valve (not shown) that operates in conjunction with the depression of a brake pedal. It is being supplied. Therefore, when the driver depresses the brake pedal, the brake valve operates to operate the brake chamber 4 via the air pressure holding valve 10.
The air is supplied to the pair of brake shoes 3 and the pair of brake shoes 3 is spread by the cylinder 5 to stop the rotation of the drum 2, that is, the rotation of the wheels 31.

The drum brake 1 is provided with a braking torque detecting means 8 for detecting the braking torque F of the drum brake 1 during braking. As the braking torque detecting means 8, for example, a strain gauge is attached to an anchor bracket fixed to an axle on the vehicle body side, and the strain of the anchor bracket corresponding to the rotational force received from the drum 2 via the brake shoe 3 is directly converted into an electric signal. The one that is taken out to detect the braking torque is used. As a means for detecting the braking torque, a means for detecting a deflection due to a reaction force of the pressing force of the friction pad of the disc brake and detecting the braking torque by the detected deflection (JP-A-4-344437) Or
A device in which a supporting member is provided between a caliper of a disc brake and a knuckle arm, and a braking torque is detected by detecting a displacement of the supporting member during braking (Japanese Patent Laid-Open No. 6-1236365).
It is also possible to use other known means such as.

As shown in FIG. 1, the braking torque F of the drum brake 1 detected by the braking torque detecting means 8 when the vehicle is stopped on an uphill is generated in a direction in which the gradient is maintained.
In other words, the braking torque F acts in the backward rotation direction of the wheel 31 (clockwise direction in the figure). Also, as shown in FIG.
When the drive torque T on the forward side is generated in the wheel 31 at the time of starting, the braking torque F of the drum brake 1 detected by the braking torque detecting means 8 is gradually reduced and the direction is reversed. Braking torque F detected by the braking torque detecting means 8 during braking
Is input to the controller 9 as a control device. Further, based on a command to the controller 9, the air pressure holding valve 10 is opened when the braking torque F becomes equal to or less than a predetermined value,
The air supplied to the brake chamber 4 is cut off to release the contact operation of the brake shoe 3 with the drum 2.

The operation of the auxiliary control for starting the slope on the controller 9 will be described with reference to FIG. When a condition for starting a slope, for example, a condition in which the door is closed, the brake is depressed, and the vehicle speed is zero, the air pressure holding valve 10 is operated to supply air to the brake chamber 4. Hold and operate the drum brake 1. In this state, it is determined whether or not there is an intention to start, that is, whether or not the clutch pedal is stepped on and the gear is in the forward gear, and if it is determined that there is an intention to start, braking is performed. The torque F is read. After the braking torque F is read, it is determined whether the braking torque F is less than or equal to a predetermined value.
When it is determined that the braking torque F is less than or equal to the predetermined value, the drive torque T in a state where the vehicle does not move backward after shifting to the starting operation.
Therefore, the air pressure holding valve 10 is opened to cut off the air supplied to the brake chamber 4 to release the contact of the brake shoe 3 with the drum 2 and release the operation of the drum brake 1. As a result, the vehicle can start on the slope without moving backward.

Incidentally, the predetermined value for judging the braking torque F is set to a value (substantially zero) in which the braking torque F and the driving torque T are balanced or set to a slightly minus side, so that an excessive load is applied to the drum brake 1. However, the predetermined value is set within a range where the vehicle can start without moving backward on a slope.

In the slope start assist device having the above-mentioned structure, when the braking torque F of the drum brake 1 is directly detected by the braking torque detecting means 8 and the controller 9 determines that the braking torque F is below a predetermined value, that is, When the vehicle does not retreat even if the rotational force in the forward direction is sufficiently obtained and the operation of the drum brake 1 is released, the air pressure holding valve 10 is opened to release the braking operation of the drum brake 1. Therefore, regardless of changes over time in the members such as wear of the clutch plate, the braking force can always be released accurately in accordance with the timing of starting without any special adjustment. Further, since the detection at the time of starting is performed by detecting the braking torque F of the drum brake 1,
It can also be applied to A / T vehicles that do not have a clutch pedal. Further, the information on the braking torque F can be applied to the braking force control other than the control at the time of starting on a slope, and the braking torque detecting means 8 can be shared.

[0021]

The slope start control device of the present invention has a fluid pressure holding means for holding the fluid pressure supplied to the braking device for obtaining a braking force by the fluid pressure, and a braking torque detecting means for detecting the braking torque of the braking device. And a control device for releasing the holding of the fluid pressure by the fluid pressure holding means when the braking torque detected by the braking torque detection means becomes a predetermined value or less when starting on an uphill. When the braking torque is such that the vehicle does not retreat even if the rotational force in the direction is sufficiently obtained and the braking force disappears, the holding of the fluid pressure by the fluid pressure holding means is released and the braking by the braking device is released. The braking force can always be released accurately in accordance with the timing at the start without any special adjustment or the like. As a result, it becomes possible to smoothly start the slope regardless of the change over time of the members. Also, since the start time is detected by detecting the braking torque,
It can also be applied to a vehicle equipped with an automatic transmission that does not have a clutch pedal.

The slope start control device of the present invention starts uphill with a drum brake for bringing a brake shoe into contact with the drum by air pressure to obtain a braking force, a braking torque detecting means for detecting a braking torque of the drum brake. At this time, when the braking torque detected by the braking torque detecting means becomes equal to or less than a predetermined value, the air pressure holding valve is opened to release the contact operation of the brake shoe with the drum. When the braking torque is such that the vehicle does not retreat even if the sufficient rotational force in the forward direction is obtained and the braking force is lost, the air pressure by the air pressure holding valve is released and the contact of the brake shoe with the drum is released. Since the braking by the drum brake is released, it is possible to always release the braking force accurately according to the timing at the start without making any special adjustment. As a result, it becomes possible to smoothly start the slope regardless of the change over time of the members. Also,
Since the start time is detected by detecting the braking torque, it can be applied to a vehicle equipped with an automatic transmission that does not have a clutch pedal.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a slope start assist device according to an embodiment of the present invention when the device is stopped.

FIG. 2 is a schematic configuration diagram at the time of starting the slope starting assist device according to the embodiment of the present invention.

FIG. 3 is a flowchart of start control

FIG. 4 is a schematic configuration diagram of a conventional slope start assist device.

[Explanation of symbols]

 1 Drum Brake 2 Drum 3 Brake Shoe 4 Brake Chamber 5 Cylinder 6 Air Tank 8 Braking Torque Detecting Device 9 Controller 10 Air Pressure Holding Valve 31 Wheel

Claims (2)

[Claims] 1. A fluid pressure holding means for holding a fluid pressure supplied to a braking device for obtaining a braking force by a fluid pressure, and a braking torque detecting means for detecting a braking torque of the braking device,
And a controller for releasing the fluid pressure held by the fluid pressure holding means when the braking torque detected by the braking torque detecting means becomes a predetermined value or less when the vehicle is stopped on an uphill. Slope start assist device. 2. The braking device is a drum brake that obtains a braking force by bringing the brake shoe into contact with the drum by air pressure, and the fluid pressure holding means holds the pressure of air for operating the brake shoe. And an air pressure holding valve to be opened, for canceling the contact operation of the brake shoe with the drum when the braking torque is reduced to a predetermined value or less when starting uphill. The hill start assist device according to claim 1, further comprising a function of opening the air pressure holding valve.