JPH0633224Y2 - Cylinder device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an improvement of a cylinder device used as a positioning and supporting member for various devices.

(Prior Art) A tilt cylinder used as a positioning and supporting member for an outboard motor for boats or the like is configured, for example, as shown in FIG.

That is, a hollow piston rod 3 is coupled to a piston 2 housed inside a cylinder body 1 in which hydraulic oil is sealed so that the piston 2 slides freely out of the cylinder body 1 to define an oil chamber defined in the piston 2. 5 and 7 are connected to the hollow portion 4 of the piston rod 3 via normally closed valves 6 and 8 provided in the piston 2. The hollow portion 4 serves as an oil reservoir and communicates with an accumulator 15 containing gas and hydraulic oil.

Since valves 6 and 8 are forcibly opened by an external operation,
A push rod 9 is provided so as to extend vertically through the piston rod 3, and a cam 11 coupled with an operating lever 10 abuts on the base end of the push rod 9 protruding outward from the piston rod 3. The tip of the push rod 9 enters the piston 2 by driving the cam 11 via the operation lever 10, pushes the valve 6 open by the taper portion 16 near the tip, and then further enters and pushes the valve 8 open by the tip. It has become.

Therefore, as shown in FIG. 5, the operating lever 10 has an A position in which only the valve 6 is opened and the valves 6 and 8 are opened.
Are set to three positions, a B position for opening both valves and a C position for closing both valves 6 and 8.

In the normal propulsion state in which the outboard motor is driven to move the boat forward, the A position is used. In this case, the sliding of the piston 2 to the compression side is locked, but when the outboard motor hits driftwood, the piston 2 temporarily slides to the extension side while reducing the pressure in the oil chamber 7 to a negative pressure. be able to. Further, when the outboard motor is rotated, the B position is used in which the piston 2 is slidable in either extension or contraction. Further, when the outboard motor is rotated in the reverse direction for braking or reverse, the reaction force of the propulsive force exerts an extension load on the piston rod 3,
To counter this, the C position is used to lock the sliding of the piston 2.

(Problem of the invention) By the way, when the operation lever is moved to the A position when the outboard motor is rotated from the raised state to the desired position,
When the valve 8 is suddenly closed, a water hammer is generated in the oil chamber 7 and a shock is applied to members such as the cylinder body 1 and the valve 8 surrounding the oil chamber 7. Therefore, these members have high rigidity to withstand the shock. There was a need. Note that such a water hammer also occurs when the outboard motor that collides with driftwood or the like in the propelled state and temporarily turns upward returns to the original state due to the negative pressure in the oil chamber 7.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cylinder device having a structure that does not cause water hammer in order to solve the above problems.

(Means for Achieving the Object) The present invention relates to a hollow piston rod coupled to a piston slidably housed inside a cylinder body containing hydraulic oil so that the piston is slidably protruded from the cylinder body. Each piston is equipped with a normally closed valve that connects each oil chamber defined on both sides of the piston to the oil reservoir through the hollow part of the piston rod, and these valves are forcibly opened by external operation. In a cylinder device provided with a push rod extending vertically through the piston rod, the hydraulic oil in the oil chamber is opened in the oil chamber when the pressure in the oil chamber on the opposite side of the piston rod rises above a certain level. A relief valve is installed on the piston to allow it to escape.

(Operation) When the sliding of the piston toward the compression side is suddenly locked by closing the valve, the pressure in the oil chamber on the opposite side of the piston rod rises rapidly, but if the pressure rises above a certain level, the relief valve Open and let the working oil in this oil chamber escape to the oil reservoir to prevent the occurrence of water hammer.

(Embodiment) FIGS. 1 to 3 show an embodiment of the present invention. The same components as those of the conventional example are designated by the same reference numerals, and detailed description thereof will be omitted.

1 is a cylinder body, 2 is a piston, 3 is a hollow part 4 inside
It is a piston rod that formed. The hollow portion 4 is an accumulator 1 provided as an oil reservoir outside the cylinder body 1.
Connect to 5. The piston 2 has a valve 6 for connecting the oil chamber 5 on the piston rod 3 side to the hollow portion 4, and an oil chamber 7 on the opposite side.
A valve 8 is provided to connect the to the hollow portion 4. Due to these valve opening operations, the push rod 9 similar to the conventional example is used.
Penetrates the hollow portion 4 and projects the base end thereof to the outside of the piston rod 3, and the cam 11 coupled to the operating lever 10 abuts on the base end.

The piston 2 is further provided with a relief valve 12 that connects the oil chamber 7 and the hollow portion 4 to each other. The relief valve 12 is formed in a spherical shape as shown in FIG. 2, and is urged by the relief spring 13 from the hollow portion 4 side to communicate with the oil chamber 7.
Close 4 When the pressure difference between the oil chamber 7 and the hollow portion 4 becomes larger than a certain value, it opens against the relief spring 13 and connects the oil chamber 7 and the hollow portion 4 through the communication hole 14. The opening pressure of the relief valve 12 depends on the weight of the outboard motor,
Oil chamber 7 against the compressive load that accompanies the forward propulsion of the boat.
The pressure is set high enough to maintain the locked state of.

Next, the operation will be described.

The push rod 9 is an operating lever 10 similar to the conventional example.
Corresponding to the three positions A to C, the oil chambers 5 and 7 and the hollow portion 4 are connected or cut off as shown in FIG.

At the A position, which is used for normal navigation, the valve 6 is opened and the valve 8 is closed, and the sliding of the piston 2 toward the compression side is locked by the hydraulic oil in the oil chamber 7. When the outboard motor collides with an obstacle such as driftwood, the tilt cylinder causes the hydraulic oil in the oil chamber 5 to flow out from the valve 6 to the accumulator 15 via the hollow portion 4, and temporarily extends to move the outboard motor upward. It turns to and absorbs the impact of the collision and spends the obstacle backward. When the obstacle leaves behind, the tilt cylinder contracts, and the outboard motor rotates to the original propulsion position. At this time,
Since the compression load due to the negative pressure of the oil chamber 7 and the own weight of the outboard motor causes the piston 2 to slide at a high speed, the tilt cylinder contracts to its original position and the sliding of the piston 2 becomes the operating oil in the oil chamber 7. With the lock, the pressure in the oil chamber 7 rapidly increases. However, as a result, when the pressure difference between the oil chamber 7 and the accumulator 15 exceeds the repulsive force of the relief spring 13, the relief valve 12 opens and the working oil in the oil chamber 7 escapes to the accumulator 15 via the hollow portion 4. The pressure in the oil chamber 7 is prevented from rising above a certain level, and there is no fear of water hammer in the oil chamber 7. It should be noted that when the momentum of the piston 2 weakens and the pressure of the rising oil chamber 7 drops, the relief valve 12 closes and the tilt cylinder returns to the normal propulsion state.

At the B position for rotating the outboard motor, the oil chambers 5 and 7 both communicate with the accumulator 15, and the tilt cylinder expands and contracts arbitrarily according to the external force applied. Even in this position, for example, if the operation lever 10 is switched to the A or C position and the valve 8 is closed at an arbitrary position in the course of rotating the outboard motor from the lifted position to the water, the rotation is continued downward. The pressure in the oil chamber 7 also suddenly rises due to the inertial force of the outboard motor, but in this case as well, if the pressure rises above a certain level, the relief valve 12 opens and some of the hydraulic oil in the oil chamber 7 escapes to the accumulator 15. Therefore, water hammer does not occur, and therefore the operation feeling of the outboard motor is also good.

(Effect of the Invention) As described above, according to the present invention, the piston is provided with the relief valve that allows the hydraulic oil in the oil chamber on the side opposite to the piston rod to escape to the oil reservoir when the pressure rises above a certain level. Even if the sliding of the piston toward the compression side is suddenly locked by closing the valve, etc., the relief valve opens to keep the pressure rise in the oil chamber below a certain level. For this reason, there is no risk of water hammer, and members such as the cylinder body surrounding the oil chamber, the piston, and the valve do not need to have so high rigidity, so that the weight and cost of the tilt cylinder can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a tilt cylinder showing an embodiment of the present invention, FIG. 2 is an enlarged vertical sectional view of a relief valve of the same, and FIG. 3 is a hydraulic circuit diagram showing an operating structure of the tilt cylinder. FIG. 4 is a vertical sectional view of a tilt cylinder showing a conventional example, and FIG. 5 is a hydraulic circuit diagram of the same. 1 ... Cylinder body, 2 ... Piston, 3 ... Piston rod, 4 ... Hollow part, 5, 7, ... Oil chamber, 6, 8 ... Valve, 9
... push rod, 10 ... operating lever, 12 ... relief valve, 15 ... accumulator.

Claims (1)

[Scope of utility model registration request] 1. A hollow piston rod is connected to a piston slidably accommodated inside a cylinder body containing hydraulic oil, and the piston rod is slidably protruded from the cylinder body. Each piston is equipped with a normally closed valve that connects each oil chamber to the oil reservoir via the hollow part of the piston rod, and push rods that vertically open these valves by external operation are inserted through the piston rod. In the cylinder device provided as described above, the piston is provided with a relief valve that opens when the pressure in the oil chamber on the side opposite to the piston rod of the oil chamber rises above a certain level and allows the working oil in this oil chamber to escape to the oil reservoir chamber. A cylinder device characterized in that