JP3123402B2 - Self-pumping shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-pumping type shock absorber for a vehicle, and in particular, has a pump function in addition to an original vibration damping or vibration absorbing function, and automatically adjusts a vehicle height by the pump function. The present invention relates to a self-pumping type shock absorber.

[0002]

2. Description of the Related Art A cylinder, a piston having a damping force generating mechanism slidably disposed in the cylinder, and a piston rod connected to the piston at one end and projecting outside from the cylinder at the other end. The shock absorber that performs the vibration absorption function has a pump function,
A self-pumping type shock absorber that automatically adjusts the vehicle height by this pump function has been proposed (JP-A-59-159441).

In the self-pumping type shock absorber, a hollow hole extending in the axial direction from an end of the piston rod connected to the piston is formed in the piston rod, a pump cylinder is disposed in the hollow hole, and the piston rod projects. A pump rod extending from the end of the cylinder opposite to the end to be inserted is movably inserted into the pump cylinder, and the pump cylinder and the pump rod define a pump chamber. The pump rod has a passage extending in the axial direction, and a low-pressure chamber, which is a reservoir for liquid, communicates with the passage. A high-pressure chamber is provided in addition to the low-pressure chamber, and the high-pressure chamber communicates with the pump chamber via an upper liquid chamber of two liquid chambers separated by a piston.

When the piston rod repeats expansion and contraction when the vehicle height decreases, the liquid sucked into the pump chamber through the passage from the low pressure chamber is pushed out of the pump chamber to the upper liquid chamber by the action of the valve. As a result, the amount of liquid in the upper liquid chamber and the high-pressure chamber increases, and the pressure rises, whereby the piston is pushed down and the piston rod extends, thereby adjusting the vehicle height. When the vehicle height reaches a predetermined height, a control passage provided in the pump rod and communicating the passage with the upper liquid chamber is opened, and the liquid in the upper liquid chamber escapes to the low-pressure chamber.
In this way, the predetermined vehicle height is maintained.

[0005]

As described above, the vehicle height is controlled by opening and closing the control passage. However, since the shock absorber vibrates constantly, when the vehicle height is near the target height, The control passage repeatedly opens and closes. In the vicinity of the target height, different behavior occurs when the wheel load is large and when the wheel load is small. That is, when the wheel load is large, the pressure in the liquid chamber above the piston is higher than when the wheel load is small, so that the flow rate when the control passage is open increases, and the speed of decreasing the vehicle height increases. . Conversely, the flow rate from the pump chamber when the control passage is closed decreases, and the speed at which the vehicle height rises decreases. As a result, the time during which the control passage is open becomes shorter, and the vehicle tends to be stabilized at a lower vehicle height than when the wheel load is small.

The present invention provides a self-pumping type shock absorber which can correct a tendency of a vehicle height to decrease with an increase in wheel load.

[0007]

SUMMARY OF THE INVENTION A self-pumping type shock absorber according to the present invention comprises a cylinder and a damper which is slidably disposed in the cylinder to partition the cylinder into an upper liquid chamber and a lower liquid chamber. A piston having a force generating mechanism, a cylindrical piston rod having one end connected to the piston and the other end protruding from the cylinder to the outside, and having the other end closed, and the piston rod A pump cylinder disposed therein, a pump rod inserted relatively movably into the pump cylinder and defining a pump chamber in conjunction with the pump cylinder, the pump rod having an axially extending passage, and communicating with the passage of the pump rod. A low-pressure chamber, a high-pressure chamber communicating with the upper liquid chamber, and a liquid from the low-pressure chamber to the high-pressure chamber via the passage, the pump chamber, and the upper liquid chamber. And a control passage provided in the pump rod, which is capable of communicating the passage of the pump rod with the upper liquid chamber, and is disposed so as to be axially movable around the pump rod. A sleeve that adjusts a communication position of the control passage with the upper liquid chamber. When the pressure acting on the upper liquid chamber increases, the sleeve lowers the communication position, and the sleeve moves to the upper liquid chamber.
When the pressure acting becomes lower, it is formed on so that raising the communicating position.

The self-pumping type shock absorber according to the present invention also has a cylinder and a damping force generating mechanism slidably disposed in the cylinder to partition the inside of the cylinder into an upper liquid chamber and a lower liquid chamber. A first piston;
A cylindrical piston rod that is coupled to the piston at one end and protrudes from the cylinder to the outside at the other end and that plugs the other end, and is inserted into the piston rod so as to be relatively movable. A pump rod having a passage extending in an axial direction, and a second pump rod attached to the pump rod and slidably disposed in the piston rod, and partitioning the inside of the piston rod into an upper pump chamber and a lower pump chamber. A piston, a low-pressure chamber communicating with the passage of the pump rod, a high-pressure chamber communicating with the upper liquid chamber, and a first for flowing liquid from the low-pressure chamber to the lower pump chamber via the passage. A check valve, a second check valve for flowing liquid from the lower pump chamber through the upper pump chamber and the upper liquid chamber to the high-pressure chamber, and the flow passage of the pump rod. A control passage provided in the pump rod capable of communicating with the upper liquid chamber, and a control passage surrounding the pump rod and movably disposed in the axial direction, and a communication position of the control passage to the upper liquid chamber. And a sleeve for adjusting the pressure. The sleeve is formed so as to lower the communication position when the pressure acting on the upper liquid chamber increases.

In any of the above inventions, the sleeve is provided with an auxiliary piston that slides in an auxiliary cylinder, and the pressure in the high-pressure chamber passes through a throttle, and the pressure in the low-pressure chamber is applied to one side of the piston. It can be formed so as to be added to the other side of the piston.

[0010]

When the automobile is running, a damping force is generated by a damping force generating mechanism provided on the piston, and the vibration is absorbed. When the vehicle height fluctuates from the predetermined height, the pump works to automatically maintain the vehicle height at the predetermined height.At this time, if the wheel load is large, the control passage of the pump rod is lowered by the sleeve. And communicates with the upper liquid chamber at the communication position. On the other hand, when the wheel load is small, the control passage communicates with the upper liquid chamber at the communication position raised by the sleeve.

When the wheel load is large, the control passage of the pump rod communicates with the upper liquid chamber at a communication position lower than the communication position where the control liquid communicates with the upper liquid chamber under a standard wheel load. This is because the piston rod is pushed downward with respect to the control passage of the pump rod, whereby the vehicle height becomes close to the target height, and the vehicle height decreases when the control passage is repeatedly opened and closed. The tendency can be corrected, and the fluctuation of the vehicle height can be suppressed.

According to the first aspect of the present invention, a pumping operation is performed during the compression stroke of the piston rod. On the other hand, according to the second aspect of the invention, the piston rod performs a pumping action during the extension stroke and the contraction stroke. As a result, the time required for adjusting the vehicle height can be reduced by effectively utilizing the energy acting on the shock absorber.

According to the third aspect of the present invention, the sleeve has an auxiliary piston that slides in the auxiliary cylinder,
Since the pressure in the high-pressure chamber acts on one side of the piston through the throttle, even if the pressure in the high-pressure chamber fluctuates repeatedly, fluctuations in the pressure acting on one side of the piston can be suppressed. Therefore, when the vehicle height is near the target height, frequent pumping action due to repeated opening and closing of the control passage can be avoided, and the influence on ride comfort can be suppressed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A shock absorber has a cylinder, a piston having a damping force generating mechanism, which is slidably disposed in the cylinder and partitions the cylinder into an upper liquid chamber and a lower liquid chamber. A cylindrical piston rod plugged at the other end with the other end protruding out of the cylinder at the other end.

According to one aspect of the invention, a pump cylinder is disposed in a piston rod, and a pump rod having an axially extending passage which defines a pump chamber in combination with the pump cylinder is movably inserted into the pump cylinder. A low-pressure chamber serving as a liquid reservoir chamber is communicated with the passage of the pump rod, and a high-pressure chamber adjacent to the high-pressure gas chamber is communicated with the upper liquid chamber. The low-pressure chamber, the high-pressure chamber and the high-pressure gas chamber are conveniently formed so as to surround the cylinder. A first check valve for flowing the liquid from the low pressure chamber through the passage to the pump chamber and a second check valve for flowing the liquid from the pump chamber to the high pressure chamber via the upper liquid chamber Are disposed in the pump chamber. A control passage capable of communicating the passage of the pump rod with the upper liquid chamber is provided in the pump rod, and a sleeve that adjusts a communication position of the control passage to the upper liquid chamber surrounds the pump rod. It is arranged to be movable in the axial direction.
The sleeve is formed so as to lower the communication position when the pressure acting on the upper liquid chamber, that is, the high-pressure chamber increases.

In another aspect of the invention, a pump rod having a passage extending in the axial direction is inserted into the piston rod so as to be relatively movable. A piston is attached to the pump rod and slidably disposed in the piston rod, and partitions the inside of the piston rod into an upper pump chamber and a lower pump chamber. Communicating a low pressure chamber with the passage of the pump rod;
The high pressure chamber communicates with the upper liquid chamber. A first check valve for flowing liquid from the low-pressure chamber to the lower pump chamber via the passage is disposed in the lower pump chamber, and the upper pump chamber and the upper liquid are moved from the lower pump chamber to the first check valve. A second check valve for flowing liquid through the chamber to the high pressure chamber is located in the upper pump chamber. A control passage capable of communicating the passage of the pump rod with the upper liquid chamber is provided in the pump rod, and a sleeve that adjusts a communication position of the control passage to the upper liquid chamber surrounds the pump rod. It is arranged to be movable in the axial direction. The sleeve is
When the pressure acting on the upper liquid chamber, that is, the high-pressure chamber increases, the communication position is lowered.

In any of the above inventions, an auxiliary cylinder is provided above the cylinder, and an auxiliary piston that slides in the auxiliary cylinder is integrally attached to the sleeve, and the pressure of the high-pressure chamber is increased above the auxiliary piston. To
It is convenient to force the pressure in the low pressure chamber below the auxiliary piston, thereby lowering the communication position of the control passage when the pressure acting on the upper liquid chamber increases. In this case, it is preferable to attach a throttle to a passage extending from the high-pressure chamber to the upper side of the auxiliary piston.

[0018]

[Example] The self-pumping type shock absorber is
Referring to FIG. 1 which is partially enlarged and FIG. 2 which shows the whole, a cylinder 10, a piston 12 and a piston rod 14 are provided.

In the embodiment shown, the cylinder 10 comprises a cylindrical first cylinder part 16 and a first cylinder part 16 which surrounds the first cylinder part 16 with a slight clearance.
6 and a second cylindrical portion 17 having a cylindrical shape. The upper end of the first cylinder portion 16 is curved inward. The lower end of the first cylinder part 16 is connected to the seal cap 18, and the upper end of the second cylinder part 17 is integral with the end cap 20. First cylinder portion 16 and second cylinder portion 17
The slight gap 19 between
It becomes a passage for the liquid when the pump works.

The piston 12 is slidably disposed in a first cylinder portion 16 of the cylinder 10 in a liquid-tight manner, and partitions the inside of the cylinder 10 into two liquid chambers 22 and 24. The piston 12 includes a damping force generation mechanism known per se, that is, a passage and a valve 26 that generate a damping force when the piston rod 14 described later expands, and a passage and a valve that generate a damping force when the piston rod 14 contracts. 28.

The piston rod 14 is connected at one end to the piston 12. The other end of the piston rod 14 projects outside through the seal cap 18 of the first cylinder portion 16 of the cylinder 10. The piston rod 14 is connected to the O-ring 3 attached to the seal cap 18.
The seal cap 18 is kept liquid-tight and can move relative to the seal cap 18. Piston rod 14 has a bore 32 extending axially from an end coupled to piston 12. That is, the piston rod 14 is cylindrical, but the end protruding from the cylinder 10 is closed.

The pump cylinder 34 is connected to the piston rod 14
It is arranged with a clearance 35 in the hollow 32. The clearance 35 serves as a liquid passage when the pump operates, as described later. The pump cylinder 34 has a cylindrical shape with its lower end closed. Referring to FIG. 4 showing details, a cylindrical member 36 having a bottom is fixed to a closed end of the pump cylinder 34 with a C clip 38, and the pump cylinder 34 is connected to a piston rod through a shim 40 and a coil spring 42. 14, the nut 44 is screwed into the piston-side end of the piston rod 14 (see FIG. 1), and the open upper end of the pump cylinder 34 is fixed to the nut 44. 34 is assembled in the hollow 32 of the piston rod 14. According to this assembling, the processing error can be absorbed by the shim 40, and the pump cylinder 34 is pressed against the nut 44 and the piston rod 14 by the coil spring 42, so that the rattling of the pump cylinder 34 can be prevented.

The pump rod 46 includes the piston rod 14
Extends toward the pump cylinder 34 from the end of the cylinder 10 opposite to the end from which it protrudes, and in combination with the pump cylinder 34, defines a pump chamber 48. Pump rod 4
6 has a passage 50 extending in the axial direction.

In the embodiment shown, the pump rod 46 has an annular mount 52 at the upper end thereof.
2 attached to the end cap 20 of the second cylinder part 17 of the cylinder. Pump rod 46
Extends downward from the end cap 20, is inserted into the pump cylinder 34 with a clearance 47, and is relatively movable with respect to the pump cylinder 34. In gap 47,
A sleeve described later enters. The passage 50 of the pump rod 46 penetrates in the axial direction.

The low pressure chamber 54 is provided with a passage 50 for the pump rod 46.
To form a reservoir for liquid. Air and other gases are sealed above the low-pressure chamber 54. In the embodiment shown, a cylindrical cylinder 56 having an integral end cap 58 is arranged outside the cylinder 10 so as to surround the cylinder 10, while at the lower end of the second cylinder portion 17 of the cylinder 10 An annular partition 60 is attached, which defines a low pressure chamber 54. When the partition 60 reaches a predetermined mounting position, the cylinder 1
It has an inner diameter that leaves a clearance 61 between the first cylinder portion 16 and the first cylinder portion 16. The clearance 61 serves as a liquid passage when the pump operates. The two ends of a generally cylindrical rubber diaphragm 62 are partitioned by a partition 60 and a lower end cap 64.
(See FIG. 1), and the cylinder 56 is put on the cylinder 10. When the end cap 58 of the cylinder 56 abuts on the end cap 20 of the second cylinder portion 17 of the cylinder 10 in such a manner, an intermediate chamber 66 is formed between them. The end cap 58 is abutted against the end cap 20, and the end cap 64 is caulked to the lower end of the cylinder 56. As a result, the low-pressure chamber 54 is formed by the cylinder 10, the cylinder 56, and the partition 60. The low pressure chamber 54 communicates with the intermediate chamber 66 by a pipe 68 extending from the end cap 20 of the cylinder 10 to the vicinity of the partition 60, and communicates with the passage 50 of the pump rod 46 via the intermediate chamber 66.

As a result of attaching the diaphragm 62 to the partition 60 and the end cap 64, the high-pressure gas chamber 70 is defined by the diaphragm 62 and the cylinder 56, and the high-pressure liquid chamber 72 is further defined by the diaphragm 62 and the cylinder 10
And the first cylinder portion 16. The high-pressure gas chamber 70 is filled with, for example, air, nitrogen gas or other inert gas of 980 kPa (10 kgf / cm ² ) or more. The high-pressure liquid chamber 72 receives the gas pressure in the high-pressure gas chamber 70 and is maintained at a pressure substantially equal to the pressure. The high-pressure liquid chamber 72 communicates with the upper liquid chamber 22 via the gap 61 and the gap 19.

The passage 5 of the pump rod 46 from the low pressure chamber 54
A valve is provided for flowing liquid toward the high-pressure liquid chamber 72 via the pump chamber 48 and the upper liquid chamber 22. In the illustrated embodiment, the valve comprises a check valve 76 for suction located at the lower end of the pump rod 46 and a pump cylinder 34.
And a check valve 78 for discharge arranged at the lower end of the discharge valve. The check valve 76 allows only the liquid flow from the passage 50 of the pump rod 46 to the pump chamber 48, and the check valve 78 allows only the liquid flow from the pump chamber 48 to the clearance 35.

The check valve 76 has a circular valve plate 80 which contacts the lower end of the pump rod 46, as shown in FIG.
, A coil spring 82 for pressing the valve plate 80 against the pump rod 46, and a cap 84 for attaching the coil spring 82 to the pump rod 46. The cap 84 has a plurality of slits 86 at intervals in the circumferential direction. The check valve 76 is connected to the negative pressure generated in the pump chamber 48 and the pump rod 4.
When the pressure of the liquid in the passage 50 exceeds the pressure set by the coil spring 82, the valve plate 80
The passage 50 is opened by moving away from 6, and the liquid flows from the passage 50 toward the pump chamber 48 through the slit 86 of the cap.

On the other hand, the check valve 78 includes a circular valve plate 90 in contact with the lower end of the pump cylinder 34, a coil spring 92 for pressing the valve plate 90 against the pump cylinder 34, and a coil, as shown in FIG. And a cylindrical member 36 for attaching the spring 92 to the pump cylinder 34. A hole 94 is formed in the bottom of the pump cylinder 34, and a plurality of grooves 96 are provided in the cylindrical member 36 at intervals in the circumferential direction. Accordingly, when the pressure in the pump chamber 48 exceeds the pressure set by the coil spring 92, the check valve 78 moves the valve plate 90 away from the pump cylinder 34, and thereby the pump chamber 4
8 is opened, and the liquid flows from the pump chamber 48 to the gap 35 through the hole 94 and the groove 96 of the cylindrical member.

As shown in FIG. 1, the pump rod 46 has a control passage 1 through which a passage 50 can communicate with the upper liquid chamber 22.
00 is provided. In the embodiment shown, the control passage 1
Reference numeral 00 denotes a first passage portion 101 opened in the pump rod 46 in the radial direction, and a second passage portion 102 provided in the outer peripheral surface of the pump rod 46 in a groove shape in the axial direction. The second passage portion 102 communicates with the first passage portion 101 at the center.

A sleeve 104 for adjusting the position of communication with the liquid chamber 22 above the control passage 100 is disposed on the pump rod 46 so as to be movable in the axial direction. The sleeve 104 is formed of a cylindrical member, can enter a clearance 47 between the pump cylinder 34 and the pump rod 46, and is located inside the pump cylinder 34 with a slight clearance. The slight clearance between the sleeve 104 and the pump cylinder 34 substantially prevents liquid leakage. Sleeve 104 has a radially drilled bore 1 communicating with second passage portion 102 of control passage 100 of pump rod 46.
06. Thus, the control passage 100 can communicate with the liquid chamber 22 via the hole 106 when the hole 106 of the sleeve 104 is within the range of the axial length of the second passage portion 102.

When the pressure acting on the upper liquid chamber 22 with the standard wheel load is applied, the sleeve 104 is in the standard communication position, that is, the hole 106 of the sleeve corresponds to the first passage portion 101 of the control passage 100. And the hole 106
Is formed so as not to be blocked by the pump cylinder 34. Further, when the pressure acting on the upper liquid chamber 22 increases, the communicating position is lowered, that is, the hole 1 in the sleeve is lowered.
Although the level of 06 decreases, the pressure in the upper liquid chamber 22 increases, so that the pump cylinder 34 is pushed down together with the piston 12, and the hole 106 is formed so as not to be closed by the pump cylinder 34.

In the embodiment shown, the sleeve 104 has an auxiliary piston 112 which slides in an auxiliary cylinder 110, the pressure in the upper liquid chamber 22 is applied above the piston 112 and the pressure in the low pressure chamber 54 is It joins below 112. The cylinder 110 is formed of a cylindrical member having a bottom, and is fitted to the first cylinder portion 17 of the cylinder 10 via the taper washer 114 so that the bottom 111 is located on the lower side. It is kept tight. On the other hand, the piston 112 is formed integrally with the upper end of the sleeve 104, is slidably disposed in the cylinder 110, and the sleeve 104 penetrates the bottom 111 of the cylinder 110, and is kept liquid-tight by the O-ring 118. I have. A passage 120 is provided in the cylinder 110 and communicates the liquid chamber 22 with a liquid chamber 122 above the piston 112. Further, the passage 124 is
A passage 126 communicating with the passage 124 is provided in the first cylinder portion 17, and communicates the liquid chamber 128 below the piston 112 with the low-pressure chamber 54. The coil spring 130 is disposed in the lower liquid chamber 128 so that the piston 112
Exerting an upward force on the piston 112 to bias the piston 112 upward.

Further, in the illustrated embodiment, a throttle 132 formed of an orifice is provided in the passage 120. The restriction 132 gives resistance to the liquid passing through the passage 120, and prevents the pressure fluctuation in the liquid chamber 22 from being immediately applied to the liquid chamber 122.

As is known per se, the self-pumping type shock absorber is used by attaching an upper end of a rod 150 projecting upward from the cylinder 56 to a vehicle body and attaching a lower end of the pithlon rod 14 to a suspension arm. I do. When the vehicle is in a bound state during traveling, the piston rod 14 contracts, and a damping force is generated by a damping force generating mechanism 28 provided on the piston 12, thereby absorbing vibration. Also, when it comes to rebound,
The piston rod 14 is extended, and a damping force is generated by a damping force generating mechanism 26 provided on the piston 12 to absorb vibration.

When the wheel load is large, the pressure in the upper liquid chamber 22 is high, and therefore the downward pressure applied to the auxiliary piston 112 is large. Therefore, the piston 112 compresses the coil spring 130 and moves downward, and the sleeve 1
04, the hole 106 is at a low level so that the control passage 100 of the pump rod 46 is
It communicates with the upper liquid chamber 22 at the communication position lowered by 04.

At this time, when the vehicle height fluctuates from a predetermined height and the vehicle height decreases, the pump cylinder 34 and the sleeve 104
Are relatively displaced, and the pump cylinder 34
Hole 106 is closed. In this state, when the piston rod 14 extends, the pressure in the pump chamber 48 decreases,
Since the check valve 76 is open but the check valve 78 is closed,
The liquid in the low-pressure chamber 54 reaches the passage 50 from the pipe 68 via the intermediate chamber 66, and flows into the pump chamber 48. Thereafter, when the piston rod 14 contracts, the pressure in the pump chamber 48 increases, and the check valve 78 is opened but the check valve 76 is closed, so that the liquid in the pump chamber 48 passes through the clearance 35 and moves upward. After flowing into the liquid chamber 22, the amount of fluid in the liquid chamber 22 increases. As a result, the liquid in the liquid chamber 22 flows into the high-pressure chamber 72 through the gap 19 and the gap 61, and at the same time, pushes down the piston 12. When the above operation is repeated and the hole 106 of the sleeve 104 communicates with the liquid chamber 22,
The liquid in the liquid chamber 22 reaches the control passage 100 from the hole 106 and escapes to the low-pressure chamber 54 via the passage 50 and the intermediate chamber 66, so that the liquid amount and the pressure in the liquid chamber 22 are balanced with the wheel load. And maintain the vehicle height at a predetermined height.

During the above operation, since the wheel load is large, the control passage 100 of the pump rod 46 is connected to the upper liquid chamber 22 at a lower communication position than the communication position that communicates with the upper liquid chamber 22 under the standard wheel load. The state communicates with the liquid chamber 22 and becomes the same state as when the piston rod 14 is pushed out. Therefore,
When the vehicle height is near the target height and the opening and closing of the control passage 100 is repeated, the decreasing tendency of the vehicle height can be corrected, and the fluctuation of the vehicle height can be suppressed.

Conversely, when the vehicle height fluctuates from the predetermined height and the vehicle height becomes higher, the pump cylinder 34 and the sleeve 104 are relatively displaced, and the hole 106 of the sleeve 104 communicates with the liquid chamber 22. When the piston rod 14 extends in this state, the pressure in the pump chamber 48 decreases, and the check valve 7
6 is open but the check valve 78 is closed, so the low-pressure chamber 54
The liquid inside reaches the passage 50 from the pipe 68 via the intermediate chamber 66, and flows into the pump chamber 48. Thereafter, when the piston rod 14 contracts, the pressure in the pump chamber 48 increases, and the check valve 78 is opened but the check valve 76 is closed, so that the liquid in the pump chamber 48 passes through the clearance 35 and moves upward. Liquid chamber 2
Flow into 2. However, the liquid chamber 22 has the hole 106 of the sleeve 104, the control passage 100, and the passage 5 of the pump rod 46.
The liquid flowing into the liquid chamber 22 escapes to the low-pressure chamber 54 because it communicates with the low-pressure chamber 54 via the intermediate chamber 66 and the pipe 68, and does not contribute to pushing down the piston 12. When the above operation is repeated and the hole 106 of the sleeve 104 reaches the upper end of the pump cylinder 34, the liquid amount and the pressure in the liquid chamber 22 are balanced with the wheel load, and the vehicle height is maintained at a predetermined height. I do.

When the wheel load is small, the pressure in the upper liquid chamber 22 is low, and therefore, the downward pressure applied to the auxiliary piston 112 is small. Therefore, the piston 112 is moved upward by the coil spring 130, and the sleeve 1
04, the hole 106 is at a high level, so that the control passage 100 of the pump rod 46
It communicates with the upper liquid chamber 22 at the communication position raised by 04.

At this time, when the vehicle height fluctuates from the predetermined height and the vehicle height decreases, the same operation as described above is repeated to maintain the vehicle height at the predetermined height. Since the pressure in the upper liquid chamber is low, the flow rate when the control passage is open decreases, and the rate of decrease in vehicle height decreases.
Conversely, the flow rate from the pump chamber when the control passage is closed increases, and the speed of increasing the vehicle height increases. As a result, the time during which the control passage is open becomes longer. As a result, the vehicle height becomes close to the target height, and fluctuations in the vehicle height when the opening and closing of the control passage 100 are repeated can be suppressed.

As in the illustrated embodiment, the liquid chamber 22 and the liquid chamber 1
When there is a throttle 132 in the passage 120 communicating with the nozzle 22,
The pressure in the liquid chamber 122 does not follow the pressure fluctuation of the liquid chamber 22,
The pressure fluctuation does not substantially occur in the liquid chamber 122. Therefore, the cylinder 126 is frequently moved up and down, whereby the sleeve 104 is frequently moved up and down, and the occurrence of the operation of repeatedly opening and closing the control passage 100 can be suppressed, and the influence on the riding comfort can be eliminated.

The self-pumping type shock absorber shown in FIGS. 5 to 7 is the same as the embodiment shown in FIGS. 1 to 4 except for a part of the structure. Therefore, components having substantially the same configuration are denoted by the same reference numerals, and description of the same configuration is omitted.

A pump rod 46 is inserted into the hollow 32 of the piston rod 14 so as to be relatively movable, and a piston 200 is attached to the pump rod 46. A piston 200 is slidably disposed within the piston rod 14 and an upper pump chamber 202 within the piston rod 14.
It is partitioned into a lower pump chamber 204. Piston 20
0 has a plurality of through passages 201 and a check valve 206
Is mounted on the upper side of the piston 200. The check valve 206 allows only the flow of the liquid from the lower pump chamber 204 to the upper pump chamber 202.

The control passage 100 of the pump rod 46 comprises a first passage portion 101 and a second passage portion 102.
In this embodiment, the second passage portion 102 includes the pump rod 4
6 is an annular groove extending over the entire circumference.

The hole 106 of the sleeve 104 can communicate on the one hand with the second passage part 102 of the control passage 100,
On the other hand, it is opened and closed by a sleeve valve 208. The sleeve valve 208 is formed of a cylinder whose upper end is divergent, which can relatively slide on the outer surface of the sleeve 104. The sleeve valve 208 is pushed upward by a coil spring 210 received at a lower end by a spring receiver 214, and abuts against an annular flange 212 provided at an open end of the piston rod 14 to hold the sleeve valve at that position. Is done. In this state, if the hole 106 of the sleeve 104 is located radially inward of the sleeve valve 208, the hole 1
06 is closed by the sleeve valve 208. Therefore, in the range of the axial length of the sleeve valve 208, even if the hole 106 of the sleeve 104 communicates with the second passage portion 102 of the control passage 100, no pumping action occurs.

When the shock absorber is used, when the wheel load is large, the pressure in the upper liquid chamber 22 is high, and therefore the downward pressure applied to the auxiliary piston 112 is large. Therefore, the piston 112 compresses the coil spring 130 and moves downward, pushing down the sleeve 104. When the hole 106 in the sleeve 104 reaches a low level beyond the sleeve valve 208, the control passage 100 of the pump rod 46 communicates with the upper liquid chamber 22 at the communication position lowered by the sleeve 104.

In the extension stroke of the piston rod 14, since the piston rod 14 and the pump rod 46 move relatively, the liquid in the upper pump chamber 202 is pushed out to the upper liquid chamber 22 by the piston 200 and passes through the clearance 19. And flows into the high pressure chamber 72. When the liquid flows into the high pressure chamber 72, the diaphragm 62 is compressed, and as a result, the high pressure air chamber 70 is compressed.
And the pressure in the upper liquid chamber 22 rises. As a result, the piston rod 14
, The vehicle height increases. At the same time, since the pressure in the lower pump chamber 204 decreases, the liquid in the low-pressure chamber 54 flows from the pipe 68 through the intermediate chamber 66 and the passage 50, pushes the check valve 76 open, and flows into the pump chamber 204.

In the contraction stroke of the piston rod 14, the liquid in the pump chamber 204 passes through the passage 201 and
6 is pushed open and pushed out into the upper pump chamber 202, further pushed out into the upper liquid chamber 22, and flows into the high-pressure chamber 72 through the gap 19. As a result, the vehicle height increases as in the extension stroke. Thus, the pumping action is performed in both the extension stroke and the contraction stroke.

When the vehicle height is higher than a predetermined height, the pawl 212 of the piston rod 14 pushes down the sleeve valve 208 against the spring force of the coil spring 210, so that the liquid in the liquid chamber 22 above the piston is released from the sleeve 104. Hole 1
From 06, it passes through the control passage 100 and the passage 50 to reach the intermediate chamber 66, and flows through the pipe 68 into the low-pressure chamber 54. Therefore, the liquid in the high-pressure chamber 72 flows to the liquid chamber 22 through the gap 19, the volume of the high-pressure air chamber 70 expands, the pressure decreases, and the pressure in the liquid chamber 22 decreases. As a result, the piston rod 14 contracts, and the vehicle height decreases.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing a main part of an embodiment of a self-pumping type shock absorber according to the present invention.

FIG. 2 is a sectional view of the self-pumping type shock absorber shown in FIG.

FIG. 3 is an enlarged sectional view showing a check valve for a liquid flowing from a low pressure chamber toward a pump chamber.

FIG. 4 is an enlarged sectional view showing a check valve for a liquid flowing from a pump chamber toward a liquid chamber above a piston.

FIG. 5 is an enlarged sectional view showing a main part of another embodiment of the self-pumping type shock absorber according to the present invention.

6 shows a piston of the shock absorber shown in FIG. 5,
It is sectional drawing which expands and shows some piston rods and pump rods.

FIG. 7 is a sectional view of the self-pumping type shock absorber shown in FIG.

[Explanation of symbols]

 Reference Signs List 10 cylinder 12, 200 piston 14 piston rod 22, 24, 122, 128 liquid chamber 26, 28 damping force generating mechanism 32 hollow hole 34 pump cylinder 46 pump rod 48, 202, 204 pump chamber 50 passage 54 low pressure chamber 72 high pressure chamber 76 , 78, 206 Check valve 100 Control passage 104 Sleeve 106 Hole 110 Auxiliary cylinder 112 Auxiliary piston 120 Passage 132 Throttle 208 Sleeve valve

Claims (3)

(57) [Claims] A piston having a damping force generating mechanism slidably disposed within the cylinder to partition the cylinder into an upper liquid chamber and a lower liquid chamber; and a piston at one end. A cylindrical piston rod closed at the other end, the other end protruding from the cylinder to the outside, a pump cylinder disposed in the piston rod, and a relative movement with respect to the pump cylinder. A pump rod having a passage extending in the axial direction, which is inserted as possible and defines a pump chamber in combination with the pump cylinder; a low-pressure chamber communicating with the passage of the pump rod; and a high-pressure chamber communicating with the upper liquid chamber. A valve for flowing liquid from the low-pressure chamber to the high-pressure chamber via the passage, the pump chamber, and the upper liquid chamber; and A control passage provided in the pump rod, which can communicate with the pump rod; and a sleeve surrounding the pump rod so as to be movable in an axial direction, and adjusting a communication position of the control passage with the upper liquid chamber. When the pressure acting on the upper liquid chamber increases, the sleeve lowers the communication position, and the pressure acting on the upper liquid chamber decreases .
When lowered, it is formed so that raised the communicating position, the self-pumping shock absorber. 2. A cylinder, a first piston slidably disposed within the cylinder and partitioning the cylinder into an upper liquid chamber and a lower liquid chamber, the first piston having a damping force generating mechanism, and one end thereof. A cylindrical piston rod closed at the other end, the other end protruding outside from the cylinder, and inserted into the piston rod so as to be relatively movable, in the axial direction A second pump rod having an extending passage; a second pump chamber attached to the first pump rod and slidably disposed in the piston rod for partitioning the inside of the piston rod into an upper pump chamber and a lower pump chamber.
A low-pressure chamber communicating with the passage of the pump rod; a high-pressure chamber communicating with the upper liquid chamber; and a first for flowing liquid from the low-pressure chamber to the lower pump chamber via the passage. A check valve, a second check valve for flowing liquid from the lower pump chamber to the high-pressure chamber through the upper pump chamber and the upper liquid chamber, and the passage of the pump rod. A control passage provided in the pump rod, which is communicable with an upper liquid chamber, and is disposed so as to be movable in an axial direction surrounding the pump rod, and adjusts a communication position of the control passage with the upper liquid chamber. A self-pumping shock absorber, wherein the sleeve is configured to lower the communication position when pressure acting on the upper liquid chamber increases. 3. The sleeve has an auxiliary piston that slides in an auxiliary cylinder, and the pressure of the high-pressure chamber passes through a throttle to one side of the piston, and the pressure of the low-pressure chamber passes to the other side of the piston. 2. The method of claim 1, wherein the first and second elements are configured to join.
Or the self-pumping type shock absorber according to 2.