JPH0516425Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field of the Invention) The present invention relates to a hydraulic shock absorber, and more particularly to a hydraulic shock absorber suitable for use in a vehicle suspension system, the damping force of which can be adjusted from the outside.

(Prior art) The damping force of the hydraulic shock absorber installed in the suspension system of a vehicle affects ride comfort and handling stability.
Hydraulic shock absorbers have been put into practical use in which the damping force can be adjusted from the outside and the damping force can be changed depending on driving conditions.

The damping force of the hydraulic shock absorber is adjusted by communicating or blocking a liquid passage, which is a bypass, provided in the piston rod with a plunger or the like. The adjustment mechanisms in this case can be roughly divided into those that electrically move the plunger and those that mechanically move or rotate the plunger. The present invention relates to the former.

The hydraulic shock absorber (hereinafter referred to as the first prior art) described in Japanese Patent Application Laid-open No. 57-173629 has a piston provided with a passage for liquid flow, and a valve body made of a magnetic material that opens and closes this passage. It is placed at one end, and an electromagnetic coil is installed inside the piston. The damping force can be continuously adjusted by changing the attraction force of the electromagnetic coil to the valve body.

The shock absorber (hereinafter referred to as the second prior art) described in Japanese Patent Application Laid-open No. 58-57534 has an electromagnetic coil built into the piston rod and a stepping mechanism that converts linear motion into rotational motion. The valve body for opening and closing the oil passage is operated by a stepping mechanism, making it possible to adjust the damping force.

(Problems to be Solved by the Invention) In the first prior art, the damping force when the piston rod is extended is adjustable, but the damping force when the piston rod is contracted is constant. Furthermore, since the electromagnetic coil is disposed within the piston, the piston and, by extension, the entire hydraulic shock absorber become larger and weigh more.

The second prior art uses a stepping mechanism to convert linear motion into rotational motion, so the structure is complicated and there is a high possibility of failure.

Incidentally, a hydraulic shock absorber used particularly in a vehicle suspension system is usually designed so that the damping force generated when the piston rod is extended is larger than the damping force generated when the piston rod is contracted. In a hydraulic shock absorber whose damping force is adjustable, even when the damping force is adjusted to each individual damping force state, it is preferable that the damping force during extension is larger than that during contraction. Has no function.

It is an object of the present invention to provide a hydraulic shock absorber in which the damping force can be adjusted when the piston rod is extended and retracted, and the damping force when the piston rod is extended is greater than that when it is retracted in each adjustment state.

Another object of the present invention is to provide a hydraulic shock absorber that can be miniaturized and has less possibility of failure.

(Means for Solving the Problems) The present invention communicates two liquid chambers partitioned in the cylinder through a passage provided in the piston rod, and adjusts the flow rate of the liquid by a valve mechanism disposed in the passage. This is a hydraulic shock absorber. The valve mechanism includes a sleeve, a core, two plungers, and a check valve. The sleeve has a radially open first passage and a second passage at axially spaced locations. The core is arranged so as to form a first space communicating with the first passage and a second space communicating with the second passage outside the sleeve in the radial direction. The core is provided with a third passage communicating with the first space and a fourth passage communicating with the second space. The third passage includes a first passage portion and the first passage portion.
a second passageway portion having a diameter smaller than the diameter of the passageway, and a fourth passageway having a diameter smaller than the diameter of the second passageway and a fourth passageway portion having a diameter smaller than the diameter of the passageway;
and a fourth passage portion having a diameter different from that of the passage portion. A plunger is disposed within the first space so as to be movable in the axial direction of the sleeve. The plunger has a fifth passage in communication with the third passage of the core and is moved by an electromagnetic coil. Another plunger is disposed within the second space and movable in the axial direction of the sleeve. The plunger has a sixth passage that can communicate with the fourth passage of the core, and is moved by an electromagnetic coil separate from the electromagnetic coil. The check valve opens and closes the first passage portion of the third passage and the third passage portion of the fourth passage, and prevents the flow of liquid when the piston rod is extended, but when the piston rod is contracted. sometimes causes liquid to flow.

(Function) When the piston rod is extended and the piston speed is low, the liquid entering the passage of the piston rod from one liquid chamber is transferred to the second passage of the third passage of the core depending on the position of the two plungers. flows through the first passage or the second passage of the sleeve to the other fluid chamber via the passage portion or the fourth passage portion or the second and fourth passage portions; or blocked. The flow rate of the liquid through the valve mechanism and the damping force generated depend on the diameter of the second or fourth passage section.

When the piston speed increases, the liquid flows outside the valve mechanism and through the damping force generating mechanism originally provided in the piston, generating a large damping force.

When the piston rod retracts, during low piston speeds, liquid entering the passage of the piston rod from the other liquid chamber reaches the core via the first passage or the second passage of the sleeve and changes the position of the two plungers. Depending on the situation, the check valve is pushed open or shut off. The liquid that pushes open the check valve passes through the first passage portion and the second passage portion of the third passage of the core, or through the third passage portion and the fourth passage portion of the fourth passage. or through all passages toward one liquid chamber. The flow rate of the liquid and the damping force generated at this time depend on the diameter of the first passage or the second passage of the sleeve.

At higher piston speeds, liquid flows out of the valve mechanism through damping force generating mechanisms that are either native to the piston or remote from the piston, but when the piston rod retracts, it flows through the passages of the piston rod. Since the amount of liquid flowing through the piston is greater than the amount of liquid flowing through the extension, the amount of liquid flowing through the original damping force generating mechanism is less than when the piston is expanding with the same amount of movement. Thereby, the generated damping force can be reduced.

(Effect of the invention) The third passage and the fourth passage of the core can be opened and closed independently by two plungers, and the diameter of the second passage part of the third passage of the core and the diameter of the fourth passage are Since the diameter of the fourth passage portion is different, the damping force can be adjusted in four steps both when the piston rod is extended and when it is contracted. During low piston speeds, i.e. while the liquid flows only through the piston rod passages, e.g.
When the fifth passage of one plunger communicates with the third passage of the core, the following flow occurs, and this flow generates a damping force.

When the piston rod is extended, the liquid in one of the liquid chambers that has reached the piston rod passage flows into the third chamber of the core.
The liquid flows through the second passage portion of the passage, the fifth passage of one plunger and the first passage of the sleeve in this order, and flows into the other liquid chamber.

The fifth passage of the plunger is connected to the third passage and the first passage.
It has only the function of communicating with the fifth passage, and the diameter of the fifth passage can be made sufficiently large. As a result, the flow rate of the liquid is reduced to the second passage in the third passage.
It can be determined by the diameter of the passage portion or the diameter of the first passage. However, since the diameter of the second passage portion of the third passage is smaller than the diameter of the first passage, the damping force is ultimately determined by the flow velocity of the second passage portion.

When the piston rod is retracted, the check valve opens as soon as pressure is generated in the other fluid chamber, so that the fluid in the other fluid chamber that has reached the passage of the piston rod flows through the first passage of the sleeve and the first passage of one plunger. The fluid flows through the No. 5 passage in this order, further flows through the first passage portion and the second passage portion of the third passage, and flows into one of the liquid chambers.

The damping force at the time of contraction can be considered to be determined by the flow velocity in the first passage or the flow velocity in the second passage portion of the third passage. The damping force determined by the former is due to the fact that the diameter of the first passage is larger than the diameter of the second passage part of the third passage, and the flow velocity is correspondingly lower. smaller than the damping force generated by Furthermore, since the amount of liquid flowing through the second passage portion of the third passage during contraction is small because the liquid flows through the first passage portion, the damping force generated in the second passage portion during contraction is equal to the damping force generated during expansion. It is smaller than the damping force generated in the second passage section.

If the piston speed increases and the liquid flows through the piston passage as well as the piston rod passage,
Damping force is generated by the liquid flowing through both passages, but the magnitude of the damping force during extension and the damping force during contraction is usually such that the damping force generated in the piston passage is greater than that generated in the piston rod passage. It is convenient to compare the damping force generated in the piston passage, since the damping force is set to be several times larger.

When the piston rod is compressed, the check valve opens immediately when pressure is generated in the liquid chamber to be compressed.
The amount of liquid flowing through the piston rod passage during contraction is greater than the amount of liquid flowing through the piston rod passage during extension, and the amount of liquid flowing through the piston rod passage is reduced accordingly. As a result, the damping force produced by the liquid flowing through the piston passage during contraction is less than the damping force produced by the liquid flowing through the piston passage during extension.

As described above, according to the present invention, the damping force generated when the piston rod is extended can be made larger than the damping force generated when the piston rod is contracted, regardless of the piston speed.

Since the electromagnetic coil that moves the plunger can be arranged in relation to the passage of the piston rod, the outer diameter of the piston can be determined independently of the size and shape of the electromagnetic coil, thereby reducing the size of the piston and, therefore, of the entire hydraulic shock absorber. can.

Since the plunger is structured to move in the axial direction of the sleeve, its structure is simple and the possibility of failure is low.

(Example) As shown in FIG. 1, the hydraulic shock absorber 10 has a piston 14 disposed within the cylinder 12 that divides the inside of the cylinder 12 into two liquid chambers A and B, and a piston rod 16 provided with the piston 14. A valve mechanism 20 communicates both liquid chambers through the passage 18 and is disposed in the passage 18.
configured to adjust the flow rate of the liquid.

The hydraulic shock absorber 10 is a so-called monotube type having a single cylinder 12, as shown by the imaginary line, or a so-called twin tube type having two coaxial cylinders. At the open end of the cylinder 12, a piston 1 is attached to the end of the piston rod 16, which is held by a rod guide and a ring nut and extends into the cylinder 12.
4 are combined. The piston 14 includes a valve that generates a damping force when the piston rod 16 is extended, and a valve that generates a damping force when the piston rod 16 is retracted. Since the configuration itself is well known, illustration and detailed explanation will be omitted.

The piston rod 16 consists of a first member 22 and a second member 24 that is screwed into and fixed to the first member, and both members 22 and 24 are made into a hollow shape by hollowing out the portion that will be placed inside the cylinder 12. It is formed. The first member 22 has a passage portion 23a and a hollow hole 23b that are opened from the outer peripheral surface to the inner peripheral surface, and a passage portion 25a and a hollow hole 25b that extend from the end surface in the axial direction of the second member 24.
As a result, a passage 18 is formed, and the liquid chambers A and B are arranged in this passage 18 in addition to the passage provided in the piston 14.
Communicate via.

The valve mechanism 20 includes a sleeve 26, a core 28,
It includes plungers 30, 32 and a check valve 34, which are disposed within the passageway 18 of the piston rod and regulate the amount of liquid flowing through the passageway 18.

The sleeve 26 is made of a cylindrical material, and includes a passage 36 opened in the radial direction and a passage 3 opened in the radial direction at a portion spaced apart from the passage 36 in the axial direction.
6. The passageway 38 has a diameter larger than that of the passageway 38.
The sleeve 26 is held by a pair of side cores, which will be described later. A plug 40 is press-fitted into the end of the sleeve 26 that is remote from the passage portion 25a of the passage 18.

The core 28 has a space 42 on the outside of the sleeve 26 that communicates with the passages 36 and 38 of the sleeve, respectively.
44. In the illustrated example, the core 28 includes a first member 46 formed in a cylindrical shape made of a magnetic material, and a second member 46 formed in a cylindrical shape made of a magnetic material disposed inside the first member 46.
It consists of 8.

In the central part of the outer periphery of the first member 46 in the axial direction,
As shown in detail in FIG. 2, a pair of chord-shaped notched valve placement portions 47a and a groove portion 47b extending in the circumferential direction so as to communicate both valve placement portions 47a are provided. On the other hand, the second member 48 has an annular groove 49 extending in the circumferential direction on its outer periphery.
The pin 45 is driven into the second member 48 from
is received in the groove 49, and the second member 48 is fixed to the first member. As a result, a space 42 and a space 44 are defined on both sides of the second member.

The first member 46 of the core 28 has a passage 50 communicating with the space 42 and a passage 52 communicating with the space 44 . In the illustrated example, the passageway 50 is connected to the valve arrangement portion 4
A passage portion 51a extending from 7a to the inner circumference, and a groove portion 4
A passage portion 51b extending from 7b to the inner circumference, and both passage portions 51a, 5 provided in the circumferential direction on the inner circumferential surface.
1b and an annular passage portion 51c that communicates with each other. The diameter of the passage portion 51b is smaller than the diameter of the passage 36 of the sleeve 26.

Passageway 52 is of substantially the same configuration as passageway 50. That is, the passage 52 includes a passage part 53a extending from the valve arrangement part 47a to the inner periphery, a passage part 53b extending from the groove part 47b to the inner periphery, and both passage parts 53a and 53b provided on the inner circumferential surface in the circumferential direction. It has an annular passage portion 53c with which it communicates. The diameter of the passage portion 53b is smaller than the diameter of the passage 38 of the sleeve 26.

A pair of plungers 30 and 32 are formed of a cylindrical magnetic material so as to be able to slide on the inner circumferential surface of the core 28, with one plunger 30 inside the space 42 and the other plunger 32 inside the space 44 of the sleeve 26. It is arranged to be movable in the axial direction. plunger 3
0 is a passage 54 that can communicate with the passage 50 of the core 28
, the plunger 32 has a passage 56 that can communicate with the passage 52 .

A check valve 34 is located in the passages 50, 52 of the core 28 to prevent the flow of liquid during extension of the piston rod 16, but to allow liquid to flow during retraction. In the illustrated example, the check valve 34 is provided in common to both passages 50 and 52. That is, the check valve 34 has a passage portion 51a and a passage portion 53a.
It consists of a plate material large enough to cover the opening of the core 28.
The valve arranging portion 47a is biased toward the openings of both passages by a coil spring 58.
The coil spring 58 is stopped by a stopper 60 press-fitted into the core 28. When the spring force of the coil spring 58 is small and a slight hydraulic pressure is generated in the liquid chamber B, the check valve 34 separates from the openings of both passages.

A pair of side cores 62 and 64 made of magnetic material are arranged at intervals from the core 28 in the axial direction. These cores 62 and 64 form a cylindrical sleeve 6
6 and is held at a predetermined distance from the central core 28. Piston 14
The core 64 closer to the hole 69 penetrates in the axial direction.
and communicates with the passage portion 25a of the passage 18 of the piston rod 16. The sleeve 26 is fitted into a pair of side cores 62 and 64. A coil spring 68 is disposed between each side core and each plunger, and connects the plunger to the second member 48 of the core 28.
bias towards.

An electromagnetic coil 7 is disposed radially outwardly of the plunger 30.
0, and an electromagnetic coil 72 is arranged radially outward of the plunger 32. Each electromagnetic coil is covered by a bobbin 74 and fitted into a sleeve 66.
In use, one or the other electromagnetic coil is selectively energized, or neither electromagnetic coil is energized, via a harness 76 extending outside of the piston rod 16.

(Effect of the embodiment) The hydraulic shock absorber 10 is installed in the suspension system of an automobile,
The cylinder 12 is used in contact with the suspension arm, and the piston rod 16 is used in contact with the vehicle body.

The electromagnetic coils 70 and 72 are energized by manual operation by the driver or by automatic operation by a CPU (computer) that makes decisions based on signals from various sensors.

When the electromagnetic coil 70 is energized, as shown in the figure,
One plunger 30 has moved to the left, and the other plunger 32 has abutted against the second member 48 of the core 28. As a result, passage 50 of core 28 is blocked and passage 52 communicates with passage 56 of plunger 32. In this state, when the piston rod 16 extends, liquid flows from the liquid chamber A to the core 2 of the valve mechanism 20.
8 and the passage 38 of the sleeve 26 toward the liquid chamber B. The amount of liquid at this time is
It is regulated by the passage portion 53b, where damping force is generated.

When the piston rod 16 retracts, the check valve 34 is pushed open, so that liquid flows from the passage 38 of the sleeve 26 into passage portions 53a and 53b.
flows through. The amount of liquid at this time is regulated by the passage 38 of the sleeve 26, which generates a damping force.

When the electromagnetic coil 70 is de-energized and, conversely, the electromagnetic coil 72 is energized, the plunger 30 moves to the second position.
The plunger 32 hits the member 48 and moves to the right. As a result, passage 50 of core 28 communicates with passage 54 of plunger 30, and passage 52 is blocked. In this case, the amount of liquid is regulated by the passage portion 51a when the piston rod 16 is extended, and by the passage 36 of the sleeve 28 when it is contracted.

When the energization to both the electromagnetic coils 70 and 72 is stopped, both the plungers 30 and 32 abut against the second member 48, so that the passage 50 of the core 28 becomes the passage 54 of the plunger 30, and the passage 52 becomes the passage 54 of the plunger 3.
The two passages 56 are connected to each other. In this state,
When the piston rod 16 is extended, the passage section 51
When contracting, the amount of liquid is regulated by the passage 36 and the passage 38 by the passage portion 53b and the passage portion 53b.

When both the electromagnetic coils 70 and 72 are energized, the plunger 30 moves to the left and the plunger 32 moves to the right. As a result, passages 50, 52 in core 28 are blocked and there is no flow of liquid through piston rod 16.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the main parts of the piston rod, taken along line 1-1 in Figure 2, and shows the plunger on the left side being attracted to the electromagnetic coil; 2 is a sectional view taken along line 2-2 in FIG. 1. FIG. 10... Hydraulic shock absorber, 12... Cylinder, 14
...Piston, 16...Piston rod, 20...
... Valve mechanism, 26 ... Sleeve, 28 ... Core, 3
0, 32...Plunger, 34...Check valve, 3
6, 38, 50, 52... passage, 70, 72...
electromagnetic coil.

Claims (1)

[Claims for Utility Model Registration] Two liquid chambers A and B partitioned within the cylinder 12
The hydraulic shock absorber communicates with the piston rod 16 through a passage 18 provided in the piston rod 16, and adjusts the flow rate of liquid by a valve mechanism 20 disposed in the passage 18, the valve mechanism 20 having an interval in the axial direction. a sleeve 26 having a first passage 36 and a second passage 38 opened in the radial direction at a portion thereof; and a first passage 36 radially outward of the sleeve 26;
The core 28 is arranged so as to form a first space 42 in communication with the second space 44 in communication with the second passage 38, and the core 28 is arranged so as to form a first space 42 in which the first passage portion 51a communicates with the second space 44 in which the second passage 38 communicates. a third passage 50 having a second passage part 51b having a diameter smaller than the diameter and communicating with the first space 42; and a third passage part 53a.
and a fourth passage portion 5 having a diameter smaller than the diameter of the second passage 38 and different from that of the second passage portion 51b.
3b and is provided with a fourth passage 52 communicating with the second space 44; and a plunger 30 disposed within the first space 42 so as to be movable in the axial direction of the sleeve 26. hand,
The plunger 30 has a fifth passage 54 that can communicate with the third passage 50 of the core 28 and is moved by the electromagnetic coil 70, and is movable in the axial direction of the sleeve 26 within the second space 44. A plunger 32 arranged,
The plunger 32 has a sixth passage 56 that can communicate with the fourth passage 52 of the core 28 and is moved by the electromagnetic coil 72; A check valve 34 which opens and closes a third passage portion 53a of the passage 52 and which is connected to the piston rod 16.
a check valve 34 that prevents liquid from flowing during extension but allows liquid to flow when retracted.