JP3029959B2 - Slope start assist device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a vehicle. The present invention relates to a driving assistance device. The present invention relates to a computer-controlled driving assistance device that assists in releasing a brake pressure when a vehicle starts moving from a stopped state on a slope.

[0002] The present invention is applied to an automobile in which a driver operates a clutch and a shift gear by a clutch pedal and a select lever. There is no clutch pedal in the driver's seat, and the clutch and the shift gear are automatically operated. It does not apply to so-called automatic vehicles that are operated manually.

[0003]

2. Description of the Related Art When starting a vehicle stopped on a hill, a driver once applies a parking brake to apply a braking force to the vehicle, selects a transmission gear as a start gear, and gradually releases a clutch while releasing a clutch. It is necessary to perform a complicated operation of depressing the pedal to increase the output of the engine and releasing the parking brake. Such an operation is a basic matter in the operation of driving a car, but in a truck or a bus, the operation is greatly different depending on the loaded load, and the engine is liable to stall or reverse in the vehicle.

As a device for assisting such a driving operation, a slope start assist device disclosed in Japanese Patent Application Laid-Open No. 60-11719 or Japanese Patent Application Laid-Open No. 4-244462 is known. Such a device has been put to practical use, installed in a car, sold and sold by HSA (Hill Start Ai).
It has been widely used under such names as d).

[0005] The conventional hill start assist device is provided with a configuration in which, when the brake pressure exceeds a predetermined value and the vehicle speed becomes zero, that is, when the vehicle stops after traveling, the vehicle may have a gradient in the traveling direction. When detected, the driver)
The brake pressure is automatically maintained even when the foot is released from the pedal. In this state, when the driver selects the select lever to the starting position, engages the clutch, and depresses the accelerator pedal, the device automatically detects it and automatically switches it at the most appropriate timing. It is configured to release brake pressure. In a vehicle equipped with such a slope start assist device, the driver can perform the slope start operation without operating the parking brake.

[0006] Even if there is no gradient in the running direction of the vehicle, if the brake pressure is maintained when the vehicle is stopped from the running state, the brake pressure is automatically maintained even when the vehicle is stopped such as at a traffic light. Sometimes it is useful, and it is used as such.

[0007] Slope start assist devices that are in practical use include:
After the brake pressure is automatically maintained, the parking
When the brake is applied, the brake pressure is automatically released. That is, when the driving operation is completed and the vehicle is stopped, the temporary holding state of the brake pressure is released so that the temporary holding state of the brake pressure is not used instead of the parking brake. Further, when a driver tries to leave the seat in a state where the brake pressure is automatically held, a safety device such as issuing a large alarm is added.

[0008]

The above-described slope start assist device is configured to detect whether or not the vehicle has stopped based on the output of the wheel rotation sensor. Then, for example, on a slippery road surface such as a snowy road, the rotation of the wheels is locked with a small brake pressure, and the vehicle starts running on a slope even though the vehicle is running in a wheel slip state. As a result, the brake pressure holding operation is performed. That is, when the brake pedal is depressed while driving on a slippery road surface and the wheel rotation is temporarily locked with a small brake pressure and the brake pressure is released when the wheels are in a slip state, the hill start assist device operates and the brake is started. The pressure is maintained, and the vehicle stops in the slip state.

This is not desirable as an operation of the slope start assist device. This can occur on snowy roads, wet roads, fine gravel roads, etc.

[0010] It is an object of the present invention to provide a slope start assist device capable of eliminating such an undesirable operation.

[0011]

SUMMARY OF THE INVENTION The present invention comprises a brake pressure sensor, a clutch sensor, a rotation sensor, and a neutral switch for indicating a neutral position of a shift lever. And a program control circuit that receives the output of each of the sensors as input and sends out the control signal, the brake pressure sensor detects a stop lamp switch. A brake pressure threshold higher than the pressure is set.

A switching circuit for switching between the brake pressure sensor and the stop lamp switch to be an input to the control circuit; and a temperature sensor for detecting an air temperature. When the brake pressure is lower than the reference value, the brake pressure can be automatically switched to the higher brake pressure threshold.
Means for determining the slip state of the wheel from the rotational speed decay gradient of the rotation sensor, such that when the switching circuit is switched to a high brake pressure threshold, the criterion for this rotational speed decay gradient is such that the gradient becomes steep. Means for changing may be included.

[0013]

When the brake pressure when the brake pedal is depressed exceeds a threshold value set higher than the detection pressure of the stop lamp switch, the brake pressure sensor sends a detection output to the program control circuit. The program control circuit receives the detection output, and when the wheel rotation speed is zero, sends a control signal to the control valve to operate the slope start assist device. That is, even if the brake pedal is released, the brake pressure is maintained and the wheel is kept in the braking state.

In the present invention, since the threshold value of the brake pressure sensor is set high, even if the braking operation is temporarily performed with a small brake pressure and the wheels are locked, the hill start assist device operates immediately. As a result, it is possible to avoid that the brake pressure is maintained and the wheels continue to be in the braking state. In other words, it is possible to prevent such a problem that the brake holding operation by the hill start assistance device is performed on a slippery road such as a snowy road even though the vehicle is continuously running.

[0015]

Next, an embodiment of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing a configuration of a first embodiment of the present invention.

In the first embodiment of the present invention, the brake pedal 1
A control valve 2 for maintaining a brake pressure in accordance with a control signal even when the brake valve is released, a stop lamp switch 3 for closing and lighting a stop lamp when the brake pressure is supplied to the control valve 2, Switch 3
And it is disposed between the control valve 2, and the detected pressure (about 0.3 kg / cm ²⁾ higher than the brake pressure threshold (5~6kg / cm ²⁾ brake pressure sensor 4, which is set in the stop lamp switch 3 A brake pressure sensor 4, a clutch sensor 5, a rotation sensor 6, a neutral switch 7 for indicating a neutral position of a shift lever, a brake pedal sensor 8 for detecting an amount of depression of a brake pedal,
And a program control circuit 10 which receives an output from the gradient sensor 9 and sends out the control signal.

Next, the operation of the first embodiment of the present invention will be described. FIG. 2 is a flowchart showing a flow of a brake holding operation of the program control circuit in the first embodiment of the present invention, and FIG. 3 is a flowchart showing a flow of a brake releasing operation of the program control circuit in the first embodiment of the present invention.

The brake holding operation is performed as shown in FIG.
The program control circuit 10 captures the output from the brake pedal sensor 8 and determines whether or not the value exceeds a preset depression amount. If the depression amount does not exceed the set value, the vehicle is not stopped by braking, so that the transmission of the control signal to the control valve 2 is prohibited and the hill start assist operation is not performed. If it exceeds the set value, the output from the rotation sensor 6 is taken in, and it is determined whether or not the wheel rotation speed is zero. If the wheel rotation speed is not zero, the vehicle is running, and therefore the transmission of the control signal to the control valve 2 is prohibited, and the hill start assist operation is not performed. If the wheel rotation speed is zero, the output from the brake pressure sensor 4 is taken in, and it is determined whether or not the value exceeds a set threshold value. Start assist operation is prohibited.

If it exceeds the threshold value, the output from the gradient sensor 9 is fetched and it is determined whether or not the current gradient exceeds a predetermined value S. If the gradient exceeds the predetermined value S, it is determined that the vehicle is on a road beyond the ability to assist on a hill, and transmission of a control signal to the control valve 2 is prohibited so that the assisting operation is not performed. If the value does not exceed the predetermined value S, the control signal is sent to the control valve 2 assuming that the vehicle is on a road requiring slope start assistance, and the slope start assist operation is executed.

As shown in FIG. 3, the brake release operation takes in the output from the clutch sensor 5 and the neutral switch 7 when the vehicle is in the brake holding state on a slope, and the clutch is depressed to shift the gear. It is determined whether the forward start position (low or second) or the reverse position is set. When the clutch is depressed and the gear is set to the start state, the clutch sensor 5
It is determined from the output of whether or not the stroke becomes equal to or less than a predetermined stroke set in advance. When the stroke becomes equal to or less than the predetermined stroke, it is determined that the vehicle is to be started, and the transmission of the control signal to the control valve 2 is prohibited and the brake is released. If the gear is not set to the start state, or if the amount of depression of the clutch is equal to or more than the predetermined stroke, the control signal is continuously transmitted to the control valve 2 to maintain the brake holding state.

As described above, when the brake pedal 1 is depressed, if the brake pressure is small, the hill-start assist operation is prohibited. Therefore, even if the brake pedal 1 is depressed frequently, the pressure is stopped. If the braking is lower than the detection pressure set in the lamp switch 3, the brake pressure is not held each time. When the wheel slips on a slippery road surface such as a snowy road, the brake holding operation is not performed even though the vehicle is not stopped.

Also, when the brake pedal 1 is depressed to some extent, the brake pressure is maintained and the hill start assisting operation is performed. Therefore, when the driver gets used to the device, the hill start assist is determined according to the degree of depression. The brake operation can be performed while being conscious of whether or not the operation is performed.

(Second Embodiment) FIG. 4 is a block diagram showing the configuration of the second embodiment of the present invention.

The second embodiment of the present invention comprises a switching circuit 11 for switching the pressure detected by the stop lamp switch 3 and the brake pressure sensor 4 and taking in the program control circuit 10;
A changeover switch 12 for operating the changeover circuit 11 is provided, and the other configuration is the same as in the first embodiment.

In the case of the second embodiment of the present invention, the output of the detection output of the brake pressure to the program control circuit 10 can be switched between when traveling on a normal road surface and when traveling on a slippery road surface. This switching is performed by the driver operating the switch 12 to operate the switching circuit 11. Therefore, whether the detection output is taken from the stop lamp switch 3 or the brake pressure sensor 4 by opening and closing the changeover switch 12 can be arbitrarily determined by the driver.

The operation when the detection output from the brake pressure sensor 4 is input to perform the slope start assist control is performed in the same manner as in the first embodiment shown in FIG. 2, and the brake release operation is also performed as shown in FIG. This is performed in the same manner as in the embodiment.

As shown in FIG. 5, the program control circuit 10 fetches the output from the brake pedal sensor 8 when the detection output from the stop lamp switch 3 is input to assist the start on the hill. It is determined whether or not the value exceeds a preset depression amount. If the set value is not exceeded, the vehicle is not stopped by braking, so that the transmission of the control signal to the control valve 2 is prohibited so that the hill start assist operation is not performed. If it exceeds the set value, the output from the rotation sensor 6 is taken in, and it is determined whether or not the wheel rotation speed is zero. If it is not zero, the vehicle is running, so that the transmission of the control signal to the control valve 2 is prohibited so that the slope start assist operation is not performed. If the wheel rotation speed is zero, the output from the stop lamp switch 3 is taken in, and it is determined whether or not the output exceeds a predetermined value. Is exceeded, the output from the gradient sensor 9 is taken in, and it is determined whether or not the current gradient exceeds a set predetermined value S. When the gradient exceeds the predetermined value S, it is determined that the vehicle is on a road that does not have the ability to start on a hill, and transmission of a control signal to the control valve 2 is prohibited, and the assisting operation is stopped. If it does not exceed the predetermined value S, it is determined that the vehicle is on a road on which hill start assist is possible, and a control signal is sent to the control valve 2 to drive the control valve 2 to execute the hill start assist operation.

In the case of the second embodiment, the driver performs the hill start assisting operation by taking in the detection output from the stop lamp switch 3 or the detection output from the brake pressure sensor 4 according to the condition of the road surface. It is possible to arbitrarily select whether to take in and perform.

(Third Embodiment) FIG. 6 is a block diagram showing the configuration of a third embodiment of the present invention.

In the third embodiment of the present invention, a temperature sensor 13 for sending a detection output to the switching circuit 11 in the second embodiment is provided. The temperature sensor 13 and the changeover switch 12 are connected to the input side of an OR circuit, and the output side of the OR circuit is connected to the changeover circuit 11. Other configurations are the same as in the first embodiment.

In the case of the third embodiment, assuming that the detection output of the brake pressure is normally taken from the stop lamp switch 3, the changeover switch 12 is in the open state and the air temperature is set to a predetermined reference value (for example, 0 ° C.) or higher, the switch of the switching circuit 11 is connected to the stop lamp switch 3 side.

When the changeover switch 12 is operated and closed in this state, the switch of the changeover circuit 11 is switched to the brake pressure sensor 4 side, and the program control circuit 10 receives the detection output from the brake pressure sensor 4. The control operation of the control valve 2 is performed. Further, since the temperature sensor 13 is provided, even when the changeover switch 12 is not operated and the switch is in the open state, when the temperature drops and becomes lower than the reference value,
A detection output is sent from the temperature sensor 13 to the switching circuit 11, and the switching circuit 11 operates to switch the connection with the program control circuit 10 from the stop lamp switch 3 to the brake pressure sensor 4.

The program control circuit 10 performs the brake holding operation and the brake releasing operation similar to the first embodiment shown in FIGS. 2 and 3 by this switching. When the switching is not performed, the brake holding operation similar to the second embodiment shown in FIG. 5 is performed.

In the case of the third embodiment, the temperature sensor 13
Since the detection output of the brake pressure can be automatically switched from the stop lamp switch 3 side to the brake pressure sensor 4 side when the outside air becomes lower than the road surface freezing temperature, the outside air temperature decreases. Driving operation can be performed without being conscious of.

(Fourth Embodiment) FIG. 7 is a block diagram showing the configuration of a fourth embodiment of the present invention.

The present invention fourth embodiment, the exciting coil and the program control circuit 10 for switching the switches of the switching circuit 11 provided in the third embodiment is connected to the program control circuit 10, the slip state of the drive wheels Means for determining from the rotation speed decay gradient of the rotation sensor 6; and means for changing the criterion of this rotation speed decay gradient so that the gradient becomes steep when the switching circuit is switched to the second threshold value of the high brake pressure. including.

A switching position signal indicating whether the switch is connected to the stop lamp switch 3 or the brake pressure sensor 4 is sent from the excitation coil of the switching circuit 11 to the program control circuit 10.

FIG. 8 is a diagram showing a wheel rotational speed attenuation gradient in the embodiment of the present invention. This shows the change in wheel rotation speed over time during braking.
The solid line A corresponds to a braking state on a normal road surface, the one-dot chain line B corresponds to the first threshold value of a low brake pressure set as a reference value corresponding to the detection output of the stop lamp switch 3, and the two-dot chain line C corresponds to the brake pressure sensor 4. the second threshold value of the high brake pressure set as reference value, also, the broken lines D ₁
The rotational speed damping state when sliding by the braking does not occur, the broken line D ₂ represents the rotation speed damping state when sliding by the braking occurs.

As shown in FIG. 8, when the switching circuit 11 is set to the second threshold value C of the high brake pressure, braking is applied, and the rotation speed at that time attenuates from v ₁ to v _2. and it came to the curve D _1. In this case, normal braking that does not cause slippage is performed because it is within the range of the second threshold value. That is, when the wheel rotates following the speed as the curve D ₁ is stopped, the operation of the brake pressure retaining as hill-start assist is performed.

However, the decay of the rotation speed of the wheel is represented by a curve D.
₂ , the time from the wheel rotation speed v ₁ to v ₂ needs to be (t ₄ −t ₃ ) on the second threshold value, whereas the time is (t ₂ -t ₂ ) due to the occurrence of slip. -T
₁ ) The rotation speed decreases in a short time.

That is, the attenuation gradient is

[0043]

(Equation 1) Since it is larger than the attenuation gradient of the second threshold value, it is assumed that a slip has occurred at this time, and the slope start assist operation is prohibited.

[0044] In other words, in the fourth embodiment the present invention, the car wheels Sri
The-up state is determined from the rotational speed damping state of the wheel, to change so that the damping gradient set threshold becomes steep, it makes a determination on the basis of the brake pressure when it exceeds the reference value The holding operation is prohibited so that the operation of holding the brake pressure is not performed in a state where the slippage occurs.

FIG. 9 is a flow chart showing the operation flow of the program control circuit according to the fourth embodiment of the present invention.

The program control circuit 10 includes a switching circuit 11
The switching circuit 11 is connected to the side of the stop lamp switch 3 having a low brake pressure (first threshold) or to the side of the brake pressure sensor 4 having a high brake pressure (second threshold). Judge whether
When it is connected to the stop lamp switch 3, the first threshold value is changed to a second threshold value of a high brake pressure.

Next, the rotational speed decay gradient of the wheel fetched from the rotation sensor 6 is compared with the second threshold value. If the decay of the wheel speed is equal to or less than the second threshold value, it is determined that a slip has occurred and the vehicle starts on a slope. The auxiliary device is prohibited, and the normal operation is executed if the decrease in the wheel speed is smaller than the second threshold value.

Thus, in the case of the fourth embodiment of the present invention,
The judgment criteria can be automatically changed according to the degree of slipperiness of the road surface, so that the driver can perform the driving operation without always being aware of the state of the slippery road surface. There is an advantage that safer traveling can be performed.

[0049]

As described above, according to the present invention, it is possible to prevent the brake pressure holding operation from being performed when the brake is temporarily applied with a small brake pressure. Therefore, when the vehicle is slipping on a slippery road such as a snowy road, a road wet with rain, or a fine gravel road, it is possible to avoid a disadvantage that the brake holding operation is performed even while the vehicle is running. effective.

Also, when the brake pedal is depressed to some extent, the slope start assist operation is performed, so that the driver can consciously perform or avoid the assist operation by increasing or decreasing the amount of depression. The driving operation can be performed easily.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a flowchart showing a flow of a brake holding operation of a program control circuit in the first embodiment of the present invention.

FIG. 3 is a flowchart showing a flow of a brake holding operation of the program control circuit in the first embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a second embodiment of the present invention.

FIG. 5 is a flowchart showing a flow of a brake holding operation based on a detection output from a stop lamp switch of a program control circuit in a second embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a third embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a fourth embodiment of the present invention.

FIG. 8 is a diagram showing a rotation speed attenuation gradient in a fourth embodiment of the present invention.

FIG. 9 is a flowchart showing an operation flow of a program control circuit according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brake pedal 2 Control valve 3 Stop lamp switch 4 Brake pressure sensor 5 Clutch sensor 6 Rotation sensor 7 Neutral switch 8 Brake pedal sensor 9 Gradient sensor 10 Program control circuit 11 Switching circuit 12 Switching switch 13 Temperature sensor

Claims (3)

(57) [Claims] 1. A control comprising a brake pressure sensor, a clutch sensor, a rotation sensor, and a neutral switch for indicating a neutral position of a shift lever, wherein the brake pressure is maintained in accordance with a control signal even when a brake pedal is released. In a hill start assist device including a valve and a program control circuit that receives the output of each sensor as an input and sends the control signal, the brake pressure sensor and the stop lamp switch are provided.
And a switching circuit that switches between the switch and the input of the control circuit.
And a brake pressure threshold value higher than a detection pressure of a stop lamp switch is set in the brake pressure sensor. Wherein a temperature sensor for detecting the air temperature, the switching circuit automatically hill start auxiliary switching is claim 1, wherein the high brake pressure threshold when the air temperature in accordance with the temperature sensor output is lower than the reference value apparatus. Wherein comprising a means for determining a slip state of the drive wheel from the rotational speed decay slope of the rotation sensor, the slope criteria of the rotational speed decay slope when said switching circuit is switched to a high brake pressure threshold The slope start assist device according to claim 1 or 2 , further comprising means for changing the vehicle speed so as to be steep.