JPH04365568A - Air motor - Google Patents

Abstract

PURPOSE:To form a high speed rotation type, to facilitate production of given torque, and to simplify structure. CONSTITUTION:An air chamber 51 from which compressed air is introduced to the interior of a rotor 53 engaged with a rotary shaft 20 is provided. A jet nozzle 52 opening in the direction of the tangential line of the peripheral part of the rotor is formed in the peripheral part of the rotor 53, compressed air is jetted through the injection hole 52, and rotation force is exerted on the rotor 53 by means of a reaction force. When the load of an air motor 50 is increased, the number of revolutions of the rotor 53 is instantaneously decreased. However, a large quantity of compressed air stored in an air reservoir 60 communicated with both the air chamber 51 and the injection nozzle 52 is continuously jetted through the jet nozzle 52, whereby the decreased number of revolutions is instantaneously increased.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air motor, and more particularly to an air motor used as a driving means for an air rotary tool.

0002

[Prior Art] Conventionally, air motors have been used to drive air rotary tools such as grinders and drills used for polishing and grinding various materials because they are suitable for light work and are highly safe. is used. There are various types of air motors, among which rotary vane type and turbine type motors are common.

[0003] A rotary vane type motor has vanes inserted into a rotor that is eccentrically attached to a casing.
Air pressure acts on the difference in pressure receiving area between adjacent vanes to generate rotational force. Further, as is well known, the turbine type motor obtains rotational force by blowing air onto a turbine.

0004

[Problems to be Solved by the Invention] However, although the rotary vane type motor has good air efficiency, it has a large number of parts and requires strict processing accuracy, so it is not suitable for reducing size and weight. . In addition, although the turbine type motor has a simple structure and can achieve high rotation speed, it has low torque, and it is difficult to quickly increase the rotation speed and maintain torque when the rotation speed decreases during work. It has its drawbacks.

That is, these motors have advantages and disadvantages, and an air motor that is suitable for small size and weight reduction, has high speed rotation, and can easily obtain a predetermined torque has not yet been realized. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems, and to provide an air motor that rotates at high speed, can easily obtain a predetermined torque, and has a simple structure.

[0006]

[Means for Solving the Problems] In order to achieve the above object, an air motor according to the present invention includes an air chamber into which compressed air is introduced into a rotor fitted to a rotating shaft, An air motor is provided with an injection hole opening in the tangential direction of the air motor, and compressed air is ejected from the injection hole to apply rotational force to the rotor by the reaction force of the injection hole, the air motor comprising:
This problem is solved by providing an air reservoir that flows through both the air chamber and the injection hole at an appropriate position within the rotor.

[0007]

[Operation] The compressed air introduced into the air chamber flows through the air reservoir and is ejected from the injection hole, and the reaction force of the ejected compressed air generates rotational force in the rotor, which drives the air motor. When the load on the air motor increases, the rotation speed of the rotor drops momentarily, but since a large amount of compressed air stored in the air reservoir continues to be jetted out from the rotor's injection holes, the drop in rotation speed is immediately reduced. rise to Therefore, even if the load suddenly increases, the output does not suddenly decrease.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a longitudinal sectional side view of an air rotary tool 10, in which an embodiment of the air motor according to the present invention is used as a drive source for an air rotary tool. In the following description, the side to which the grinding member is connected to the air rotary tool 10 will be referred to as the front, front surface, front end, etc., and the side to which compressed air is supplied will be referred to as the rear, back surface, rear end, etc.

Reference numeral 12 denotes a cylindrical housing of the air rotary tool 10. A rotary shaft 20 is supported by bearings 16 and 17 inside the front housing 13 formed to have a small diameter. is formed into a chuck shape, and a grinding member (not shown) of a rotary tool such as an air grinder is inserted into this chuck part 21, and the nut 22 is inserted into the chuck part 21.
The grinding member can be fixed to the rotary shaft 20 by tightening with. 24 is the rotating shaft 2
0, and 26 and 27 are for inserting pins into the rotating shaft 20 to prevent the rotating shaft 20 from rotating when tightening the nut 22.
This is a through hole provided in the front housing 13 and the rotating shaft 20 in the radial direction. A compressed air introduction path 28 is provided at the rear end of the rotating shaft 20 in the axial direction.

The rear part 14 of the housing 12 is formed to have a large diameter, and a female thread 15 is formed on the inner peripheral surface of the rear end. A large diameter front part 31 of a casing 30 whose rear part is narrowed to a smaller diameter than the front part is fitted into the inner peripheral surface of the housing rear part 14, and a cap 4 having a female thread 41 and a male thread 42 on the inner and outer peripheral surfaces of the front part.
0 male thread 42 is screwed into the female thread 15 of the housing rear part 14 via the O ring 44, and the front end 43 of the cap 40 is brought into contact with the rear surface of the throttle part 32 of the casing 30 perpendicular to the axis. This secures the casing 30 within the housing rear part 14. In this way, an exhaust chamber 49 is formed by the housing rear part 14 and the large-diameter front part 31 of the casing 30, and the air motor 5 is installed inside the exhaust chamber 49.
Set 0.

The air motor 50 mainly has a rotating shaft 2.
The rotor 53 has an air chamber 51 to which compressed air is supplied, and an air chamber 51 is formed inside the rotor 53 to which compressed air is supplied. An injection hole 52 communicating with the chamber 51 is provided.

[0012] The air motor 50 is usually equipped with a speed adjustment device to prevent over-rotation and maintain an optimum rotational speed. The speed adjusting device of this embodiment is of the same type as that of Utility Model Application No. 103290/1999, which is the earlier application of the present application, and a plurality of flow holes 54 are formed radially in the rotor 53. A deformable ball 55 is movably housed, and the flow rate of compressed air flowing in the air chamber 51 is controlled by utilizing the deformation of the ball 55, which moves in a centrifugal direction depending on the magnitude of centrifugal force, to control the air motor 50. It adjusts the rotation speed.

[0013] In addition to this, other speed adjusting devices include:
The so-called butterfly weight type, as described in Japanese Utility Model Publication No. 35-23885, etc., controls the opening of the regulating valve by using a rotating centrifugal force to push a weight built into a frame directly connected to the rotor outward. It may be something.

Next, the structure of the rotor 53 will be explained with reference to FIGS. 2 to 6. The rotor 53 consists of two members: a concave front rotor 56 and a convex rear rotor 57. When both rotors 56 and 57 are fitted together, the air chamber 51 is formed into an annular shape. 2 is a rear view of the front rotor 56, and FIG. 3 is a side view taken along line III--III in FIG. Moreover, FIG. 4 is a front view of the rear rotor 57,
FIG. 5 is a side view taken along line V-V in FIG. 4.

At the circular rear end of the front rotor 56, four arcuate protrusions 58 extending from the inner circumferential side to the outer circumferential side of the rear end are formed at point symmetrical positions. Matching protrusion 58
Each starting point and each ending point are slightly juxtaposed, and a groove 59 is formed between them. This groove 59 becomes the injection hole 52 as shown in FIG. 6 when the front rotor 56 and the rear rotor 57 are fitted together. Further, a gap 59a formed on the outer circumferential portion of the protrusion 58 and continuing to the groove 59 is formed on both rotors 56, 57.
In the fitted state, an edge circumferential groove 59b is formed.

The number of protrusions 58 should be two or more so that they are point symmetrical, and the length of the protrusions 58 should be as long as possible so that a large amount of compressed air, which will be described later, can be retained. It is better to do so. It is advantageous to make the groove 59 as parallel as possible to the tangent to the outer circumferential surface of the rotor, since this increases the torque of the air motor 50.

A streamlined space is provided outside the air chamber 51 and inside the protrusion 58 to form an air reservoir 60. That is, when both rotors 56 and 57 are fitted together, a substantially magatite-shaped air pocket 60 is formed on the inside of the protrusion 58, and a substantially magatite-shaped peripheral groove 59b is formed on the outside. Note that the communication portion between the air reservoir 60 and the groove 59 is configured with a curved surface so that the compressed air can flow smoothly. Further, the number of air reservoirs 60 does not necessarily have to match the number of grooves 59, that is, the number of injection holes 52.

Reference numeral 61 denotes a deterrent wall for restricting movement of the ball 55 in the centrifugal direction, and is provided near the starting point on the inner circumferential side of the protruding strip 58, facing the outer open end of the communication hole 54. . Further, reference numeral 62 is a strip that protrudes further rearward on the arc-shaped convex strip 58 in order to tightly fit both rotors 56 and 57, and reference numeral 65 is a strip that protrudes further rearward from the arc-shaped convex strip 58 in order to tightly fit the two rotors 56 and 57 together.
This is a bush that is inserted to fit into the 0.

On the other hand, as mentioned above, the rear rotor 57 is
When fitted with the concave front rotor 56, both rotors 5
An air chamber 51 is formed between 6 and 57, and the outer end communicates with this air chamber 51, and the inner end connects to the rotating shaft 2.
Four communication holes 54 communicating with the introduction path 28 of 0 are formed radially. Each communication hole 54 movably accommodates a deformable rubber ball 55 having a required mass and slightly smaller than the inner diameter of the communication hole 54 . The ball 55 may be made of various elastic materials other than rubber. Note that if the elastic material is selected after determining the Poisson's ratio (ratio of expansion in a direction perpendicular to the compression in the centrifugal direction) of the ball 55, the aperture ratio of the flow hole 54 can be changed. Therefore, the desired purpose can be achieved by considering not only the dimensions of the ball but also its physical properties.

Reference numeral 63 indicates a concave groove corresponding to the strip 62, and the two fit together to connect the front rotor 56 and the rear rotor 5.
7 are joined together. Further, reference numeral 66 is an O-ring for sealing between the front rotor 56 and the rear rotor 57.

Next, referring back to FIG. 1, the compressed air valve mechanism will be explained. A valve outer cylinder 70 is slidably inserted into the outer circumferential surface of the small diameter rear part 33 of the casing 30, and a valve inner cylinder from which a compressed air supply port 71 protrudes is inserted into the rear inner circumferential surface of the valve outer cylinder 70. 72 are fitted together. By rotating the male thread 73 formed on the front outer peripheral surface of the valve outer cylinder 70 with respect to the cap 40, the valve outer cylinder 70 can be moved in the axial direction (left and right direction in FIG. 1).
When the valve outer cylinder 70 is most retracted as shown in FIG. The fluid flow path 74 within the valve inner cylinder 72 is closed by closely contacting the valve seat 37 formed as a surface.

An air supply air hose 75 is fixedly connected to the air supply port 71 of the valve inner cylinder 72 with a hose band 76, and the air hose 75 is connected to the rear open end 78 of the valve outer cylinder 70. Surround it and connect the exhaust hose 77. The air expanded in the exhaust chamber 49 passes through the constriction section 32 of the casing 30.
The exhaust hose 77 is passed from the exhaust hole 39 drilled in the valve outer cylinder 70 to the exhaust hole 79 provided in the valve outer cylinder 70 parallel to its axis.
It is configured to be distributed to

Note that reference numeral 81 is a brake rod that is linked to the opening and closing operations of the valve, and reference numeral 82 is a brake disc fixed to the rear end surface of the rear rotor 57. The means are configured.

Next, the operation of this embodiment will be explained. Figure 1
In the open state of the valve shown in FIG. It flows through the reservoir 60 and flows through the injection hole 52 to the exhaust chamber 4.
It is ejected at 9. The reaction force generated by the ejection of compressed air generates rotational force in the rotor 53, which drives the air motor 50.

The compressed air ejected from the injection hole 52 is not immediately injected and diffused, but flows out along the edge circumferential groove 59b formed at the front of the injection hole 52, so that the rotor 5
Increase the torque of 3. The compressed air blown into the exhaust chamber 49 is exhausted from the exhaust hole 39.

When a large centrifugal force acts on the ball 55 housed in the communication hole 54 due to the rotation of the rotor 53, the ball 55 is urged in the centrifugal direction. Therefore, when the rotary tool 10 is under no load or when the load is small, the ball 55 comes into contact with the restraining wall 61, and the ball 55 receives the reaction and deforms in the direction perpendicular to the centrifugal direction.
Narrows the compressed air flow path and reduces the flow rate of compressed air.

On the other hand, when the load on the rotary tool 10 increases, the rotational speed of the rotor 53 momentarily decreases, but the kinetic energy of the compressed air remaining downstream of the ball 55 is absorbed by the rotor. It contributes to the rotational force of 53. In this embodiment, since a large amount of compressed air stored in the air chamber 51 and the air reservoir 60 continues to be ejected from the injection hole 52, the rotation speed that has temporarily decreased immediately increases.

As the rotational speed of the rotor 53 decreases, the centrifugal force on the ball 55 also decreases, so that the deformation of the ball 55 decreases, contrary to the case in the no-load state.
The flow passage cross-sectional area of the communication hole 54 and the supply amount of compressed air increase, thereby increasing the rotation speed of the rotor 53. In this way, the rotational speed and torque of the rotor 53 increase or decrease depending on the presence or absence of a load on the rotary tool 10 and its degree, so even if the load suddenly increases, the output does not drop suddenly and remains stable. High output can be obtained.

On the other hand, to stop driving the rotary tool 10, the valve outer cylinder 70 is moved forward to close the fluid passage 74 and the supply of driving compressed air is stopped. At this time, the brake rod 81 interlocked with the valve outer cylinder 70 moves forward and contacts the brake disc 82, pressing the disc 82 to apply the brake, and the rotation of the air motor 50 is immediately stopped.

[0030]

[Effects of the Invention] The air motor according to the present invention has a simple structure and is therefore suitable for reduction in size and weight.It also rotates at high speed and can easily obtain a predetermined torque. In other words, even when the load on the air motor increases, the rotor's rotational speed momentarily drops, but the rotational speed quickly returns to normal due to the energy of the compressed air stored in the air chamber and air reservoir. can obtain high output.

Furthermore, since the structure can be made of resin, the manufacturing cost is low, and since the number of parts constituting the air motor is small, assembly work is easy.
Because of its simple structure, it has the excellent effect of quickly responding to changes in the load applied to the rotating tool.

[Brief explanation of drawings]

FIG. 1 is a longitudinal side view of an air motor 50. FIG.

FIG. 2 is a rear view of the front rotor 56.

FIG. 3 is a side view taken along line III-III in FIG. 2;

FIG. 4 is a front view of the rear rotor 57.

FIG. 5 is a side view taken along line V-V in FIG. 4;

FIG. 6 is a side view of the rotor 53.

[Explanation of symbols]

20 Rotation axis 50 Air motor 51 Air chamber 52 Injection hole 53 Rotor 54 Flow hole 55 Ball 56 Front rotor 57 Rear rotor 58 Convex strip 59b Edge circumferential groove 60 Air reservoir

Claims (2)

[Claims] 1. A rotor attached to a rotating shaft is provided with an annular air chamber inside the rotor, and a plurality of radial flow passages are formed in the rotor from a compressed air introduction passage to the air chamber, and the flow passages are mutually connected to each other. An air motor is provided with an air reservoir on the outer periphery of the air chamber between the air chambers, and compressed air injection holes are formed along the outer periphery of the rotor from the air reservoir toward the outside of the rotor. 2. The air motor according to claim 1, wherein the rotor is composed of two members, a front rotor and a rear rotor, and the injection holes are formed at a joint surface of the two members.