JPS6240782Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a new system that uses a pilot valve to allow easy operation and control of rotational speed in large (large flow type) or pneumatic tools that operate with high air pressure. The present invention relates to a valve device that is useful from the viewpoint of safe operation of a match tool.

Conventionally, in the case of a large-sized or high-pressure pneumatic tool, such as a grinder, as shown in Figure 1, the air pressure applied to the main valve is large, and operating the main valve with a lever on the valve rod requires a large amount of force, so one hand is required. It may be difficult to operate. To solve this problem, a pilot valve is provided to open and close the main valve, and the main valve is opened and closed lightly by operating the pilot valve. However, in this pilot valve system, the main valve must be operated to either open or close, making it difficult to adjust the opening/closing degree of the main valve, that is, control the rotational speed. The sudden high-speed rotation of a pneumatic tool can cause early wear and damage of structural parts, and the sudden high-speed rotation of a grinding wheel such as a grinder can cause damage to the grinding wheel.

In view of these drawbacks, the present invention was devised in order to open and close the main valve by a light operation of a pilot valve, and also to control the rotational speed of the pneumatic tool.

The present invention will be explained below based on the illustrated embodiments.

In the figure, 1 is the main body of the pneumatic tool,
Although a grinder is shown in the figure, this is not limited to a grinder, and various air tools may be used. Therefore, detailed description of the inside of the main body 1 will be omitted. A handle portion 2 is protruded from a part of the main body 1, and an operating lever 3 is provided on the handle portion 2.
is pivotally attached via a pin P so that it can be operated with the hand holding the handle. A safety rod 4 is provided adjacent to this operating lever 3.
A safety device may be used to prevent the operating lever from being operated unless the lever is operated and the lock is released. The operating lever 3 and the safety rod 4 are of a conventional type, and detailed explanation thereof will be omitted.

A valve chamber 5 is bored in the handle portion 2 so as to be electrically connected to the air supply connection port I, and a pipe-shaped valve bushing 6 having an air supply port 6a partially bored on the outer periphery is fitted into the hole 5. The air passage 7 is fixed and connected to the air supply port 6a.
Moreover, it shall be provided in the handle portion so as to lead to the air motor chamber R. A valve cover 8 having an orifice 8a drilled therein is fixed to the rear end of the valve bush 6, and a spring SP is interposed between the valve cover 8 and a valve 9 slidably fitted in the valve bush. 9 so that it presses against the tip of the valve bushing.
This valve 9 is provided with an air supply hole 9a whose diameter is determined so as to supply air to a ball 10 serving as a pilot valve and to send enough air to rotate the pneumatic tool at a low speed.
Please note that this valve, valve lid, and valve bushing are O.
Attach a ring, etc. to maintain airtightness.
Also, inside the handle part 2 is an orifice 8 for the valve lid.
An air passage 12 is provided so as to connect a and a pilot valve chamber 11 in which a pilot valve 10 is installed. A ball and a spring 13 for holding the ball are provided in the pilot valve chamber.
The valve seat is pressed by the air pressure supplied from the air supply hole 9a, and the hole 6a is closed by the valve 9, so that the air supply is stopped. A valve rod 14 is provided opposite the ball, and this valve rod 14 is slidably supported by the handle part by a bush 15, and the tip of the valve rod contacts the ball and the other end contacts the operating lever. It is.

Now, when driving the pneumatic tool, by pressing the operating lever, air is supplied from the supply port I through the air supply hole 9a of the valve, the inside of the valve bush 6, the orifice 8a of the valve lid, and the air passage 12 to the valve chamber 11. When the lever is pressed, the supplied air passes through the valve rod, causing the ball to move away from the valve seat and open the valve. At this time, since the diameter of the ball is small, the air pressure applied to the ball does not increase so much, and the ball 10 can be pressed down sufficiently with one hand even without strong force. When the valve is opened by the movement of the ball, air is introduced into the motor chamber through the air supply hole 9a and the air motor rotates, but since the amount of supplied air is limited by the air supply hole 9a, the rotation speed is kept at the set low speed. Become. (See Figure 3) In this case, the valve 9 has not yet slid, but when the opening degree of the ball exceeds a certain level, the pressure inside the valve bushing becomes lower than the air supply port I, and this pressure difference acts on both end faces of the valve. The pressure difference causes the valve to be pushed down, as shown in Figure 4, and the main valve, that is, valve 9, is opened, and the set air is supplied from the air passage 7 to the motor chamber, and the motor is driven at the set high speed rotation. It is something that will be done.

Depending on the operating lever technique, the valve 10
It is also possible to adjust the amount of sliding, that is, to slide to an intermediate position between FIGS. 3 and 4, and to control the rotation at a medium speed between the low speed rotation and the set high speed rotation. Controlling the rotation speed by controlling the air flow rate at the initial stage of valve operation is an effective means not only for grinders but also for general pneumatic tools in terms of operation and safety.

According to the present invention, the pilot pressure to be applied to the pilot valve is supplied from the air supply hole 9a drilled in the main valve, and thereby the adjustment of the pressure inside the valve bushing is controlled by the amount of depression of the ball. This has the advantage that the main valve can be opened and closed easily, and the rotational speed can also be controlled by adjusting the amount by which the operating lever is pressed.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the grinder, FIGS. 2, 3, and 4 are cross-sectional views showing the order of operation of the valves, and FIG. 5 is a cross-sectional view taken in the direction of the arrow in FIG. 4. DESCRIPTION OF SYMBOLS 1...Main body, 2...Handle part, 3...Operation lever, 4...Safety rod, 5...Valve chamber, 6...Valve bush, 6a...Air supply port, 7...Operation passage, 8... Valve lid, 9... Valve, 10...
Ball, 11...Pilot valve chamber, 12...
Air passage, 13...spring, 14...valve rod, 15...button.

Claims (1)

[Scope of utility model registration request] There is an air passage in the handle of the pneumatic tool body that supplies air from the air supply port to the air motor chamber when the valve in the valve bush is pushed down, and from the valve bush through the ball of the pilot valve, which is opened and closed by operating the operating lever. In addition, an air passage is provided to supply air to the air motor chamber, and the air motor is installed in a valve bush fitted in the handle portion so that the air motor rotates at a lower speed than the set high speed rotation, and the pilot valve is easily operated so that the air flows down. A valve device for a pneumatic tool consisting of a valve that is slidably fitted with an air supply hole having a predetermined volume and diameter.