JP3346056B2 - Suspension system for four-wheel vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension system for a four-wheel vehicle in which wheels are suspended by a variable damping force type shock absorber.

[0002]

2. Description of the Related Art A suspension device shown in FIG. 7 has been proposed as a suspension device for controlling rolling of a vehicle body of a four-wheeled vehicle (see Japanese Patent Application Laid-Open No. 6-72127).

FIG. 7 is a block diagram of a conventional suspension system for a four-wheeled vehicle, in which 101 (101FL, 101F) is shown.
R, 101RL, 101RR) are shock absorbers for suspending each wheel (not shown) on the vehicle body 100 side. Each shock absorber 101 includes a cylinder 102 and a piston rod 103 inserted into the cylinder 102 from below.
And a piston 105 that is connected to the upper end of the piston rod 103 and slides up and down in the cylinder 102. Oil chambers S ₁ and S ₂ are defined in each cylinder 102 by a piston 105, and a throttle 127 is provided in an oil hole 126 formed in the piston 105.

Also, left and right shock absorbers 101FL
A pressure regulating device 160 is provided between the pressure regulating device 101FR and 101RL and 101RL and 101RR, and a pair of left and right cylinders 161L and 161R that are bifurcated are formed at an upper portion of a cylinder body 161 of the pressure regulating device 160. . Free pistons 162L, 162R are slidably fitted to the respective cylinders 161L, 161R, and the free pistons 162L, 162
Oil chamber S _A and the gas chamber S _G is defined by R.
The left and right free pistons 162L, 162R are connected to each other by a connecting member 163.

[0005] Further, the left shock absorber 101F
L, and an oil chamber S ₁ and the pressure regulator 160 left cylinder 161L oil chamber S _A formed within of 101RL oil passage 164
Shock absorber 1 on the right side
01FR, the oil passage 1 and the oil chamber S _A which is formed on the right side of the cylinder 161R oil chamber S ₁ and the pressure regulator 160 101RR
65. And both oil passages 164,
The communication path 165 is connected by a communication path 166, and a throttle 167 is provided in the communication path 166. The oil chambers S ₁ , S ₂ , S _A , the oil passages 164, 165 and the communication passage 1
66 oil is filled in the high pressure gas is sealed in the gas chamber S _G.

The left and right shock absorbers 101
If FL and 101FR and 101RL and 101RR of the piston rod 103 is contracted (upward) at the same speed for example, a part of the oil chamber of S ₁ oil piston 105
Oil holes 126 and through the aperture 127 flows into the oil chamber S _2, the other part flowing oil passage 164, 165 of the through respective pressure regulator 160 side. At this time, since the oil pressures of the oil passages 164 and 165 are substantially equal to each other, most of the oil flowing through the oil passages 164 and 165 is mostly supplied to the oil chamber S of the pressure regulator 160.
_A flows into _A and pushes down the free pistons 162L, 162R in the cylinders 161L, 161R. Therefore, the oil hardly passes through the throttle 167, and a damping force is generated only by the flow resistance when the oil passes through the throttle 127 of the piston 105.

On the other hand, when the vehicle body 100 makes a right turn, for example, the left shock absorbers 101FL and 101FR contract, and the right shock absorbers 101FR and 101FR contract.
If the RR is extended (downward), the left side of the shock absorber 101FL, with oil in oil chamber S ₁ as described above flows through the throttle 127 of the piston 105 to the oil chamber S ₂ For 101RL, The oil flows to the pressure adjusting device 160 through the oil passage 164. In contrast, the right shock absorber 101FR, in 101RR, with flowing oil in the oil chamber S ₂ passes through the aperture 127 of the piston 105 into the oil chamber S _1, the oil in the oil chamber S _A oil through the road 165 flows into the oil chamber S _1. At this time,
Since the oil pressure of the oil passage 164 is higher than that of the oil passage 165, a part of the oil flowing through the oil passage 164 passes through the communication passage 166 and the throttle 167, and the oil chamber S of the right cylinder 161R.
_A , and through the oil passage 165 as described above, the right shock absorbers 101FR and 101RR.
Flows of the oil chamber S _1. Therefore, at this time, the aperture 1
When oil passes through both 27 and 167, a high damping force is generated in the suspension due to the flow resistance, thereby suppressing rolling of the vehicle body 101 during turning.

[0008]

However, in the above-mentioned conventional suspension, the left and right shock absorbers 101 are not provided.
Since piping for connecting FL and 101FR, and 101RL and 101RR, and pressure regulating device 160 with oil passages 164 and 165, respectively, is required, there is a problem that assembly and maintenance are poor.

[0009] When only one wheel gets over the convex portion of the road surface, the oil from the shock absorber (101FL) on the side of the wheel (for example, the left front wheel) that gets over flows through the throttle 167. Therefore, high damping force is generated,
There was also a problem that the riding comfort of the vehicle became poor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a suspension system for a four-wheeled vehicle which is capable of improving the ride comfort of a vehicle and which is excellent in assemblability and maintainability. Is to do.

[0011]

In order to achieve the above object, the present invention provides a variable damping force type shock absorber for suspending each wheel of a four-wheeled vehicle, which is provided with a speed sensor, and a shock detected by each speed sensor. The base damping force depends on the piston speed and vehicle speed of the absorber.
Decide on the Sorva, as well as the front left
According to the piston speed difference of the right side shock absorber
The damping force is applied to each of the front left and front right shock absorbers.
To the rear left and rear right
Damping force according to the piston speed difference of the shock absorber
The rear left and rear right shock absorber bases.
The damping force is added to the damping force, and the damping force according to the absolute value of the difference between the piston speed difference of the front left and right shock absorbers and the piston speed difference of the rear left and right shock absorbers is 4
Control means for reducing the base damping force of each of the shock absorbers .

[0012]

According to the present invention, the piping conventionally required for connecting the left and right shock absorbers is not required.
The assemblability and maintainability of the suspension device are improved.

For example, when one of the left and right front wheels passes through a convex portion or a concave portion on the road surface, the difference ΔV between the piston speeds V _FL and V _FR of the front left and right shock absorbers is obtained.
_{Although F} (= V _FL −V _FR ) is generated, there is no difference between the piston speeds V _FL and V _{FR of} the rear left and right shock absorbers. Accordingly, the absolute value ΔV (= | ΔV _F −ΔV _R |) of the difference between the piston speed difference ΔV _F of the front left and right shock absorbers and the piston speed difference ΔV _R (= 0) of the rear left and right shock absorbers is ΔV _F Equal to (ΔV
= ΔV _F ). For this reason, regarding the damping force generated in the front left and right shock absorbers, the damping force corresponding to ΔV _F and the damping force corresponding to ΔV (= ΔV _F ) cancel each other, and eventually, the front left and right shock absorbers have a base. Even when a damping force close to the damping force is generated and one of the wheels passes through the convex portion or the concave portion of the road surface, a high damping force is not generated, and the riding comfort of the vehicle is not impaired.

[0014]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a basic configuration diagram of a suspension system for a four-wheeled vehicle according to the present invention, FIG. 2 is a block diagram showing the configuration of a controller, and FIG. 3 shows a base current map determined for piston speed and vehicle speed. Fig. 4 is a cutaway side view of the variable damping force type shock absorber, and Figs. 5 and 6 are enlarged cross-sectional views of main parts of the shock absorber.

As shown in FIG. 1, the suspension system according to the present invention has a variable damping force type shock absorber 1 (1FL) for suspending each wheel (a pair of left and right front wheels and rear wheels) of a four-wheeled vehicle (not shown). , 1FR, 1RL, 1RR) and speed sensors 30 (30FL, 30FR, 30RL, 30RL) for detecting the piston speed of each shock absorber 1.
RR), the piston speeds V _FL , V _FR , V _RL , V _{RR of the} shock absorbers 1FL, 1FR, 1RL, 1RR detected by the speed sensor 30, and FIGS.
The controller 50 as a control means for controlling the damping force generated by each shock absorber 1 based on the vehicle speed S detected by the vehicle speed sensor 40 shown in FIG.
0 is electrically connected to the controller 50.

Here, the configuration of the variable damping force type shock absorber 1 will be described in detail with reference to FIGS.

As shown in FIG. 4, the shock absorber 1 has a cylinder 2 connected to the vehicle body and a piston rod 3 inserted into the cylinder 2 from below.
The lower end of the piston rod 3 extending out of the cylinder 2 is a wheel.
Connected to the side . The cylinder 2 may be connected to the wheel and the piston rod 3 may be connected to the vehicle body.

In the cylinder 2, the cylinder 2
Free piston 4 which divides into a gas chamber S _G and the oil chamber S _O are fitted slidably to an inner oil chamber S _O is the piston 5, which is bound on the upper end side of the piston rod 3 It is partitioned into an upper chamber S _O1 and a lower chamber S _O2 . Incidentally, the high-pressure gas is sealed in the gas chamber S _G, the oil is filled in the oil chamber S _O.

As shown in FIGS. 5 and 6, a solenoid case 6 is connected to the upper end of the piston rod 3, and a piston support for supporting the piston 5 is provided above the solenoid case 6. The shaft 7 is screwed. An electromagnetic control valve 8 is housed in the solenoid case 6, and the electromagnetic control valve 8 includes a ring-shaped solenoid 10 housed in a cylindrical case 9, a plunger 11 that can move up and down, and an adjustment member 12. The plunger 11 is movably held up and down by the cylindrical case 9 and the adjusting member 12, and the spring 1
3 upwardly biased. The solenoid 10
Is electrically connected to the controller 50 (see FIG. 1) via a lead wire 14.

A circular hole 15 is formed through the axial center of the piston support shaft 7, and a valve body 16 is fitted in the circular hole 15 so as to be vertically movable. A concave groove 16a is formed on the outer periphery of 16 over the entire periphery. The valve body 16 is urged downward by a spring 17 and its lower end surface is in contact with the upper end surface of the plunger 11.

On the other hand, the piston 5 has a plurality of oil holes 1.
8 and 19 are penetrated, and one oil hole 18 is provided in the valve 2.
0, the lower end opening is closed, and the other oil hole 19 is closed.
Is closed at its upper end by a valve 21. A ring-shaped groove 22 is formed in the inner peripheral portion of the piston 5, and the piston support shaft 7 is formed in the groove 22.
A plurality of oil holes 23 formed in the radial direction are opened.
The groove 22 communicates with the oil hole 18 via a plurality of oil holes 24 formed in the piston 5. still,
In a lower position than piston 5 of the piston support shaft 7, a plurality of oil holes 25 opening into the lower chamber S _O2 is formed in the radial direction.

Next, the operation of the shock absorber 1 will be described.

When the electromagnetic control valve 8 is not operated, that is, when the solenoid 10 is not energized, the solenoid 1
When 0 is in the non-excited state, the plunger 11 is at the lower limit position while maintaining the floating state as shown in FIG. 5, and a predetermined gap is formed between the plunger 11 and the adjustment member 12.
At this time, the valve body 16 is also positioned at the lower limit, and the upper chamber S _O1 and the lower chamber S _{O2 of} the oil chamber S _O are connected to the oil holes 18 and 24 and the concave groove 2.
2. The oil passage 23 is in communication with the oil passage formed by the oil hole 23, the groove 16a, and the oil hole 25. Is kept to a maximum.

In the compression stroke in which the piston rod 3 contracts and the piston 5 moves upward with respect to the cylinder 2, the oil in the upper chamber S _O1 of the oil chamber S passes through the oil hole 18 of the piston 5. The valve 20 is pushed open by the pressure to flow into the lower chamber S ₀₂ , and the oil holes 18, 24, the concave groove 22,
Oil hole 23 flows into the lower chamber S _O2 through the oil passage formed in the groove 16a and the oil holes 25, oil damping force is generated by the flow resistance when passing through the valve 20 and the oil passage. At this time, since the cross-sectional area of the oil passage is kept at the maximum as described above, the oil flows through the oil passage with almost no resistance, and thus the generated damping force is suppressed to a small value.

Next, when the solenoid 10 is energized and excited, the plunger 11
The valve element 1 moves upward by an amount proportional to the magnitude of the
6 to push up against the urging force of the spring 17,
The opening area of the concave groove 16a of the valve body 16 to the oil hole 25, that is, the opening area of the oil passage gradually decreases. Accordingly, as the amount of oil passing through the valve 20 from the oil hole 18 of the piston 5 increases, the flow resistance of the oil flowing through the oil passage increases, and the damping force gradually increases.
As described above, when the electromagnetic control valve 8 is not actuated, the plunger 11 does not come into contact with the adjustment member 12 and is kept in a floating state. Therefore, the initial load for moving the plunger 11 becomes zero, and the solenoid 10 The plunger 11 can be moved at the same time as the current is supplied.

When the plunger 11 moves up to the upper limit position where it comes into contact with the cylindrical case 9 as shown in FIG. 6, the oil hole 25 is closed by the valve body 16, so that the damping force becomes maximum.

By controlling the current supplied to the solenoid 10 as described above, the damping force can be made variable.

In the extension stroke in which the piston rod 3 extends and the piston 5 moves downward with respect to the cylinder 2,
Some of the oil chamber S _O lower chamber S _O2 in the oil of pushes open the valve 21 in the pressure through the oil hole 19 of the piston 5 flows into the upper chamber S _O1, other oil holes 25, concave groove 16a, the oil hole 23 through the oil passage formed in the grooves 22 and oil holes 18, 24 and flows into the upper chamber S _O1, but the required damping force is generated by the flow resistance of the oil in this case .

Next, the configuration and operation of the controller 50 will be described with reference to FIG.

The controller 50 has a built-in arithmetic processing unit 51 and a memory unit 52, and the arithmetic processing unit 51 includes a piston speed arithmetic unit 53 and a current value arithmetic unit 54.

The front left and right speed sensors 30FL,
Piston speeds V _FL , V _{FR of} front left and right shock absorbers 1FL, 1FR detected by 30FR and piston speeds V _{RL of} rear left and right shock absorbers 1RL, 1RR detected by rear left and right speed sensors 30RL, 30RR. V _RR is the interface (I /
This is input to the piston speed calculation unit 53 of the controller 50 via F). Then, in the piston speed calculation unit 53, the front left and right shock absorbers 1FL,
The difference ΔV _F between the piston speeds V _FL and V _FR of 1FR, the difference ΔV _R between the piston speeds V _RL and V _RR of the rear left and right shock absorbers 1RL and 1RR, the difference between the front left and right piston speeds ΔV _F and the rear left and right pistons. speed difference ΔV _R
Is calculated by the following equation.

[0033]

ΔV _F = V _FL −V _FR (1) ΔV _R = V _RL −V _RR (2) ΔV = | ΔV _F −ΔV _R | (3) ΔV calculated by equation (3)
_{F, ΔV R, ΔV} is inputted to the current value calculation unit 54.
The vehicle speed S detected by the vehicle speed sensor 40 is input to the current value calculation unit 54.

Then, in the current value calculating section 54, the current values I _FL and I _FR to be supplied to the solenoids 10FL and 10FR of the front left and right shock absorbers 1FL and 1FR and the solenoids 10RL of the rear left and right shock absorbers 1RL and 1RR. , the current to be supplied to 10RR value I _RL, I _RR
Are calculated by the following equations.

[0035]

[Number 2] _{I FL = I BF (V FL} , S) + A F (| ΔV F |) -B F (ΔV) ... (4) I FR = I BF (V FR, S) + A F (| ΔV F _{|) -B F (ΔV) ...} (5) I RL = I BR (V RL, S) + A R (| ΔV R |) -B R (ΔV) ... (6) I RR = I BR (V RR, _{S) + A R (| ΔV} R |) in _{-B R (ΔV) ... (7} ) above equation, I _BF, I _BR is the shock absorbers 1
(1FL, 1FR, 1RL, 1RR) are base current values that generate a base damping force, which are functions of the piston speeds V _FL , V _FR , V _RL , V _RR and the vehicle speed S. For example, Previous example left and right shock absorbers 1FL, 1
The base current value I _BF for _FR is determined as shown in FIG. 3 based on the piston speed V _FL (V _FR ) and the vehicle speed S on the compression side and the expansion side.

A _F and A _R represent each shock absorber 1
(1FL, 1FR, 1RL, 1RR ) a current value which generates a damping force applied to the base damping force, which piston speed difference [Delta] V _F of the left and right, are given as a function of [Delta] V _R. Furthermore, B _F, B _R is the shock absorbers 1 (1FL, 1FR, 1RL, 1RR) a current value which generates a damping force which is subtracted from the base damping force of the piston speed difference between the right and left thereof, respectively Δ
It is given as a function of the absolute value [Delta] V of the difference between V _F and [Delta] V _R.

The above I _BF , I _BR , A _F , A _R , B
_F and _BR are mapped and stored in the memory unit 52 of the controller 50.

The supply current I _FL , calculated by the current value calculation section 54 based on the above equations (4) to (7),
I _FR , I _RL , and I _RR are connected to each shock absorber 1FL, 1FR, 1RL, 1R via an interface (I / F).
R solenoid 10 (10FL, 10FR, 10RL,
10RR), and each shock absorber 1FL,
1FR, 1RL, 1RR are supply currents I _FL , I _FR , I _RL ,
Generating a damping force having a magnitude corresponding to the I _RR.

Therefore, for example, when all the wheels are displaced vertically in the same direction and at the same speed while the vehicle is running, ΔV
_{Since F} = ΔV _R = ΔV = 0, only the base damping force is generated in each of the shock absorbers 1FL, 1FR, 1RL, 1RR.

Further, for example, when the vehicle turns right, the front and rear shock absorbers 1FL, 1RL on the left side contract,
Right front and rear shock absorbers 1FR, since the _{ΔV F = ΔV R, ΔV =} 0 if 1RR is extended, the shock absorbers 1FL, 1FR, 1RL, current A _F based damping force in 1RR, A _R Damping force (ΔV
_F , a damping force according to ΔV _R ) is added, and the rolling of the vehicle body is suppressed to be small.

In the present embodiment, for example, when one of the left and right of the front wheel passes through a convex portion or a concave portion on the road surface, between the piston speeds V _FL , V _FR of the front left and right shock absorbers 1FL, 1FR. Is the difference ΔV _F (≠ 0)
The shock absorber 1R on the left and right sides of the rear side
There is no difference between the piston speeds V _RL , V _RR of L, 1 _RR (ie, ΔV _R = 0).

Accordingly, the front piston speed difference ΔV _F
A difference ΔV is generated between the piston speed difference ΔV _R (= 0) and the rear piston speed difference, and the value of ΔV is equal to ΔV _F (ΔV = Δ
V _F). For this reason, the supply current values A _F (ΔV _F ) and B _F (ΔV) calculated by the above equations (4) and (5) cancel each other, and only the base current I _BF is changed to the front left and right shock absorbers 1FL. , 1FR, and only a base damping force is generated in the shock absorbers 1FL, 1FR. Even when one wheel passes through a convex portion or a concave portion of the road surface, no high damping force is generated, and the ride comfort of the vehicle is reduced. Is not harmed.

When only one of the right and left rear wheels passes through the convex or concave portion of the road surface, similarly, only the base damping force is generated in the rear left and right shock absorbers 1RL and 1RR. Sex is not impaired. Further, the above holds when assuming that the characteristics of the current values A _F and B _F are the same. However, even when the characteristics of A _F and B _F are different, the above holds qualitatively. .

If one of the right and left sides of the front wheel (for example, the left side) passes through the convex portion or concave portion of the road, and the other side (the right side) of the rear wheel also passes through the convex portion or concave portion of the road surface, From the above equations (1) and (2), ΔV _F = V _FL , ΔV _R =
−V _RR , ΔV = | V _FL + V _RR |
な る 2V _FL . Therefore, the (4) to (7) the values of B _F and B _R becomes large in the equation, the shock absorbers 1FL, 1FR, 1RL, solenoid 10F of 1RR
The current values I _FL , I _FR , I _RL , and I _RR to be supplied to L, 10 _FR , 10 _RL , and 10 _RR are reduced, and as a result, the damping force generated in the shock absorbers 1 _FL , 1 _FR , 1 _RL , 1 _RR is reduced, and the wheels are reduced. Followability of the vehicle on the road surface is enhanced.

In addition, in the suspension system according to the present embodiment, each of the shock absorbers 1FL, 1FR, 1RL, 1
Since the RR is independently controlled by the controller 50, there is no need to connect them to each other as in the related art.
Therefore, the piping required conventionally is unnecessary, and the assemblability and maintainability of the suspension device can be improved.

[0046]

As is apparent from the above description, according to the present invention, a speed sensor is provided for each of the variable damping type shock absorbers for suspending each wheel of the four-wheeled vehicle, and the shock detected by each speed sensor is provided. The base damping force is set according to the piston speed and the vehicle speed of each absorber.
About each, and the front left and front right
Damping force according to the piston speed difference of the shock absorber
The base of the front left and front right shock absorbers
Rear left and rear right shores, while adding to debilitation
The damping force according to the bus speed difference
For each base damping force of the left and rear right shock absorbers
The damping force according to the absolute value of the difference between the piston speed difference of the front left and right shock absorbers and the piston speed difference of the rear left and right shock absorbers is added to four shocks.
Since the control means for reducing the damping force of each base of the shock absorber is provided, it is possible to obtain a suspension device for a four-wheel vehicle excellent in assemblability and maintenance that can improve the ride comfort of the vehicle.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a suspension device for a four-wheeled vehicle according to the present invention.

FIG. 2 is a block diagram illustrating a configuration of a controller.

FIG. 3 is a diagram showing a base current map determined for a piston speed and a vehicle speed.

FIG. 4 is a cutaway side view of the variable damping force type shock absorber.

FIG. 5 is an enlarged sectional view of a main part of a variable damping force type shock absorber.

FIG. 6 is an enlarged sectional view of a main part of a variable damping force type shock absorber.

FIG. 7 is a basic configuration diagram of a conventional suspension system for a four-wheeled vehicle.

[Explanation of symbols]

 Reference Signs List 1 damping force variable shock absorber 30 speed sensor 40 vehicle speed sensor 50 controller (control means) 51 arithmetic processing unit 52 memory unit 53 piston speed calculation unit 54 current value calculation unit

Claims (1)

(57) [Claims] 1. A variable damping force type shock absorber for suspending each wheel of a four-wheeled vehicle is provided with a speed sensor, and a base damping force is determined by a shock absorber piston speed and a vehicle speed detected by each speed sensor.
Decide on the Sorva, as well as the front left and front
According to the piston speed difference of the right side shock absorber
The damping force is applied to each of the front left and front right shock absorbers.
To the rear left and rear right
Damping force according to the piston speed difference of the shock absorber
The rear left and rear right shock absorber bases.
The damping force is added to the damping force, and the damping force according to the absolute value of the difference between the piston speed difference of the front left and right shock absorbers and the piston speed difference of the rear left and right shock absorbers is 4
A suspension system for a four-wheeled vehicle, comprising control means for reducing each base damping force of one shock absorber .