JPH044109B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic torque wrench that uses a hydraulic transmission that generates impact torque.

In a hydraulic torque wrench, a hydraulic transmission consisting of a rotor and a cylinder having vanes is rotatably mounted inside the outer cylinder of the torque wrench, and an output shaft integrated with the rotor is made to protrude in front of the outer cylinder. It is driven by an air motor installed on the shaft, and a rotary tool attached to the output shaft engages the target nut, etc., to tighten or loosen it.
When the rotor stops rotating together with the output shaft when tightening a nut, the oil trapped between the cylinder and rotor generates an impactful rotational torque.

The impact torque mentioned above is generated between the rotor and cylinder when high pressure is generated in one side of the oil chamber between the rotor and cylinder, which is partitioned by vanes, so when the oil pressure on this high pressure side reaches a predetermined height. A relief valve is installed to release oil from the high pressure side to the low pressure side. Conventional relief valves like this are installed in the middle of a communication path that communicates the high-pressure side and low-pressure side of the oil chamber, and are a type of throttle valve, and by adjusting the throttle valve, bolts and nuts can be tightened. The tightening torque is set.

However, since the flow rate remains constant after adjusting the tightening torque to a constant value, a problem arises in that the loosening torque is too weak when loosening bolts or nuts by rotating the rotor in reverse.

To solve this problem, a ball-shaped valve element is movably inserted into the valve chamber of the relief valve, and when the rotor rotates in the tightening direction, the valve element is idle.
When the rotor rotates in the loosening direction, oil flowing backward through the valve chamber of the relief valve causes the valve body to close the valve port, preventing the backward flow of oil and generating high torque.

However, when using a floating ball-shaped valve body as described above, the position of the ball-shaped valve body becomes unstable when rotating in the tightening direction, and the opening area changes, resulting in the disadvantage that the tightening torque is not constant. be.

The purpose of this invention is to solve the problems of the conventional torque wrench as described above, and to provide a torque wrench that can obtain sufficient impact torque even when loosening bolts and nuts by rotating the rotor in reverse. It is something.

The structure of this invention uses a hydraulic power transmission in which a high-pressure side oil chamber and a low-pressure side oil chamber, which are partitioned by a rotor and vanes, are communicated by a relief valve, and the valve body of the relief valve is shaped like a needle valve. In the torque wrench, a movable sleeve is fitted to the outside of the valve body, and the sleeve closes the valve opening that is throttled by the needle valve due to the backflow of oil when the cylinder is reversed. be.

The details of the torque wrench of the present invention will be explained below based on an embodiment shown in the accompanying drawings.

In Figure 1, 1 is the main body of the torque wrench;
There is a known air motor inside, and a handle 2 is formed at the bottom of the main body 1, and a valve for starting or stopping the air motor and a forward/reverse switching valve for the air motor are provided in the handle 2, and these valves are operated. Move the start/stop lever 3 and the forward/reverse lever 4 to the handle 2.
provided at the front of the

Reference numeral 5 denotes an outer cylinder fixed to the front part of the main body 1, and a hydraulic transmission A is provided inside the outer cylinder. This transmission A consists of a rotor 6, a cylinder 7 outside the rotor 6, and vanes 8 provided on the rotor 6. The inner surface of the cylinder 7 is a circle eccentric to the center of rotation of the rotor 6, and the vane 8 is pressed against the inner surface of the cylinder 7 by a spring 9.

A front wall 10 is integrally provided at the front part of the cylinder 7,
A rear wall 11 is fixed to the rear of the cylinder 7, and an output shaft 12 at the front end of the rotor 6 penetrates the front wall 10 and projects forward. A shaft 13 is integrally provided on the rear side of the rear wall 11, and this shaft 13 is coupled to an output shaft of an air motor.

On the inside of the cylinder 7, axial protrusions 14 and 15 are provided on opposite sides, and when the vane 8 and the protrusion 16 on the back of the rotor 6 are in contact with the protrusions 15 and 14 of the cylinder 7, the rotor 6 The oil chambers a and b between the cylinder 7 and the cylinder 7 are shut off so that the oil is contained, but at other positions, the oil chambers a and b communicate with each other through a recess in the inner periphery of the cylinder 7.

B is a relief valve provided in the cylinder 7. As shown in FIG.
8, an O-ring 20 is fitted into the circumferential groove formed in the large-diameter portion 19 at the rear end, and the O-ring 20 is brought into close contact with the inner surface of the valve chamber 17. 21 is screwed into the female thread at the rear end of the valve chamber.

A communication passage 23 communicating with the oil chamber a in the cylinder 7 is provided on the front side of the valve chamber 17, and a valve port 22 that is constricted by the valve body 18 is provided at the front end of the valve chamber 17. The communication passage 24 communicates with the oil chamber b inside the cylinder 7.

Reference numeral 25 indicates a communication path that communicates with the gap 26 between the outer circumference of the valve body 18 and the inner circumference of the valve chamber 17 and the oil chamber b; 27 indicates the valve body 1;
This is a sleeve that is fitted on the outside of 8 and can move forward and backward.

The torque wrench of this invention has the above configuration,
When a rotary tool fixed to the tip of the output shaft 12 is engaged with a nut, etc., the lever 4 is rotated in the normal direction, and the lever 3 is pushed, the cylinder 7 of the hydraulic transmission A is rotated clockwise toward the direction shown in Fig. 2 by the air motor. let At first, there is almost no resistance in the nut, so the rotation of the cylinder 7 is transmitted to the vane 8 and rotor 6 via the oil in the oil chamber a.
The output shaft 12 rotates to rotate the nut at high speed.

When the nut is turned in this way and begins to tighten the object, the load increases and the nut becomes difficult to turn.
Cylinder 7 continues to rotate further. Therefore, since the rotor 6 and vane 8 lag behind the rotation of the cylinder 7, the oil chamber a on the right side in FIG. 2 contracts, and the oil chamber b on the left side expands. Therefore, although the oil pressure in the oil chamber a is increased, the protrusion 16 of the rotor 6 is not the same as the protrusion 14 of the cylinder 7.
When it deviates from the above, oil chambers a and b are in communication, so the oil pressure in oil chamber a does not increase that much. However, as shown in Figure 2, the moment the ridges 14 and 15 of the cylinder 7 line up with the ridges 16 of the rotor 6 and the vane 8, both oil chambers a and b are shut off, and the oil pressure in the oil chamber a rises rapidly. , gives an impactful rotational force to the vane 8 in the clockwise rotation direction.

When the oil pressure in the oil chamber a rises as described above, the high-pressure oil passes through the communication passage 23, passes through the valve port 22 squeezed at the tip of the valve body 18, and flows into the low-pressure oil chamber b from the communication passage 24. The cylinder 7 continues to rotate while suppressing the pressure difference between the oil chambers a and b from rising above a certain level.

The above action is repeated every time the cylinder 7 rotates once, applying an impulsive torque to the output shaft 12 to tighten the nut.

Further, when loosening the nut, the lever 4 is reversed to reverse the air motor, and the hydraulic transmission A is reversed to loosen the nut.

At this time, the cylinder 7 rotates counterclockwise toward FIG. 2, so when the protrusions 16 of the rotor 6 and the vanes 8 coincide with the protrusions 14 and 15 of the cylinder 7, the oil pressure in the oil chamber b rises rapidly. For this reason, the sleeve 27
Due to the hydraulic pressure of the oil chamber b applied to the rear part through the communication passage 25 and the flow of oil from the communication passage 24 to the communication passage 23, it is pulled toward the valve port 22 side and moves forward, and the communication passage 24 and the valve port 22 , the flow of oil between oil chambers a and b is blocked.

Therefore, a torque close to the maximum torque acts on the rotor 6.

In this invention, as described above, the valve element of the relief valve is a needle valve element, so that the flow rate of the relief valve at the time of tightening can be accurately set, so that variations in tightening torque are reduced.

In addition, when loosening a nut, etc., the valve opening of the relief valve is automatically closed by the moved sleeve, so the torque when loosening is close to the maximum torque, and even tightly tightened nuts and bolts can be loosened easily. It is.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view of a main part of a torque wrench of the present invention, FIG. 2 is an enlarged longitudinal sectional rear view taken along the line of FIG. 1, and FIG. 3 is an enlarged longitudinal sectional side view of a relief valve. 6... Rotor, 7... Cylinder, 8... Vane, 12... Output shaft, 18... Valve body, 19... Large diameter section, 27... Sleeve, a, b... Oil chamber, A...
...Hydraulic transmission, B...Relief valve.

Claims (1)

[Claims] 1 A rotor with vanes that drives an output shaft is installed in a cylinder driven by a drive source such as an air motor, and whenever the cylinder rotates by a predetermined angle with respect to the rotor, the oil pressure in the oil chamber partitioned by the rotor and vanes increases. Using a hydraulic power transmission that applies an impulsive torque to the output shaft through a containment action and that communicates the high-pressure side oil chamber and low-pressure side oil chamber separated by the rotor and vanes with a relief valve, the above-mentioned In a torque wrench in which the valve body of the relief valve is in the shape of a needle valve, a movable sleeve is fitted to the outside of the valve body, and the sleeve is throttled by the needle valve due to the backflow of oil when the cylinder is reversed. A torque wrench configured to close the valve port.