JP2709067B2 - Cylinder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cylinder used as a positioning member for various devices and as a support member.

(Prior Art) As a tilt damper interposed between the hull and the outboard motor for positioning and supporting the outboard motor for a boat, for example, oil chambers on both sides are mounted on a piston slidably housed in a cylinder body. A cylinder is known in which a communicating orifice and a relief valve are provided, a piston rod connected to a piston is projected in an axial direction from a cylinder body, and gas is sealed in an upper part of an oil chamber above the piston. No. 5480).

The orifice provided in the piston gives a moderate resistance to the expansion and contraction of the piston rod, smoothing the rotation of the outboard motor, and the relief valve opens for a certain load or more, causing the outboard motor to collide with obstacles etc. Reduce the impact of time. In addition, the gas sealed in the upper part of the cylinder body compensates for oil amount fluctuations caused by sliding of the piston, pressurizes the hydraulic oil, urges the piston in the extension direction due to the pressure receiving area difference, and raises the outboard motor. It is designed to assist.

(Problems of the Invention) However, in this tilt damper, since the oil chambers on both sides of the piston are always in communication with the orifices, the outboard motor can be set between the propulsion position and the floating position, but at the intermediate rotation position. Cannot be stopped. For this reason, it is impossible to set the outboard motor at a desired angle in accordance with the water depth, etc., unless a supporting member is separately prepared. It is difficult to apply to a device that wants to be held at an arbitrary position.

Furthermore, although this cylinder has gas sealed in the upper part of the cylinder body, it is necessary to fill a large amount of gas in order to stably urge the piston rod in the extension direction over the entire stroke. In addition, there has been a problem that the overall length of the cylinder body is long and the interposition position is limited.

The present invention has been made to solve the above problems, and has as its object to provide a cylinder that can be positioned and held at an arbitrary extended position and has a short overall length.

(Means for Achieving the Object) According to the present invention, a hollow piston rod is connected to a piston slidably housed inside a cylinder body, and is slidably protruded from the cylinder body, so that the piston is positioned in front of the piston. The piston is provided with a relief valve communicating the oil chamber A with the hollow portion of the piston rod, and an operating means for opening the relief valve by an external operation is provided. On the other hand, an oil chamber B and a hollow portion defined behind the piston are provided. And a gas chamber filled with a gas for pressurizing the hydraulic oil in the oil chambers A and B through the hollow portion is provided outside the cylinder body.

(Operation) When the relief valve is opened by operating the operating means, the oil chamber A communicates with the oil chamber B and the hollow part of the piston rod, so that the piston rod expands or contracts in accordance with the applied external force. Move. At this time, the pressure in the gas chamber acts on the hydraulic oil in the oil chambers A and B via the hollow portion of the piston rod, and exerts an extension force on the piston rod according to the pressure receiving area difference of the piston. The provided gas chamber can have a sufficient gas capacity, and exerts a stable extension force on the piston rod regardless of the stroke position.

On the other hand, when the relief valve is closed by operating the operating means, the outflow and the inflow of the hydraulic oil into the oil chamber A are shut off, so that the piston rod is stably held at that position. However, even in this state, the relief valve opens to allow the piston rod to expand under the action of an excessive expansion load.

(Embodiment) FIG. 1 shows a first embodiment of the present invention.

In this figure, 1 is a cylinder body filled with hydraulic oil, 2 is a piston slidably housed in the cylinder body, 3 is a hollow piston which is connected to the piston 2 and protrudes freely from the cylinder body 1 It is a rod.

The inside of the cylinder body 1 is defined by a piston 2 into an oil chamber A at the front and an oil chamber B at the rear. The hollow portion of the piston rod 3 is defined by an oil reservoir chamber 5 filled with hydraulic oil and an air chamber 6A filled with compressed air as a gas chamber by a free piston 4 housed slidably. Further, an air chamber 6B communicating with the air chamber 6A via the port 14 is provided outside the base end of the piston rod 3.

A port 7 that connects the oil chamber B and the oil reservoir 5 to the piston 3
, A relief valve 8 for communicating the oil chamber A with the oil reservoir 5 is provided. The relief valve 8 is provided at the center of the piston 3 from the oil chamber A side to the oil reservoir 5, and is urged by a relief spring 8 A interposed on the oil chamber A side to form a valve seat 9 formed on the piston 3. To sit down.

On the other hand, an operating rod 10 is provided as an operating means for forcibly opening the relief valve 8, penetrating the hollow portion of the piston rod 3. The operating rod 10 has one end at the oil reservoir 5
After coming into contact with the relief valve 7 from the side and slidably penetrating the free piston 4, the other end is slidably projected outside the plug 11 defining the air chamber 6 </ b> B at the base end of the piston rod 3. An operating lever 13 slidably attached to a bracket 12 integral with the plug 11 abuts on this protruding end.
Reference numeral 15 is an air valve for replenishing the air chambers 6A and 6B with air.

 Next, the operation will be described.

To extend or contract the piston rod 3, the operating lever 13 is operated to move the operating rod 10 to the piston rod 3.
, The relief valve 8 opens against the relief spring 8A, and the oil chamber A communicates with the oil reservoir chamber 5.

When an external force is applied in this state, the piston rod 3 and the piston 2 slide toward the extension side or the contraction side according to the direction of the external force, and the hydraulic oil flows through the port 7 and the relief valve 8. Fluctuations in the amount of oil in the oil chambers A and B due to the sliding are compensated by sliding of the free piston 4 facing the oil reservoir 5 of the accumulator.

Since the air chamber 6B is provided outside the piston rod 3 and a sufficient air capacity is secured together with the air chamber 6A, the free piston 4 slides due to a change in the amount of oil accompanying the sliding of the piston 2. Also, the pressure in the air chambers 6A and 6B does not greatly change, and a stable stretching force acts on the piston rod 3 regardless of the sliding position. Therefore, for example, when interposed in the outboard motor, the outboard motor rotates smoothly by applying a constant external force. In addition, since the capacity of the air chamber 6A can be reduced by providing the air chamber 6B outside, it is not necessary to lengthen the entire cylinder in order to secure the air capacity.

When the piston rod 3 has moved to the desired position, the operating lever 13 is returned and the relief valve 8 is set to the relief spring.
The valve is opened while pushing back the operating rod 10 with the repulsive force of 8A. As a result, the flow of hydraulic oil into and out of the oil chamber A is shut off, and the piston rod 3 stops at that position. Therefore, by operating the operation lever 13, for example, the outboard motor can be stopped at an arbitrary position during the rotation.

The compression load applied to the piston rod 3 in this state is supported by the hydraulic oil in the oil chamber A whose outflow is locked, so that sliding of the piston 2 toward the compression side is completely prevented. When an extension load is applied, the piston 2 tends to slide in the extension direction. At this time, the oil chamber A, in which the inflow of the hydraulic oil is blocked by the relief valve 8, becomes negative pressure, and a large pressure difference occurs on both sides of the piston 2. Generate. This pressure difference is
In addition to applying a resistance to the sliding of the piston 2, the sliding load is removed, and at the same time, the slid piston 2 is returned to the original stop position. Thus, the piston 2 and the piston rod 3
Is stably held at the stop position in the range of normal load fluctuation.

On the other hand, for example, when the outboard motor collides with an underwater obstacle, an abnormal extension force (impact) acts on the cylinder. In this case, the pressure difference between the both sides of the piston 2 that increases rapidly exceeds the relief pressure of the relief spring 8A, so that the relief valve 8 is opened. Thereby, the piston 2 slides in the extending direction while the hydraulic oil flows from the oil reservoir chamber 5 into the oil chamber A, and at the same time, generates a damping force based on the relief pressure of the relief valve 8 and is applied to the outboard motor. Absorbs and reduces shock. In this case, even after the impact load has disappeared, the piston 2 and the piston rod 3 do not return to the original positions but remain at the same positions.

 FIG. 2 shows a second embodiment of the present invention.

Here, an accumulator 20 including a free piston 4, an oil reservoir 5, and an air chamber 6 is provided outside the cylinder body 1 independently of the piston rod 3.
The oil chambers A and B communicate with the oil reservoir 5 of the accumulator 20 via an oil passage 21 formed inside the piston rod 3. Other configurations are the same as those of the first embodiment.

In this case, since no air chamber is provided inside the piston rod 3, the overall length of the cylinder can be further reduced.

(Effects of the Invention) As described above, the present invention provides an operating means for providing a relief valve between an oil chamber in front of a piston inside a cylinder body and a hollow portion of a piston rod, and opening the relief valve by an external operation. The piston rod can be extended or contracted to an arbitrary position when the relief valve is opened via the operating means, and the piston rod can be held at that position by closing the relief valve.

Further, since the gas chamber for pressurizing the hydraulic oil is formed outside, a sufficient gas capacity can be obtained. As a result, the piston rod is stably urged in the extension direction, and the dimensions of the piston rod and the cylinder body can be set regardless of the gas volume, so the overall length of the cylinder is short, and the interposition position of the cylinder can be selected more freely. can do.

Therefore, according to the present invention, the function improvement and downsizing of the positioning and supporting cylinder are realized.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a cylinder showing a first embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of a cylinder showing a second embodiment of the same. 1 ... cylinder body, 2 ... piston, 3 ... piston rod, 4 ... free piston, 5 ... oil chamber, 6, 6A, 6
B: air chamber, 8: relief valve, 10: operating rod, 1
3 ... Operation lever, 20 ... Accumulator, A, B ... Oil chamber.

Claims (1)

(57) [Claims] A hollow piston rod is connected to a piston which is freely slidably housed inside a cylinder body, and is slidably protruded from the cylinder body so that an oil chamber A in front of the piston enters the piston rod. The piston is provided with a relief valve communicating with the piston portion, and an operating means for opening the relief valve by an external operation is provided. On the other hand, the oil chamber B defined behind the intrusion of the piston directly communicates with the hollow portion. A cylinder provided with a gas chamber in which a gas for pressurizing the hydraulic oil in the oil chambers A and B via a portion is enclosed outside the cylinder body.