JPS5923810Y2 - Automatic return device for operating lever - Google Patents

Description

[Detailed Description of the Invention] This invention mainly relates to an automatic return device for an ejector operating lever of a construction machine such as a scraper.

Conventionally, the ejector operation lever of this type of construction machinery automatically returns to the neutral position and stops the ejector operation when the ejector cylinder reaches the stroke end. Conventionally, this automatic return mechanism was installed inside the operation valve. It was installed in a hydraulic system and operated hydraulically.

In other words, the structure is such that the head-side hydraulic pressure that rises when the ejector cylinder reaches the stroke end is introduced into the spool held by the detent to release the detent, which has the disadvantage of a complicated structure. Ta.

This invention was made with the purpose of eliminating such drawbacks, and the return of the ejector is detected by a switching valve provided at the ejector return position, and the operating lever is automatically moved to the neutral position by the fluid sent by switching the switching valve. It is an object of the present invention to provide an automatic return device for an operation lever, which has a simple structure and is capable of returning to its original state.

An example in which this invention is applied to a construction machine such as a scraper will be described in detail below.

In the figure, reference numeral 1 denotes an ejector installed in the bowl of a scraper (not shown), which can be moved back and forth within the bowl by an ejector cylinder 2. This ejector cylinder 2 is supplied with hydraulic pressure (not shown) via a hydraulic switching valve 3. connected to the source.

The hydraulic switching valve 3 has a structure in which a spool (not shown) is switched by an air cylinder 4, and the tip of a piston rod 4a of the air cylinder 4 is pivotally connected to a lever 3a that interlocks with the spool.

Further, the air cylinder 4 is connected to an air supply source (not shown) via an operating valve 5 provided in a driver's cab (not shown).

The operating valve 5 has an operating lever 6, and the operating lever 6 is provided with a tent mechanism 7 for temporarily holding the operating position.

This tent mechanism 7 is intercepted, for example, as shown in FIG.

That is, the tent mechanism 7 is composed of a cylinder 7a and an operating rod 7b that is slidably inserted into the cylinder 7a. It is pivoted on the side.

A small diameter portion 7C is formed at the lower end of the operating rod 7b, and a ball 9 pressed by a compression spring 8 is removably fitted into the small diameter portion 7C.

Furthermore, the lower end of the cylinder 7a is attached via a universal joint 15 to the floor of a driver's cab (not shown), and the pressure chamber 7d within the cylinder 7a is attached via a conduit 10 to the retracted position of the ejector 1. The switching valve 11 is connected to the switching valve 11.

This switching valve 11 is closed during normal times, and when the ejector 1 returns, the ejector 1 presses the spool 11a and opens the switching valve 11, and the rod side pressure of the air cylinder 4 is introduced through the conduit 12.

However, when the operating lever 6 is operated to the position shown by the broken line in FIG. 1 in order to move the ejector 1 backward, the ball 9 of the detent mechanism 7 is fitted into the small diameter portion 7C of the operating rod 7b, and the operating lever 6 is moved to the operating position. The hydraulic switching valve 3 is switched by the air cylinder 4, and the ejector 1 is moved backward by the ejector cylinder 2.

When the ejector 1 reaches the return position, the switching valve 11 is opened by the ejector 1, so that part of the pressure that was being supplied to the air cylinder 4 is transferred into the cylinder 7a of the detent mechanism 7 via the pipe 12.10. The liquid flows in and pushes up the operating rod 7b.

As a result, the locking by the ball 9 is released, so that the operation lever 6 is automatically returned to the neutral position, and the ejector 1 is also stopped at the return position.

Note that FIG. 3 shows another embodiment of the detent mechanism 7.

That is, a sleeve 13 having a taper 13a whose upper surface slopes low toward the operating rod 7b is provided in the cylinder 7a, and the ball 9 is placed on the tapered portion 13a of this sleeve 13, and the operating rod 7b is connected to the compression spring 14. is biased upward.

In the tent mechanism 7 configured as described above, the switching valve 11 is set so that air is constantly supplied to the pressure chamber 7d in the cylinder 7a, and the operating lever 7b is operated by operating the operating lever 6.
When the ball 9 is pushed into the cylinder 7a, the ball 9 pushed up by the sleeve 13 is guided by the taper 13a, fits into the small diameter portion 7C of the operating rod 7b, and is locked there.

Next, when the switching valve 11 is closed due to the return of the ejector 1, the snow 13 is lowered and the operating rod 7b is activated by the ball 9.
Since the lock is released, the operating rod 7b is raised by the compression spring 14, and the operating lever is automatically returned to the neutral position.

As detailed above, this device automatically returns the operating lever by detecting a pressure signal using the switching valve that is switched when the ejector returns and releasing the tent mechanism provided on the operating lever. Even in machines equipped with a large number of operating levers, such as construction machinery, the number of times the operating levers are operated can be halved, thereby reducing driver fatigue and reducing the risk of erroneous operation.

In addition, since the existing air circuit can be used, it is only necessary to provide a switching valve that is opened and closed by the work equipment, and a tent mechanism that locks the operating lever. Since it does not require an electronic circuit, it can be provided at low cost and there is little risk of failure.

[Brief explanation of the drawing]

The drawings show one embodiment of this invention, with FIG. 1 being a circuit diagram, FIG. 2 being an enlarged sectional view of a detent mechanism, and FIG. 3 being an enlarged sectional view of a detent mechanism according to another embodiment. 1 is an ejector, 2 is an ejector cylinder, 3 is a hydraulic switching valve, 5 is an operating valve, 6 is an operating lever, 7 is a detent mechanism,
7a is a cylinder, 7b is an operating rod, 7C is a small diameter portion, 7b is a pressure chamber, 9 is a ball, 10 is a pipe, 11 is a switching valve, 13
1 is a sleeve, 13a is a taper, and 14 is a compression spring.

Claims (1)

[Scope of utility model registration request] An ejector cylinder 2 that moves the ejector 1 back and forth, a hydraulic switching valve 3 that switches the hydraulic pressure supplied to the ejector cylinder 2, and an air cylinder 4 that is connected to the lever 3a of the hydraulic switching valve 3 and that operates to switch the hydraulic switching valve 3. and an operating valve 5 for switching the air pressure supplied to the air cylinder 4.
and an operating lever 6 of the operating valve 5.
One end of the operating rod 7b is connected to the operating lever 6 nearby,
In addition, a tent mechanism 7 is provided which is fitted into a cylinder 7a having a pressure chamber 7b at the other end or bottom, and when the operating lever 6 is operated to the working position, the tent mechanism 7 has a small diameter provided on the operating rod 7b. A ball 9 that falls into the portion 7c and holds the operating lever 6 in the working position is provided, and a pressure chamber 7d inside the cylinder 7a is provided at the return position of the ejector 1, so that the ejector 1 reaches the return position. An automatic return device for an operating lever is connected to an air circuit of an air cylinder 4 via a switching valve 11 that is switched by the ejector 1 when the operation lever is switched.