JPH1078446A - Vehicle stop detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the running state and the stopping state of a vehicle accurately. SOLUTION: An acceleration sensor 2 detects the acceleration in the vehicle running direction. A vehicle-stop detecting circuit 3 nullifies the output of the vehicle-stop detection when the vibration exceeding a specified amplitude (a) is included in the output signal. When the vibration exceeding the specified amplitude disappears in the output signal of the acceleration sensor 2, the vehicle-stop detection output is made effective even if there is the negative acceleration having the absolute value larger than the specified value (-α) in the output signal of the accleration sensor 2. By this constitution, even when the vehicle runs on the slippery road surface or runs on the down-grade road surface, the stopping state of the vehicle can be accurately detected, and the auxiliary operation for slope-road starting without erroneous operation can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention is applied to automobiles. The invention relates to a device for identifying that a vehicle has completely stopped. The present invention has been developed for use in a slope start assist device, but can be widely used as a device for detecting a stopped state.

[0002]

2. Description of the Related Art A hill start assist device is a device for assisting a driver with a delicate operation when an automobile starts on a hill, and has recently been widely used for medium-sized trucks and the like. The hill start assist device automatically activates when the brake pedal is released after the vehicle depresses the brake pedal, stops, the clutch pedal is depressed, and the gear is shifted to the start position (or reverse position). The brake pressure is set so that the brake pressure is maintained as it is when the brake pedal is released. In this state, if the driver slowly depresses the clutch pedal while depressing the accelerator pedal little by little, the brake pressure is automatically released at a position where the clutch has properly met.

[0003] Since this device is easy to operate when starting uphill and can reduce the possibility of inadvertent reverse, etc., it has been well received as a product manufactured and sold by the present applicant. It has gained.

[0004] An acceleration sensor has been used for this slope start assist device (refer to the specification and drawings of Japanese Patent Application No. 8-130249, not disclosed at the time of filing the present application). By mounting an acceleration sensor sensitive to the traveling direction on the vehicle and measuring the gradient at the stop position of the vehicle, the operation of the accelerator or the clutch can be automatically adjusted according to the magnitude of the gradient.

[0005] The slope start assist device is not limited to being used not only on uphill roads, but also on flat roads in traffic or downhill roads, depending on the wishes of users or drivers. That is, in a state where the vehicle stops and starts repeatedly on a flat road where traffic is congested, a delicate operation of the clutch, brake and accelerator is repeated, and the driver gets tired. At this time, if the hill start assist device is used, it is possible to drive with less fatigue, for example, it is not necessary to keep depressing the brake pedal when the vehicle is stopped during a traffic jam. After getting used to such driving, even when the vehicle is stopped on a downhill, it is preferable to drive assuming that the slope start assist device operates. When starting from a state where the vehicle is stopped on a downhill, there is a demand that the hill start assist device should be able to be used, although the hill start assist device is originally unnecessary. In other words, when starting downhill, when the clutch pedal is depressed and the gear is engaged, the brake pressure is maintained even when the brake pedal is released, and when the clutch pedal is in the half-clutch position. The brake pressure is set to be automatically released.

[0006]

On the other hand, in order to operate the slope start assist device swiftly and safely, stop detection has become useful. If the brake is used while the vehicle is traveling on a slippery road with snow or ice, there may be a time when the wheel rotation is stopped but the vehicle is not actually stopped. To detect this, an acceleration sensor has been used. That is, it is assumed that when the vehicle is decelerating by using the brake, the road surface slips easily and the wheel rotation stops. Then, no output signal comes from the wheel rotation sensor, and the slope start assist device operates as if the vehicle has stopped. That is, if the brake pedal is depressed, the clutch pedal is depressed, and the gear is shifted to the start position, the brake pressure is maintained even when the brake pedal is released. Such control is confusing to the driver because it is not in the driver's consciousness.

For this purpose, the output of the acceleration sensor is taken,
When the acceleration sensor has a deceleration (negative acceleration), it is assumed that the vehicle is still running even if there is no output signal from the wheel rotation sensor. By using the acceleration sensor, the stop detection can be performed.

As a result, even when the wheels slide on the road surface, the stop detection is correctly performed. However, when the vehicle is stopped on a descending slope having a relatively large slope,
Since negative acceleration is detected by the acceleration sensor,
Conversely, it is determined that the vehicle is decelerating even though the vehicle is stopped, and the stop state cannot be accurately recognized.

The present invention has been made in view of such a background, and has as its object to accurately detect a running state and a stopped state of a vehicle. The present invention detects the stop state of a vehicle accurately by an output signal of a wheel rotation sensor and an output signal of an acceleration sensor even when traveling on a slippery road surface or when traveling on a downhill road surface. It is an object of the present invention to provide a stop detection device that can perform the stop. It is another object of the present invention to provide a hill start assist device that incorporates the stop detection device and that does not malfunction.

[0010]

SUMMARY OF THE INVENTION The present invention accurately detects whether a vehicle is stopped even if the vehicle stops on a relatively steep downhill slope and a negative acceleration is detected by an acceleration sensor. The control is not performed.

That is, a first aspect of the present invention is to detect the running or stopping of the vehicle by detecting the vibration of the acceleration in the running direction (x direction) of the vehicle. A rotation sensor that generates an output signal every time, an x-direction acceleration sensor that detects acceleration in the vehicle traveling direction, and a stop detection output that generates a stop detection output when the output signal of the rotation sensor is interrupted for a predetermined time t. A stop detection circuit for invalidating the stop detection output when a negative acceleration having an absolute value greater than a predetermined value (-α) is included in the output signal, wherein the stop detection circuit includes the acceleration sensor When the output signal of the acceleration sensor includes a vibration exceeding a predetermined amplitude a, the stop detection output is invalidated. The predetermined value to the output signal of the capacitors (-
a) means for making the stop detection output valid even when there is a negative acceleration having an absolute value larger than α).

The fact that the output signal of the acceleration sensor includes a vibration exceeding a predetermined amplitude a indicates that the vehicle is moving on the road surface even when the rotation of the wheels is stopped. For example, if a brake is applied while traveling on a slippery road surface with snow or ice, the wheel rotation is stopped, but the vehicle moves on the road surface due to slip, and the vibration caused by this movement is detected by the acceleration sensor. You. If the amplitude of the vibration exceeds a predetermined value a, it is determined that the vehicle is not in a stopped state, and the stop detection output is invalidated.

If the output signal of the acceleration sensor does not include a vibration exceeding a predetermined amplitude a, it indicates that the wheel rotation is in a stopped state and the vehicle is not in a moving state. Even if a negative acceleration having an absolute value larger than the predetermined value (-α) is indicated, the stop detection output is validated assuming that the vehicle is completely stopped on a descending slope having a relatively large gradient.

Thus, whether the vehicle is in a running state or a stopped state, even when the vehicle is running on a slippery road surface or when it is running on a downhill road surface. Can be accurately detected.

A second aspect of the present invention is to detect the vibration of acceleration not only in the traveling direction (x direction) of the vehicle but also in a direction perpendicular thereto, and the vibrations are substantially orthogonal to the x direction, respectively. Y-direction and z approximately orthogonal to each other
A y-direction acceleration sensor and a z-direction acceleration sensor for detecting accelerations in the respective directions, and when the output signals of the y-direction acceleration sensor or the z-direction acceleration sensor include vibrations exceeding predetermined amplitudes b and c, respectively, the stop detection output Is disabled, and when the output signals of the y-direction acceleration sensor or the z-direction acceleration sensor have eliminated vibrations exceeding the predetermined amplitudes b and c, respectively, the output signal of the x-direction acceleration sensor becomes smaller than the predetermined value (-α). A means for making the stop detection output valid even when there is a negative acceleration having a large absolute value is provided.

By providing an x-direction acceleration sensor, a y-direction acceleration sensor, and a z-direction acceleration sensor as acceleration sensors, accelerations caused by acceleration / deceleration of the vehicle, accelerations caused by vibrations, and accelerations caused by rocking are simultaneously detected. can do. Also in this case, it is assumed that the vehicle is not in a stopped state when each output signal of the y-direction acceleration sensor or the z-direction acceleration sensor includes a vibration exceeding a predetermined amplitude b or c, respectively. If the output signal of the y-direction acceleration sensor or the z-direction acceleration sensor does not include a vibration exceeding the predetermined amplitude b or c, the output signal of the x-direction acceleration sensor has a negative value having an absolute value larger than the predetermined value (−α). Even if the acceleration is indicated, the vehicle sends the stop detection output on the assumption that the vehicle is completely stopped on the downhill road surface. The provision of the three-direction acceleration sensor in this way makes it possible to more accurately detect the traveling state and the stopped state of the vehicle.

A third aspect of the present invention is a hill start assistance device for assisting hill start. Take the stop detection output from the stop detection circuit, when there is this stop detection output,
When the starting gear is turned on and the clutch pedal is depressed, a means for maintaining the brake pressure even when the brake pedal is released is provided.

When the vehicle stops on a relatively downhill slope, the acceleration sensor detects a negative acceleration (-α).
Is detected. Even if the output signal indicates a negative acceleration having an absolute value larger than the predetermined value (-α), the complete stop state of the vehicle is accurately detected by the stop detection circuit.
Slope start assistance can be automatically performed even on a downhill road. That is, when the clutch pedal is depressed and the gear is shifted to the start position, the brake pressure is maintained even when the brake pedal is released, and the brake pressure is automatically released when the clutch pedal is in the half-clutch position. Is done. By incorporating the stop detecting device according to the present invention into the slope start assist device in this way, it is possible to reliably perform the slope start assist without malfunction.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

[0020]

Next, an embodiment of the present invention will be described with reference to the drawings. The embodiment of the present invention will be described assuming that the stop detecting device is incorporated in the slope start assist device.

(First Embodiment) FIG. 1 is a block diagram showing the structure of a main part of a first embodiment of the present invention, and FIG. 2 shows the structure of a main part of a slope start assist device according to the first embodiment of the present invention. It is a block diagram.

The first embodiment of the present invention comprises a rotation sensor 1 for generating an output signal at each constant rotation angle of a wheel, an x-direction acceleration sensor 2 for detecting an acceleration in a vehicle running direction, and a rotation sensor 1 for a predetermined time t. When the output signal of (x) is interrupted, a stop detection output is generated, and when the output signal of the x-direction acceleration sensor 2 has a negative acceleration whose absolute value is larger than a predetermined value (-α), the stop detection output is invalidated. A detection circuit 3 is provided. The stop detection circuit 3 invalidates the stop detection output when the output signal of the x-direction acceleration sensor 2 includes a vibration exceeding a predetermined amplitude a, and outputs the output signal of the x-direction acceleration sensor 2. When the vibration exceeding the predetermined amplitude a has disappeared, the output signal of the x-direction acceleration sensor 2 has the predetermined value (-
Means are provided for validating the stop detection output even if there is a negative acceleration having an absolute value greater than α).

The hill start assist device 10 incorporating the present embodiment includes a clutch hydraulic switch 101, a brake sensor 102, a clutch sensor 103, a neutral switch 104 indicating a neutral position of a shift lever, and a brake. Control valve 10 that maintains brake pressure in accordance with a control signal even when pedal 111 is released
5 and a program control circuit 100 that receives the output of each of the sensors and switches and sends out a control signal. Outputs of the rotation sensor 1, the x-direction acceleration sensor 2 and the stop detection circuit 3 are sent to the program control circuit 100.

When the output of the brake sensor 102 indicates a braking state and the vehicle speed is zero, the program control circuit 100 sends a control signal to the control valve 105 to maintain the brake pressure. Control means, in a state where the brake pressure is held by the first control means,
A second control unit that indicates a forward start position or a reverse position, and that sends a control signal for releasing brake pressure when the clutch sensor 103 detects a predetermined stroke; Control means for releasing the brake pressure when the start is detected regardless of the control signal sent from the second control means.

In the driver's seat, a control unit 2 shown in FIGS. 2 and 5 is provided at a position where the driver can perform an operation while driving. The control unit 2 is provided with a main switch 21, a 7-segment display 22, a release adjustment switch 23, and an initial adjustment switch 24.

The main switch 21 opens and closes the power supply to the apparatus. In this example, the switch knob is closed to drive the apparatus when the switch knob is raised, and is stopped when the switch knob is lowered. 7-segment display 22 is decimal point 2
This is a 7-segment numeral display with a numeral, and a numeral is displayed in the course of adjustment.

FIG. 3 is an exploded perspective view showing the structure of the x-direction acceleration sensor used in the first embodiment of the present invention, and FIG. 4 is shown in FIG. 3 of the x-direction acceleration sensor used in the first embodiment of the present invention. 5 is a perspective view showing a configuration example of a control unit of the slope start assist device according to the first embodiment of the present invention.

The x-direction acceleration sensor 2 comprises a first frame 11 made of an insulator and a second frame 1 made of an insulator.
It is sandwiched between the second and third frames 13. The first frame 11 has a built-in weight 15 supported by a leaf spring 14, and movable electrodes are formed on both surfaces of the weight 15. Further, fixed electrodes 16 are provided at positions corresponding to the movable electrodes of the second frame 12 and the third frame 13, and the fixed electrodes 16 are formed between both surfaces of the weight 15 and the second frame 12 and the third frame 13. A space is provided between each. This acceleration sensor is sensitive to acceleration in the direction of the arrow shown in FIG. This type of acceleration sensor is already commercially available as a capacitance type, and it is possible to detect the acceleration in the traveling direction (x direction) of the vehicle by using this acceleration sensor, and the gravitational acceleration applied to the acceleration sensor is very small. It is structured so that it can be set to be. That is, as shown in FIG. 5, the x-direction acceleration sensor 2 is attached to the case 26 of the control unit 20,
When the control unit 20 is mounted on a vehicle body to be detected, for example, a ceiling of a driver's seat, the leaf spring 1 supporting the weight 15 is provided.
The influence of the gravitational acceleration can be eliminated by adjusting the angle of the bent portion 27 so that the angle of the bent portion 27 becomes vertical so that the minute acceleration can be detected with high accuracy. it can.

When the vehicle starts or stops or when the vehicle is on a slope, the weight (movable electrode) 15 moves in the direction of the arrow, and the gap between the weight (movable electrode) 15 and the fixed electrode 16 is increased. Changes. The change in the gap changes the dielectric constant. By taking this change in the dielectric constant as an electric signal and performing the processing, a very small acceleration of 1% unit of the gravitational acceleration can be detected.

Here, the operation of the first embodiment of the present invention configured as described above will be described. FIG. 6 is a flowchart showing the flow of the operation of the first embodiment of the present invention.

The stop detection circuit 3 takes in an output signal generated from the rotation sensor 1 at every constant rotation angle of the wheel, and determines whether or not the rotation speed is zero. If the rotation speed of the wheel is zero, the output of the x-direction acceleration sensor 2 (deceleration acceleration)
Then, it is determined whether or not the output signal includes a vibration exceeding a predetermined amplitude a.

If a vibration exceeding a predetermined amplitude a is included, the stop detection output is invalidated assuming that the vehicle is not stopped due to slip even if the wheel rotation indicates zero.
As a result, the program control circuit 10 of the slope start assist device
At 0, the stop detection signal is not transmitted, and the slope start assist operation is not executed.

If a vibration exceeding the predetermined amplitude a is not included, the output signal of the x-direction acceleration sensor 2 becomes a predetermined value (-
α), the brake sensor 10 determines that the vehicle is stopped on a downhill even if a negative acceleration having a large absolute value is shown.
2 is taken, and it is determined whether or not the brake pedal 111 is depressed beyond a set value. Brake pedal 1
If the step 11 is stepped on beyond the set value, it is assumed that the vehicle has stopped on a descending slope having a relatively large gradient, and the stop detection output is made valid and transmitted to the program control circuit 100.

Upon receiving the stop detection output, the program control circuit 100 sends a control signal to the control valve 105, drives the control valve 105, operates the brake valve 112, and performs the slope start assisting operation. As a result, when the clutch pedal is depressed and the gear is shifted to the start position,
Even when the brake pedal 111 is released, the brake pressure is maintained. When the stroke of the clutch pedal falls below a predetermined value, the brake pressure is automatically released, and the hill start assisting operation is released.

(Second Embodiment) FIG. 7 is a block diagram showing a configuration of a main part of a second embodiment of the present invention, and FIG. 8 is a block diagram showing an internal configuration of a stop detection circuit in a second embodiment of the present invention. .

The second embodiment of the present invention comprises an x-direction acceleration sensor for detecting acceleration in the vehicle traveling direction, and a y-direction for detecting accelerations in the y-direction and the z-direction substantially orthogonal to each other in the x-direction, respectively. Acceleration sensor and z
A three-way acceleration sensor 32 including a directional acceleration sensor is provided. Further, when the output signals of the y-direction acceleration sensor or the z-direction acceleration sensor include vibrations exceeding the fixed amplitudes b and c, the stop detection output is invalidated. , When the vibrations exceeding the predetermined amplitudes b and c have disappeared in the output signals of the y-direction acceleration sensor or the z-direction acceleration sensor, respectively, the output signal of the x-direction acceleration sensor has a negative value having an absolute value larger than a predetermined value (−α). A stop detection circuit 33 provided with means for validating the stop detection output even when there is acceleration is provided.

The stop detecting circuit 33, as shown in FIG.
A switch 331 for switching an output signal from the three-directional acceleration sensor 32 in accordance with a switch signal, a threshold slice circuit 332 for setting a threshold in accordance with a threshold change signal, and a switch signal sent to the switch 331 and a threshold slice circuit 332 And a detection circuit 333 for detecting vibrations in the x, y, and z directions according to the set threshold.

As shown in FIG. 9, an acceleration sensor for detecting accelerations in the x-direction (traveling direction), the y-direction (lateral direction) and the z-direction (vertical direction) is integrally incorporated in the three-direction acceleration sensor 32. Alternatively, a structure in which three acceleration sensors in one direction in the first embodiment are attached in the x, y, and z directions can be used. The three-directional acceleration sensor 33 is attached to the case 26 of the control unit 20 shown in FIG.

The slope start assist device according to the second embodiment is configured in the same manner as the first embodiment shown in FIG.

The operation of the second embodiment of the present invention will now be described. FIG. 10 is a flowchart showing the flow of the operation of the second embodiment of the present invention.

The stop detection circuit 33 takes in an output signal generated from the rotation sensor 1 for each constant rotation angle of the wheel, and determines whether or not the rotation speed is zero. If the rotation speed of the wheel is zero, the x-direction acceleration α _x , the y-direction acceleration α _y and z
The directional acceleration α _Z is taken in, and a comparison with a threshold set in the threshold slice circuit 332 is performed by switching of the switch 331.

First, it is determined whether or not the x-direction acceleration (acceleration / deceleration) includes an impression exceeding a predetermined amplitude a. If a vibration exceeding the predetermined amplitude a is included, the vehicle is moved by slipping even if the wheel rotation is zero, and the stop detection output is invalidated as being not in a stopped state. Therefore, the stop detection signal is not sent to the program control circuit 100 of the slope start assist device, and the slope start assist operation is not executed.

If a vibration exceeding the predetermined amplitude a is not included, it is determined whether or not a vibration exceeding the predetermined amplitude b is included in the y-direction acceleration (lateral acceleration). Predetermined amplitude b
If the vibration exceeds the threshold, it is determined that the vehicle is moving, the stop detection output is invalidated, and the slope start assist operation is stopped. If the vibration exceeding the predetermined amplitude b is not included, it is determined whether or not the z-direction acceleration (vertical acceleration) includes the vibration exceeding the predetermined amplitude c.

If a vibration exceeding the predetermined amplitude c is included, the vehicle is not in a completely stopped state, the stop detection output is invalidated, and the slope start assist operation is stopped. If no vibration exceeding the predetermined amplitude c is included, as shown in FIG.
Even if the output signal of the x-direction acceleration sensor indicates a negative acceleration having an absolute value larger than a predetermined value (-α), the output of the brake sensor 102 is taken as the vehicle is stopped on a downhill, and the brake pedal 111 is taken. It is determined whether or not is stepped over the set value. If the brake pedal 11 is depressed beyond the set value, the stop detection output is made valid and transmitted to the program control circuit 100. Program control circuit 1
00 executes the slope start assisting operation as in the first embodiment.

[0045]

As described above, according to the present invention, the running state and the stopped state of the vehicle can be accurately detected. Thereby, even when the vehicle travels on a slippery road surface, or when traveling on a downhill road surface, or when stopping on a steep downhill, the vehicle stop state is accurately detected, Slope start assistance without malfunction can be performed.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a configuration of a main part of the slope start assist device according to the first embodiment of the present invention.

FIG. 3 is an exploded perspective view showing a structure of an x-direction acceleration sensor used in the first embodiment of the present invention.

FIG. 4 is a sectional view of the x-direction acceleration sensor used in the first embodiment of the present invention, taken along the line AA shown in FIG. 3;

FIG. 5 is a perspective view showing a configuration example of a control unit of the slope start assist device according to the first embodiment of the present invention.

FIG. 6 is a flowchart showing the flow of the operation of the first embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a main part of a second embodiment of the present invention.

FIG. 8 is a block diagram showing an internal configuration of a stop detection circuit according to a second embodiment of the present invention.

FIG. 9 is a diagram showing a detection direction of a three-way acceleration sensor according to the embodiment of the present invention.

FIG. 10 is a flowchart showing the flow of the operation of the second embodiment of the present invention.

FIG. 11 is a diagram illustrating acceleration detection by a three-way acceleration sensor according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotation sensor 2 x direction acceleration sensor 3, 33 Stop detection circuit 10 Slope start assist device 11 First frame 12 Second frame 13 Third frame 14 Leaf spring 15 Weight (movable electrode) 16 Fixed electrode 20 Control unit 21 Main switch 22 7-segment display 23 Release adjustment switch 24 Initial adjustment switch 25 Decimal point 26 Case 27 Bending part 32 Three-way acceleration sensor 100 Program control circuit 101 Clutch hydraulic switch 102 Brake sensor 103 Clutch sensor 104 Neutral・ Switch 105 Control valve 111 Brake pedal 112 Brake valve 331 Switch 332 Threshold slice circuit 333 Detection circuit

Claims (3)

[Claims] 1. A rotation sensor for generating an output signal for each constant rotation angle of a wheel, and an x for detecting an acceleration in a vehicle traveling direction.
A direction acceleration sensor and a stop detection output when the output signal of the rotation sensor is interrupted for a predetermined time t, and a negative acceleration having an absolute value larger than a predetermined value (−α) is present in the output signal of the acceleration sensor. A stop detection circuit for invalidating the stop detection output, wherein the stop detection circuit invalidates the stop detection output when the output signal of the acceleration sensor includes a vibration exceeding a predetermined amplitude a. When the output signal of the acceleration sensor has no vibration exceeding a predetermined amplitude a, even if the output signal of the acceleration sensor has a negative acceleration whose absolute value is larger than the predetermined value (-α), the stop detection output is output. A vehicle stop detecting device comprising means for making the vehicle effective. 2. A y-direction acceleration sensor and a z-direction acceleration sensor for respectively detecting accelerations in a y-direction and a z-direction substantially orthogonal to the x-direction and substantially orthogonal to each other, wherein the y-direction acceleration sensor or the z-direction acceleration When the output signals of the sensors include vibrations exceeding the predetermined amplitudes b and c, the stop detection output is invalidated, and the output signals of the y-direction acceleration sensor or the z-direction acceleration sensor include vibrations exceeding the predetermined amplitudes b and c, respectively. Means for enabling the stop detection output even when the output signal of the x-direction acceleration sensor has a negative acceleration having an absolute value greater than the predetermined value (-α) when the signal has disappeared. Stop detection device. 3. The stop detection output according to claim 1 or 2, wherein when the stop detection output is present, when the starting gear is engaged and the clutch pedal is depressed, the brake pressure is reduced even if the brake pedal is released. Slope start assist device with holding means.