JPH1038009A - Load sensitive type shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a load sensitive type shock absorber easily loaded on a vehicle, and ensure riding comfortableness of the vehicle while the damping ratio is kept in a prescribed range when variable controlling the damping characteristics. SOLUTION: Bypass oil passages 23, 24 are provided so that they separately bypass an extension side damping valve 11 and a pressure side damping valve 12, the inlet sides of the bypass oil passages 23, 24 are communicated to oil chambers A, B which become operation sides at the time, through throttles 26, 27, the outlet sides are communicated to the low pressure side oil chambers A, B through ports 32, 35, the passage areas of which are variable controlled by a control valve 24, and the section between the throttles 26, 27 and the ports 32, 35 are communicated to back pressure chambers 13, 14 provided on the back faces of the extension side- and pressure side damping valves 11, 12. By introducing the internal pressure of an air suspension device into the operating surface of a control valve 25 from outside through a conduction passage 42, the control valve 25 is operated due to the change in the internal pressure to variably control the passage areas of the ports 32, 35 on the outlet sides of the bypass oil passages 23, 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a load-sensitive shock absorber that automatically adjusts the damping characteristic automatically by utilizing a change in internal pressure of an air suspension device depending on the presence or absence of a load.

[0002]

2. Description of the Related Art In general, in a vehicle using an air suspension device as a suspension device, the internal pressure of the air suspension device changes depending on the amount of load (spring load) or the presence or absence of the load. Changes the spring constant.

[0003] As a result, if the damping characteristic of the shock absorber used in conjunction with the air suspension device is constant, the vibration damping performance (damping characteristic) of the shock absorber becomes excessive or insufficient depending on the amount and presence or absence of the loaded load. It will be uncomfortable.

[0004] This is particularly pronounced in trucks and buses in which the sprung load changes significantly depending on the load and the number of passengers, and it is not possible to maintain optimal damping characteristics between when the vehicle is empty and when the vehicle is loaded.

Therefore, conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 158912/1983, the diameter of the adjusting rod inserted through the piston rod is rotated from the outside together with the air suspension device to obtain the diameter. And a variable damping force type shock absorber that can adjust the damping characteristics while selecting different orifices.

A change in the internal pressure of the air suspension device due to the amount of the load is taken out as an expansion / contraction operation of the air cylinder, ie, a linear motion, and this linear motion is converted into a rotary motion by a lever to rotate the adjusting rod of the shock absorber. Thus, there has been proposed a shock absorber in which the damping characteristic of the shock absorber is adjusted in accordance with a change in the internal pressure of the air suspension device.

[0007]

However, in this method, the internal pressure of the air suspension device is taken out as a linear motion by an air cylinder, and this linear motion is converted into a rotary motion by a lever to adjust the damping characteristic of the shock absorber. Therefore, there is a problem that a large space is required for attaching them, and the mounting property is inferior.

In addition, in order to stably absorb the vibration on the spring without damaging the ride comfort of the vehicle by adjusting the damping characteristics, the spring constant of the air suspension device and the damping of the shock absorber must be adjusted. It is necessary to keep the coefficient ratio, that is, the damping ratio, as constant as possible.

On the other hand, in a shock absorber in which damping characteristics are adjusted by selecting orifices having different diameters, the damping characteristics increase in a quadratic curve with an increase in the expansion / contraction speed. In addition, while maintaining the damping ratio in a predetermined range corresponding to the change in the spring constant, it is difficult to adjust the damping characteristics of the shock absorber in accordance therewith, and the ride comfort is reduced. .

Accordingly, an object of the present invention is to provide a load capacity that can be easily mounted on a vehicle, and at the same time, can maintain the damping ratio in a predetermined range and also maintain the riding comfort of the vehicle when performing variable control of the damping characteristics. An object of the present invention is to provide a sensitive shock absorber.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to form a back pressure chamber on the rear side of a damping valve in a shock absorber, and to provide a bypass oil passage bypassing the damping valve and the back pressure chamber. The inlet side of the bypass oil passage communicates with the working-side oil chamber through a throttle, and the outlet side communicates with the low-pressure side oil chamber through a port for variably controlling the passage area by a control valve. And a communication path for guiding the internal pressure of the air suspension device from the outside to the operation surface of the control valve, and the control is performed according to the change in the internal pressure. This is achieved by variably controlling the passage area of the port on the outlet side of the bypass oil passage by operating a valve.

Further, a back pressure chamber is formed on the rear side of the damping valve in the shock absorber, a bypass oil passage is provided to bypass the damping valve and the back pressure chamber, and the inlet side of the bypass oil passage is connected to the operating oil. In addition to communicating with the chamber through a throttle, the outlet side communicates with a low-pressure side oil chamber through a port for variably controlling the passage area by a control valve, and a back provided between the throttle and the port on the back side of the damping valve. A communication path that communicates with the pressure chamber and that guides the internal pressure of the air suspension device from the outside to the operation surface of the control valve is provided. A port on the outlet side of the bypass oil passage is operated by operating the control valve according to a change in the internal pressure. This is also achieved by controlling the passage area in two steps.

That is, with the above-described configuration, in the former shock absorber, the hydraulic oil pushed out from the oil chamber on the operating side in accordance with the expansion and contraction operation is connected to the throttle on the inlet side by the bypass oil passage. The oil flows to the low-pressure oil chamber through the outlet port, and also flows to the low-pressure oil chamber while opening the damping valve in parallel with the flow of the hydraulic oil as the expansion speed increases. .

In this case, the passage area of the port on the outlet side of the bypass oil passage is continuously variably controlled by a control valve which is switched in accordance with a change in the internal pressure of the air suspension device, that is, the amount of load.
Together with the above diaphragm, it functions as a variable series two-stage diaphragm.

Accordingly, the hydraulic oil pressure between the throttle on the inlet side and the port on the outlet side in the bypass oil passage is such that the oil chamber pressure on the low pressure side is maintained while the passage area of the port is larger than the throttle on the inlet side. When it is closed, it becomes equal to the oil chamber pressure on the operating side, and during that time, it rises with a decrease in the port passage area.

Further, in the latter shock absorber, the control valve is switched on / off according to the presence or absence of a load or a change in the internal pressure of the air suspension device at a predetermined load, and the outlet port is connected to the control valve. By switching the passage area in two stages, the hydraulic oil pressure between the inlet-side throttle and the outlet-side port can be switched between high and low.

Since the hydraulic oil pressure between the throttle and the port is guided to the back pressure chamber on the back side of the damping valve, in any case, the cracking pressure of the damping valve increases the load of the load. It changes continuously depending on the number, or changes according to the change in the internal pressure of the air suspension device at the presence or absence of a load or a predetermined load.

From this, by controlling the switching amount of the control valve in accordance with the change in the internal pressure of the air suspension device, that is, the change in the spring constant due to the presence or absence of the load or the like, the low-speed range before and after the adjustment of the damping characteristic is controlled. While adjusting the damping characteristics (orifice characteristics) by the throttle and maintaining the damping ratio of the damping characteristics (valve characteristics) by the damping valve in the middle and high speed range within a predetermined range, a load-sensitive type with good riding comfort. It can be a shock absorber.

In addition, a back pressure chamber, a bypass oil passage, a control valve, and a conduction path for guiding the internal pressure of the air suspension device are arranged inside the shock absorber on the operation surface of the control valve, and externally controlled only through the conduction path. What is necessary is just to guide the internal pressure of the air suspension device to the operation surface of the valve.

Therefore, no switching mechanism is required outside the shock absorber. For example, the shock absorber may be connected to the air suspension device by one or two branched pipes or the like. So
The assemblability and mountability of the shock absorber to a vehicle are also significantly improved.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

The load-sensitive shock absorber 1 illustrated in FIG. 1 includes a cylinder 2 and an outer shell 3 arranged in an inner / outer double cylinder structure, a piston 4 slidably inserted into the cylinder 2, and The piston 4 includes a piston 4 extending from the piston 4 to the cylinder 2 and a sealing rod at the upper end of the outer shell 3 and extending outward.

The lower ends of the cylinder 2 and the outer shell 3 are closed by bottom caps 6 welded to the outer shell 3, respectively, thereby defining a reservoir chamber R between the cylinder 2 and the outer shell 3. .

The piston 4 and the piston rod 5 are
The interior of the cylinder 2 is interconnected by the piston 4 by a piston rod 5.
And a lower hydraulic oil chamber B on the bottom cap 6 side.

The upper hydraulic oil chamber A and the lower hydraulic oil chamber B
Communicates with each other through an extension side port 8 and a compression side port 9 penetrating the piston 4 and extending obliquely, and a lower hydraulic oil chamber B is provided with a bottom orifice 10
Communicates with the reservoir chamber R.

On both sides of the piston 4, the extension side damping valve 1 is provided.
1 and a compression-side damping valve 12 are attached to each other with an inner peripheral portion thereof interposed therebetween. A lower end of the expansion-side port 8 of the piston 4 is closed by the expansion-side damping valve 11, and a compression-side The upper end is closed.

The structure described above is a structure that has been well known in general shock absorbers, and the following structure, which will be described below, forms a structure that is particularly important in practicing the present invention.

That is, on the back side of the extension side damping valve 11 and the compression side damping valve 12, the extension side back pressure chamber 13 and the compression side back pressure chamber 14 are separated from the lower hydraulic oil chamber B and the upper hydraulic oil chamber A.
Are formed separately from each other.

In the case of this embodiment, the back pressure chamber 13,
As shown in the detailed view of FIG. 2, guide rings 17 and 18 are fixedly mounted on the rear side of the extension side and compression side damping valves 11 and 12 with spacers 15 and 16 interposed therebetween.
The partition rings 19 and 20 are slidably fitted into the reference numerals 7 and 18, respectively.

The springs 21 with the distal ends of the partition rings 19, 20 interposed between the guide rings 17, 18 are provided.
The back pressure chambers 13 and 14 are kept oil-tight from the upper and lower hydraulic oil chambers A and B by pressing the back pressure chambers 13 and 14 against the rear sides of the extension side and compression side damping valves 11 and 12 at 22.

Thus, the spacer 15 and the guide ring 1
7, a partition ring 19, and a spring 21 constitute a control mechanism on the extension side having a back pressure chamber 13. Similarly, a spacer 16, a guide ring 18, a partition ring 20, and a spring 22 have a back pressure chamber 14. The compression-side control mechanisms are respectively configured, and these expansion-side and compression-side control mechanisms are disposed on the back sides of the expansion-side damping valve 11 and the compression-side damping valve 12, respectively.

Each of the back pressure chambers 13 and 14 is provided with bypass oil passages 23 and 24 for bypassing the upper hydraulic oil chamber A and the lower hydraulic oil chamber B and communicating with each other. And is provided over the piston 4 and the piston rod 5.

On the other hand, these bypass oil passages 23, 24 are connected to the expansion side and compression side ports 8, 9 of the piston 4 through throttles 26, 27 provided by embossing the bank on the inner peripheral side of the piston 4. The upper hydraulic oil chamber A and the lower hydraulic oil chamber B communicate with the upper hydraulic oil chamber A and the lower hydraulic oil chamber B through these extension-side and compression-side ports 8 and 9, thereby forming an oil path on the inlet side.

On the other hand, the outlet side is provided with annular grooves 28, 29 on the outer peripheral surface formed on the piston rod 5 from the throttles 26, 27.
The lower hydraulic oil chamber B and the upper hydraulic oil chamber A communicate with the lower hydraulic oil chamber B through the ports 32, 33, 34, and 35, and the annular grooves 30, 31 of the control valve 25 connecting the ports 32, 33 and the ports 34, 35. I have.

In this case, the port 33 is
The lower hydraulic oil chamber B communicates with the lower hydraulic oil chamber B through an oil hole 36 formed in the piston nut 7, thereby forming an oil passage on the outlet side.

An annular groove 28 which forms a part of the oil passage on the outlet side of the bypass oil passage 23 is extended to communicate with the back pressure chamber 13 on the extension side.
Control valve 25 which forms a part of the oil passage on the outlet side
The annular groove 31 communicates with the pressure-side back pressure chamber 14 through an oil hole 37 formed in the piston rod 5.

On the other hand, the annular grooves 30 and 31 of the control valve 25 connecting the ports 32 and 33 and the ports 34 and 35 on the piston rod 5 side are connected to the ports 32 and 33 and the port 34 with the switching operation of the control valve 25. , 35 and the passage area of the ports 32, 35 is variably controlled, or these ports 3
It is configured such that communication with the ports 33 and 34 is cut off by closing the ports 2 and 35.

The lower end surface of the control valve 25 is provided with a plug 38 fitted to the piston rod 5 between the air chamber 3 and the plug 38.
9, the operating surface on the upper end side is pressed against the stopper member 41 by the air pressure of the air chamber 39 and the restoring force of the internal spring 40, and in this state, the piston rod 5
Side ports 32,35 are offset to an upper position where they are maximally opened by the annular grooves 30,31.

The operating surface of the control valve 25 is guided to the outside through an axial communication path 42 formed in the piston rod 5, and the internal pressure of the air suspension device (not shown) is controlled through the operation path 42 by operating the control valve 25. I try to add it to the surface.

In this way, the control valve 25 is configured as a sliding type spool valve that reduces the passage area of the ports 32 and 35 while pushing the control valve 25 downward with the presence or absence of a load or a specific load. I have.

In addition to the above, in the present embodiment, the constant orifice 43
And the constant orifice 4
The first-order lag pressure chamber 44 is provided on the operation surface of the control valve 25 by introducing the internal pressure of the air suspension device through
Is formed.

The first-order lag pressure chamber 44 suppresses the transmission of the fluctuation to the operation surface of the control valve 25 as much as possible even if the internal pressure of the air suspension device fluctuates due to high-frequency vibration during running of the vehicle. This is to prevent control instability due to 25 frequent switching.

Therefore, the above-mentioned constant orifice 43 does not necessarily need to be provided in the stopper member 41, but may be provided in a passage for guiding the internal pressure of the air suspension device to the operation surface of the control valve 25. In addition, although it is preferable to carry out the present invention, it is not always essential.

Thus, the shock absorber 1 embodying the present invention operates as follows to dampen the vibration of the vehicle.

That is, during the extension stroke in the low-speed range, the hydraulic oil in the upper hydraulic oil chamber A, which has been compressed by the piston 4 and has become the oil chamber on the operation side, flows from the expansion port 8 to the throttle 26 and the annular groove 28. , The port 32, the annular groove 30, the port 33 and the oil hole 36 to be pushed out to the lower hydraulic oil chamber B.

At the same time, the annular groove 31 and the port 34, the annular groove 29, the throttle 27
The pressure is pushed out to the lower hydraulic oil chamber B through the pressure side port 9 and the flow resistance of the hydraulic oil passing through the throttles 26 and 27 generates the expansion side damping force of the orifice characteristic.

On the other hand, when the extension speed of the piston 4 increases and enters the middle / high speed range from the latter half of the low speed range, the expansion port 8 is combined with the flow of the hydraulic oil passing through the throttles 26 and 27. The hydraulic oil starts to flow to the lower hydraulic oil chamber B by pushing and opening the extension side damping valve 11 from above, and the flow-side resistance of the hydraulic oil when the extension side damping valve 11 flows by pushing and opening the extension side damping force of the valve characteristic. Occurs.

Further, in addition to the above, the cylinder 2
Hydraulic oil in the lower hydraulic oil chamber B is sucked from the reservoir chamber R through the bottom orifice 10 into the lower hydraulic oil chamber B, and the hydraulic oil in the lower hydraulic oil chamber B is generated by the hydraulic oil. Make up for the shortfall.

On the other hand, in this case, the control valve 25
Is switched continuously or in two stages to a position that balances the return force on the air chamber 39 side in response to the magnitude and presence or absence of the load or a change in the internal pressure of the air suspension device at a specific load.

By switching the control valve 25, the degree of throttle of the ports 32 and 35 is changed to continuously or variably control the passage area in two stages, and the throttle 26 and the port 32 and the port 35 and the throttle 27 are connected in series. A variable stage aperture mechanism or a two-stage aperture mechanism is configured, and if necessary, the ports 32 and 35 are closed to switch the aperture resistance to infinity.

Thus, the extension damping force of the orifice characteristic in the low-speed range described above is continuously or abruptly changed according to the magnitude or presence or absence of the load or a change in the internal pressure of the air suspension device at a specific load. It is controlled high and low.

In the above, while the passage areas of the ports 32 and 35 are sufficiently larger than the throttles 26 and 27,
The extension side back pressure chamber 15 communicating with the annular groove 28 between the throttle 26 and the port 32 is maintained at a pressure substantially equal to that of the lower hydraulic oil chamber B on the low pressure side. The communicating pressure side back pressure chamber 14 is maintained at substantially the same pressure as the upper working oil chamber A on the operation side.

However, when the passage areas of the ports 32 and 35 decrease and they start to function as throttles, the ports 32 and 35 cooperate with the throttles 26 and 27 to function as a series two-stage throttle. First, as the pressure in the annular groove 28 increases, the pressure in the extension-side back pressure chamber 13 increases, and the pressure in the compression-side back pressure chamber 14 decreases as the pressure in the annular groove 31 decreases.

As a result, the cracking pressure of the expansion-side damping valve 11 increases as the pressure of the expansion-side back pressure chamber 13 increases. The extension side damping force due to the valve characteristics from the latter half of the low speed range to the middle and high speed ranges is also continuously adjusted in response to the amount and presence or absence of the load, or the internal pressure change of the air suspension device at the boundary of the specific load. Alternatively, the damping action is performed while controlling the height in two steps.

On the other hand, at the time of the compression stroke, on the other hand, an amount of hydraulic oil corresponding to the volume of the penetrating piston rod 5 is pushed out from the lower hydraulic oil chamber B to the reservoir chamber R through the bottom orifice 10. , The hydraulic oil pressure in the lower hydraulic oil chamber B is maintained.

Thus, in the low-speed range, the hydraulic oil in the lower hydraulic oil chamber B passes through the upper hydraulic oil chamber A from the oil hole 36 and the pressure-side port 9 through the throttles 26 and 27, respectively, in a direction opposite to the direction of the above-described extension stroke. At the same time, in the middle / high speed range, the pressure side damping valve 12 is also pushed open from the pressure side port 9 to flow into the upper hydraulic oil chamber A.

As a result, during the compression stroke, only the compression damping valve 12 works in place of the expansion damping valve 11 as compared with the preceding expansion stroke, and in the low speed range, the port 32 and the throttle 23 and the throttle 27 and the port 27 A compression damping force having orifice characteristics is generated by the combined throttle resistance of
In the high-speed range, the pressure resistance of the valve oil is generated by the flow resistance of the operating oil flowing by pushing and opening the compression-side damping valve 12.

Even in this case, the control valve 25 balances the return force on the air chamber 47 side in accordance with the magnitude of the load and the presence or absence of the load or a change in the internal pressure of the air suspension device due to the specific load. The position is switched to the position, the passage area of the ports 32 and 35 is variably controlled continuously or in two stages, and if necessary, both the ports 32 and 35 are closed.

As a result, even during the compression stroke, similarly to the expansion stroke, the passage area of the ports 32 and 35 is controlled by the change in the internal pressure of the air suspension device, so that the compression damping characteristic of the orifice characteristic in the low speed range is reduced. Control high and low.

In the middle / high-speed range, the pressure-side damping of the valve characteristic is controlled while controlling the cracking pressure of the pressure-side damping valve 12 in accordance with the pressure change of the pressure-side pressure chamber 14 applied through the port 37. The vibration is controlled by controlling the height.

In this way, in both the expansion and compression strokes, the damping characteristics of the orifice characteristics in the low speed range and the damping characteristics of the valve characteristics in the middle and high speed ranges are controlled to be high and low by changing the internal pressure of the air suspension device. Therefore, the vibration is suppressed.

Accordingly, the control valve 25 responds to the change in the spring constant due to the change in the internal pressure of the air suspension device at the level of the presence or absence of the load or the specific load.
By setting the switching amount, the damping ratio, which is the ratio between the spring constant and the damping coefficient, is kept within a predetermined range, and the load-sensitive shock absorber with a good ride comfort while controlling the extension side and compression side damping characteristics. It can be 1.

In the above-described embodiment, the case where the present invention is applied to the double-cylinder type shock absorber 1 having the bottom orifice 10 has been described. It can be easily understood that the present invention can be similarly applied to a known single-cylinder shock absorber in which a part of the inside of the cylinder 2 is partitioned as a gas chamber.

In addition, the present invention is applied to a multi-cylinder type shock absorber having a base valve as described below, and the extension side and compression side damping characteristics are individually adjusted by the respective control valves. You can also.

That is, FIG. 3 shows an embodiment in that case. In the shock absorber 1a, the valve closing the pressure side port 9 of the piston 4 is changed to the pressure side rear valve 12a having a low cracking pressure. , Or a pressure-side check valve).

A control valve is not provided for the pressure-side rear valve 12a, and the base orifice 10 provided on the lower side surface of the cylinder 2 is eliminated, and the base valve 45 is provided at the lower end of the cylinder 2. doing.

The control mechanism of the expansion damping valve 11 has the same structure as that of the embodiment of FIG. 2 described above, and accordingly, only the annular groove 30 for controlling the passage area of the port 32 is provided. Is used.

Therefore, the description of these components is omitted by giving the same reference numerals to the same parts, and only the configuration of the base valve 45 will be described below.

The base valve 45 is formed by fitting the outer peripheral surface of the upper end of the valve case 46 to the lower end of the cylinder 2 and pressing the lower end of the cylinder 2 through the valve case 46 against the inner bottom surface of the bottom cap 6. Are centered with respect to the outer shell 3.

The valve case 46 is provided with an expansion port 8b and a compression port 9b formed in the axial direction. The lower hydraulic oil chamber B and the reservoir chamber R are formed through the expansion port 8b and the compression port 9b. Communicate with each other.

An extension check valve 11b is provided on the upper surface of the valve case 46 and guided by a center pin 47, and the extension check valve 11b closes the upper end of the extension port 8b.

On the lower surface of the valve case 46, a pressure-side damping valve 12 b and a pressure-side control mechanism having a back pressure chamber 14 are clamped by a center pin 47 with a center plate 47 sandwiching the receiving plate 48. The lower end of the compression-side port 9b is closed by the compression-side damping valve 12b.

The pressure side control mechanism described above is different from the pressure side control mechanism in the previous embodiment in that the partition ring 20
Since only the shape of b and the interposition position of the spring 22 are different, the detailed description of the structure is omitted.

The center pin 47 has a bypass oil passage 24b at the center thereof, which bypasses the extension port 8b and the compression port 9b of the valve case 46 and communicates the lower hydraulic oil chamber B and the reservoir chamber R with each other. A throttle 27b and a valve seat 49 are attached to the entrance of the path 24b.

The bypass oil passage 24b between the throttle 27b and the valve seat 49 communicates with the pressure-side back pressure chamber 14 through an oil hole 37b formed in the center pin 47.

On the other hand, the poppet 5 is
0 is installed facing the valve seat 49 in the bypass oil passage 24b, and the poppet 50 is offset in a direction to open the valve seat 49 to the maximum by a spring 51 interposed between the poppet 50 and the center pin 47.

In this way, the control valve 25b is constituted by the valve seat 49 and the poppet 50, and the control valve 25b bypasses the expansion-side check valve 11b and the compression-side damping valve 12b, and connects the lower hydraulic oil chamber B to the reservoir. The passage area of the bypass oil passage 24b directly communicating with the chamber R is controlled continuously or in two stages.

In addition, the operation surface, which is the lower end surface of the poppet 50, is guided to the outside by a conduction path 42b formed in the bottom cap 6, and the internal pressure of the air suspension device is applied to the operation surface of the poppet 50 through the conduction path 42b to carry the load. The structure is such that the poppet 50 is pushed forward at the boundary of the load, the presence or absence of the load, or a specific load, and the passage area of the bypass oil passage 24b is reduced.

In this case, the conduction path 4
A constant orifice 43b is provided in the middle of 2b to guide the internal pressure of the air suspension device, thereby forming a portion of the conduction path 42b facing the operation surface of the control valve 25b as a first-order lag pressure chamber 44b.

As a result, the shock absorber 1a
In the low-speed range during the extension stroke of the piston, the hydraulic oil in the upper hydraulic oil chamber A is restricted by the piston 4 from the expansion port 8 to the throttle port 2.
6, flows into the lower hydraulic oil chamber B through the control valve 25a, the port 33 and the oil hole 36, and generates the extension side damping force of the orifice characteristic by the flow resistance of the throttle 26.

Then, in the latter half of the low speed range to the middle and high speed ranges, the expansion side damping valve 11 is also pushed open from the expansion side port 8 to flow into the lower hydraulic oil chamber B in conjunction with the above. An expansion damping force of the valve characteristic is generated by the flow resistance of the hydraulic oil when the fluid 11 is pushed open while flowing against the flexural rigidity of itself and the pressure of the back pressure chamber 13.

In addition to these, the piston rod 5
The hydraulic oil in an amount corresponding to the rejected volume integral is supplied from the reservoir chamber R through the expansion port 8b of the base valve 45 to open the expansion check valve 11b, and from the bypass oil passage 24b of the center pin 47 to the lower part through the throttle 27b. The hydraulic oil is sucked into the hydraulic oil chamber B, and the hydraulic oil compensates for the shortage of the hydraulic oil in the lower hydraulic oil chamber B caused at that time.

In addition, the operation of sucking the hydraulic oil into the lower hydraulic oil chamber B at this time is sufficient if the flow rate of the hydraulic oil supplied by opening the expansion-side check valve 11b from the expansion-side port 8b of the base valve 45 is sufficient. From the control valve 25b
The variable control of the passage area of the bypass oil passage 24b does not have any effect on the extension-side damping characteristics at that time.

Therefore, the shock absorber 1a shown in FIG. 3 also reduces or increases the passage area of the bypass oil passage 24 with respect to the back pressure chamber 13 on the extension side when the load is large or small, or when a specific load is applied. At the same time, the flow resistance of the working oil flowing therethrough is changed to control the extension damping characteristic of the orifice characteristic in the low-speed range to be high or low.

Further, the decrease or increase in the passage area of the bypass oil passage 24 causes the back pressure chamber 1 in the extension side control mechanism to increase.
The cracking pressure of the expansion damping valve 11 is switched between high and low by changing the pressure of No. 3 as well, and accordingly, the expansion damping characteristic of the valve characteristics in the latter half of the low speed range to the middle and high speed ranges is controlled to be high and low, and the vibration is damped. Perform the action.

On the other hand, at the time of the compression stroke, the hydraulic oil in the lower hydraulic oil chamber B is caused to flow from the pressure side port 9 to the upper hydraulic oil chamber A by opening the compression side rear valve 12a by the piston 4.
The pressure-side rear valve 12a compensates for the shortage of hydraulic oil generated in the upper hydraulic oil chamber A while maintaining the hydraulic oil pressure in the lower hydraulic oil chamber B at a predetermined pressure.

As a result, the operation of sucking the hydraulic oil into the upper hydraulic oil chamber A is also sufficient at the flow rate of the hydraulic oil supplied by opening the pressure side rear valve 12b. The variable control of the passage area of the port 32 by 25a does not affect the compression-side damping characteristics.

In addition, in the low-speed range, the amount of hydraulic oil corresponding to the integral volume of the piston rod 5 penetrates from the lower hydraulic oil chamber B in the low-speed range.
Then, the gas flows into the reservoir chamber R through the bypass oil passage 24b for the pressure-side back pressure chamber 14, and generates a pressure-side damping force having an orifice characteristic by the flow resistance of the throttle 27b.

In the middle / high speed range, in addition to the above, the compression side damping valve 12b is also pushed open from the compression side port 9b to flow into the reservoir chamber R.
A pressure-side damping force of a valve characteristic is generated by the flow resistance of the hydraulic oil when the fluid is pushed open while flowing against the cracking pressure caused by its own flexural rigidity and the pressure of the back pressure chamber 14.

Therefore, even during the compression stroke, the passage area of the bypass oil passage 24b is reduced or increased with or without the presence or absence of the load or a specific load.
The pressure resistance of the orifice characteristic in the low speed range is controlled to be high or low by changing the flow resistance of the hydraulic oil flowing therethrough, and the pressure in the back pressure chamber 14 is also changed to change the pressure side damping valve 12b.
While controlling the cracking pressure, the damping action is performed by controlling the pressure-side damping characteristics of the valve characteristics in the middle and high speed ranges to be high and low.

Thus, the shock absorber 1a shown in FIG.
In the same manner as in the shock absorber 1 described above, the switching amount of the control valves 25a and 25b is changed in accordance with the magnitude and presence or absence of the load or a change in the spring constant of the air suspension device at a specific load. By setting the shock absorber 1a, it is possible to provide a load-amount-sensitive shock absorber 1a having a comfortable ride while maintaining the damping ratio in a predetermined range.

In the embodiment of FIG. 3, the control valve 25b on the side of the base valve 45 is constituted by a spool valve. However, as in the embodiment shown in FIG. 4, the control valve 25b is formed as a rotary valve of a spring offset type. You may comprise.

That is, in the embodiment shown in FIG. 4, a rotary control valve 25c is attached to the bottom cap 6.
And the tip of the control valve 25c is connected to the bypass oil passage 2 of the center pin 47 of the base valve 45.
4b.

The control valve 25c has a vertical hole 52 opened at the tip and a horizontal hole 53 for guiding the vertical hole 52 to the side wall. The horizontal hole 53 is formed with a slit 54 formed in the inner bottom of the bottom cap 6. The passage area of the bypass oil passage 24b is variably controlled by the vertical hole 52, the horizontal hole 53, and the slit 54.

On the other hand, the base end side of the control valve 25c is shown in FIG.
As shown in FIG. 7, the fan-shaped portion 55 is fitted into the fan-shaped chamber 56 of the bottom cap 6, and the horizontal hole 53 of the control valve 25 c is maximally formed in the slit 54 on the bottom cap 6 side by a spring 57 disposed in the fan-shaped chamber 56. It is offset so as to maintain communication with the passage area.

Then, the internal pressure of the air suspension device is guided from the outside to the operation surface of the fan-shaped portion 55 through the constant orifice 43b and the first-order lag pressure chamber 44b by the conduction path 42b. The through holes 58 open to the outside.

As a result, the control valve 25c pivots in response to the internal pressure of the air suspension device.
Since the lateral hole 53 is shifted in the circumferential direction with respect to the slit 54 and the degree of communication changes, the passage hole area of the bypass oil passage 24b is controlled in accordance with the change in the spring constant of the air suspension device. Therefore, the same operation as the embodiment of FIG. 3 can be achieved.

[0098]

As described above, according to the first aspect of the present invention, the pressure of the back pressure chamber provided on the back side of the control valve is continuously increased according to the change in the internal pressure of the air suspension device due to the amount of the load. In addition to being able to variably control the damping characteristics of the shock absorber in accordance with the amount of the load, the damping ratio can be adjusted within a predetermined range while changing the damping coefficient according to the change in the spring constant of the air suspension device. And the riding comfort of the vehicle can be improved.

Further, in the above, since the back pressure chamber, the control valve, and the conduction path for leading the internal pressure of the air suspension device to the operation surface of the control valve can be respectively provided inside the shock absorber, the outside of the shock absorber can be provided. No switching mechanism is required, and therefore the assemblability and mountability of the shock absorber to a vehicle can be significantly improved.

According to the second aspect of the present invention, the assembling property and the mountability to the vehicle are ensured well, and the back provided on the back side of the control valve with respect to the presence or absence of a load or a specific load. The same effect as above can be exerted while controlling the pressure of the pressure chamber in two stages.

According to the third aspect of the present invention, the present invention is applied to a single-cylinder type shock absorber provided with an extension damping valve and a compression-side damping valve for a piston, or a double-cylinder shock absorber of a bottom orifice type. The above-described effects can be provided easily by implementing the present invention.

According to the fourth aspect of the present invention, the present invention is applied to a double-cylinder type shock absorber of a base valve type, and the above-described effects are obtained while finely controlling the extension side and compression side damping characteristics individually. be able to.

According to the fifth aspect of the present invention, in addition to the above-described effects, the control valve is frequently switched in response to a change in the internal pressure of the air suspension device at a high frequency during running of the vehicle. While preventing control instability.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing an embodiment in which the present invention is applied to a bottom orifice type double cylinder type shock absorber.

FIG. 2 is a vertical cross-sectional front view showing an enlarged main part of the same.

FIG. 3 is an enlarged longitudinal sectional front view of a main part showing an embodiment in which the present invention is applied to a base valve type double-cylinder shock absorber.

FIG. 4 is an enlarged vertical sectional front view of a main part showing another embodiment of the control mechanism in the base valve.

FIG. 5 is a partially enlarged plan view showing the operation portion of the control mechanism in a transverse direction.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1, 1a Shock absorber 2 Cylinder 3 Outer shell 4 Piston 5 Piston rod 6 Bottom cap 8, 8b Expansion port 9, 9b Compression port 11 Extension damping valve 11b Extension check valve 12, 12b Compression damping valve 12a Compression rear valve 13 Extension Side back pressure chamber 14 pressure side back pressure chamber 15, 16 spacer 17, 18 guide ring 19, 20, 20b partition ring 23 extension side bypass oil passage 24, 24b compression side bypass oil passage 25 dual use for extension side and compression side Control valve 25a Control valve exclusively for extension side 25b, 25c Control valve exclusively for compression side 26 Restrictor in extension side bypass oil passage 27, 27b Restriction in compression side bypass oil passage 28, 30 Annular groove for extension side bypass oil passage 29, 31 Annular groove for compression side bypass oil passage 32, 33 Port for extension side bypass oil passage 34, 3 Port for compression side bypass oil passage 36 Oil hole for extension side bypass oil passage 37, 37b Oil hole for connecting compression side bypass oil passage to compression side back pressure chamber 42, 42b Conduction passage 43, 43b Constant orifice 44, 44b Primary delay pressure chamber 45 Base valve 46 Valve case of base valve A Upper hydraulic oil chamber B Lower hydraulic oil chamber R Reservoir chamber

Claims (5)

[Claims] 1. A back pressure chamber is formed on the back side of a damping valve,
A port for bypassing the damping valve and the back pressure chamber, providing a bypass oil passage, communicating the inlet side of the bypass oil passage with the oil chamber on the operation side through a throttle, and variably controlling the outlet side of the bypass oil passage with a control valve. And a communication between the throttle and the port to a back pressure chamber provided on the back side of the damping valve, and from the outside to an operation surface of the control valve. A load-sensitive shock absorber characterized in that a conduction path for guiding the internal pressure is provided, and a control valve is operated in accordance with a change in the internal pressure to variably control a passage area of a port on an outlet side of a bypass oil passage. 2. A back pressure chamber is formed on the back side of the damping valve,
A port for bypassing the damping valve and the back pressure chamber, providing a bypass oil passage, communicating the inlet side of the bypass oil passage with the oil chamber on the operation side through a throttle, and variably controlling the outlet side of the bypass oil passage with a control valve. And a communication between the throttle and the port to a back pressure chamber provided on the back side of the damping valve, and from the outside to an operation surface of the control valve. A load-sensitive shock absorber characterized in that a conduction path for guiding the internal pressure is provided, and a control valve is operated in accordance with a change in the internal pressure to control the passage area of the port on the outlet side of the bypass oil passage in two stages. . 3. A back pressure chamber is formed on the back side of the expansion damping valve and the compression damping valve provided on the piston, respectively, and the expansion damping valve, the back pressure chamber, and the compression damping valve and the back pressure chamber are individually formed. A control valve that variably controls the bypass oil passages to be detoured and a passage area of a port provided on the outlet side of each bypass oil passage is provided inside the piston rod, and the control valve is provided from the outside through the piston rod. 3. The load-sensitive shock absorber according to claim 1, wherein a conduction path for guiding an internal pressure of the air suspension device is formed on the operation surface of the shock absorber. 4. A back pressure chamber is formed on the back side of the expansion damping valve provided on the piston and the compression damping valve provided on the base valve, respectively, and the expansion damping valve, the back pressure chamber, the compression damping valve and the back are formed. The bypass oil passages that individually detour the pressure chambers and the control valves that individually and variably control the passage areas of the ports provided on the outlet side of the respective bypass oil passages are respectively provided in the piston rod and the base valve valve case. 3. A load-sensitive shock according to claim 1 or 2, wherein a conductive path for guiding the internal pressure of the air suspension device to the operation surface of each control valve through the piston rod and the valve case of the base valve from the outside is formed and arranged, respectively. Absorber. 5. The load-sensitive shock absorber according to claim 3, wherein the internal pressure of the air suspension device is applied to the operation surface of the control valve by a conduction path through a constant orifice for a primary delay.