JP3335415B2 - Variable damping force type hydraulic 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 variable damping force type hydraulic shock absorber which changes a damping force by changing an opening area of an oil passage by an electromagnetically driven control valve.

[0002]

2. Description of the Related Art A conventional hydraulic shock absorber of this type is disclosed, for example, in Japanese Patent Application Laid-Open No. 5-78338. The hydraulic shock absorber disclosed in this publication is configured such that a piston with a throttle is slidably fitted in a cylinder filled with oil, and an electromagnetically driven control valve is mounted on a piston rod connected to the piston. It had been.

[0003] The electromagnetically driven control valve includes a solenoid,
A plunger that moves to the solenoid side along the cylinder axis direction when the solenoid is excited and moves to the opposite side to the solenoid by a return spring when de-energized, and a valve body provided integrally with the plunger. The valve has a structure in which a communication passage formed in the piston rod and communicating with both sides of the piston is opened and closed by the valve body. Also, a throttle having a resistance smaller than the throttle of the piston is interposed in the communication passage.

That is, when the solenoid is not energized, the damping force becomes relatively large because the communication passage is closed and the entire amount of oil flows through the throttle of the piston.
On the other hand, when the communication path is opened by exciting the solenoid, the damping force is smaller than the damping force because oil mainly flows through the communication path.

[0005] The conventional variable damping force type hydraulic shock absorber is configured to obtain a damping force that differs in magnitude as described above.

[0006]

However, the conventional variable damping force type hydraulic shock absorber merely switches the magnitude of the damping force, so that the degree of freedom in setting the damping force is small.

In order to solve such a problem, the damping force is controlled by increasing or decreasing the amount of current in the solenoid to move the plunger stepwise or gradually, so that the opening area of the communication passage becomes gradually larger or smaller. Good. However, the conventional variable damping force type shock absorber is configured so that the damping force can be adjusted as described above, and there is a problem in mass-producing this as an industrial product.

[0008] This is because when mass-producing a hydraulic shock absorber having such a configuration, the characteristics of electronic components such as solenoids and the dimensions of each component are likely to vary, so that the relationship between the amount of current and the damping force is completely reduced. It is necessary to perform quality control so as to make the hydraulic shock absorber uniform, but it is extremely troublesome to perform the same with the conventional damping force variable shock absorber configured as described above. In other words, in order to finely adjust the throttle amount with each hydraulic shock absorber, the cylinder must be disassembled and each internal component must be replaced with one that can obtain a desired damping force characteristic.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has an object to increase the degree of freedom in setting the damping force and to enable fine adjustment of the damping force by a simple operation after the assembly is completed. Aim.

[0010]

According to the present invention, a variable damping force type hydraulic shock absorber according to the present invention has a structure in which an electromagnetically driven control valve has a structure in which a plunger movement amount changes in accordance with a current amount, and a piston rod has:
The piston rod includes an adjusting rod extending from the outer end of the cylinder to the plunger mounting portion and being movable back and forth along the cylinder axis direction, and a coil spring elastically mounted between the adjusting rod and the plunger. A structure in which damping force adjusting means is provided, the adjust rod is screwed into the piston rod, and the adjust rod is rotated with respect to the piston rod, whereby the adjust rod advances and retreats, and the spring force of the coil spring increases and decreases. It was done.

[0011]

The damping force is increased or decreased in accordance with the amount of current supplied to the electromagnetically driven control valve, and the adjusting rod is rotated with respect to the piston rod to advance and retreat by the action of a screw. The load when moving is increased or decreased. Since the adjusting rod moves forward and backward by the action of the screw, it is easy to perform the fine adjustment operation, and the fine adjustment can be performed reliably.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIGS. FIG. 1 is a side view showing a main part of a variable damping force type hydraulic shock absorber according to the present invention in a cutaway manner. FIG. 2 is an enlarged sectional view showing a main part of a variable damping force type hydraulic shock absorber according to the present invention. FIG. 3 is a perspective view of the push rod, which is partially cut away for easy understanding. 4 is a sectional view taken along line IV-IV in FIG. 1, and FIG. 5 is a sectional view taken along line V-V in FIG.
It is a line sectional view.

In these figures, reference numeral 1 denotes a variable damping force type hydraulic shock absorber according to the present invention. The hydraulic shock absorber 1 is interposed between the vehicle body side and the wheel side of an automobile. And a piston rod 3 connected to the piston rod. In addition, this hydraulic shock absorber 1
The mounting direction may be opposite to the above-described direction by connecting the cylinder 2 to the wheel side and connecting the piston rod 3 to the vehicle body side.

In the cylinder 2, a free piston 6 which defines a high-pressure gas chamber 4 and an oil chamber 5 in the cylinder 2.
Are fitted so as to be able to advance and retreat along the cylinder axis direction. The high-pressure gas chamber 4 is filled with a high-pressure gas and the oil chamber 5
Is filled with oil as hydraulic oil for a hydraulic shock absorber. The oil chamber 5 is provided with the piston rod 3
The upper oil chamber 5a and the lower oil chamber 5b are defined by a throttled piston 7 provided at the end on the cylinder side.

The piston rod 3 includes a hollow shaft 9 passing through a lower end cover member 8 of the cylinder 2, a solenoid case 10 screwed to the cylinder-side end of the hollow shaft 9, and an upper end of the solenoid case 10. (The end on the side of the piston 7).
As shown in FIG. 2, the solenoid case 10 includes a bolt portion 12 screwed to the hollow shaft 9 and a bolt portion 1.
2 and a cylindrical portion 13 integrally provided. A through hole 14 is formed in the axial center of the solenoid case 10 to communicate the space inside the cylindrical portion 13 with the hollow portion of the hollow shaft 9.

The piston support shaft 11 is provided on the cylindrical portion 1.
3 is formed by a cylindrical portion 15 screwed to the outer peripheral portion of the cylindrical portion 13 so as to close the opening, and a shaft portion 16 provided integrally with the cylindrical portion 15 and to which the piston 7 is fixed.
A through hole 17 is formed in the axial center of the piston support shaft 11 so as to extend through the piston support shaft 11 along the cylinder axis direction.

The piston 7 attached to the shaft portion 16 has a conventionally well-known structure, and a plurality of elastic diaphragm plates 19 are stacked on the upper and lower sides of a disk-shaped piston body 18 respectively. The piston ring 20 is attached to the cylinder 2 and is fitted into the cylinder 2 so as to be able to advance and retreat along the cylinder axis direction. The throttle plate 19 is configured to close one end side openings of the oil passages 21 and 22 formed so as to communicate the upper end side and the lower end side of the piston 7 with the disc-shaped piston main body 18. I have. In this embodiment, the lower end opening of the oil passage 21 located on the left side in FIG. 2 is closed by the throttle plate 19, and the other upper end of the oil passage 22 is closed by the throttle plate 19.

In the piston 7 constructed as described above, when the piston rod 3 moves upward in FIG. 2, the oil in the oil passage 21 elastically deforms the throttle plate 19 located therebelow to lower it. It will flow to the side oil chamber 5b. Also, when the piston rod 3 moves downward, the oil in the oil passage 22 elastically deforms the throttle plate 19 located above it upward and flows into the upper oil chamber 5a. That is, when the piston rod 3 moves up and down, the diaphragm plate 19 becomes a resistance, and the vertical movement is attenuated.

The shaft 16 supporting the piston 7
Are provided with oil passages 23, 2 of an electromagnetically driven control valve described later.
4, 25 and 26 are provided so as to penetrate the shaft portion 16 in the radial direction. The oil passages 23 and 24 are formed at positions corresponding to the disc-shaped piston main body 18, and have one end having an annular concave groove 18 a of the disc-shaped piston main body 18 and the communication hole 1.
The other end communicates with the space inside the through-hole 17 through the oil passage 21 via 8b. Oil passage 2
5 and 26 are formed at positions closer to the cylindrical portion 15 than the piston 7, one end thereof communicates with the lower oil chamber 5 b, and the other end penetrates through an annular groove 16 a formed in the shaft 16. It communicates with the space inside the hole 17.

That is, the oil passage 21 of the piston 7, which communicates with the upper oil chamber 5a, includes the communication hole 18b, the space inside the annular groove 18a, the oil passages 23, 24, the space inside the through hole 17, the space inside the annular groove 16a, and Oil passages 25, 26
Through the lower oil chamber 5b. The electromagnetically driven control valve according to the present invention is configured such that the passage cross-sectional area of the oil passage formed in the through hole 17 is made larger or smaller by a valve body described later, so that the upper oil chamber 5a can pass through the series of oil passages described above. The flow rate of the oil flowing into and out of the lower oil chamber 5b is controlled to adjust the damping force of the piston 7. Hereinafter, the configuration of the electromagnetically driven control valve will be described.

Reference numeral 31 denotes an electromagnetically driven control valve according to the present invention. The electromagnetically driven control valve 31 is configured to gradually move the plunger by increasing or decreasing the amount of current in the proportional solenoid, and to drive the valve element with the plunger. In FIG. 2, a proportional solenoid (hereinafter simply referred to as a solenoid) is indicated by reference numeral 32, a plunger is indicated by reference numeral 33,
The valve body is indicated by reference numeral 34. In FIG. 2, the left side from the center line C indicates an excited state, and the right side indicates a non-excited state.

The solenoid 32 is formed by embedding an annular coil 32 a in a substantially bottomed cylindrical case 32 b, and the cylindrical portion 13 of the solenoid case 10.
And a cylindrical portion 15 of the piston support shaft 11. The case 32b in FIG. 2 is configured such that the upper pressure portion is a magnetic portion and the other portions are non-magnetic portions, and the piston support shaft 11 is screwed to the solenoid case 10 so as to be held therebetween. A cylindrical plunger 33 is inserted into the hollow portion of the solenoid 32. The solenoid 32 used in the present embodiment is configured to move the plunger 33 upward in FIG. 2 by being excited. When the plunger 33 is not excited, the plunger 33 is pushed downward by a spring force of a return spring described later and returns to the initial position. Reference numeral 32c denotes a lead wire of the coil 32a. The lead wire 32c is led out of the cylinder through the axial center of the piston rod 3.

The plunger 33 has pins 3 at both ends in the axial direction.
3a and 33b are protruded, and are supported by the solenoid 32 via these pins so as to be able to advance and retreat in the axial direction. Specifically, the pin 3 located on the upper side in FIG.
3a is slidably supported by the bottom of the bottomed cylindrical case 32b, and a pin 33b located on the lower side is
2 is slidably supported by a lid 35 that closes the axial opening and restricts the downward movement of the plunger 33.
The lid 35 is formed of a magnetic material, and a magnetic path is formed by the lid 35 and the thick portion of the case 32b to increase the magnetic force.

The lid 35 has an O-ring 35a on its outer periphery.
Is mounted to maintain the airtightness of the solenoid, and is attached to the solenoid 32 so as to be able to advance and retreat in the axial direction. That is, the plunger 33 is
The stroke S when moving back and forth between the bottom of b and the lid 35 and reciprocating is determined according to the position of the lid 35.

Between the lid 35 and the plunger 33, an adjusting spring 36 made of a compression coil spring for urging the plunger 33 upward in the figure is elastically mounted.

The valve body 34 is formed by providing a groove 37 for forming an oil passage on the outer periphery of a round bar in a series over the entire circumference, and moves in the through hole 17 of the piston support shaft 11 along the cylinder axis direction. It is freely inserted. The valve element 34 is urged downward from above by a return spring 38 so that the lower end thereof is
Is in contact with The return spring 38 is composed of a compression coil spring and is elastically mounted between a plug 39 screwed to an upper end of the piston support shaft 11 and an upper end of the valve body 34. The return spring 38 has a greater spring force than the adjusting spring 36 for urging the plunger 33 upward.

Therefore, when the solenoid 32 is in the non-excited state, the valve body 34 is pushed downward by the spring force of the return spring 38 and the plunger 33 is closed, as shown on the right side of the center line C in FIG. 35 will be positioned at the position where it is in contact with 35. When the solenoid 32 is excited, the valve body 34 resists the spring force of the return spring 38 by the combined force of the thrust applied from the solenoid 32 to the plunger 33 and the spring force applied from the adjustment spring 36 to the plunger 33. And is moved upward. And
At the time of the maximum excitation when the exciting current of the solenoid 32 becomes the maximum amount, as shown on the left side of the center line C in FIG.
Reference numeral 4 denotes a position where the plunger 33 is in contact with the case 32b. The stroke when the valve element 34 reciprocates is equal to the stroke S of the plunger 33.

The groove 37 on the outer periphery of the valve body 34
The opening width (width in the vertical direction) of the oil passage 2
It is formed so as to be larger than the interval between 3, 3 and the annular groove 16a. When the solenoid 32 is in the non-excited state, the formation position of the concave groove 37 is determined by the oil passages 23 and 2.
Both the groove 4 and the annular groove 16a are communicated via the groove 37, and the annular groove 16 is set so as to be closed by the outer peripheral surface of the valve body below the groove 37 at the time of maximum excitation. For this reason, the passage cross-sectional area of the oil passage in the through hole 17 changes according to the position of the valve body 34 in the vertical direction.

That is, in the non-excited state, the through hole 1
The cross-sectional area of the oil passage in the cylinder 7 is maximized, and the upper oil chamber 5a and the lower oil chamber 5b in the cylinder 2 communicate with each other via this oil passage. In this state, the damping force is small because oil flows between the upper oil chamber 5a and the lower oil chamber 5b through the oil passage. Further, when the solenoid 32 is excited, the valve body 34 gradually rises as the exciting current increases, and accordingly, the cross-sectional area of the oil passage is gradually narrowed. For this reason, the damping force gradually increases.

At the time of maximum excitation, the oil passage is closed by the valve body 34, and the entire amount of oil passing through the piston 7 receives the resistance of the throttle plate 19, so that the damping force is maximized.

The hole indicated by reference numeral 40 formed in the valve body 34 is a communication hole for preventing the resistance from increasing as a substantial piston when the valve body 34 moves forward and backward. Through this communication hole, a space for housing a return spring located above the valve body 34 and a space for housing a plunger located below the valve body 34 are communicated.

In the electromagnetically driven control valve 31 configured as described above, after the cylinder 2 is assembled, the amount of movement of the valve body 34 with respect to the amount of current is adjusted by damping force adjusting means 41 described later. In other words, the damping force is adjusted to a predetermined value without changing the amount of current supplied to the solenoid 32. Hereinafter, the damping force adjusting means 41 will be described.

The damping force adjusting means 41 includes the plunger 3
The structure is such that the spring force of the adjustment spring 36 elastically mounted between the cover 3 and the lid 35 is changed. That is, the position of the lid 35 with which one end of the adjusting spring 36 contacts is changed by the push rod 42 to increase or decrease the spring force of the adjusting spring 36, and the resultant force of the thrust of the solenoid 32 and the spring force of the adjusting spring 36. The driving force of the plunger is changed.

As shown in FIG. 3, the push rod 42 is formed by forming two concave grooves 43 extending along the axial direction on the outer peripheral portion of a round bar made of an aluminum alloy. A projection 44 that fits into the groove 35 is formed, and a notch 45 that is continuous with the two concave grooves 43 is formed at the other end. Further, the push rod 42 is provided in the through hole 1 of the solenoid case 10 which is the axis of the piston rod 3.
4 is slidably fitted in the hollow portion of the hollow shaft 9 along the axial direction. The protrusion 44 at one end is fitted to the lid 35, and the other end is prevented from coming off by the adjustment bolt 46. I have. The adjusting bolt 46 is a bolt that is screwed into the hollow shaft 9. A through hole 46 a is formed in the shaft center, and a tool for turning the adjusting bolt 46 is engaged with an end exposed outside the piston rod. Groove 46b
Are formed.

The lead wire 32c of the solenoid 32
Is led out of the piston rod through the concave groove 43 of the push rod 42 and the through hole 46a of the adjusting bolt 46, and is connected to a current amount controller (not shown).

As shown in FIG. 2, by tightening or loosening the adjustment bolt 46 with the push rod 42 interposed between the lid 35 and the adjustment bolt 46, the push rod 42 and the lid 35 are removed. Move up and down in the figure. When the adjustment bolt 46 is turned, the push rod 42 in contact with the adjustment bolt 46 is turned.
Also try to rotate in the same direction, but the rotation at this time is
Is regulated by the friction between the O-ring 35a and the solenoid 32.

When the lid 35 moves upward in the figure, the spring force of the adjusting spring 36 increases, and the resistance when the solenoid 32 moves the plunger 33 and the valve 34 decreases accordingly. When the adjustment bolt 46 is tightened in this way, assuming that the amount of current in the solenoid 32 is unchanged compared to before the adjustment bolt 46 is tightened,
Since the valve body 34 moves upward (fully closed side) by a dimension corresponding to the tightening amount, the damping force increases by that amount. When the adjusting bolt 46 is loosened,
Conversely, the damping force can be reduced.

For this reason, the damping force adjusting means 41 is elastically mounted between the adjusting rod 47 comprising the push rod 42, the lid 35 at both ends thereof, and the adjusting bolt 46, and between the adjusting rod 47 and the plunger 33. The hydraulic shock absorber 1
By assembling the adjusting rod 47 with respect to the piston rod 3 after assembling, the load when the plunger 33 of the electromagnetically driven control valve 31 advances and retreats increases and decreases.

Therefore, in the hydraulic shock absorber 1 according to the present invention, even after the cylinder 2 is assembled with the throttled piston 7 and the electromagnetically driven control valve 31, the adjustment bolt 4
By turning 6, the relationship between the amount of exciting current and the damping force can be changed.

In this embodiment, the adjusting rod 47 is used.
Is formed of an aluminum alloy, but a metal having a large thermal expansion coefficient such as a magnesium alloy can be used as a material of the push rod 42 in addition to the aluminum alloy. As described above, the push rod 4 is made of a metal material having a large thermal expansion coefficient.
When the hydraulic shock absorber 1 is formed, the oil may generate heat and its viscosity may be reduced due to overuse of the hydraulic shock absorber 1, but in such a case, the push rod 42 may be used.
Is extended by thermal expansion, so that the damping force is increased.

In the embodiment described above, the adjusting rod 47 is constituted by the push rod 42, the lid 35 and the adjusting bolt 46. However, the adjusting rod 47 is formed by a single round bar, and this rod-shaped adjusting rod is used as the piston rod 3. You may make it screw together. In this case, the lead wire 32c of the solenoid 32 is led out to the outside through a through hole formed in the axis of the rod-shaped adjust rod.

Further, in this embodiment, an example in which the oil passage is fully opened when the solenoid 32 is not excited is shown. However, as shown in FIG. 6, the oil passage may be fully closed when it is not excited. Can also.

FIG. 6 is a cross-sectional view showing another example of the valve element. In the figure, the same or equivalent members as those described in FIGS. 1 to 5 are denoted by the same reference numerals, and detailed description is omitted. . When the solenoid 32 is not excited, the valve body 34 shown in FIG. 6 completely closes the oil passage in the through hole 17 as shown on the left side of the center line C, and gradually increases the oil passage as the exciting current increases. The passage area is configured to be large. When the exciting current becomes maximum, the oil passage is fully opened as shown on the right side of the center line C.

In addition, in each of the above examples, the solenoid 32
Although the direction of the thrust is directed to the piston 7 side, the direction of the thrust may be downward in the drawing, contrary to the above. When doing so, the plunger 3 is not energized.
The spring force of the adjusting spring 36 is made larger than that of the return spring 38 in order to position the position 3 at the upper position. Further, in this case, if the plunger 33 and the valve body 34 are formed integrally, the return spring 38 can be omitted.

[0045]

As described above, in the variable damping force type hydraulic shock absorber according to the present invention, the electromagnetically driven control valve has a structure in which the amount of plunger movement changes according to the amount of current, and the piston rod has Damping force adjusting means comprising an adjusting rod extending from the outer end of the cylinder to the plunger mounting portion and capable of moving forward and backward along the cylinder axis direction, and a coil spring elastically mounted between the adjusting rod and the plunger. Is provided, the adjusting rod is screwed into the piston rod, and the adjusting rod is rotated with respect to the piston rod,
Since the adjusting rod moves forward and backward to increase or decrease the spring force of the coil spring, the damping force is increased or decreased according to the amount of current supplied to the electromagnetically driven control valve, and the adjusting rod is rotated with respect to the piston rod. By moving the plunger of the electromagnetically driven control valve forward and backward by the action of the screw, the load increases and decreases.

Accordingly, the degree of freedom in setting the damping force can be increased, and the damping force can be finely adjusted with a simple operation after the assembly is completed.

[Brief description of the drawings]

FIG. 1 is a side view showing a main part of a variable damping force type hydraulic shock absorber according to the present invention in a cutaway manner.

FIG. 2 is an enlarged sectional view showing a main part of the variable damping force type hydraulic shock absorber according to the present invention.

FIG. 3 is an exploded perspective view of an adjusting rod.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a sectional view taken along line VV in FIG. 2;

FIG. 6 is a sectional view showing another example of the valve element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic shock absorber 2 Cylinder 3 Piston rod 7 Piston 17 Through-hole 31 Electromagnetic drive type control valve 32 Solenoid 33 Plunger 34 Valve body 35 Cover 36 Adjusting spring 37 Depression groove 38 Return spring 41 Damping force adjusting means 42 Push rod 46 Adjust bolt 47 Adjusting rod

Claims (1)

(57) [Claims] An electromagnetically driven control valve is provided with a communication passage that communicates with a piston rod for a hydraulic shock absorber on both sides of a throttled piston and a plunger that moves in the cylinder axial direction in the piston rod. In the variable damping force type hydraulic shock absorber which changes the opening area of the passage, the electromagnetically driven control valve has a structure in which a plunger movement amount changes in accordance with an amount of current supplied, and the piston rod has An attenuation rod comprising an adjusting rod extending from an end located outside the cylinder to the plunger mounting portion and capable of moving back and forth along the cylinder axis direction, and a coil spring elastically mounted between the adjusting rod and the plunger. set the force adjustment means,
Screw the adjustment rod onto the piston rod,
Rotate the adjustment rod with respect to the piston rod
The adjusting rod moves back and forth,
A variable damping force type hydraulic shock absorber having a structure in which a spring force of a spring is increased or decreased .