JP2003054392A - Hill-start aid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of a hill-start aid capable of dispensing with a gradient sensor by discriminating whether a road surface where a vehicle being going to start is stopped, is up hill or down hill without using the gradient sensor. SOLUTION: In the vehicle being going to stat by using this hill-start aid, an operating amount of an accelerator pedal operated by a driver or an engine rotating speed in response to the operating amount of the accelerator pedal is detected to discriminate the gradient of the road surface where the vehicle is stopped, whereby a release point of the brake pressure is changed and controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used as a device for improving the driving operability of an automobile. The present invention is used in a vehicle equipped with a clutch pedal. According to the present invention, when the vehicle starts from a state where the vehicle is stopped on a slope, the brake is automatically held even if the driver releases his foot from the brake pedal, and the clutch pedal crosses a preset release point. The present invention relates to an improvement of a slope start assist device that automatically releases a brake when released.

[0002]

2. Description of the Related Art When a vehicle stopped on a slope road surface is started in the direction of climbing the slope road, the driver once depresses the clutch pedal to apply the braking force to the vehicle and starts the transmission gear. Set to, loosen the brake while gently depressing the clutch pedal, and depress the accelerator pedal to increase the engine output. Such an operation is a basic procedure for driving an automobile having a clutch / pedal as a hill start operation. For large vehicles such as trucks and buses, the amount of operation varies greatly depending on the size of the load and the number of passengers, and it is easy for the engine to stop or the vehicle to retreat when starting on a slope. As a device for assisting such a driving operation, a slope start assist device has come to be widely used (Japanese Patent Laid-Open No. 60-11719, Japanese Patent Laid-Open No. 4119/1992).
-244462, etc.).

Such a device automatically brakes when the driver releases his / her foot from the brake pedal when the vehicle speed becomes zero while the brake pressure exceeds a certain value by the operation of the brake pedal. It is configured to hold pressure. In this state, the driver depresses the clutch pedal, operates the gear shift lever to put the transmission in the starting gear, and then withdraws the clutch pedal, and the preset value is set according to the stroke of the clutch pedal. At the release point, the held brake pressure is controlled to be automatically released. By using this device, the driver needs to know how much to operate the stroke of the clutch with his left foot, when to change his right foot from the brake pedal to the accelerator pedal, and when to change the timing quickly. You don't have to use.

With the popularization of such a hill start assist device, a driver not only uses the device for hill start, but also frequently uses it for a stop start operation on a congested road. Such a hill start assist device can be operated and set to an effective state or an ineffective state by turning on and off an operation switch provided in a driver's seat. If the device is operated in a valid state even when the vehicle is moving downhill or the road is congested with traffic, it may cause the vehicle to move slightly forward and stop. In addition, the driver does not need to step on the brake pedal or operate the parking brake after stopping the vehicle by depressing the brake pedal. That is, even if the vehicle is stopped and the foot is released from the brake pedal, the brake pressure is maintained, and the brake pressure is automatically released when the vehicle is started, so some driving operations may be omitted. it can. As a result, the driver can reduce fatigue on the congested road. In reality, it has been clarified from the investigation of the usage state of the hill start assist device that the frequency of use on a road surface where such starting and stopping is repeated is considerably higher than the frequency of use on an uphill road surface.

Further, a device utilizing a gradient sensor has been developed for such a slope starting assist device (Japanese Patent Laid-Open No. 8-11).
3122 publication). This equips the vehicle with a gradient sensor,
The sensor output is connected to the hill start assist device as one of the control inputs. Then, when the vehicle is started using the slope starting device, the release point position corresponding to the stroke of the clutch pedal where the brake pressure is released is changed according to the grade of the slope. Is. When the vehicle is stopped and the grade of the uphill road is gentle, releasing the brake pressure at a position with a large clutch stroke does not cause the vehicle to retreat, which in turn puts a burden on the clutch and engine. It doesn't take. When the vehicle is stopped and the road is steeply rising, even if the load on the clutch and engine increases, the brake pressure should be maintained until the clutch reaches a certain extent to prevent the vehicle from moving backward. Is desirable. The gradient sensor mounted on the vehicle detects the gradient of the stopped road surface and automatically adjusts and controls it.

When the slope starting assist device is used also when starting a downhill road surface as described above, control by a slope sensor for automatically identifying the slope condition of the road surface is particularly effective. For example, the release position of the brake pressure is set as the standard setting position at which the clutch starts to meet. When the vehicle is stopped on an uphill slope with a large gradient, the brake pressure release position is set to the standard setting position so that the stroke of the clutch pedal is small so that the brake pressure is released after the clutch has met to some extent. Automatically move to the side. Also, when the vehicle is stopped on a downhill road surface, the brake pressure release position is automatically moved from its standard setting position to a position where the stroke of the clutch pedal before the clutch meets is large. be able to.

[0007]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention In a hill start assist device for a vehicle which is not equipped with a gradient sensor, a clutch is provided to some extent to prevent the vehicle from retreating when the brake pressure is released even on a steep uphill. Meet and then adjust to release brake pressure. Therefore, when this is used on a downhill road surface as described above, when the clutch pedal is gradually depressed, forward power is applied to the vehicle at the moment when the brake pressure is released. Then, the vehicle suddenly jumps forward. Such movement may be dangerous depending on the road surface condition. Under such circumstances, users have come to like a slope start assist device that is equipped with a gradient sensor and slightly changes the position where the brake pressure is released.

However, gradient sensors are expensive. The gradient sensor requires fine processing on the internal parts, and the assembly process requires high-precision control, and the vehicle equipped with the gradient sensor is inevitably expensive. On the other hand, vehicles for freight transport are in a state of intense price competition in the market, and there is no way to control the slope start assist device by distinguishing between flat ground and slopes without equipping a gradient sensor. Came to think of.

The present invention has been made against such a background, and it is an object of the present invention to provide a slope start assisting device capable of identifying the slope of a starting road surface and changing the control thereof even without a slope sensor. To aim. SUMMARY OF THE INVENTION It is an object of the present invention to provide a slope start assist device that can eliminate the phenomenon of a vehicle jumping out when a slope start assist device is used on a downhill road surface even if the slope sensor is not equipped. An object of the present invention is to provide a slope start assist device at low cost. An object of the present invention is to provide a vehicle equipped with a slope start assist device at low cost.

[0010]

The greatest feature of the present invention is that the slope of the road surface on which the vehicle is stopped is determined by the depression amount of the accelerator pedal operated by the driver. With a hill start assist device that is not equipped with a gradient sensor, the driver may have
If you do not press the pedal, the engine will rotate at an abnormally low speed when the brake pressure is automatically released.
Or you will experience a phenomenon such as stalling. From such experience of operation, the driver becomes aware of the road surface slope at which the vehicle has stopped and uses the slope start assisting device while operating the accelerator pedal. Therefore,
The present invention detects the depression amount of the accelerator pedal at the timing when the stroke of the clutch pedal is operated once after the depression of the clutch pedal, and the clutch pedal is detected according to the depression amount of the accelerator pedal.
We decided to change the release point position of the brake pressure with respect to the pedal stroke.

That is, according to the present invention, a means for holding the brake pressure even when the brake pedal is depressed to stop the vehicle and the brake pedal is released, and the means for holding the brake pressure by this means. The clutch pedal is depressed while the transmission is in the starting position and the stroke of the clutch pedal becomes smaller than a preset release point, the brake pressure held by the means is released. In the slope start assist device, a means for detecting the depression amount of the accelerator pedal when the clutch pedal is depressed and the brake pressure is maintained, and the preset amount corresponding to the depression amount of the accelerator pedal It is characterized in that it includes means for moving the release point. The means for moving the release point may include means for moving the release point to the clutch release side of the clutch stroke when the depression amount of the accelerator pedal is equal to or less than a predetermined value.

With this configuration, even if the slope starting assist device is not equipped with a slope sensor, it is possible to identify the actual road slope by the amount of depression of the accelerator pedal operated by the driver. Similarly to the device equipped with the gradient sensor, when the uphill gradient in the starting direction is large at the release point of the brake pressure for the clutch stroke, the uphill gradient is also located at the position where the clutch stroke is small (the clutch connection side). When it is small, change control can be performed to a position where the clutch stroke is large (clutch release side).

As described above, it is preferable to notify the driver of the operation for adjusting the depression amount of the accelerator pedal due to the slope of the road surface on which the vehicle is stopped, by using an operation manual or the like. However, even if the operator does not read the operation manual well, the driver can properly learn the adjustment of the operation by using the slope start assist device to experience the start operation on the road surface with different slopes several times. . Vehicles equipped with such devices are in most cases operated by professional drivers, and it is no problem to learn to perform such operations safely and properly. . When the start operation is repeated using the slope start assisting device according to the present invention, the driver will learn to properly perform the accelerator pedal depression / decrease depending on the size of the load. As a result, the driving operation can be smoothly performed without causing the vehicle to start or the engine rotation speed to abnormally decrease when the vehicle starts. In other words, the driver who starts the vehicle by using the slope start assisting device becomes accustomed to the vehicle having this structure and depresses the accelerator pedal by an amount corresponding to the gradient of the stopped road surface and the load.

The phrase "the transmission is in the starting position" means that the transmission is in the gear position having a large conversion ratio such as the first forward speed or the second speed or the reverse gear. That is, the device of the present invention can be used both when performing a starting operation by moving forward and when performing a starting operation when moving backward.

It is most desirable to set the release point to a position where the stroke of the clutch pedal is large and the clutch is not engaged when the depression amount of the accelerator pedal is zero. As a result, it is possible to eliminate a phenomenon in which the vehicle suddenly jumps out as the brake pressure is released when the vehicle is stopped on a downhill road surface.

The amount of depression of the accelerator pedal can be configured to directly detect the stroke of the accelerator pedal. This utilizes, for example, a sensor output that detects the operation amount of the accelerator pedal. However, the number corresponding to the depression amount of the accelerator pedal can be detected by the engine rotation speed that changes in response to the depression amount of the accelerator pedal. This configuration is more economical.

The device of the present invention detects the amount of depression of the accelerator pedal and utilizes it when the vehicle is stopped and the clutch pedal is depressed and the engine is not loaded. Therefore, the accelerator pedal depression amount corresponds well to the engine rotation speed except in special cases such as during warm-up operation. In addition, the rotation sensor for detecting the engine rotation speed is equipped for the engine related control devices other than the slope start assist device to use as input information, so a new detection element can be added by using this. It will not be done.
Furthermore, even in the conventional slope start assist device, in many forms,
As one of the control input information, it is already configured to capture the engine rotation speed information.
Since the amount of pedal depression is indirectly detected by the engine rotation speed information, no hardware is required to take in new input information. When the engine rotation speed information is used as described above, the present invention can be implemented by changing the software of the control circuit.

Further, according to the present invention, the release point can be moved in correspondence with the depression amount of the accelerator pedal, but this can be simplified so that when the depression amount of the accelerator pedal is less than a predetermined value. The release point can be set on the clutch release side of the clutch stroke, and can be simplified by gradually reducing the number of stages. To simplify this further, when the accelerator pedal is zero, it means that the vehicle is parked on a road with a downward slope, and when the accelerator pedal is depressed, the vehicle has an upward slope. It is also possible to assume that the vehicle is parked on the (or flat) road surface and to simply move the release point between two preset points.

By setting the release point to the position where the clutch is released when the accelerator pedal is zero, the slope start assist device is used when the vehicle starts downhill. However, the phenomenon that the vehicle jumps out disappears.

It is expressed that the release point of the brake pressure is moved in accordance with the clutch stroke according to the amount of depression of the accelerator pedal. This means that the release point position of the brake pressure corresponding to the clutch stroke is the accelerator pedal. It can be understood by the expression that it is set as a function of the pedal depression amount.

[0021]

1 is a block diagram of an apparatus according to an embodiment of the present invention. This device includes a vehicle speed sensor 1, a clutch stroke sensor 2, a service brake switch 3 that detects the operating state of a service brake, a parking brake switch 4 that detects the operating state of a parking brake, and a gear that detects the state of a transmission. The switch 5 and the control circuit 10 using the output electric signals of the engine rotation sensor 6 as input information. The control circuit 10 is a program control circuit. The engine rotation sensor 6 is a sensor that generates a pulse signal according to the rotation of the engine,
By counting the number of this pulse signal per unit time, the rotational speed of the engine can be detected. The operation control output of the control circuit 10 is the brake valve 1
2 is supplied to the solenoid valve 9 for driving the motor 2 and the alarm device 14.

Explaining the brake system, the pneumatic tank 1
From 5, the air pressure is supplied to the brake valve 12 via the rear brake valve 16 and the front brake valve 17, which are opened and closed according to the operation of the brake pedal 11. The air pressure controlled by the brake valve 12 is supplied to the rear brake booster 18 and the front brake booster 19. When a control signal is sent to the solenoid valve 9 while air pressure is being sent to the rear brake booster 18 and the front brake booster 19, the air pressure is maintained even when the brake pedal 11 is released, and the solenoid valve 9 The air pressure is released when the control signal of is lost. Operation unit 13
Is provided in the driver's seat, and when the operation switch 13a is operated in the ON state, the slope start assisting device becomes effective. The operation switch 13a is in the off state when the hill start assist device is not required.

Here, the feature of the present invention is the operation logic of the hill start assisting device, that is, the brake pedal 1
Even when 1 is released, when the solenoid valve 9 maintains the brake pressure and the clutch pedal is stepped on with a large stroke, the clutch pedal The release point of the brake pressure set corresponding to the stroke of the pedal is changed according to the amount of depression of the accelerator pedal. Moreover, in this embodiment, as described above, the amount of depression of the accelerator pedal is indirectly detected by the rotation sensor 6 of the engine, instead of directly detecting the amount of depression of the accelerator pedal.

In this embodiment, when the accelerator pedal is not depressed at all, the engine speed is at the idling speed. At this time, the clutch pedal is deeply depressed at the release point of the brake pressure, and the clutch is released. It is set to a position where it is not connected at all. Then, as the accelerator pedal is stepped on gradually, that is, as the engine speed increases, the release point of the brake pressure is at the position where the clutch starts to slip while the clutch is slipping, or further toward the direction where the clutch is connected. Adjust and set to move. This is to move the release point in the control logic, ie by software, and this movement cannot be directly observed from the outside.

When driving a vehicle equipped with the device of this embodiment, the driver should be aware of the state of the road surface on which the vehicle is stopped, and when the vehicle is in the state of starting uphill, the clutch pedal Operate to depress the accelerator pedal at the timing of operating the stroke in the shallow direction. The larger the upward slope of the road surface on which the vehicle is stopped, the larger the depression amount of the accelerator pedal is operated. When the road is downhill, do not step on the accelerator pedal when starting. By such a driving operation, the vehicle is prevented from suddenly jumping forward when the brake pressure is released when the vehicle is about to start on a road surface having a downward slope. In addition, the engine output will not become insufficient when the brake pressure is released when the vehicle starts on an uphill road surface. Such operation of the driver is acquired by habituation while driving a vehicle equipped with this device.

FIG. 2 is a control flowchart of the main part of the device control circuit according to the embodiment of the present invention. Explaining the operation of this embodiment, the control circuit 10 monitors the vehicle speed when the hill-start assisting device is in an effective state, and when the vehicle speed becomes zero from the running state, the state of the parking brake and the transmission are changed. State, the state of the clutch is taken in, the parking brake is released, the transmission is set to the starting gear (forward 1st stage, 2nd stage, or reverse), and the clutch is disengaged,
The control circuit 10 keeps monitoring the state of the clutch. When the clutch stroke exceeds the release point and is operated to the clutch connecting side, the control signal to the solenoid valve 9 is stopped to control to release the held brake pressure.

Here, the feature of the present invention resides in that the release point of the brake pressure set in the clutch stroke is changed according to the depression amount of the accelerator pedal. In this embodiment, the accelerator pedal depression amount is calculated and detected by software based on the engine rotation speed. That is, when the engine speed is the idling speed, the release point is at the position where the clutch is not engaged at all. When the accelerator pedal is depressed and the engine speed becomes high, the clutch is released by Δα.
Move to the side where the pedal is removed (the side where the clutch is connected).
This Δα is a function of the engine speed. It is difficult to determine this function using a simple theoretical formula because complex elements such as the accelerator control system and clutch structure are entangled, and it is necessary to measure and set the actual model for each vehicle model. Is most appropriate.

This properly operates according to the driver's habit even when the size of the load changes. When attempting to start uphill when the load is large, the hill start assist device is used with the accelerator pedal slightly depressed compared to when the load is small.
As a result, without observing the undercarriage slope with a slope sensor,
By the driver's recognition and operation, the hill start operation can be properly performed.

[0029]

According to the present invention, it is possible to discriminate whether the vehicle is starting on an uphill road surface or a downhill road surface (or a flat road surface) without installing an expensive gradient sensor, and As in the case of a vehicle equipped with a sensor, a device capable of appropriately moving and controlling the release point of the brake pressure can be obtained. In the slope start assist device embodying the present invention, when the vehicle is used for starting a downhill road surface, a phenomenon in which the vehicle suddenly jumps forward is eliminated. Since the apparatus of the present invention does not need to be equipped with an expensive gradient sensor, it is possible to reduce the price of the hill start assist device and to provide the vehicle equipped with the hill start assist device at a low price.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the main part of the control circuit of the device of the embodiment of the present invention.

[Explanation of symbols]

1 vehicle speed sensor 2 Clutch stroke sensor 3 Service brake switch 4 Parking brake switch 5 gear switch 6 Engine rotation sensor 9 Solenoid valve 10 Control circuit 11 Brake pedal 12 Brake valves 13 Operation unit 13a Operation switch 14 Alarm device 14a Alarm buzzer 14b alarm lamp 15 Pneumatic tank 16 Rear brake valve 17 Front brake valve 18 Rear brake booster 19 Front brake booster

Claims (4)

[Claims] Claim: What is claimed is: 1. A means for holding the brake pressure even when the brake pedal is depressed to stop the vehicle and the brake pedal is released, and a means for holding the brake pressure by this means. When the clutch pedal is depressed and the transmission is put into the starting position, and when the stroke of the clutch pedal becomes smaller than a preset release point, a means for releasing the brake pressure held by the means is provided. In the auxiliary device, the means for detecting the depression amount of the accelerator pedal when the clutch pedal is depressed and the brake pressure is maintained, and the preset release point according to the depression amount of the accelerator pedal are provided. A hill start assisting device comprising means for moving. 2. The means for moving the release point, when the depression amount of the accelerator pedal is less than a predetermined value,
The slope start assist device according to claim 1, further comprising means for moving the release point to a clutch release side of a clutch stroke. 3. The slope start assist system according to claim 2, wherein the release point is set to a position where the clutch is released when the amount of depression of the accelerator pedal is zero. 4. The slope start assist device according to claim 1, wherein the means for detecting the depression amount of the accelerator pedal includes means for detecting the rotational speed of the engine.