JPS5813770B2 - If you want to know how to use it, please do not hesitate to contact us. - Google Patents

Description

[Detailed Description of the Invention] The present invention is a hydraulic damper used in combination with a suspension spring, which adapts to the driving conditions such as the quality of the road surface, the magnitude of the load, etc., in order to alleviate the bounce caused by the rebound of the suspension spring when the suspension spring is extended. In this way, the damping force of the hydraulic damper can be adjusted externally while it is still attached to the vehicle body, and the damping performance is improved by using a damping force that is approximately proportional to the piston speed, thereby increasing vehicle running stability and ride comfort. The purpose of this invention is to provide a hydraulic damper for a vehicle that has a compact structure.

To explain the present invention with reference to the embodiments shown in the drawings, 1 is an inner cylinder;
2 is an outer cylinder whose upper end is sealed by a packing case 3 and a bearing 4, the lower end of the inner cylinder 1 is sealed by a bottom member 5, and the lower end of the outer cylinder 2 is sealed by a lid 6, An oil tank chamber C is formed between them.

A piston γ is slidably inserted into the inner cylinder 1, and the inner cylinder 1 is divided into an upper oil chamber A and a lower oil chamber B.

A piston rod 8 has a base fixed to the piston 7 by a nut member 9, and a tip extending outside through the bearing 4 and the packing case 3 is screwed to the upper fitting 10.

A suspension spring 11 is attached to the upper mounting bracket 10 and is installed between a seat 12 and a seat 13 attached to the outer cylinder 2.

14 is a passage provided in the piston 7 to connect the upper and lower oil chambers A and B. A check valve 15 provided in this passage allows the hydraulic oil in the lower oil chamber B to flow to the upper oil chamber A. Prevent backflow.

The piston rod 8 has a cylindrical hollow part 16 below thereof open toward the lower oil chamber B, into which a suffistone 17 is slidably inserted.

This sub-piston 17 has a small diameter portion 17' on its outer circumference.
A passage is formed between the inner peripheral surface of the hollow part 16 of the bistron rod 8 and the inner peripheral surface of the hollow part 16 of the bistron rod 8.

The lower end of this passage opens to the end of the sub-piston 17, and the upper end increases or decreases the opening area of an orifice 18 formed in the side wall of the hollow portion 16 by vertical displacement of the sub-piston 17.

Reference numeral 19 denotes a cylindrical relief valve inserted from below between the outer periphery of the small diameter part 17' of the sub-piston and the inner periphery of the hollow part 16 of the piston rod, and is directed upward by a spring 20 installed between it and the washer 21 of the nut member 9. are being oppressed.

A spring 22 is installed between the lower end of the sub-piston 17 and the washer 23 of the relief valve 19, and is set to have a lower elasticity than the spring 20.

Reference numeral 24 denotes an orifice passage bored in the small diameter portion 17' of the sub-piston, the upper end of which opens into the hollow portion 16, and the lower end of which opens toward the lower oil chamber B side.

This orifice passage 24 has a smaller cross-sectional area than the orifice 18, and its effective area is increased or decreased by relative displacement of the relief valve tip 19' with respect to the opening 24'.

Reference numeral 25 denotes a notch groove bored on the outer periphery of the small diameter portion 17' of the sub-piston 17 slightly below the opening 24' of the orifice passage 24. When sliding downward,
The notch groove 25 opens into the hollow portion 16 according to the amount of displacement.

26 is a push rod that is slidably fitted into a vertical hole bored in the axis of the piston rod 8, and is inserted into the piston hollow portion 16.
The lower end protrudes from the end of the sub-piston 17 due to the elasticity of the spring 22, and the upper end protrudes from the end of the piston rod 8.

A plug 27 is rotatably fitted from the outside into a horizontal hole provided in the upper mounting bracket 10, and a plurality of recesses 28 are provided on the outer periphery of the plug.

These recesses have different depths, and by turning the plug 27 from the outside, one of the recesses with different depths can be selectively joined to the tip of the push rod 26. This allows the sub-piston 17 to move upward and downward relative to the piston rod 8. The position can be changed against the elasticity of the spring 22.

The bottom member 5 has a small hole 31 in the set metal fitting 32 and a notch in the bottom member in order to guide hydraulic oil corresponding to the volume entered by the piston rod 8 from the lower oil chamber B of the inner cylinder 1 to the oil tank chamber C during compression. A communication passage 30 is provided, and a reservoir passage 34 that guides hydraulic oil corresponding to the advancing volume of the piston rond from the oil tank chamber C through the notched passage 30 to the lower oil chamber B when the piston is extended, and the outlet of this passage are checked. A valve 32 is provided.

The inner cylinder 1 is filled with hydraulic oil, and the cylinder 2 stores the hydraulic oil with an air chamber left in a part.

In the figure, reference numeral 35 denotes a lower mounting bracket, which is attached together with the upper mounting bracket 10 to the vehicle body side and the axle side, respectively.

To explain the operation of this device configured as above, first, during the compression stroke of the piston, the suspension spring 11 is compressed and the lower oil chamber B is compressed by the lowering of the piston 7.
of hydraulic oil flows into the upper oil chamber A through the passage 14 and the check valve 15, and hydraulic oil equivalent to the entering volume of the piston rod 8 is introduced into the oil tank chamber C through the small hole 31 of the bottom member 5 and the notched passage 30. A damping force is generated by the small hole 31.

In this case, since the check valve 15 is open, damping resistance in the orifice passage 24 due to the pressure difference between the upper and lower oil chambers A and B is almost never generated.

Next, in the extension stroke, the suspension spring 11 is extended and the hydraulic oil in the upper oil chamber A passes through the orifice 18 to the hollow part 1.
6, that is, the oil is introduced to the outer periphery of the small diameter portion 17' of the sub-piston 17, and then flows into the lower oil chamber B via the orifice passage 24 of the sub-piston.

Since the cross-sectional area of the orifice passage 24 is set smaller than that of the orifice 18, the flow resistance that occurs in this case is mainly generated by the orifice passage 24, and its damping characteristic is shown by the curve (0-A in Figure 3). The piston speed further increases and the pressure in the hollow part 16 increases to the relief valve 1.
When the set pressure of 9 is exceeded, the spring 20 is compressed, the valve is displaced downward, and the sub-piston 17, which had been closed until then, is
The upper end of the cutout groove 25 opens in response to pressure.

The flow resistance that occurs in this case is mainly caused by the opening area of the notched groove 25 and the orifice 24, which are opened by the displacement of the relief valve tip 19' that moves against the spring 20, and its damping effect is is shown by the curve (A-B) in Figure 3 as a relief spring characteristic, and as the piston speed increases, the pressure in the hollow part 16 rises, the relief valve 19 is displaced downward, and its tip 19' Opening 24' and cutout groove 2
The effective area of the orifice 5 is made larger than that of the orifice 1.
If the area becomes larger than 8, the total flow will no longer flow through orifice 1.
The orifice 18 exerts a damping effect under the limit of B, and the damping characteristic at that time is shown by the curve (B-C) in FIG.

Therefore, as a result of combining these damping characteristics in the low speed region, medium speed region, and high speed region of the piston, a damping characteristic similar to the theoretical characteristic shown by the nine-dot chain line can be obtained over the entire piston speed range.

As described above, when the piston extends, hydraulic oil corresponding to the volume of the piston rod 8 that extends from the oil tank C flows into the lower oil chamber B via the notch passage 30 and the check valve 33.

Next, when changing the damping force, turn the plug 27 and selectively engage the outer peripheral recess 28 with the tip of the push rod 26. The sub-piston 17 will be displaced according to the depth of the recess, and the orifice 18 and orifice passage Opening 24'
as well as the end face 19' of the relief valve 19 and the notch groove 2.
The initial setting pressure of the relief valve 19 is adjusted by changing the lap length with the upper end of the relief valve 19.

For example, when the push rod 26 is engaged with the deeper recess 28 of the plug 27, the effective area of the orifice 18 and the orifice passage opening 24' is expanded, and the upward displacement of the sub-piston 17 causes the upper end of the notched groove 25 and the relief valve 19 to be The lap dimension with the tip 19' becomes smaller and the relief valve 19 opens with a slight downward displacement.As a result, the set pressure of the relief valve 19 becomes lower and the damping characteristic (0'- A'-B'-C'
) is obtained.

With the above configuration, a damping force approximately proportional to the piston speed can be obtained during extension, and the magnitude of this damping force can be easily adjusted from the outside while the piston is mounted on the vehicle body.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, FIG. 2 is an enlarged longitudinal sectional view of a piston portion, and FIG. 3 shows damping characteristics. 7... Piston, 8... Piston Rondo, 9...
Nut member, 10... Upper mounting member, 16... Hollow part, 17... Sub-piston, 18... Orifice,
19... Lily 7 valve, 19'... Tip, 20...
・Spring, 22... Spring, 24... Orifice passage,
24'... Opening, 25... Notch groove, 26... Push rod, 27... Plug, 28... Recess,
17'...Small diameter part.

Claims (1)

[Claims] 1. A cylindrical hollow part 16 that opens to the lower oil chamber B side of the piston 7 is provided at the base of the piston rod 8, and the hollow part 1
A sub-piston 17 is slidably inserted into the sub-piston 17, and an orifice 24 is bored in the sub-piston 17, and a cutout groove 25 is provided on the outer periphery, and the piston 7 is inserted through these passages.
The upper and lower liquid chambers A and B, which are divided by 19 is slidably inserted, and the spring 2 is attached between the nut member 9 fixed to the piston rod 8.
0, the relief valve 19 is pressed to close the notch groove 25, and the spring 22, which is weaker than the spring 20, holds the sub-piston 17 under pressure and allows it to slide freely on the piston rod 8. One end of the fitted push rod 26 is brought into contact with the sub-piston 17, and the other end of the push rod 26 is rotatably fitted into the mounting bracket 10.
This is a damping force adjusting device for the extension side of a hydraulic damper for a vehicle.