Vehicle height adjustment device

1. A vehicle height adjustment device comprising:

a spring having one end supported at a side of a body of a vehicle and another end supported at a side of a wheel of the vehicle;

an adjustor comprising an accommodation chamber capable of accommodating a fluid, the adjustor being configured to adjust a length of the spring in accordance with an amount of the fluid in the accommodation chamber;

a storage chamber capable of storing the fluid;

a pump comprising a cylinder and being configured to take into the cylinder the fluid stored in the storage chamber when a relative distance between the body and the wheel increases, and configured to discharge the fluid out of the cylinder when the relative distance between the body and the wheel decreases; and

a passage switch unit configured to switch among a first state in which the fluid discharged from the pump is guided into the accommodation chamber to increase the amount of the fluid in the accommodation chamber, a second state in which the fluid in the accommodation chamber is guided into the storage chamber to decrease the amount of the fluid in the accommodation chamber, and a third state in which the amount of the fluid in the accommodation chamber is maintained, the passage switch unit being configured to maintain the third state when no electric current is supplied to the passage switch unit.

2. The vehicle height adjustment device according to claim 1 ,

wherein the passage switch unit comprises

a first communication passage through which the cylinder and the storage chamber communicate with each other,

a second communication passage through which the cylinder and the accommodation chamber communicate with each other,

a second communication passage switch valve disposed on the second communication passage to allow the fluid to flow from the cylinder into the accommodation chamber and to inhibit the fluid from flowing from the accommodation chamber into the cylinder, and

a third communication passage through which the accommodation chamber and the storage chamber communicate with each other,

wherein when the electric current supplied to the passage switch unit is less than a first reference electric current, the passage switch unit is configured to open the first communication passage and configured to close the third communication passage, and

wherein when the electric current supplied to the passage switch unit is equal to or higher than the first reference electric current, the passage switch unit is configured to switch, in accordance with an amount of the electric current, between a fourth state in which the first communication passage and the third communication passage are closed and a fifth state in which the first communication passage is closed and the third communication passage is open.

3. The vehicle height adjustment device according to claim 2 ,

wherein when the electric current supplied to the passage switch unit is equal to or higher than the first reference electric current and less than a second reference electric current which is higher than the first reference electric current, the passage switch unit is configured to close the first communication passage and the third communication passage, and

wherein when the electric current supplied to the passage switch unit is equal to or higher than the second reference electric current, the passage switch unit is configured to close the first communication passage and configured to open the third communication passage.

4. The vehicle height adjustment device according to claim 2 ,

wherein the passage switch unit comprises a solenoid comprising:

an operation rod protruding from a case by an amount that increases as the amount of the electric current supplied to the passage switch unit increases; and

a planar valve mounted on the operation rod, and

wherein when the electric current supplied to the passage switch unit is equal to or higher than the first reference electric current, the operation rod protrudes to a position at which the valve closes the first communication passage.

5. The vehicle height adjustment device according to claim 4 ,

wherein the passage switch unit comprises

a valve body resting on a resting surface, and

a push rod movable by being pushed by the operation rod of the solenoid, and

wherein when the electric current supplied to the passage switch unit is equal to or higher than the second reference electric current, the push rod is pushed by the operation rod to push the valve body off the resting surface, so as to open the third communication passage.

6. The vehicle height adjustment device according to claim 1 , wherein the passage switch unit comprises

a first communication passage switch valve configured to open and close the first communication passage, and

a third communication passage switch valve configured to open and close the third communication passage.

7. The vehicle height adjustment device according to claim 3 ,

wherein the passage switch unit comprises a solenoid comprising:

an operation rod protruding from a case by an amount that increases as the amount of the electric current supplied to the passage switch unit increases; and

a planar valve mounted on the operation rod, and

wherein when the electric current supplied to the passage switch unit is equal to or higher than the first reference electric current, the operation rod protrudes to a position at which the valve closes the first communication passage.

8. The vehicle height adjustment device according to claim 7 ,

wherein the passage switch unit comprises

a valve body resting on a resting surface, and

a push rod movable by being pushed by the operation rod of the solenoid, and

wherein when the electric current supplied to the passage switch unit is equal to or higher than the second reference electric current, the push rod is pushed by the operation rod to push the valve body off the resting surface, so as to open the third communication passage.