JP2000219021A - Shock absorber - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a shock absorber capable of properly adjusting a braking force of front, rear, left and right wheels by appropriately operating an adjustment valve for adjusting a brake balance of front, rear, left and right wheels. SOLUTION: A pressure sensor 60 for detecting an internal pressure of a gas chamber 6b and inputting it to a CPU 61 as a detection signal G is provided. The CPU 61 detects a large value of the detection signal G (when the loading load increases).
The adjustment signal H is input to the solenoid 70, and the load sensing valve 64 is operated so that the distribution of the rear oil pressure B to the front oil pressure A becomes larger than when the vehicle is idle. When the loaded load is heavy, the ratio of the braking force of the rear wheel brake mechanism 65 to the braking force of the front wheel brake mechanism 66 is larger than when the vehicle is idle, so that an appropriate braking effect according to the vehicle weight is obtained and steering stability is obtained. The performance and ride comfort can be improved. By combining the self-leveling type hydraulic shock absorber and the load sensing valve, the non-adjustment of the braking force of the front and rear wheels due to the non-operation of the load sensing valve, which can occur conventionally, can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorber having a vehicle height adjusting function mounted on a suspension system of a vehicle such as an automobile.

[0002]

2. Description of the Related Art Generally, in a vehicle such as an automobile, a shock absorber using a working fluid such as an oil solution is mounted between a sprung portion and a unsprung portion of a suspension device to attenuate the sprung and unsprung vibrations. Thereby, the ride comfort and the steering stability are improved.

[0003] Meanwhile, in a vehicle having a relatively large loading weight such as a van or a wagon, a change in the loading load caused by the occupant getting on and off, loading and unloading of the luggage causes a great change in the vehicle height, and the riding comfort and steering stability. Performance may be reduced. For this reason, there is a demand for a suspension device that can automatically maintain a constant vehicle height regardless of the load weight.

Therefore, conventionally, for example, Japanese Patent Application Laid-Open No. 60-261
No. 713, an oil tank and a reservoir filled with a high-pressure gas, a pump means for supplying the oil liquid in the oil tank into the cylinder by expansion and contraction of a piston rod, and an expansion and contraction position of the piston rod. Pump means and return means for returning pressurized oil from the cylinder to the oil tank. The pump means and return means are operated by utilizing the vibration of the suspension device during running to appropriately adjust the pressure in the cylinder to thereby adjust the piston rod. There has been proposed a so-called self-leveling type hydraulic shock absorber in which a constant vehicle height is automatically maintained by adjusting the extension length of the self-leveling.

[0005]

By the way, vehicles have
A load sensing proportioning valve (hereinafter referred to as a load sensing valve (adjustment valve)) for adjusting the brake balance of the front, rear, left and right wheels is provided. Some adjust the power distribution. Then, it is conceivable to mount the self-leveling type hydraulic shock absorber on the vehicle. However, in this case, due to the self-leveling function of the self-leveling type hydraulic shock absorber,
The load sensing valve does not operate because the vehicle height is within the predetermined range regardless of the loaded load, and it becomes impossible to obtain a well-balanced and appropriate braking force with the front and rear left and right wheels.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a control valve for adjusting the brake balance of the front and rear left and right wheels is always operated properly irrespective of the vehicle height and the loaded load, so that the front and rear and left and right can be controlled. An object of the present invention is to provide a shock absorber capable of favorably adjusting a braking force of a wheel.

[0007]

SUMMARY OF THE INVENTION The present invention provides a cylinder filled with hydraulic fluid, a piston slidably fitted in the cylinder, and one end connected to the piston and the other end of the cylinder. A piston rod extended to the outside, a tank for storing hydraulic fluid, and a hydraulic fluid is supplied and discharged between the tank and the cylinder by expansion and contraction of the piston rod to extend the piston rod within a predetermined range. A pressure sensor for detecting the internal pressure of the cylinder, and an adjusting valve for adjusting the brake balance of the front, rear, left and right wheels of the vehicle based on the detection signal of the pressure sensor. It is characterized by being actuated.

[0008]

An embodiment of the present invention will be described below with reference to the drawings. In the present embodiment, a hydraulic shock absorber using an oil liquid as a working fluid will be described as an example. In addition,
The hydraulic fluid is not limited to the oil liquid, and may be another liquid. FIG.
As shown in FIG. 2 and FIG. 2, the hydraulic shock absorber 1 has a so-called inverted type structure in which a main body side including a cylinder is disposed at an upper part and a rod side is disposed at a lower part. Has a double-cylinder structure in which a cylinder 3 is inserted into an outer cylinder 2. At the lower ends of the outer cylinder 2 and the cylinder 3,
An annular reservoir 6 is formed between the cylinder 3 and the outer cylinder 2 with the guide seal 4 and the oil seal 5 attached.

A substantially cylindrical partition member 7 is fitted between the side wall near the bottom of the outer cylinder 2 and the cylinder 3, and an annular oil passage 8 is formed between the partition member 7 and the outer cylinder 2. , Partition member 7
An annular oil passage 9 is formed between the cylinder and the cylinder 3. The reservoir 6 is formed between the cylinder 3 by a substantially cylindrical bladder 10 (flexible film) made of a flexible material such as rubber and clamped to the partition member 7 and the guide seal 4 at both ends. An oil chamber 6a communicating with the annular oil passage 9;
Gas chamber formed between outer cylinder 2 and filled with high-pressure gas
6b.

An oil chamber 12 on the bottom side (upper side in FIG. 1) of the outer cylinder 2 communicating with the annular chamber 8 and the inside of the cylinder 3 are partitioned by a base member 11 fitted to the upper end of the partition member 7. ing. The inside of the cylinder 3 is communicated with the annular oil passage 9 by an oil passage 13 provided on a side wall near the upper end of the cylinder 3.

A piston 14 is slidably fitted in the cylinder 3.
The inside is defined as two chambers, a cylinder upper chamber 3a and a cylinder lower chamber 3b. One end of a hollow piston rod 15 is connected to the piston 14 by a nut 17 via a piston bolt 16, and the other end of the piston rod 15 is connected to a guide mounted on the lower end of the outer cylinder 2 and the cylinder 3. It is inserted through the seal 4 and the oil seal 5 and extends outside the cylinder 3. An oil liquid is sealed in the cylinder upper and lower chambers 3a and 3b and the oil chamber 6a of the reservoir 6.

The piston 14 has oil passages 18 and 19 for communicating between the cylinder upper and lower chambers 3a and 3b, and an orifice and a disc valve for controlling the flow of oil flowing through the oil passages 18 and 19 to generate a damping force. Damping force generating mechanism 20,
21 are provided.

An oil tank (tank) 23 is attached to a side wall near the upper end of the outer cylinder 2 by a connection pipe 24. The oil tank 23 has a free piston 26 slidably fitted in a cylinder member 25 thereof.
Is defined as two chambers, an oil chamber 28 and a gas chamber 29, which communicate with the annular oil passage 8 via the connection pipe 24. Oil chamber 28
Is filled with an oil liquid, and the gas chamber 29 is filled with a gas.

A pump tube 33 is inserted into the hollow piston rod 15 and is fixed by being urged by a spring 34. Inside the pump tube 33, along its axis,
A tubular pump rod 35 is provided. Pump rod
A base end (upper side in FIG. 1) of 35 is connected to the base member 11 and an oil passage 36 therein communicates with the oil chamber 12, and a front end side (lower side in FIG. 1) slides into the pump tube 33. Mated as possible,
A pump chamber 37 is formed in the pump tube 33.

The pump chamber 37 is provided with a check valve 38 provided at the distal end of the pump tube 33 and an oil passage 39 and an oil passage 39a formed between the pump tube 33 and the piston rod 15. Communicated with 3b. The check valve 38 allows only the flow of the oil liquid from the pump chamber 37 to the oil passage 39 side. The pump chamber 37 includes a check valve 40 provided at the tip of the pump rod 35, an oil passage 36 in the pump rod 35,
The oil chamber 12, the annular oil passage 8, and the connection pipe 24 communicate with the oil chamber 28 of the oil tank 23. Check valve 40 is an oil passage
Only the flow of the oil liquid from 36 to the pump chamber 37 is permitted.

A groove 41 extending in the axial direction and a radial orifice passage 42 are provided on the side surface of the pump rod 35, and when the extension length of the piston rod 15 reaches a predetermined range, the pump chamber 37 is opened. Is the cylinder upper and lower chamber 3 through the groove 41
When the extension length of the piston rod 15 exceeds a predetermined range, the cylinder upper and lower chambers 3a and 3b are directly connected to the oil passage 36 of the pump rod 35 via the orifice passage 42. I have.

In the above configuration, the pump tube 33,
The pump rod 35, the pump chamber 37, the check valves 38 and 40, the groove 41, and the orifice passage 42 adjust the extension length of the piston rod 15 by supplying and discharging oil to the cylinder 3 by expansion and contraction of the piston rod 15. It constitutes a self-leveling mechanism.

When the pressure of the oil liquid on the reservoir 6 side, that is, on the cylinder upper and lower chambers 3a and 3b side reaches a predetermined pressure, the base member 11 is opened and the hydraulic pressure is moved to the oil chamber 12 side, that is, the oil tank 23 side. A relief valve 43 for relief is provided.

The gas chamber of the reservoir 6 in the outer cylinder 2
A pressure sensor 60 is fitted in a part facing the gas chamber 6b, detects the internal pressure of the gas chamber 6b, and outputs a detection signal G to a CPU 61 described later.
To enter. The oil chamber 6a of the reservoir 6 communicates with the inside of the cylinder 3 (the cylinder upper chamber 3a) via the annular oil passage 9 and the oil passage 13 as described above, and through the bladder 10 according to the internal pressure of the cylinder 3. The internal pressure of the gas chamber 6b changes. The pressure sensor 60 detects the internal pressure of the gas chamber 6b and thus detects the internal pressure of the cylinder 3.

The value of the detection signal G of the pressure sensor 60 changes depending on the load on the vehicle. For example, when the load is heavy, the pressure of the cylinder upper and lower chambers 3a and 3b, and thus the gas chamber of the reservoir 6, The internal pressure of 6b increases, and the value of the detection signal G increases.

The hydraulic shock absorber 1 has a mounting portion 51 fixed to the bottom of the outer cylinder 2 connected to a vehicle body side of a suspension device (not shown), and a mounting portion fixed to a distal end portion of the piston rod 15. 52 is connected to the axle side of the right rear wheel and mounted on the vehicle. The pressure sensor 60 attached to the hydraulic shock absorber 1 has C
PU61 is connected. The vehicle is provided with a hydraulic shock absorber having the same configuration as the hydraulic shock absorber 1 shown in FIG. 1 corresponding to the left rear wheel, and a pressure sensor (not shown) of the hydraulic shock absorber is also connected to the CPU 61. I have. The CPU 61 generates an adjustment signal H when the average value of the detection signal G of the pressure sensor 60 and the detection signal G of the pressure sensor of the left rear wheel side hydraulic shock absorber is equal to or larger than a predetermined value.

On the other hand, a load sensing valve (adjustment valve) 64 is connected to the brake pedal 62 via a master cylinder 63 that generates a hydraulic pressure having a magnitude corresponding to the operation of the brake pedal 62. The load sensing valve 64 has a valve body 69 having a flow path (not shown) communicating with a rear pipe 67 and a front pipe 68 to which a rear wheel brake mechanism 65 and a front wheel brake mechanism 66 are connected, respectively, on the distal end side. A movable body (not shown) movably provided in the flow path of the valve body 69, and a solenoid 70 which is actuated by an adjustment signal H from the CPU 61 to displace the movable body.
The distribution of the supply hydraulic pressure to the rear pipe 67 and the front pipe 68 is adjusted by the displacement of the movable body due to the operation of the 70.

When the adjustment signal H is not output from the CPU 61, the solenoid 70 does not operate, and the load sensing valve 64 operates as a brake fluid pressure characteristic indicated by reference symbol D in FIG. Function). When the adjustment signal H is output from the CPU 61, the solenoid 70 is operated, and the load sensing valve 64 exhibits the brake fluid pressure characteristic indicated by the reference symbol E in FIG. Works like that.

Here, in FIG. 3, the horizontal axis indicates the hydraulic pressure A supplied to the front pipe 68 (front side hydraulic pressure), and the vertical axis indicates the rear pipe 67.
FIG. 4 is a characteristic diagram in which a supply hydraulic pressure (rear-side hydraulic pressure) B is supplied to the vehicle. The brake fluid pressure characteristic D when the vehicle is idle is represented by the front hydraulic pressure A
Against a bare first characteristic portion D ₁ showing the rear hydraulic B is substantially equal value, the hydraulic pressure is a predetermined value to the front side hydraulic A (hereinafter, referred to as a first predetermined value.) When the above M increasing the proportion of the front-side hydraulic a is made from bare second characteristic portion D ₂ Metropolitan made larger than the rate of increase of the rear hydraulic B in characteristics.
The loading-time brake fluid pressure characteristic E is a loading-time first characteristic portion E in which the rear-side oil pressure B shows substantially the same value as the front-side oil pressure A.
₁ and the hydraulic pressure to the front side hydraulic pressure A is a predetermined value [hereinafter, the second
It is referred to as a predetermined value N. (First predetermined value M) <(second predetermined value N)] The loading second characteristic portion E in which the increase rate of the front-side hydraulic pressure A is larger than the increase rate of the rear-side hydraulic pressure B in the characteristics at the time of not less than _{It consists of two} .

When the load is light (ie, the value of the detection signal G is small), the CPU 61 does not output the adjustment signal H, whereby the solenoid 70 is not operated, and the idle brake fluid pressure characteristic shown in FIG. D is exhibited. When the load is heavy (that is, when the value of the detection signal G is large), the CPU 61 outputs the adjustment signal H having a large value, whereby the solenoid 70 is operated, and the brake fluid pressure characteristic during loading shown in FIG. E is exhibited.

In the hydraulic shock absorber 1 configured as described above, the movement of the piston 14 with the expansion and contraction of the piston rod 15 causes the oil liquid to flow between the cylinder upper and lower chambers 3a and 3b.
The damping force is generated by the damping force generating mechanisms 20 and 21 through the circulation of the damper 19. At this time, the cylinder upper and lower chambers 3 enter and exit the cylinder 2 as the piston rod 15 expands and contracts.
Changes in the volumes of a and 3b are compensated by the compression and expansion of the gas in the gas chamber 6b of the reservoir 6.

Normally, when the vehicle is idle, the extension length of the piston rod 15 is set within a predetermined standard range.
When the load increases due to a load or the like loaded on the vehicle, the vehicle height decreases. When the extension length of the piston rod 15 becomes shorter than a predetermined standard range due to the decrease in the vehicle height, the cylinder upper and lower chambers 3a and 3b are formed in the grooves 41. Be cut off from. In this state, when the piston rod 15 expands and contracts due to the vibration of the suspension during traveling, during the extension stroke, the pump rod 35 retreats and the pressure in the pump chamber 37 is reduced, the check valve 40 is opened, and the oil tank is opened.
The oil in the oil chamber 28 is connected to the connecting pipe 24, the annular oil passage 8, and the oil chamber.
12. It is introduced into the pump chamber 37 through the oil chamber 36 of the pump rod 35. During the contraction stroke, the pump rod 35 moves forward to pressurize the oil liquid in the pump chamber 37 to open the check valve 38, and the oil passage 39
The oil is supplied to the cylinder lower chamber 3b through the oil passage 39a, and the pressure in the cylinder upper and lower chambers 3a, 3b rises to increase the piston rod 15b.
Is extended.

As described above, the pumping operation is repeated using the vibration during traveling, thereby extending the piston rod 15 and increasing the vehicle height. When the vehicle height reaches a predetermined standard range, the cylinder upper and lower chambers 3a,
3b and the pump chamber 37 are communicated, and the pumping operation is released. When the loaded load increases in this way, the pressures in the cylinder upper and lower chambers 3a and 3b, and thus the internal pressure of the gas chamber 6b, become larger than when the vehicle is empty, and the value of the detection signal G detected by the pressure sensor 60 becomes larger. . Then, the CPU 61 outputs the adjustment signal H, whereby the solenoid 70 is operated, and the on-load brake fluid pressure characteristic E shown in FIG. 3 is exhibited.
When the load becomes heavy, the brake hydraulic pressure characteristic D when the vehicle is empty is changed to the brake hydraulic pressure characteristic E when the vehicle is empty, and the distribution of the rear hydraulic pressure B to the front hydraulic pressure A is increased as compared with the case of the empty vehicle. The hydraulic pressure distribution to the rear wheel brake mechanism 65 and the front wheel brake mechanism 66 changes. For this reason, when the load becomes heavy, the rear wheel brake mechanism with respect to the braking force generated by the front wheel brake mechanism 66.
The ratio of the braking force that generates 65 becomes larger than when the vehicle is empty, and an appropriate braking effect according to the vehicle weight can be obtained.

When the vehicle height rises due to a decrease in the load or the like and the extension length of the piston rod 15 exceeds a predetermined standard range, the cylinder upper and lower chambers 3a and 3b are connected to the orifice passage 42.
Through the orifice passage 42, the oil passage 36, the oil chamber 12, the annular oil passage 8 and the connection pipe 24. The gas in the gas chamber 29 is compressed by returning to the oil chamber 28 of the oil tank 23, and the oil liquid in the oil chamber 6 a is returned to the oil chamber 28 via the oil passage 8 and is stored in the gas chamber 6 b of the reservoir 6. As the gas expands, the piston rod 15 shortens and the vehicle height decreases. When the vehicle height decreases and the extension length of the piston rod 15 is reduced to a predetermined standard range, the orifice passage
42 is shut off from the cylinder upper and lower chambers 3a and 3b, the operation of returning the oil liquid from the cylinder upper and lower chambers 3a and 3b to the oil tank 23 side is released, and the vehicle height is maintained. When the load decreases, the pressures in the cylinder upper and lower chambers 3a and 3b, and thus the internal pressure of the gas chamber 6b, decrease, and the pressure sensor
The value of the detection signal G detected by 60 decreases. And C
PU61 does not output the adjustment signal H, and the solenoid
70 does not operate, and the brake fluid pressure characteristic D at the time of an empty vehicle in FIG. 3 is exhibited. Then, when the load becomes lighter, the load-time brake fluid pressure characteristic E in FIG. 3 changes to the empty vehicle-use brake fluid pressure characteristic D, and the distribution of the rear-side hydraulic pressure B to the front-side hydraulic pressure A becomes smaller than when the load is heavy. Become smaller. For this reason, it is possible to obtain an appropriate braking effect according to a state where the loaded load is light.

As described above, the pumping operation and the returning operation are appropriately repeated by using the vibration caused by the traveling, so that the extension length of the piston rod 15 is adjusted to a predetermined standard range, and the vehicle is irrespective of the loaded load. The height can be automatically adjusted to a constant. If the pressure of the oil liquid in the cylinder 3 rises excessively due to a pumping operation and a thrust from the road surface during traveling, the relief valve 43 is opened and the oil liquid in the cylinder 3 is discharged to the oil tank 23 side. By the relief, the load on the connecting portion and the sealing portion of each member can be reduced, and the impact on the vehicle body can be buffered.

Further, while the self-leveling function is exhibited as described above, the load sensing valve 64 is properly operated even when the load increases, so that the braking force of the front and rear wheels can be improved regardless of the load of the load. Can be adjusted. That is, the front and rear wheel control caused by the inactivity of the load sensing valve, which can occur with the prior art constituted by a combination of a shock absorber having a self-leveling mechanism and a load sensing valve that operates in response to a change in vehicle height. Power non-adjustment can be avoided. As described above, the braking force of the front and rear wheels can be adjusted favorably, so that steering stability and riding comfort can be improved.

In the present embodiment, the case where the pressure sensor 60 detects the internal pressure of the gas chamber 6b of the reservoir 6 has been described as an example. Instead, the pressure sensor 60 is configured to detect the internal pressure of the oil chamber 6a of the reservoir 6. Alternatively, the internal pressure of the cylinder chamber 3 may be detected. Further, in the present embodiment, the case where the distribution of the front side hydraulic pressure A and the rear side hydraulic pressure B is adjusted has been described as an example, but the brake mechanism for the left wheel and the brake mechanism for the right wheel are provided. The hydraulic pressure distribution to the right wheel brake mechanism may be adjusted. Further, a wheel brake mechanism corresponding to the left, right, front and rear wheels may be provided, and a pressure sensor may be provided corresponding to each wheel to adjust the hydraulic pressure distribution to each wheel brake mechanism. Further, in the present embodiment, an example is described in which the CPU 61 calculates the average value of the detection signal G of the pressure sensor 60 and the detection signal G of the pressure sensor of the hydraulic shock absorber on the left rear wheel side. Thus, the hydraulic pressure distribution may be adjusted using only one of the detection signals G.

[0033]

According to the first aspect of the present invention, the internal pressure of the cylinder changes according to the change of the load, and when the internal pressure of the cylinder changes, the adjusting valve is operated to adjust the brake balance of the front, rear, left and right wheels of the vehicle. Since the adjustment can be performed, an appropriate braking force can be applied to the front, rear, left and right wheels according to the change in the vehicle weight. For this reason, steering stability and riding comfort can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing the hydraulic shock absorber of FIG.

FIG. 3 is a diagram showing hydraulic characteristics obtained by the load sensing valve of FIG. 1;

[Explanation of symbols]

 1 Hydraulic shock absorber (buffer) 3 Cylinder 14 Piston 15 Piston rod 33 Pump tube (Self-leveling mechanism) 35 Pump rod (Self-leveling mechanism) 37 Pump room (Self-leveling mechanism) 38,40 Check valve (Self-leveling mechanism) 41 Groove (self-leveling mechanism) 42 Orifice (self-leveling mechanism) 60 Pressure sensor 64 Load sensing valve (adjustment valve) 65 Rear wheel brake mechanism 66 Front wheel brake mechanism

Claims (1)

[Claims] 1. A cylinder filled with hydraulic fluid, a piston slidably fitted in the cylinder, and a piston rod having one end connected to the piston and the other end extending outside the cylinder. A tank for storing hydraulic fluid, and a self-leveling mechanism for adjusting the extension length of the piston rod to a predetermined range by supplying and discharging hydraulic fluid between the tank and the cylinder by expansion and contraction of the piston rod. In the shock absorber provided, a pressure sensor for detecting the internal pressure of the cylinder is provided, and an adjustment valve for adjusting a brake balance of front, rear, left and right wheels of the vehicle is operated based on a detection signal of the pressure sensor. Shock absorber.