JPS641128Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shock absorber that damps vibrations of a suspension spring.

If the axle on which the wheels of a car are attached is directly attached to the car body, the impact force caused by uneven road surfaces is directly transmitted from the wheels to the car body, resulting in extremely poor ride comfort. Therefore, the wheels of automobiles have conventionally been attached to frames via suspension springs. Furthermore, a shock absorber is installed between the axle and the frame, and the shock absorber damps vibrations of the suspension spring. A shock absorber has a piston placed inside an oil cylinder and an oil passage hole formed in the piston. When the distance between the axle and the frame changes, the piston moves relative to the cylinder, allowing the oil to pass through. passes through the oil passage hole, and the resistance of the oil at this time weakens the impact and absorbs vibrations.

When a vehicle equipped with such a suspension system consisting of a suspension spring and a shock absorber travels on a rough road for a long period of time, a large load is placed on the shock absorber, causing the temperature of the internal oil to rise. As a result, the viscosity of the oil decreases, and as a result, its ability to weaken shocks or absorb vibrations gradually decreases. Therefore, when the temperature of the oil in the shock absorber increases, the riding comfort deteriorates.

In addition, to prevent such temperature rise,
For example, as seen in Japanese Utility Model Application No. 55-13109, a water jacket is provided around the outer periphery of a shock absorber, and the pressure inside the water jacket is lowered by using the wind of the vehicle to lower the boiling point of water. Therefore, some devices are designed to prevent the temperature of the shock absorber from becoming higher than the boiling point of water.

However, in such a system in which the boiling point of water is used for cooling, the temperature of the shock absorber still becomes too high, so that the properties of the oil sealed in the cylinder of the shock absorber are determined. Furthermore, heating of the shock absorber is not necessarily avoided when running wind cannot be used, such as in running tests using a road simulator, which tests the durability of the entire vehicle by inputting the road surface conditions from the wheels using a hydraulic vibration device. Otherwise, the damping characteristics of the shock absorber cannot be stabilized over a long period of time because the amount of water decreases over time and eventually it becomes impossible to perform cooling. There was a problem.

The present invention was developed in view of these circumstances, and it is possible to stabilize damping performance over a long period of time even when running wind cannot be used, such as in running tests using a road simulator. The purpose is to provide a shock absorber with excellent reliability and durability.

In order to achieve such an object, the present invention provides a shock absorber for damping the vibrations of a suspension spring, in which a water jacket is provided around the outer periphery of the cylinder of the shock absorber, and a cooling water supply hole provided in the water jacket is connected to the cooling water jacket. A cooler is connected for circulation to the water discharge hole via a pump. In addition, the upstream and downstream sides of the cooler are bypass-connected via a bypass pipe line, and when it is detected that the temperature of the water in the water jacket is higher than a predetermined value, the pump is operated to drain the water. a temperature sensor that circulates water between the jacket and the cooler; and a switching valve that operates to reduce the rate of water flowing through the bypass line as the temperature of the water exiting the water jacket increases. It is characterized by the fact that it has been established.

Because of this configuration, even if the temperature of the cylinder (shock absorber) rises due to vibration damping, the cylinder is cooled by the water in the water jacket provided around the outer periphery of the cylinder. The water that performs this cooling action is sent to a cooler by a pump when its temperature rises, and after being cooled by this cooler, it is returned to the water jacket, and as the temperature of the water rises, The proportion of water flowing through the bypass line is reduced. Therefore, the temperature of the water returned to the water jacket is maintained at a nearly constant value, and since the water is recycled to prevent its temperature from decreasing, the damping characteristics of the shock absorber can be maintained over an extremely long period of time. It can be held as intended.

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a rear wheel suspension system for a truck equipped with a shock absorber according to this embodiment. That is, the rear wheels 1 are attached to both ends of the axle 2. The axle 2 is attached to the frame 4 by a suspension spring 3 made of a leaf spring. The front end of the leaf spring 3 is attached to an eye pin 6 of a bracket 5, and the rear end of the leaf spring 3 is connected to a bracket 8 via a shackle 7. This bracket 8 is attached to the frame 4. Furthermore, a shock absorber 9 is interposed between the axle 2 and the frame 4.

The shock absorber 9 includes a cylinder 10, as shown in FIG. 2, and a piston 11 is disposed within the cylinder 10. The piston 11 is provided with a small oil passage hole 12, and as the oil in the cylinder 10 passes through this passage hole 12, the piston 11 moves within the cylinder 10. and piston 11
The piston rod 13 connected to the bracket 1
4 to the frame 4, and the cylinder 10 is connected to the axle 2 via a beam 15 (see FIG. 1). Further, a bellows boot 16 is attached to the upper part of the cylinder 10 so as to cover the piston rod 13.

Furthermore, this shock absorber 9 is provided with a water jacket 17 on the outer periphery of its cylinder 10. A cooling water supply hole 18 is provided at the lower end of the jacket 17, and this supply hole 18 is connected to a pump 19. Note that the pump 19 is driven by a motor 20. The pump 19 is connected to a water tank 21. On the other hand, a cooling water discharge hole 22 of the water jacket 17 is connected to a cooler 24 via a switching valve 23 equipped with a thermostat. The cooler 24 is connected to the water tank 21. Furthermore, the switching valve 2
A bypass pipe line 25 is provided in a portion 3, and the cooling water is circulated without passing through the cooler 24. A temperature sensor 26 is provided within the water jacket 17, and the sensor 26 controls a switch 27 via, for example, a relay coil (not shown). In addition, switch 27 is battery 28
and the motor 20.

In the above configuration, the shock transmitted from the road surface to the axle 2 via the rear wheel 1 is buffered by the suspension spring 3 made of a leaf spring, so that vibrations caused by unevenness of the road surface are transmitted to the frame 4. This can be prevented. Furthermore, the vibration of the leaf spring 3 is damped by a shock absorber 9. That is, when the leaf spring 3 deforms, the distance between the frame 4 and the axle 2 changes, and as a result, the piston 11 of the shock absorber 9 moves within the cylinder 10, so that the oil passage hole of the piston 11 changes. The impact is weakened by the resistance of the oil as it passes through 12, and vibrations are absorbed.

Moreover, this shock absorber 9 is equipped with a jacket 17, and cooling water is circulated between the jacket 17 and the cooler 24. That is, when the temperature sensor 26 detects that the temperature of the cooling water in the jacket 17 is higher than a predetermined temperature, the switch 27 is activated via a relay coil or the like based on the detection by the sensor 26.
is closed and the motor 20 is driven. Therefore, the pump 19 sucks water from the water tank 21 and supplies it into the jacket 17. The water in the jacket 17 is discharged from the cooling water discharge hole 22, guided to the bypass pipe 25 by the switching valve 23, and then transferred to the water tank 2.
It will return to 1.

Further, when the thermostat of the switching valve 23 detects that the temperature of the cooling water in the water jacket 17 has increased, the switching valve 23 is switched in conjunction with the detection of this thermostat, and the cooling water in the jacket 17 is switched. The cooling water exiting the cooling water discharge hole 22 is led to a cooler 24, and after being cooled by the cooler 24, it returns to the water tank 21.

In this way, the shock absorber 9 according to this embodiment allows the cooling water to flow back into the jacket 17 when the temperature thereof becomes a little high, and returns this cooling water to the cooler 24 when the temperature rises further. By circulating the cooling water while cooling the oil cylinder 10, the temperature of the oil in the oil cylinder 10 is maintained at a substantially constant value. Therefore, it is possible to prevent the viscosity from decreasing due to an increase in the temperature of the oil in the cylinder 10 of the shock absorber 9. Therefore, this makes it possible to maintain the driving performance and riding comfort of the vehicle at approximately constant values. In addition, since the oil temperature of the shock absorber 9 can be maintained appropriately,
It also becomes possible to improve the lifespan.

Although the present invention has been described above with reference to an illustrated embodiment,
The present invention is not limited to the above embodiments, and various modifications can be made based on the technical idea of the present invention. For example, the above embodiment relates to a shock absorber 9 used together with a suspension spring 3 made of a leaf spring, but the present invention can also be applied to a shock absorber used together with a spring such as a coil spring or an air spring. .

As described above, the present invention provides a jacket for the shock absorber, and only when the temperature of the water in the jacket becomes higher than a predetermined value, coolant is circulated between the cooler and the jacket. As the temperature of the cooling water that flows out increases, the proportion of water that bypasses the cooler is reduced. Therefore, even when running wind cannot be used, such as in a bench test using a road simulator, the temperature of the oil in the cylinder of the shock absorber can be maintained at a nearly constant value for a long period of time. This makes it possible to prevent the shock absorber from deteriorating due to a decrease in oil viscosity. Therefore, according to the present invention, it is possible to maintain the running performance and riding comfort of the vehicle in a substantially constant state at all times.
Furthermore, by maintaining the oil temperature of the shock absorber at an appropriate level, the life of the shock absorber can be extended.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a suspension system equipped with a shock absorber according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing a pipe line for circulating cooling water to the shock absorber. In addition, in the symbols used in the drawings, 3...plate spring (suspension spring), 9...shock absorber, 17...
...Water jacket, 19...Pump, 20...
... motor, 21 ... water tank, 23 ... switching valve, 24 ... cooler, 25 ... bypass pipe line, 26 ... temperature sensor.

Claims (1)

[Scope of utility model registration request] A shock absorber that damps vibrations of a suspension spring includes a water jacket provided on the outer periphery of a cylinder of the shock absorber, a cooling water supply hole and a cooling water discharge hole provided in the water jacket, and the cooling water discharge hole. A cooler is connected to the cooling water supply hole for circulation via a pump, a bypass pipe connects the upstream and downstream of the cooler by bypass, and the water jacket is connected to the cooling water jacket when the temperature of the water in the water jacket is equal to or higher than a predetermined value. a temperature sensor that activates the pump to circulate water between the water jacket and the cooler when detected; and a temperature sensor that activates the pump to circulate water between the water jacket and the cooler; A shock absorber comprising a switching valve that operates to reduce the proportion of water flowing through the channel.