JPS6227294B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shock absorber whose damping characteristics can be automatically changed in accordance with the loaded weight of a vehicle.

For shock absorbers used in vehicles including two-wheeled vehicles and four-wheeled vehicles, especially vehicles with large body load fluctuations such as light vans and trucks,
It is required that the damping force changes depending on the loading condition of the vehicle.

Conventional shock absorbers with such characteristics required relatively difficult-to-process ports and side passages, but
This invention has a simple structure that is easy to process, and the damping force characteristics on the rebound and compression sides can be adjusted simultaneously when the vehicle is empty and when it is loaded, and it also improves ride comfort when installed on an actual vehicle. It is an object of the present invention to provide a shock absorber having a so-called back diaphragm type damping force generating means that exhibits excellent effects.

In order to achieve the above object, the present invention includes a rebound damping valve that allows flow only from the upper chamber to the lower chamber when the piston is in operation, and a damping valve that allows flow only from the upper chamber to the lower chamber when the piston is in operation. A pressure-side damping valve that only allows flow from the expansion-side damping valve to the upper chamber is arranged in parallel, and a constant port and a variable port are arranged in parallel in the upstream passage of the expansion-side damping valve. On the other hand, a plurality of switching ports are provided in parallel, and these variable ports and switching ports are connected to each port that is provided so as to be displaced according to changes in the relative position of the piston by a spring interposed between the bearing of the piston rod and the piston. It opens and closes via a common sleeve.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4 of the accompanying drawings.

First, to explain the structure, in the figure, 1 is an outer cylinder, 2 is an inner cylinder, 3 is a base valve, 4 is a piston, and 5 is a piston rod. The piston 4 divides the inside of the cylinder 2 into an upper chamber 6 and a lower chamber 7. .

As shown in FIGS. 2 and 3, the piston 4 has an extension passageway through which oil in the upper chamber 6 flows toward the lower chamber 7 via an extension damping valve 8 during the extension stroke of the shock absorber. 9 is provided, and a sleeve 1 opens and closes a constant port 10 provided in the middle of the extension side passage 9 and a variable port 11 arranged in parallel in response to changes in the relative position of the piston 4.
2 is slidably inserted via a guide 13.

The variable port (oil passage) 11 is formed by a flange-like extension side valve part 14 protruding from the outer peripheral wall of the sleeve 12 and an annular groove part 15 in the center of the inner peripheral wall of the piston 4, and the upper end of the piston has the same diameter as the valve part 14. The inner circumferential wall (valve seat surface) 16 and the valve portion 14 come into sliding contact to be closed. The constant port 10 is provided passing through the valve portion 14 in the axial direction, communicates between the upper chamber 6 and the expansion side damping valve 8, and is not affected by movement of the sleeve 12. The rebound damping valve 8 is a leaf valve constructed by coaxially stacking annular leaf springs, and is a one-way valve that is disposed on the lower chamber 7 side and has a rebound passage 9 opened on its back surface (back surface). It is. In addition, a constant orifice 17 is formed by cutting out a portion of the outer periphery of the valve seat surface of the expansion-side damping valve 8 to form a constant orifice 17 that communicates the expansion-side passage 9 with the lower chamber 7, thereby smoothing the rise characteristics.

The relative position of the piston 4 is detected and the sleeve 1 is
A position detection spring (control spring) 18 for driving 2 is disposed in the upper chamber 6, and its tip 18a is not fixed, but its rear end 18b is not fixed.
is fixed to the flange portion 19 of the sleeve 12. Further, a spring 20 that biases the sleeve 12 in opposition to the position detection spring 18 is connected to the lower surface of the valve portion 14 of the sleeve 12 and the bottom 4 of the piston 4.
The set load of the spring 20 is set smaller than that of the position detection spring 18 of the former.

When the vehicle is empty and the loaded weight is small, the piston 4 strokes at the upper part of the inner cylinder 2. Therefore, as shown in FIG. The sleeve 12 is brought into contact with the bearing (or seal portion, etc.) 21 and pushed down against the urging force of the opposing spring 20 until it lands on the bottom 4a of the piston 4. Therefore, the extension side valve portion 1 of the sleeve 12
4 separates from the valve seat surface 16 of the stepped portion of the inner circumferential wall of the piston 4 and descends, opening the variable port 11.

Therefore, during the rebound stroke of the shock absorber when the vehicle is empty, as the piston 4 rises, the oil in the upper chamber 6 flows between the sleeve 12 and the piston 4, as shown by the thick solid arrow A in FIG. It enters the formed annular extension passage 9, passes through the bottom 4a of the piston 4 through both the constant port 10 and the variable port 11 arranged in parallel along the way, and passes through the bottom 4a of the piston 4 in an area where the speed of the piston 4 is very slow (for example, 0.1 m /sec
(below), it flows into the lower chamber 7 through the constant orifice 17, but in a region where the speed of the piston 4 is high (for example, 0.1 m/sec or more), the expansion side damping valve 8 is simultaneously pushed open and the flow flows into the lower chamber 7.

On the other hand, when loading a vehicle with a large load, as shown in FIG. 3, the piston 4 strokes at the bottom of the inner cylinder 2, so the position detection spring 18 separates from the thrust bearing 21 and becomes a free length. The influence on the sleeve 12 is cut off. Therefore, the sleeve 12 is pushed up by the spring 20 disposed at the lower part of the sleeve 12 and the step 13 of the guide 13 is pushed up.
a, and the extension side valve portion 14 and the valve seat surface 16 come into sliding contact to close the variable port 11.

Therefore, during the extension stroke of the shock absorber during loading, the oil that enters the extension passage 9 from the upper chamber 6 passes only through the constant port 10 and is elongated, as shown by the thick solid arrow A' in Fig. 3. side damping valve 8
In the region where the speed of the piston 4 is very slow, the flow passes through the constant orifice 17 and flows into the lower chamber 7. However, in the region where the speed of the piston 4 is high, the expansion side damping valve 8 is simultaneously pushed open and the flow flows into the lower chamber 7. flows to

Therefore, the damping force generated during the rebound stroke when the vehicle is empty is determined by the sum of the effective areas of the constant port 10 and the variable port 11 and the set load (spring rigidity) of the rebound damping valve 8. Therefore,
These 10 constant ports and 1 variable port
By setting the effective area of 1 and the set load of the rebound damping valve 8 to match the required damping characteristic b during the rebound stroke when the vehicle is empty as shown in Fig. 4, the damping characteristic that matches the required characteristic b can be obtained. can demonstrate. On the other hand, the damping force generated during the rebound stroke during loading is relatively increased as the effective area of the stretch passage 9 decreases by the proportion that the variable port 11 is closed and the port resistance increases. Therefore, by setting the effective area of the constant port 10 and the set load of the rebound damping valve 8 to match the required damping characteristic a during the rebound stroke when loading a vehicle as shown in FIG. 4, the required characteristic a can be obtained. This results in a large damping characteristic suitable for the

On the other hand, a contraction side passage 22 is formed between the inner circumferential wall of the sleeve 12 and the guide 13 through which oil in the lower chamber 7 flows toward the upper chamber 6 during the compression side (compression side) stroke of the shock absorber. A first port 24 that allows oil in the lower chamber 7 to flow toward the upper chamber 6 via the compression damping valve 23, and a first compression damping valve 23.
and the second compression side damping valve 25 to the lower chamber 7.
A second port 26 that allows the oil to flow toward the upper chamber 6 is arranged in parallel with the piston 4 in isolation, and the first port 24 and the second port 26, which are switching ports for these pressure-side damping valves, are connected to each other by adjusting the relative positions of the piston 4. A contraction side valve portion 27 that selectively opens and closes in response to changes is provided protruding from the inner wall of the sleeve 12. The first compression-side damping valve 23 is a large-diameter leaf valve, and is coaxially stacked (tandem-type) on the second compression-side damping valve 25, which is a small-diameter leaf valve, so that they can cooperate with each other. An annular first port 24 is opened on the back surface of the first damping valve 23, and an annular second port 26 is opened on the back surface of the second damping valve 25. Also, both damping valves 23, 2
Constant orifices 28 and 29 are formed by cutting out a portion of the valve seat surface of No. 6 to smooth the start-up characteristics. Therefore, during the contraction side stroke, the second port 26 which opens below the first port 24 is closed by the contraction side valve part 27 as the sleeve 12 descends in the state shown in FIG. 2 when the vehicle is empty. , as shown by the thin arrow B in FIG. is introduced into the first port 24 and flows into the upper chamber 6 through the constant orifice 28 in a region where the speed of the piston 4 is very slow, but at the same time pushes the first compression side damping valve 23 in a region where the speed of the piston 4 is high. It opens and flows into the upper chamber 6, and at the same time oil corresponding to the volume of entry of the piston rod 5 flows from the lower chamber 7 through the base valve 3 into the chamber 40. For this reason, the set loads of the first compression damping valve 23 and the base valve 3 and the area of the constant orifice 28 are set to match the required damping characteristic d during the rebound stroke when the vehicle is empty, as shown in FIG. By doing so, it is possible to exhibit a damping characteristic that meets the required characteristic d. Moreover, when loading the cars as shown in Figure 3,
As the sleeve 12 rises, the first port 24 is closed by the contraction side valve part 27, so the oil in the lower chamber 7 flows from the contraction side passage 22 to the second port 26, as shown by the thin arrow B' in FIG. In the region where the speed of the piston 4 is very low, it flows through the constant orifices 29 and 28 to the upper chamber 6, but in the region where the speed of the piston 4 is high, the second compression side damping valve 25 and the first compression side damping valve 25 are introduced at the same time. The damping valve 23 is pushed open and oil flows into the upper chamber 6, and at the same time oil corresponding to the volume of entry of the piston rod 5 flows from the lower chamber 7 through the base valve 3 into the chamber 40. For this reason,
Since the port resistance increases by a proportion corresponding to the set load of the second compression side damping valve 25 and the damping force increases, the combined set load of the first damping valve 23 and the second damping valve 25 and the set load of the base valve 3 By setting the area of the constant orifices 29 and 28 to match the required damping characteristic c during the contraction side stroke during loading as shown in Fig. 4, a large damping characteristic matching the required characteristic c can be obtained. .

As described above, according to the present invention, firstly, the sleeve is structured so that the damping force on the compression side and the rebound side can be changed and adjusted simultaneously from the soft state to the hard state both when the vehicle is empty and when the vehicle is loaded. Since the piston oil passage can be simplified and made more compact, it is possible to improve workability and thereby reduce production costs, and the simple structure can also be expected to improve durability. Secondly, in the structure of the damping valve for generating damping force, by providing a so-called back throttle type structure for the flexible valve as an [orifice + valve] structure, ideal damping force characteristics can be obtained and it can be applied to actual vehicles. Provides excellent riding comfort when worn.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view of the shock absorber of the present invention, Fig. 2 is an enlarged sectional view of the piston portion of Fig. 1 when the vehicle is empty, and Fig. 3 is an enlarged sectional view of the piston portion when the vehicle is loaded. The cross-sectional view shown in FIG. 4 is a graph showing the attenuation characteristics of the present invention. 1...Outer cylinder, 2...Inner cylinder, 3...Base valve, 4...
Piston, 5... Piston rod, 6... Upper chamber, 7
...lower chamber, 8...growth side damping valve, 9...growth side passage,
10...constant port, 11...variable port,
12...Sleeve, 13...Guide, 14...Extension side valve part, 15...Groove part, 16...Valve seat surface, 17...Constant orifice, 18...Position detection spring, 2
0...Spring.

Claims (1)

[Claims] 1. A damping valve on the rebound side that only allows flow from the upper chamber to the lower chamber when the sleeve is slidable relative to the piston and the piston when the piston is in operation, and a damping valve on the rebound side that only allows flow from the lower chamber to the upper chamber during the operation on the compression side. A compression side damping valve is arranged in parallel, a constant port and a variable port are arranged in parallel in the upstream passage of the expansion side damping valve, and a plurality of switching ports are provided in parallel with the compression side damping valve. , these variable ports and switching ports are configured to open and close via a sleeve provided so as to be displaced in accordance with changes in the relative position of the piston by a spring interposed between the bearing of the piston rod and the piston. Shock absorber.