Vehicle height adjusting device

1. A vehicle height adjusting device capable of adjusting a vehicle height of a vehicle comprising:

a cylinder charged with working fluid;

a rod inserted in the cylinder so as to have a back and forward movement;

a piston connected to the rod and movable within the cylinder in a freely sliding manner, and defining a rod side chamber and an non-rod side chamber in the cylinder, the piston including a damping part for generating a damping force when the working fluid passes though the damping part during the back and forward movement of the rod;

a low pressure chamber provided outside the cylinder and charged with low pressure gas in a part thereof;

a high pressure chamber having a higher pressure than a pressure of the low pressure chamber and being provided outside the cylinder and charged with high pressure gas in a part thereof;

a pump chamber for adjusting the vehicle height of the vehicle by supplying working fluid in the low pressure chamber into the non-rod side chamber with the back and forward movement of the rod;

a communicating path for allowing fluid communication between the non-rod side chamber and the high pressure chamber;

a valve body, movably disposed in a valve section of the communicating path between the non-rod side chamber and the high pressure chamber, the valve body movable between first and second ends of said valve section, for increasing and reducing a cross-sectional area of the communicating path in said valve section depending on a fluid pressure of the high pressure chamber that is applied to a back side of the valve body and a fluid pressure of the low pressure chamber that is applied to a front side of the valve body, said back side facing said first end of said valve section, said front side facing said second end of said valve section, said valve body and said valve section being arranged so that movement of said valve body toward said second end reduces said cross-sectional area, the valve body at any position in said valve section maintaining fluid communication between the non-rod side chamber and the high pressure chamber; and

a biasing member biasing the valve body against the fluid pressure of the high pressure chamber,

the valve body reducing said cross-sectional area by moving toward said second end so as to increase a resistance to working fluid that passes by the valve body from the non-rod side chamber to the high pressure chamber if a load that is based upon a pressure difference between the high pressure chamber and the low pressure chamber is greater than a biasing force of the biasing member.

2. The vehicle height adjusting device according to claim 1 further comprising a bottom block blocking an end part opening of the non-rod side chamber in the cylinder and formed with the communicating path penetrating therethrough, wherein the valve body is disposed within the bottom block in a freely sliding manner to increase and reduce said cross-sectional area by moving back and forward depending on the fluid pressure of the high pressure chamber which is applied to the back side of the valve body.

3. The vehicle height adjusting device according to claim 2 wherein:

the bottom block comprises a pilot chamber into which the working fluid of the low pressure chamber is guided;

the valve body comprises a guide part inserted into the pilot chamber in a freely sliding manner; and

the pilot chamber is contained within the biasing member.

4. The vehicle height adjusting device according to claim 1 , further comprising a path for communicating the high pressure chamber and the low pressure chamber, wherein the path is provided with a relieving valve allowing a flow of working fluid from the high pressure chamber to the low pressure chamber, when the pressure in the high pressure chamber exceeds the pressure in the low pressure chamber by a predetermined amount.