JPH10264634A - Vehicular turning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce minimum turning radius with a simplified structure and also make it applicable to general vehicles as well. SOLUTION: Each wheel W position is provided with a hydraulic suspension mechanism 10 including a hydraulic cylinder 11. A microcomputer 20 controls a pressure control valve 12 through respective drive circuits 21 and variably controls oil pressure of the hydraulic cylinder 11. When a vehicle makes a turn, the microcomputer 20 raises the hydraulic cylinder 11 oil pressure corresponding to a front wheel W on the outer side of the turn and lowers the hydraulic cylinder 11 oil pressure corresponding to a front wheel W on the inner side of the turn based on the detection of a steering angle sensor 23. Thus the grounding load of the front W on the outer side of the turn increases and the vehicular minimum turning. radius becomes small by the vehicular turning center displacing to the body side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turning device for a vehicle in which a pair of left and right front wheels are steered to turn the vehicle in accordance with the turning of a steering wheel.

[0002]

2. Description of the Related Art Conventionally, as a method of reducing a minimum turning radius of a vehicle, a first method of increasing a maximum steering angle of a front wheel is described.
And a second method of steering the rear wheels in the opposite phase to the front wheels. In a special vehicle such as a tractor, for example, as disclosed in Japanese Patent Application Laid-Open No. 2-34479, a turning radius is reduced by floating an inner front wheel during turning to form a three-wheel state. Is also known.

[0003]

However, in the above-mentioned first conventional method, it is necessary to increase the size of the wheel house in order to increase the maximum steering angle of the front wheels. There is a problem that space for the space is insufficient. Further, the second conventional method has a problem that a complicated device for steering the rear wheels is required. In addition, the method for a special vehicle such as the tractor described above becomes very unstable when the vehicle runs, and therefore cannot be applied to general vehicles such as passenger cars and trucks that run on general roads carrying humans, cargo, and the like. Moreover, the above-mentioned publication does not disclose any control means for driving the vehicle in a three-wheel state.

SUMMARY OF THE INVENTION The present invention has been made to address these problems, and has as its object to reduce the minimum turning radius with a simple structure and to turn a vehicle which can be applied to general vehicles. It is to provide a device.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the constitutional features of the present invention are: a ground contact load varying mechanism capable of changing the distribution of a ground contact load between a pair of left and right front wheels; A steering angle sensor for detecting at least a turning direction of the steering wheel, and a ground contact load of a wheel on the outer side of the turning of the pair of left and right front wheels by controlling a ground contact load varying mechanism based on the turning direction of the steering wheel detected by the steering angle sensor. And a contact load control means for increasing the distribution of the load.

[0006]

In the turning device for a vehicle having the above-mentioned structural features of the present invention, when the steering wheel is turned and the vehicle turns in the same turning direction, the ground load control means sets the steering angle. The ground load variable mechanism is controlled based on the detection of the turning direction of the steering wheel by the sensor, and the distribution of the ground load of the outer wheel of the pair of left and right front wheels is increased.
At this time, as shown in FIG. 6, as the distribution of the ground contact load of the wheels outside the turning increases, the turning center of the vehicle moves from the Z point side to the X point side, and the turning radius decreases. Therefore, according to the present invention, the minimum turning radius of the vehicle can be reduced with a simple configuration without increasing the size of the wheel house. Further, in this case, the present invention can be applied to a general vehicle running on a general road because only the ground load of the left and right front wheels is controlled and the left and right front wheels remain in contact with the road surface.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

a. First Embodiment First, a first embodiment of the present invention in which the present invention is applied to an existing hydraulic suspension device will be described with reference to the drawings. FIG. 1 schematically shows the entire vehicle according to the embodiment.

The vehicle is provided with hydraulic cylinders 11 as actuators constituting the hydraulic suspension mechanism 10 at each of the front, rear, left and right wheel W positions (only one is shown). Each hydraulic cylinder 11 supports the vehicle body BD by hydraulic pressure, and changes the distance between each corresponding wheel W and the vehicle body BD according to the hydraulic pressure. In this case, for the pair of left and right hydraulic cylinders 11 and 11 and the front wheels W and W, the hydraulic pressure of one cylinder 11 is increased to increase the distance between the corresponding one front wheel W and the vehicle body BD, or the other cylinder 11 When the distance between the corresponding front wheel W and the vehicle body BD is reduced by lowering the hydraulic pressure, the distribution of the ground contact load of the same front wheel W increases. A pressure control valve 12 is connected to a pair of oil chambers of each hydraulic cylinder 11. Each pressure control valve 12
Is connected to the hydraulic pump 13 at the supply port and connected to the reservoir 14 at the discharge port, and controls the hydraulic pressure in each hydraulic cylinder 11 to a value corresponding to the input control signal.

This vehicle has a microcomputer 20. The microcomputer 20 repeatedly executes a program corresponding to the flowchart of FIG. 2 every predetermined short time, outputs a control signal to each pressure control valve 12 via each drive circuit 21, and outputs a control signal to each hydraulic cylinder 11.
The hydraulic pressure in each is controlled independently. The microcomputer 20 is also connected to a vehicle speed sensor 22 for detecting a vehicle speed V and a steering angle sensor 23 for detecting a steering angle θ of a steering wheel (not shown). Note that the steering angle θ
Represents a steering angle from the neutral state of the steering wheel to the right direction with a positive value, and represents a steering angle from the neutral state of the steering wheel to the left direction with a negative value.

Next, the first embodiment of the present invention configured as described above is described.
The operation of the embodiment will be described with reference to the flowchart of FIG. The microcomputer 20 performs step 100 in accordance with the operation of turning on an ignition switch (not shown).
At step 102, the vehicle speed V and the steering angle θ detected by the vehicle speed sensor 22 and the steering angle sensor 23 are input. Then, in steps 104 and 106, it is determined whether or not the input vehicle speed V is equal to or less than a predetermined vehicle speed V0 (for example, 10 km / h), and the absolute value of the input steering angle θ is determined. It is determined whether or not the angle is equal to or larger than a predetermined angle θ0 (for example, a steering wheel angle of 270 degrees, that is, a wheel steering angle of 25 degrees).

First, when the vehicle is traveling at a medium or high speed or is almost in a straight line, the input vehicle speed V is greater than a predetermined vehicle speed V0 or the absolute value of the input steering angle θ is less than a predetermined angle θ0. A case will be described. In this case, the microcomputer 20 advances the program to step 108 and subsequent steps based on the determination of “NO” in step 104 or 106, and executes processing for keeping the hydraulic pressure of each hydraulic cylinder 11 at its reference hydraulic pressure.

The microcomputer 20 performs step 1
At 08, the target hydraulic pressures PL, PR of the left and right front wheels W, W are set to the reference hydraulic pressures PL0, PR0, respectively. Each of the reference oil pressures PL0 and PR0 is set according to the loaded weight of the vehicle, the driver's selection, and the like by executing a program (not shown). In step 110, control signals are output to the pressure control valves 12, 12 corresponding to the left and right front wheels W, W via the drive circuits 21, 21, respectively.
The hydraulic pressures of the hydraulic cylinders 11, 11 corresponding to the front wheels W, W are controlled to the set target hydraulic pressures PL, PR, respectively. Thereby, at this time, each of the hydraulic cylinders 11,
Each of the hydraulic pressures 11 is maintained at the reference hydraulic pressure. Then, the microcomputer 20 ends the execution of this program in step 118.

In this state, the distribution of the ground load between the left and right front wheels W, W is substantially equal, and the turning center of the vehicle is shown in FIG.
And the vehicle turns with a normal turning radius even when the steering wheel is turned.

Next, the vehicle is running at a low speed and is in a sharp turning state, the input vehicle speed V is equal to or lower than a predetermined vehicle speed V0, and the absolute value of the input steering angle θ is equal to the predetermined angle θ.
The case where the value is 0 or more will be described. In this case, the microcomputer 20 advances the program to step 112 and subsequent steps based on the determination of “YES” in steps 104 and 106, and executes a process of changing the hydraulic pressure of each hydraulic cylinder 11.

The microcomputer 20 performs step 1
At 12, the target ground load change amounts △ WL, △ WR of the left and right front wheels W, W corresponding to the input steering angle θ are calculated with reference to a map (FIG. 3) provided in the computer 20. . In this map, the solid line rising to the right and the dashed dotted line falling to the right indicate the target contact load change amounts △ WL, △ WR of the left and right front wheels W, W with respect to the steering angle θ, respectively. Thus, a positive value is calculated as the target contact load change amount of the front wheel W on the outside of the turn, and a negative value is calculated as the target contact load change amount of the front wheel W on the inside of the turn.

After the processing in step 112, the microcomputer 20 determines in step 114 the hydraulic cylinders 11, 11 corresponding to the left and right front wheels W, W from the calculated target contact load change amounts 荷重 WL, △ WR, respectively. Are calculated. Specifically, for each of the reference hydraulic pressures PL0 and PR0 of each of the hydraulic cylinders 11 and 11, a coefficient K set in advance for each of the target contact load change amounts △ WL and △ WR.
The values multiplied by 1 are added to obtain target hydraulic pressures PL, PR of the hydraulic cylinders 11, 11, respectively. Coefficient K
1 is the amount of change in the ground contact load △ WL, △ WR of the left and right front wheels W, W
And hydraulic cylinders 11, 11 corresponding to the front wheels W, W, respectively.
And the amount of change in hydraulic pressure.

After the processing in step 114, the microcomputer 20 executes processing similar to the processing in step 110 in step 116 to execute the left and right front wheels 11, 1
The hydraulic pressures of the hydraulic cylinders 11 corresponding to 1 are controlled to the calculated target hydraulic pressures PL and PR, respectively. Then, in step 118, the execution of this program ends.

As described above, the target contact load change amount △ W
Since the target contact load change amount for the front wheel W on the outside of turning is a positive value and the target contact load change amount for the front wheel W on the inside of the turn is a negative value among L and △ WR, the target hydraulic pressure PL,
In PR, the target oil pressure for the front wheel W on the outside of turning is higher than the reference oil pressure of the front wheel W, and the target oil pressure for the front wheel W on the inside of turning is lower than the reference oil pressure of the front wheel W. Thereby, the distribution of the ground load of the wheel W on the outer side of the turn among the left and right front wheels W, W increases, and the turning radius of the vehicle decreases.

This will be described with reference to the drawings. FIG. 6A is a diagram showing the turning operation of the vehicle. In the figure, Y is the turning center of the vehicle when the ground load is evenly distributed to the left and right front wheels, and X is the case where the ground load is distributed only to the outer front wheel of the left and right front wheels. Is the turning center of the vehicle, and Z in the figure is the turning center of the vehicle when the grounding load is distributed only to the front wheel on the inside of the turn among the left and right front wheels. FIG. 6B is a graph showing the relationship between the contact load distribution and the turning center of the vehicle. That is, as the distribution of the ground load of the front wheels on the outer side of the turn among the left and right front wheels increases, the turning center of the vehicle becomes Z
Since the vehicle moves from the side to the X side, the turning radius of the vehicle is reduced.

Therefore, according to the first embodiment,
Since the existing hydraulic suspension device can be used without increasing the size of the wheel house, the minimum turning radius of the vehicle can be reduced with a simple configuration. Further, since the left and right front wheels W, W only control the ground contact load, and the left and right front wheels W, W are kept in contact with the road surface, the present invention can be applied to a general vehicle amount traveling on a general road.

In the first embodiment, the turning is performed by increasing the hydraulic pressure of the hydraulic cylinder 11 corresponding to the front wheel W on the outside of turning and decreasing the hydraulic pressure of the hydraulic cylinder 11 corresponding to the front wheel W on the inside of turning. Outer front wheel W
Although the distribution of the ground load is increased, the distribution of the ground load of the front wheel W on the outside of the turn may be increased only by the hydraulic control of one of the hydraulic cylinders 11. That is, only by increasing the hydraulic pressure of the hydraulic cylinder 11 corresponding to the front wheel W on the outside of the turn, or by decreasing the hydraulic pressure of the hydraulic cylinder 11 corresponding to the front wheel W on the inside of the turn, the left and right front wheels W, W have the outermost turn. The distribution of the ground load of the wheel W may be increased.

B. Second Embodiment Next, a second embodiment of the present invention in which the present invention is applied to an existing air suspension device will be described with reference to the drawings. FIG. 4 schematically shows the entire vehicle according to the embodiment.

This vehicle has a damper 3 constituting an air suspension mechanism 30 at each of front, rear, left and right wheel W positions.
1. An air chamber 32 as an actuator and a vehicle height sensor 33 are provided (only one set is shown).
Each damper 31 and the air chamber 32 cooperate to form the vehicle body BD.
Each air chamber 32 changes the distance (vehicle height) between each corresponding wheel W and the vehicle body BD according to the air pressure. In this case, for the pair of left and right air chambers 32, 32 and the front wheels W, W, the air pressure in one chamber 32 is increased to increase the distance between the corresponding one front wheel W and the vehicle body BD, or the other chamber 3
2 and the other front wheel W and body BD
, The distribution of the grounding load of the same front wheel W increases.

Each vehicle height sensor 33 detects the distance (vehicle height) between the corresponding wheel W and the vehicle body BD. Each air chamber 32 is connected to a common compressor 35 via an electromagnetic valve 34. Each electromagnetic valve 3
4 selectively opens and closes the air flow path for each air chamber 32 (in the illustrated closed state). Compressor 35
Are selectively driven by an electric motor 36 to supply air to each air chamber 32. An electromagnetic valve 37 communicating with the atmosphere is connected to a common flow path for each air chamber 32 downstream of the discharge port of the compressor 35. The electromagnetic valve 37 selectively communicates the common flow path with the outside air (not shown in the drawing).

This vehicle has a microcomputer 40. The microcomputer 40 repeatedly executes a program corresponding to the flowchart of FIG. 5 every predetermined short time, and operates the electromagnetic valves 34, the electric motor 36, and the electromagnetic valve 37 based on the detection of the vehicle height sensors 33. The distance between each wheel W and the vehicle body BD is controlled independently. The microcomputer 40 is also connected to a vehicle speed sensor 41 and a steering angle sensor 42, which are respectively similar to the vehicle speed sensor 22 and the steering angle sensor 23 in the first embodiment.

Next, the second embodiment of the present invention constructed as described above
The operation of the embodiment will be described with reference to the flowchart of FIG. This flowchart corresponds to steps 108 and 11 in the flowchart of FIG. 2 described in the first embodiment.
The processing of steps 0, 114, and 116 is replaced with the processing of steps 120 to 126.

If the vehicle is traveling at a medium or high speed or is almost in a straight line, the vehicle speed V input in step 102 is greater than the predetermined vehicle speed V0, or the absolute value of the steering angle θ input in step 102 is If the angle is less than the predetermined angle θ0, the microcomputer 20 advances the program to step 120 and subsequent steps based on the determination of “NO” in step 104 or 106, and the vehicle body B of the left and right front wheels W, W
A process for keeping the distance to D at the reference distance is executed.

In this case, the microcomputer 20
At step 120, each target distance H of the left and right front wheels W, W
L and HR are set to the values of the reference distances HL0 and HR0, respectively. The values of the reference distances HL0 and HR0 are set by executing a program (not shown) according to the loaded weight of the vehicle, the driver's selection, and the like. In step 122, the operation of the electromagnetic valves 34, 34, the electric motor 36, and the electromagnetic valve 37 is controlled based on the detection of the vehicle height sensors 33, 33, and the left and right front wheels W, W and the vehicle body BD are controlled.
Are controlled to the respective set target distances HL and HR.

Specifically, when the distance between the wheel W and the vehicle body BD detected by the vehicle height sensor 33 is smaller than the target distance, the microcomputer 20 controls the electric motor 36
Is operated to drive the compressor 35, and the electromagnetic valve 34 corresponding to the sensor 33 is switched from the illustrated state to open the air flow path to the air chamber 32 corresponding to the sensor 33. Thereby, the air discharged from the compressor 35 is supplied to the air chamber 32 via the electromagnetic valve 34, and the air pressure in the air chamber 32 increases, so that the distance between the wheel W and the vehicle body BD increases. When the distance reaches the target distance, the operation of the electric motor 36 is stopped, and the electromagnetic valve 34 is returned to the illustrated state.

On the other hand, when the distance between the wheel W and the vehicle body BD detected by the vehicle height sensor 33 is larger than the target distance, the microcomputer 20 switches the electromagnetic valves 37 from the state shown in FIG. The passage is communicated with the outside air, and the electromagnetic valve 34 corresponding to the sensor 33 is switched from the illustrated state to open the air flow path to the air chamber 32 corresponding to the sensor 33. As a result, the air in the air chamber 32 is removed from the electromagnetic valve 3.
4, the air pressure is released to the outside air via the air chamber 32 and the air pressure in the air chamber 32 is reduced, and the distance between the wheel W and the vehicle body BD is reduced. When the distance reaches the target distance, the electromagnetic valves 34 and 37 are returned to the illustrated state.

By the above-mentioned respective controls, the left and right front wheels W,
The distance between W and the vehicle body BD is maintained at the reference distance. Then, the microcomputer 20 executes step 11
At 8, the execution of this program is terminated. In this state, as in the case of the first embodiment, the turning center of the vehicle is near point Y in FIG. 6A.

On the other hand, when the vehicle is traveling at a low speed and is in a sharp turning state, the input vehicle speed V is equal to or lower than the predetermined vehicle speed V0, and the absolute value of the input steering angle θ is equal to the predetermined angle θ.
If it is 0 or more, the microcomputer 20 advances the program to step 108 and thereafter based on the determination of “YES” in steps 104 and 106, and changes the distance between the left and right front wheels W and W to the vehicle body BD. Execute the processing to be performed.

In this case, the microcomputer 20
In step 112, the ground contact load change amounts △ WL, △ WR of the left and right front wheels W, W are calculated using the map of FIG. 3 as in the case of the first embodiment. The target distances HL, HR of the left and right front wheels W, W to the vehicle body BD are calculated from the load change amounts △ WL, △ WR. Specifically, for each of the reference distances HL0, HR0 of each of the front wheels W, W to the vehicle body BD, each target contact load change amount △ W
The values obtained by multiplying L and 値 WR by a preset coefficient K2 are respectively added to obtain target distances HL and HR of the front wheels W and W to the vehicle body BD. The coefficient K2 is determined by the left and right front wheels W,
And the front wheel W, W
And the amount of change in the distance from the vehicle body BD.

After the process of step 124, the microcomputer 20 executes a process similar to the process of step 122 in step 126 to calculate the distances between the left and right front wheels W, W and the vehicle body BD. Distance HL, HR
Respectively. Then, in step 118, the execution of this program ends.

As described above, the target contact load change amount △ W
Since the target contact load change amount for the front wheel W outside the turn is a positive value and the target contact load change amount for the front wheel W inside the turn is a negative value among L and △ WR, the target distances HL,
Of the HR, the target distance to the front wheel W on the outside of turning is larger than the reference distance of the front wheel W, and the target distance to the front wheel W on the inside of turning is smaller than the reference distance of the front wheel W.
As a result, of the left and right front wheels W, W,
Since the distribution of the ground contact load increases and the turning radius of the vehicle decreases, the same effect as in the first embodiment can be expected.

In the second embodiment, the distance between the outer front wheel W and the vehicle body BD is increased while the distance between the inner front wheel W and the vehicle body BD is reduced. Although the distribution of the grounding load is increased, the distribution of the grounding load of the front wheel W on the outside of the turn may be increased by controlling only the distance between one of the wheels W, W and the vehicle body. That is, only by increasing the distance between the outer front wheel W and the vehicle body BD or by decreasing the distance between the inner front wheel W and the vehicle body BD, of the left and right front wheels W, W, The distribution of the grounding load may be increased.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram of a vehicle according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a program executed by the microcomputer of FIG.

FIG. 3 shows a steering angle θ and a target contact load change amount △ WL, △ WR in a map built in the microcomputer of FIG. 1;
6 is a graph showing a relationship with the graph.

FIG. 4 is an overall schematic diagram of a vehicle according to a second embodiment of the present invention.

FIG. 5 is a flowchart showing a program executed by the microcomputer of FIG. 4;

6A is a diagram illustrating a turning operation of the vehicle for explaining the principle of the present invention, and FIG. 6B illustrates a relationship between a turning center point of FIG. It is a graph.

[Explanation of symbols]

W: Wheel, BD: Body, 10: Hydraulic suspension mechanism, 11: Hydraulic cylinder, 12: Pressure control valve, 2
0, 40: microcomputer, 23, 42: steering angle sensor, 30: air suspension mechanism, 32: air chamber, 33: vehicle height sensor, 34, 37 solenoid valve, 35
…compressor.

Claims (1)

[Claims] 1. A turning device for a vehicle in which a pair of left and right front wheels are steered in the same turning direction in response to turning of a steering wheel to turn the vehicle in the same turning direction. A grounding load variable mechanism capable of changing a load distribution, a steering angle sensor for detecting at least a turning direction with respect to a neutral state of the steering wheel, and the grounding based on a turning direction of the steering wheel detected by the steering angle sensor. A turning device for a vehicle, comprising: a ground load control unit that controls a load variable mechanism to increase a distribution of a ground load of a wheel on a turning outside of the pair of left and right front wheels.