WO2024190213A1

WO2024190213A1 - Vehicle attitude control device

Info

Publication number: WO2024190213A1
Application number: PCT/JP2024/004540
Authority: WO
Inventors: 洋平牧田
Original assignee: 株式会社アイシン
Priority date: 2023-03-13
Filing date: 2024-02-09
Publication date: 2024-09-19

Abstract

Provided is a vehicle attitude control device (S) in which: left and right wheels (T) are attached to a vehicle body (3) by way of springs (1) and dampers (2); a left telescopic unit (4L) and a right telescopic unit (4R) that utilize fluid pressure are individually provided between the left and right springs (1) and the vehicle body (3) or the wheels (T); an accumulator (5) that holds fluid at the same pressure is connected to each of the left and right telescopic units (4L, 4R) by way of a first flow path (R1); a second flow path (R2) that can be connected and disconnected separately from the first flow path (R1) is connected together with a first control valve (V1) across the left and right telescopic sections (4L, 4R); a pump (P) having a reservoir function is connected by way of a second control valve (V2) so as to communicate with the first flow path (R1) or the second flow path (R2); and the vehicle attitude control device (S) is provided with a control unit (ECU) that operates the first control valve (V1), the second control valve (V2), and the pump (P).

Description

Vehicle attitude control device

The present invention relates to a vehicle attitude control device that utilizes fluid pressure and is provided, for example, on the left and right front wheels and/or the left and right rear wheels of a four-wheel vehicle.

Conventional vehicle attitude control devices include, for example, those shown in Patent Document 1 (see Figure 1 for [0010], [0031], [0038], [0043], [0062] to [0064]).

This technology includes suspension springs and hydraulic cylinders 1-4 that perform functions similar to shock absorbers, and also includes vehicle height adjustment devices 41-44 that are attached to the hydraulic cylinders 1-4 and adjust the vehicle height.

Pistons 1B-4B inserted into hydraulic cylinders 1-4 move up and down due to hydraulic oil contained inside, cushioning the pitching, rolling, and other shaking vibrations that occur in the vehicle body 100. In order to achieve both the vehicle's ability to travel on rough roads and its handling stability on good roads, for example, the upper chamber A and lower chamber B of the left and right

hydraulic cylinders

1, 2 are cross-piped with first and second connecting

pipes

5, 6.

When damping vibrations, hydraulic oil flows between the right-side and left-side communication passages 23 and 24 and the left and right accumulator devices 25. The damping valves 29 of each accumulator device 25 generate a damping force by throttling resistance to the hydraulic oil flowing therethrough, damping the expansion and contraction movements of the hydraulic cylinders 1 to 4. The driver of the vehicle manually operates a roll stiffness selection switch to adjust the accumulator device 25 to a specified pressure, switching the roll stiffness of the suspension device.

Meanwhile, the vehicle height adjustment device 41 adjusts the relative distance between the vehicle body 100 and the wheels W by pressure oil supplied from the pump 33 via the supply and exhaust line 35, the vehicle height adjustment line 39, and the vehicle height control valve 45. The vehicle height control valve 45 is, for example, a normally closed solenoid valve, and normally blocks the vehicle height adjustment device 41 from the vehicle height adjustment line 39.

As a result, the height adjustment device 41 on the left front wheel side raises the height of the body 100 on the left front wheel Wfl side when pressurized oil from the pump 33 is supplied via the height adjustment pipe 39 and the height control valve 45. On the other hand, when the pressurized oil in the height adjustment device 41 is discharged to the tank 34 side via the height control valve 45, the height adjustment pipe 39, and the supply and discharge pipe 35, the vehicle height is lowered on the left front wheel Wfl side.

This device is said to be able to dampen pitching, rolling, and other shaking vibrations that occur in the vehicle body 100, and also to raise and lower the vehicle height of the vehicle body 100.

JP 2020-157797 A

In the above-mentioned conventional vehicle attitude control device, both the hydraulic cylinders 1-4, which dampen the pitching, rolling, and other swaying vibrations that occur in the vehicle body 100, and the vehicle height adjustment devices 41-44, which adjust the vehicle height, are controlled using hydraulic oil. This makes the piping configuration for the hydraulic oil extremely complicated.

In addition, because the piping related to the hydraulic cylinders 1-4 and the piping related to the vehicle height adjustment devices 41-44 are connected, many control valves must be operated to distinguish the supply and discharge of hydraulic oil to each, making the control work complicated. In this way, the hydraulic cylinders and accumulators take over the damper function of a typical vehicle, resulting in an unsatisfactory ride.

As such, conventional vehicle attitude control devices have various issues that need to be resolved, and there is a demand for a vehicle attitude control device that has a simple structure and can effectively control the vehicle's lateral sway characteristics and adjust the vehicle height.

(Characteristics)
The vehicle attitude control device according to the present invention has the following characteristic configuration:
The left and right wheels are attached to the body via springs and dampers,
In each of the left and right springs, a left telescopic portion and a right telescopic portion utilizing fluid pressure are provided between the spring and the vehicle body or between the spring and the wheel,
An accumulator that holds the fluid at the same pressure as the fluid in the left and right telescopic portions is connected to each of the left and right telescopic portions via a first flow path,
a second flow passage that can be opened and closed separately from the first flow passage is connected between the left telescopic portion and the right telescopic portion, the second flow passage being accompanied by a first control valve;
a pump having a reservoir function is connected to the first flow path or the second flow path via a second control valve;
A control unit is provided to operate the first control valve, the second control valve, and the pump.

(effect)
In this configuration, by providing left and right expansion sections for the springs supporting the left and right wheels, and providing a second flow path and a first control valve across these left and right expansion sections, it is possible to improve the lateral sway characteristics when the vehicle is traveling.

For example, when the vehicle is running normally, the second control valve is shut off by the control unit. This restricts the flow of fluid between the left and right telescopic sections, and the left and right telescopic sections mainly supply and discharge fluid to and from the accumulator via the first flow path. When the vehicle is turning, the flow of fluid from the telescopic section that is shrinking on the outside of the turn toward the accumulator is resisted by the function of the accumulator. Meanwhile, on the inside of the turn, where the ground load is decreasing, fluid is supplied from the accumulator to the telescopic section, where the internal pressure is decreasing. This can increase the stability of the vehicle body when turning.

On the other hand, for example, when the vehicle is traveling on a rough road, the control unit opens the first control valve. On the other hand, when the telescopic section tries to contract suddenly, the fluid in that telescopic section with increased internal pressure tends to move to the other telescopic section via the second flow path. As a result, the left and right wheels can easily move up and down, reducing lateral shaking of the vehicle body.

In addition, in this configuration, by operating the pump and the second control valve, the amount of fluid in the left and right telescopic sections can be increased, thereby raising the vehicle height. On the other hand, by operating only the second control valve, the vehicle weight can move the fluid in the left and right telescopic sections to the reservoir, allowing the vehicle height to be lowered quickly.

Even if the left and right telescopic parts of this configuration are impaired, the vehicle will not become unable to move because it is equipped with springs and dampers.

(Characteristics)
In the vehicle attitude control device of the present invention, it is advantageous to provide third valves between the accumulator and the left telescopic section, and between the accumulator and the right telescopic section, which allow the fluid to flow from the accumulator to the left telescopic section and the right telescopic section, and block the flow of the fluid from the left telescopic section to the accumulator, and from the right telescopic section to the accumulator, at or above a predetermined flow rate.

(effect)
By providing the third valve between the left and right telescopic sections and the accumulator, the lateral sway characteristics of the vehicle can be improved even when the first control valve is in a shutoff state.

For example, when making gentle turns, the third valve is open, allowing fluid to move freely between the left and right telescopic sections. This results in a natural and mild tilting behavior of the vehicle body when making gentle turns. On the other hand, when making a sudden turn, the flow rate of fluid moving between the left and right telescopic sections increases, and the third valve is shut off. This prevents further tilting of the vehicle body and stabilizes turning.

In addition, when the left and right telescopic sections attempt to retract during sudden acceleration or braking, the third valve is shut off and fluid stops flowing from the left and right telescopic sections to the accumulator. This effectively prevents the vehicle body from sinking. On the other hand, when the left and right telescopic sections attempt to extend, fluid flows from the accumulator toward the left and right telescopic sections. This makes it possible to prevent a decrease in the pressing force of the wheels against the road surface.

Therefore, for example, if a vehicle attitude control device of this configuration is installed on the front wheels, when the left and right telescopic sections attempt to retract during sudden braking, the third valve is shut off and hydraulic oil does not flow from the left and right telescopic sections to the accumulator. This effectively prevents the vehicle body from sinking, allowing the front wheels to exhibit a good braking effect.

On the other hand, when the left and right telescopic sections try to extend during rapid acceleration, hydraulic oil flows smoothly from the accumulator into the left and right telescopic sections. This allows the left and right telescopic sections to extend, mitigating the reduction in the contact pressure of the wheels against the road surface and preventing a deterioration in acceleration characteristics.

(Characteristics)
In the vehicle attitude control device according to the present invention, the pump and the second control valve can be connected to the first flow path and the third valve at the same position as the position at which the accumulator is attached.

(effect)
If the pump and the second control valve are connected in the same state as the accumulator, the flow rate of the fluid into the left and right telescopic sections can be increased by controlling only the second control valve to be open, particularly when the pump is driven to supply fluid to the left and right telescopic sections. This allows for a quick operation of raising the vehicle height while maintaining a simple configuration.

FIG. 1 is an explanatory diagram showing a configuration of a vehicle attitude control device according to a first embodiment; FIG. 2 is an explanatory diagram showing an example of an operation mode of the vehicle attitude control device according to the first embodiment; FIG. 2 is an explanatory diagram showing an example of an operation mode of the vehicle attitude control device according to the first embodiment; FIG. 2 is an explanatory diagram showing an example of an operation mode of the vehicle attitude control device according to the first embodiment; FIG. 11 is an explanatory diagram showing a configuration of a vehicle attitude control device according to a second embodiment;

First Embodiment
(overview)
The vehicle attitude control device S (hereinafter simply referred to as "device S") according to the first embodiment of the present invention is provided, for example, on the left and right front wheels and/or the left and right rear wheels of a four-wheel vehicle, and controls the vehicle attitude by utilizing fluid pressure.

For example, Figure 1 shows an example in which the device S is provided on the left wheel TL and the right wheel TR. The left and right wheels TL, TR are attached to the vehicle body 3 via a suspension having a spring 1 and a damper 2. The spring 1 is, for example, a general coil spring, and the damper 2 is a normal hydraulic shock absorber or the like.

In this embodiment, an expansion/contraction section 4 is provided between the spring 1 and the vehicle body 3, or between the spring 1 and the wheel T, particularly in each of the left and right springs 1. Here, a cylinder 4a and a piston 4b are provided between the spring 1 and the vehicle body 3 as the expansion/contraction section 4 that utilizes hydraulic pressure, for example. More specifically, the cylinder 4a is fixed to the vehicle body 3, and the piston 4b that slides within it is attached to the spring 1, and the left and right vehicle heights are raised and lowered by supplying and discharging oil to the expansion/contraction section 4.

As shown in FIG. 1, the accumulator 5 is connected to each of the left telescopic section 4L and the right telescopic section 4R via the first flow path R1. The first flow path R1 may be independent for the left and right, but in this embodiment, the first flow path R1 is connected across the left telescopic section 4L and the right telescopic section 4R.

The accumulator 5 is filled with hydraulic oil as a fluid, and hydraulic oil can be supplied to and discharged from the left telescopic section 4L and the right telescopic section 4R in accordance with the up and down movement of the left and right wheels TL, TR. The pressure of the hydraulic oil sealed in the accumulator 5 and the left telescopic section 4L and right telescopic section 4R is the same.

In the first flow path R1, a third valve V3 is provided between the accumulator 5 and the left telescopic portion 4L, and between the accumulator 5 and the right telescopic portion 4R. The third valve V3 has a ball 6, which is a valve body, a valve spring 9 that normally separates the ball 6 from the valve seat, and a pair of throttle portions 10.

The ball 6 is normally separated from the valve seat by the valve spring 9. This allows hydraulic oil to flow between the left telescopic section 4L and the right telescopic section 4R via the pair of throttling sections 10, and between the accumulator 5 and the left telescopic section 4L, and between the accumulator 5 and the right telescopic section 4R via the throttling section 10. However, for hydraulic oil flowing into the third valve V3 from the left telescopic section 4L and hydraulic oil flowing into the third valve V3 from the right telescopic section 4R, the third valve V3 is shut off when the flow rate of hydraulic oil is equal to or greater than a predetermined amount. In other words, this is because the ball 6 abuts against the valve seat against the valve spring 9, blocking the throttling section 10.

The third valve V3 effectively maintains the vehicle height. If the third valve V3 were not provided, and the first control valve V1 and the second control valve V2 were constantly shut off, the hydraulic oil would be held in the shut off circuit. In this case, if the temperature of the hydraulic oil changes, the volume of the hydraulic fluid would change, causing the vehicle height to become unstable. However, by providing the third valve V3, when the attitude control device S is not operating, such as when the vehicle is stopped, the left telescopic section 4L and the accumulator 5, and the right telescopic section 4R and the accumulator 5 are connected to each other. Therefore, the volume change of the hydraulic oil due to temperature change can be absorbed by the accumulator 5, and changes in the vehicle height are suppressed. Note that a solenoid valve can be used instead of a check valve such as the third valve V3.

On the other hand, when the flow rate of hydraulic oil in the third valve V3 is high, the third valve V3 functions as follows. As shown in FIG. 1, when the vehicle is normally running, hydraulic oil flows smoothly in the direction in which the third valve V3 opens, that is, in the direction from the accumulator 5 to the left telescopic section 4L or the right telescopic section 4R. However, in the opposite direction, the hydraulic oil presses the ball 6 against the biasing force of the separating spring toward the valve seat, and when the flow rate of hydraulic oil reaches a predetermined level or more, the ball 6 abuts against the valve seat and the flow of hydraulic oil is blocked.

The third valve V3 stabilizes the vehicle's posture when it makes a turn, for example. When making a gentle turn, the vehicle body 3 has little tendency to tilt, and the difference in extension and contraction between the left telescopic section 4L and the right telescopic section 4R is small. This reduces the amount of hydraulic oil flowing through the first flow path R1, and the third valve V3 is maintained in an open state. For this reason, as shown in FIG. 2, for example, when making a gentle turn to the left, hydraulic oil flows from the right telescopic section 4R, which is contracting, to the left telescopic section 4L, which is expanding, and the vehicle tilts gently. In this way, the tilting behavior of the vehicle body 3 when making a gentle turn is natural and mild.

On the other hand, as shown in Figure 3, when the vehicle makes a sharp left turn, the body 3 tends to lean outward suddenly, increasing the difference in expansion and contraction between the left telescopic section 4L and the right telescopic section 4R. At this time, the third valve V3 of the first flow path R1 connected to the right telescopic section 4R that is contracting is shut off, preventing the right telescopic section 4R from contracting any further. Meanwhile, hydraulic oil flows from the accumulator 5 via the third valve V3 into the left telescopic section 4L that is expanding, displacing the piston 4b to a slightly extended position. This keeps the suspension spring 1 in good contact with the ground, stabilizing cornering.

Also, as shown in FIG. 4, when the left and right

telescopic sections

4L, 4R try to extend during sudden acceleration, hydraulic oil flows smoothly from the accumulator 5 to the left and right

telescopic sections

4L, 4R. This causes the left and right

telescopic sections

4L, 4R to extend, and the left and right springs 1 keep the wheel T in good contact with the road surface, suppressing deterioration of acceleration characteristics. On the other hand, although not shown, when the left telescopic section 4L and the right telescopic section 4R try to contract during sudden braking, the third valve V3 is shut off and hydraulic oil does not flow from the left and right

telescopic sections

4L, 4R to the accumulator 5. This effectively prevents the vehicle body 3 from sinking, allowing the front wheels to exhibit good braking effect.

As shown in FIG. 1, a second flow path R2 is connected between the left telescopic section 4L and the right telescopic section 4R in addition to the first flow path R1. In other words, it is a flow path in parallel with the third valve V3. A first control valve V1 is provided in this second flow path R2, and it can be switched between a connected state and a blocked state by a signal from the control unit ECU.

When the vehicle is in a normal driving state, the first control valve V1 is maintained in a shutoff state by the control unit ECU. This causes the vehicle to change its posture based on the function of the first flow path R1 as described above. In particular, when the vehicle makes a sharp turn, the outflow of fluid from the expansion and contraction section 4, which is attempting to contract on the outside of the turn, is stopped. This prevents further tilting of the vehicle body 3 and increases stability during turns.

On the other hand, when the vehicle is traveling on a rough road, the first control valve V1 is maintained in a connected state by the control unit ECU. In this state, the flow resistance of the hydraulic oil flowing through the second flow path R2 is low, and the hydraulic oil moves back and forth between the left telescopic section 4L and the right telescopic section 4R in response to changes in the vehicle's posture. This makes it easier for the left and right

telescopic sections

4L, 4R to telescope, improving the ground contact of the left and right wheels TL, TR. By providing the second flow path R2 and the first control valve V1 in this configuration, it is possible to improve the lateral sway characteristics when the vehicle is traveling.

As shown in FIG. 1, in this embodiment, a pump P is provided in communication with the second flow path R2. This pump P has a reservoir function, and a second control valve V2 is provided between the pump P and the second flow path R2. The second control valve V2 is in a shutoff state when the vehicle is in a normal driving state.

The control unit ECU operates the pump P and the second control valve V2 to simultaneously increase the amount of hydraulic oil in the left telescopic section 4L and the right telescopic section 4R, thereby raising the vehicle height. On the other hand, by operating only the second control valve V2, the fluid in the left and right

telescopic sections

4L, 4R can be moved to the reservoir by the vehicle weight, allowing the vehicle height to be lowered quickly. The vehicle height can be detected using the vehicle height sensor 8 installed between the wheel mounting section and the vehicle body 3.

In addition, a pressure sensor 7 is provided in the first flow path R1 or the second flow path R2, and the control unit ECU operates the pump P and the second control valve V2 based on the measurement value of the pressure sensor 7, and can maintain the internal pressure of the left and

right expansion sections

4L, 4R and the accumulator 5 at a predetermined value.

In this manner, in the device S of this embodiment, the first flow path R1 and the second flow path R2 are provided in parallel across the left telescopic section 4L and the right telescopic section 4R. The first flow path R1 is provided with a third valve V3 having a check valve function whose operating mode changes depending on the flow rate, and the second flow path R2 is provided with a first control valve V1 that opens and closes the flow path by the control unit ECU. With this configuration, good lateral sway control is possible in response to many driving conditions, such as normal driving and driving on rough roads, and the same configuration can also be used to adjust the vehicle height. Thus, a vehicle attitude control device S can be obtained that has a simple configuration but is capable of effectively controlling the vehicle attitude.

Even if the left and right

expandable parts

4L and 4R of this configuration are impaired, the vehicle will not become unable to run because it is equipped with a spring 1 and a damper 2.

Second Embodiment
The vehicle attitude control device S according to the second embodiment is shown in Fig. 5. In this embodiment, the pump P and the second control valve V2 are provided in the first flow path R1. In the first flow path R1, a third valve V3 is provided at a position adjacent to the left telescopic section 4L and a position adjacent to the right telescopic section 4R, and here, the pump P and the second control valve V2 are connected between the two third valves V3. In other words, in the first flow path R1, the pump P and the second control valve V2 are connected to the same position where the accumulator 5 is attached.

With this configuration, particularly when the pump P is driven to supply fluid to the left and right

telescopic sections

4L, 4R, only the second control valve V2 is controlled to be open, allowing hydraulic oil to be supplied quickly to the left and right

telescopic sections

4L, 4R. This makes the vehicle height raising operation particularly swift, and when the device S is attached to the left and right front wheels TL, TR, it is possible to improve the braking effect by reducing the sinking of the front of the vehicle body 3 during braking. Also, when the device S is attached to the front and rear left and right wheels TL, TR, it is possible to quickly raise the vehicle height when driving on rough roads, etc., and prevent the vehicle body 3 from interfering with the ground.

The vehicle attitude control device of the present invention is provided on the left and right front wheels and/or the left and right rear wheels of a four-wheel vehicle, and can be widely used in devices that use fluid pressure to adjust the vehicle's lateral sway attitude and vehicle height.

Reference Signs List 1 Spring 2 Damper 3 Vehicle body 4L (4) Left telescopic portion 4R (4) Right telescopic portion 5 Accumulator ECU Control unit P Pump R1 First flow path R2 Second flow path S Vehicle attitude control device TL (T) Left wheel TR (T) Right wheel V1 First control valve V2 Second control valve V3 Third valve

Claims

The left and right wheels (TL, TR) are attached to the vehicle body (3) via springs (1) and dampers (2),
In each of the left and right springs (1), a left telescopic section (4L) and a right telescopic section (4R) utilizing fluid pressure are provided between the spring (1) and the vehicle body (3) or between the spring (1) and the wheel (TL, TR),
An accumulator (5) that holds the fluid at the same pressure as the fluid in the left and right telescopic portions (4L, 4R) is connected to each of the left and right telescopic portions (4L, 4R) via a first flow path (R1),
a second flow path (R2) that can be opened and closed separately from the first flow path (R1) is connected across the left telescopic portion (4L) and the right telescopic portion (4R) together with a first control valve (V1);
a pump (P) having a reservoir function is connected to the first flow path (R1) or the second flow path (R2) via a second control valve (V2);
A vehicle attitude control device (S) is provided with a control unit (ECU) that operates the first control valve (V1), the second control valve (V2), and the pump (P).
The vehicle attitude control device (S) of claim 1, wherein a third valve (V3) is provided between the accumulator (5) and the left telescopic section (4L) and between the accumulator (5) and the right telescopic section (4R) to allow the fluid to flow from the accumulator (5) to the left telescopic section (4L) and the right telescopic section (4R), and to block the flow of the fluid from the left telescopic section (4L) to the accumulator (5) and from the right telescopic section (4R) to the accumulator (5) at a flow rate above a predetermined flow rate.
The vehicle attitude control device (S) according to claim 2, wherein the pump (P) and the second control valve (V2) are connected to the first flow path (R1) and the third valve (V3) at the same position as the accumulator (5) is attached.