JPH07103208A - Hydraulic cylinder - Google Patents

Abstract

PURPOSE:To provide a hydraulic cylinder improved in such a way as to stop piston rods in the neutral positions besides in the right or left direction of course, without requiring electric equipment such as a solenoid valve causing the steep rise of cost. CONSTITUTION:The rear end parts of two cylinder tubes A-1, A-2 respectively having piston rods 1, 2 are coaxially jointed to each other so as to turn the piston rods 1, 2 in the mutually opposite directions. The forward or backward moving limit of the piston of one or both cylinder tubes A-1, A-2 can be made the maximum expansion stroke, minimum contraction stroke and neutral state of the piston rods 1, 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic cylinder, for example, a hydraulic cylinder applied as a steering direction changing drive device for changing the direction of traveling wheels of a harvesting machine which is pulled by a tractor or the like to perform harvesting work of agricultural products. Related to the improvement of.

[0002]

2. Description of the Related Art Conventionally known hydraulic cylinders have a front end of a single cylinder tube.
It is common to have a single piston rod that expands and retracts when oil is supplied to the internal cylinder chamber. The retractable stroke of the piston rod is the length of the inner cylinder chamber of the cylinder tube formed in a cylindrical shape of a predetermined length, and the piston that is slidably movable in the same chamber moves back and forth with the supply of oil. It depends on the quantity. However, in a generally known hydraulic cylinder, the piston moves out from the rear end side due to the supply of oil, and the forward movement amount that collides with the front cover fixed to the front end of the cylinder tube becomes the maximum extension stroke of the piston rod, and The amount of backward movement of the rear cover fixed to the rear end of the cylinder tube is the maximum reduction stroke of the piston rod. That is, when used as a steering direction switching drive device that changes the direction of the traveling wheels of a harvesting machine that harvests agricultural products, the oil must be stopped at the middle (neutral) of the cylinder stroke. As shown in, it is troublesome to see that the steering gauge 20 has reached the neutral (straight ahead) position and operate the control valve to stop the oil supply.

Therefore, conventionally, a solenoid valve for controlling the movement of the piston to a neutral position is inserted, and a neutral return switch (sensor rod) for opening and closing the solenoid valve is newly added to the traveling wheels. When the neutral state (straight posture) is entered from the right or left direction, the neutral return switch moves and the electric control system for automatically returning the traveling wheels 8 to the neutral position by closing the solenoid valve is required. As a result, not only the manufacturing cost rises but also it causes a failure.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and can be mechanically moved to the right or left without the need for electric equipment such as a solenoid valve that causes a steep rise. Of course, it is an object of the invention to provide an improved hydraulic cylinder capable of stopping the piston rod in the neutral position.

[0005]

The technical means taken by the present invention to achieve the above-mentioned object is to coaxially join the rear end portions of two cylinder tubes each having a piston rod to each other to form the piston. It is characterized in that the rods are directed in opposite directions.

[0006]

[Operation] Therefore, according to the above-mentioned technical means of the present invention, the oil is fed into one of the two coaxially connected cylinder tubes to move the piston rod from the front end of the tube. When the protruding and extended state is neutral, the maximum extension stroke is achieved by feeding oil to the other tube and projecting and extending the piston rod from the front end of the tube. Then, both piston rods are retracted and contracted in both cylinder tubes, so that the stroke becomes the smallest.

[0007]

EXAMPLE An example of the embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a hydraulic cylinder A of the present embodiment, and two cylinder tubes A-1 having piston rods 1 and 2, respectively. The rear ends of the A-2 are coaxially joined as shown in the figure. The cylinder walls of the cylinder tubes A-1 and A-2, which are formed into a cylindrical shape of a predetermined length, are connected to the internal cylinder chambers 3 and 4 to move oil (pressure) which moves a piston (not shown) forward or backward. Forward and backward supply ports 5 and 6 for sending oil) are opened respectively. By switching the supply of oil from both supply ports 5 and 6, the piston rods 1 and 2 can be extended or retracted by projecting. It is a double-acting cylinder configured.

Incidentally, it is desirable that the rear end portions of both cylinder tubes A-1 and A-2 are welded to each other with an inclusion 7 interposed. Next, an example of the use of the hydraulic cylinder A of the present embodiment configured as described above, for example, the orientation of the traveling wheels 8 of the harvesting machine B that is towed by a tractor (not shown) as shown in FIG. The case of application as a steering direction switching drive device for changing the steering will be described. Two cylinder tubes A-1, A-2 coaxially connected
Among them, the tip of the piston rod 2 of one tube A-2 is pivotally attached to the axle 9 of the vehicle body frame that rotatably supports the traveling wheels 8, and the tip of the piston rod 1 of the other tube A-1 is steered. The hydraulic cylinder A is attached to the harvesting machine B by being pivotally attached to the operation unit 11 of 10 (see FIG. 3).
reference).

The oil can be supplied to both the cylinder tubes A-1 and A-2 by switching the switches provided on the driver's seat of the tractor to the right side, the left side and the neutral side.

Then, as shown in FIG.
When the oil is sent to the cylinder tube A-1 in which the tip of the rod 1 is pivotally attached to the operation portion 11 of 10 and the piston rod 1 is projected and extended from the front end of the tube A-1, when it is neutral (straight), Oil is sent to a cylinder tube A-2 in which the tip of the rod 2 is pivotally attached to the axle 9, and the tube A-
By extending and extending the piston rod 2 from the front end of 2, the maximum extension stroke is achieved, and the traveling wheels 8 move in the traveling direction X.
It turns to the right and turns to the right (state of (c)). By retracting both piston rods 1 and 2 into both cylinder tubes A-1 and A-2 at the same time, the stroke is reduced to the maximum, and the traveling wheels 8 turn left with respect to the traveling direction X to the left. It will be in a state of turning (state of (a)). From this state, by feeding oil into the cylinder tube A-1 and projecting and extending only the piston rod 1, the traveling wheels 8 change their direction to the traveling direction X and are returned to the neutral state where they travel straight (state (b)). ).

In the figure, 12 is a cylinder tube A-1 or A-2.
It is a twist prevention rod attached to the cylinder wall of the hydraulic cylinder A in a direction orthogonal to the axial direction, and by inserting and locking the tip end of the guide frame 13 attached to the axle 9, the hydraulic cylinder A
It is designed to prevent twisting.

The cylinder tubes A-1 and A-2 and the piston rods 1 and 2 may have different lengths. Of course, the length can be appropriately changed, for example, the length of the cylinder tube A-2 is made shorter than the length of the cylinder tube A-1. Examples of the harvesting machine B include a potato harvester and a beet harvester.

[0013]

Since the hydraulic cylinder of the present invention is constructed as described above, it has the following operational effects. If oil is sent to one of the two cylinder tubes and the piston rod is projected and extended from the front end of the tube to make it neutral, the oil is sent to the other tube and the piston is fed from the front end of the tube. The maximum extension stroke is achieved by projecting and extending the rod, and the maximum reduction stroke is achieved by retracting and retracting both piston rods in both cylinder tubes.In this state, oil is sent to only one cylinder tube and the front end By pulling out and extending the piston rod from, it can be returned to neutral. Therefore, according to the hydraulic cylinder of the present invention, by switching the supply of oil to both cylinder tubes, neutral, maximum stroke, minimum stroke,
And because it can be returned to neutral, when applied as a steering direction switching drive device that changes the direction of the traveling wheels of a harvesting machine that is towed by a tractor etc. to perform harvesting work of agricultural products, it will soar like a conventional cylinder. The piston rod can be stopped in a neutral position that turns the traveling wheels to the right or to the left and to the straight direction without the need for electrical equipment such as solenoid valves. Moreover,
The forward or backward movement limit of the piston of one or both cylinder tubes is the maximum extension stroke of the piston rod,
Since the stroke is the smallest and neutral, the direction of the traveling wheels of the harvesting machine, in particular, the neutral position in which the vehicle travels straight in the traveling direction X can be reliably switched without using a direction confirmation gauge or the like.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of implementation of a hydraulic cylinder of the present invention.

FIG. 2 is a side view of the same.

FIG. 3 is a perspective view showing a state where the harvester is attached to the harvesting machine.

FIG. 4 is a plan view showing the movement of the traveling wheels of the harvesting machine according to the movement of the hydraulic cylinder of the present invention, in which (a) shows a state in which the traveling wheels are directed leftward with respect to the traveling direction, (b)
Indicates a neutral state in which the traveling wheels are oriented in the traveling direction,
(C) shows a state where the traveling wheels are turned to the right with respect to the traveling direction.

FIG. 5 is a perspective view showing an example of a direction confirmation gauge that indicates the direction of the traveling wheels.

[Explanation of symbols]

A ... Hydraulic cylinders A-1, A-2 ... Cylinder tubes 1, 2 ... Piston rods

Claims (1)

[Claims] 1. Rear ends of two cylinder tubes each having a piston rod are coaxially joined to each other,
A hydraulic cylinder, wherein the piston rods are directed in opposite directions.