JP2747782B2 - Air motor in air tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air motor for reducing the frictional resistance of a blade tip sliding portion of a rotor rotating in a cylinder in an air tool such as an air grinder or an impact wrench.

[0002]

2. Description of the Related Art Conventionally, an air motor of an air tool such as an air grinder, an impact wrench, an air driver or the like has a rotor in which a blade is inserted into and retracted from a cylindrical cylinder so that the rotor is rotatable. While rotating while sliding on the inner peripheral surface of the cylinder,
The shape of the tip of the blade of this air motor is changed so that the contact between the cylinder and the tip of the blade can be made smooth in order to prevent wear due to friction with the inner peripheral surface of the cylinder and reduce resistance. It has an arc shape. And
Air supply into the cylinder is performed from an air supply port opened to the cylinder inner peripheral surface through an air passage provided in the cylinder peripheral wall from the cylinder upper lid, and an exhaust port is set at a cylinder position at a predetermined angle from this air supply port. It is provided and exhausted. The tip of the blade of the rotor that slides and rotates on the inner peripheral surface of the cylinder contacts the entire inner peripheral surface of the cylinder and rotates while maintaining airtightness.

[0003]

Therefore, when the tip of the blade is made to have an arc shape as in the prior art, and the contact between the cylinder and the tip of the blade is made substantially uniform over the entire inner peripheral surface of the cylinder, the contact is caused. And the frictional resistance becomes large,
There are drawbacks such as a decrease in output, mainly a decrease in the number of revolutions, a decrease in efficiency due to an increase in the amount of generated heat, and a rise in the temperature of the cylinder and the blade. In general, a rotor having a plurality of blades has a pressure receiving area at a maximum projecting position of the blade at a rotation angle, a pressure difference between front and rear blades, and a torque corresponding to a distance from a rotation center of the rotor to a pressure receiving center of the blade. Rotate. Each of the blades inserted into the rotor is rotated (slid) by being pressed against the inner peripheral surface of the cylinder by centrifugal force generated by the rotation of the rotor. The process that requires an airtight state between the tip of the sliding blade and the inner peripheral surface of the cylinder is only the expansion process of the blade chamber c shown in FIG. 2. In other blade chambers, each blade and the inner peripheral surface of the cylinder are not necessarily separated. There is no need to make contact, it is only necessary to guide the blades.Contact between the blade tip and the inner peripheral surface of the cylinder other than during this expansion process generates unnecessary frictional resistance, thus reducing the efficiency of the air motor and However, the above-mentioned drawbacks occur.

[0004] In view of the above problems, the present invention maintains the airtightness between the blade and the inner peripheral surface of the cylinder only during the expansion process when the rotor is rotating, and reduces the contact area between the two as much as possible in other processes. An object of the present invention is to improve the efficiency of an air motor by reducing frictional resistance due to unnecessary contact.

[0005]

In order to achieve the above object, an air motor in an air tool according to the present invention has a plurality of blades inserted and retracted into a cylinder having an air supply port and an air exhaust port. The rotor is provided so as to rotate by the air supply into the cylinder, and an air motor is constructed.The peripheral surface positions of the air supply port and the exhaust port are each ground to form a step with the cylinder inner peripheral surface to form a depression. At the inlet and outlet positions, the blade tip is slidably contacted and guided by a non-ground surface excluding the depression.

[0006]

The air motor in the air tool constructed as described above uses a rotor in which a plurality of blades are inserted and retracted into a cylinder having an air supply port and an exhaust port to supply air to the cylinder. Are provided so as to be rotated, and the peripheral surface positions of the air supply port and the exhaust port are respectively ground to form a depression so as to generate a step with the inner peripheral surface of the cylinder. In order to slidably contact the non-grinding surface excluding the dent part, the contact of the blade with the inner peripheral surface of the cylinder contacts the entire width only during the expansion process of compressed air, and the dent part does not contact in other strokes In addition, the recess at the intake port position and the recess at the exhaust port position formed in the cylinder are arranged so that the contact position with the tip of the blade is different in the longitudinal direction of the cylinder. Contact position with inner peripheral surface By changing in the width direction, uniform contact can be made in the longitudinal direction (width direction) of the blade, the friction coefficient and the amount of wear of the blade are reduced, and low vibration, low noise and long life can be achieved. High efficiency of the air motor can be achieved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An air motor in an air tool according to the present invention will be described below with reference to the illustrated embodiment. 1 to 5 show only an air motor used for an air tool such as an air grinder, an impact wrench, and a driver.

The air motor A has a rotor 2 in which a plurality of blades 3 are removably inserted into a cylindrical cylinder 1 having a required diameter and length, and is provided at both ends of the cylinder. The cylinder upper lid 4 and the cylinder lower lid 5 are arranged in an airtight manner, and ball bearings 6 and 7 are provided so as to be incorporated into the upper and lower cylinder lids. The rotor 2 is rotatable via the ball bearings 6 and 7. In this manner, the inside of the cylinder is kept airtight, and compressed air is introduced into the cylinder from an air supply port 10 in the cylinder via air passages 8 and 9 provided in the cylinder top cover and the cylinder peripheral wall. 2 is rotated in the direction shown in the figure by the action of high-pressure compressed air. Further, the cylinder 1 is provided with exhaust ports 11 and 12 at a position separated from the air supply port by a predetermined rotation angle to discharge exhaust gas. To do That.

On the outer peripheral surface of the rotor 2 of the air motor A, a plurality of blade grooves 2a having a predetermined depth and width are formed at predetermined intervals in parallel with the central axis in the central longitudinal direction. The blades 3 are inserted and slidably inserted into and out of the inside, and each of the blades protrudes and presses against the inner peripheral surface of the cylinder by the centrifugal force generated by the rotation of the rotor to slide.
Since this configuration is the same as the conventional one, a detailed description thereof will be omitted.

A recess 13 is formed on the inner peripheral surface 1S of the cylinder 1 at a peripheral position of the air supply port 10 opened into the cylinder as shown in FIGS.
The cylinder inner peripheral surface at the position having 0 is ground except for both side surfaces of the cylinder to provide a position and a step of the depression 13 on the cylinder inner peripheral surface. The peripheral surface is continuous with the inner peripheral surface, and the non-grinding surfaces 15 and 16 are brought into sliding contact with the blade tip surface to guide the rotating blade.

The cylinder 1 is formed with holes 11 and 12 formed in the front and rear direction with respect to the rotation direction of the rotor, and a recess 14 is formed at a position on the peripheral surface of the exhaust ports 11 and 12. As with the depression 13, the depression 14 also has a non-ground surface 16 on the outer peripheral surface of the exhaust ports 11 and 12 and the depression 1.
A step is formed between the blade 4 and the non-grinding surface 16, and the blade at the position of the exhaust port is brought into sliding contact with the blade to guide the blade in the rotational direction.

When the recesses 13 and 14 are formed at the peripheral surface positions of the intake port 10 and the exhaust ports 11 and 12 so as to form a step with the non-ground surfaces 15 and 16 of the inner peripheral surface of the cylinder, FIGS. As shown in the figure, the cylinder inner chamber in which the blade tip slides and moves on the cylinder inner peripheral surface 1S by the rotation of the rotor is the cylinder inner peripheral surface 1S, the blade 3, the cylinder upper lid 4, the cylinder lower lid 5
In the rotor rotation direction from the air supply port position,
It is separated from d and o and changes sequentially with the movement of the blade. At this time, it is necessary to maintain airtightness only in the blade chamber c in which the high-pressure compressed air supplied into the cylinder is in the process of expansion. Since there is no relation to the efficiency of the above, a part or all of the depression 13 or the depression 14 is located in the blade chambers A, A, D, and E.

The rotation of the air motor constructed as described above will now be described. High-pressure compressed air is passed through an air passage 8 provided on the cylinder top cover 4 and an air passage 9 provided on the peripheral wall of the cylinder 1, and the rotor 2, the blade 3-1, the cylinder top cover 4, the blade chamber formed by the cylinder lower lid 5, and the blade chamber A formed by the cylinder 1, the rotor 2, the blade 3-1, the blade 3-2, the cylinder upper lid 4, and the cylinder lower lid 5. At this time, the blade 3-2 receives the high-pressure compressed air and rotates the rotor 2 in the direction of the arrow, and the blade 3-1 moves in the direction of the blade 3-2.
-2 moves in the direction of the blade 3-3. The blade 3-3 moves in the direction of the blade 3-4, and the blade 3-4 moves in the direction of the blade 3-1. The compressed air is discharged from the blade chamber D and the exhaust ports 11 and 12 opened to the cylinder 1 from the blade chamber D. The blade chamber U formed by the cylinder 1, the rotor 2, the blades 3-3, the cylinder upper lid 4, and the cylinder lower lid 5 is an expansion process of the compressed air, and the rotation of the rotor 2 increases the volume of the blade chamber C. . Therefore, the compressed air expands and the pressure decreases.

A blade chamber D composed of a cylinder 1, a rotor 2, a blade 3-3, a blade 3-4, a cylinder upper lid 4, and a cylinder lower lid 5, and a cylinder 1, a rotor 2, a blade 3-4, a cylinder upper lid 4 The blade chamber e formed by the cylinder lower lid 5 is in the exhaust process as described above, and rotates the rotor 2 to discharge the supply air after the work is completed. At this time, the rotational torque of the rotor is the maximum of the blades. The torque corresponds to the pressure receiving area at the projecting position, the pressure difference between the front and rear of the blade, and the distance from the rotation center of the rotor to the pressure receiving center of the blade. The tip surfaces of all the blades are slid while being pressed against and contacting the inner circumferential surface 1S of the cylinder due to the centrifugal force generated by the rotation of the rotor. As a result, airtightness is maintained by contact with the inner peripheral surface of the cylinder, and the frictional resistance of the blades increases.

However, at the positions of the air supply port 10 and the exhaust ports 11 and 12, depressions 13 and 14 are formed in the inner peripheral surface of the cylinder to generate a step. The frictional resistance is small because it is in contact with only the blade 16, so that unnecessary contact between the blade and the inner peripheral surface of the cylinder is suppressed.

Further, in order to suppress the friction at the tip of the blade,
Non-grinding surfaces 15, 16 provided at inlet and outlet positions
As shown in FIG. 5, the rotor is arranged so that the contact position with the blade during rotation of the rotor is different along the longitudinal axis of the cylinder. Due to this, the blade tip position contacting on the non-grinding surface 15 and the blade tip position contacting on the non-grinding surface 16 are different,
The blade can be uniformly contacted with the inner circumferential surface over the entire width in the longitudinal direction (width direction) of the blade.

[0017]

According to the air motor of the air tool of the present invention, a rotor having a plurality of blades removably inserted into a cylinder having an air supply port and an exhaust port is used for supplying air to the cylinder. Are provided so as to be rotated, and the peripheral surface positions of the air supply port and the exhaust port are respectively ground to form a depression so as to generate a step with the inner peripheral surface of the cylinder. In order to slidably contact the non-grinding surface excluding the recessed portion, the blade and the inner peripheral surface of the blade contact the entire width only during the expansion process of the compressed air, and do not contact the recessed portion in other strokes Therefore, it is possible to reduce the amount of wear at the blade tip, reduce vibration, reduce noise and extend the life, and to increase the efficiency of the air motor. Further, since the depression at the intake port position and the depression at the exhaust port position formed in the cylinder of the air motor are arranged so that the contact position with the tip of the blade differs in the longitudinal direction of the cylinder, the blade cylinder The contact position with the inner peripheral surface is changed to make uniform contact, the friction coefficient and the amount of wear of the blades are reduced, and the efficiency of the air motor can be improved.

[Brief description of the drawings]

FIG. 1 is a partially broken external view showing an embodiment of an air motor in an air tool of the present invention.

FIG. 2 is a side vertical sectional view of an air motor.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a sectional view taken along line BB of FIG. 2;

FIGS. 5A and 5B are cross-sectional views showing an inner peripheral surface shape of a cylinder in the air motor of the present invention, wherein FIG. 5A shows an air supply port portion and FIG.

[Explanation of symbols]

 A Air motor 1 Cylinder 2 Rotor 2a Blade groove 3 Blade 4 Cylinder upper lid 5 Cylinder lower lid 6,7 Ball bearing 8,9 Air passage 10 Air supply port 11,12 Exhaust port 13 Air supply side dent 14 Exhaust side dent 15 Non-grinding Surface 16 Non-ground surface

Claims (2)

(57) [Claims] An air motor in an air tool provided with a rotor having a plurality of blades inserted and retracted in a cylinder having an air supply port and an exhaust port so as to rotate by air supply into the cylinder. In the above, the peripheral surface positions of the intake port and the exhaust port are respectively ground to form a recess so as to generate a step with the inner peripheral surface of the cylinder, and at the intake port and the exhaust port position, the blade tips are formed by removing the recesses. An air motor for an air tool, wherein the air guide is slidably guided by a ground surface. 2. The air tool according to claim 1, wherein the depression at the intake port position and the depression at the exhaust port position are arranged so that the contact position with the blade tip differs in the longitudinal direction of the cylinder. Air motor.