JP6494805B2 - Pneumatic tool - Google Patents

Description

  The present invention relates to an air tool provided with an air motor, and more particularly, to an air tool that improves the operating efficiency of an air motor by providing an expansion chamber having a large volume at a position close to the air motor in an exhaust passage from the air motor.

  An air grinder, which is an air tool, generally includes a tool drive shaft that is drivingly connected to a rotary drive output shaft of an air motor via a bevel gear device, and rotates at the tip of the tool drive shaft. A structure in which a polishing disk is attached (for example, Patent Document 1).

  In such an air grinder, in order to improve the operating efficiency of the air motor, the pressure on the exhaust side from the air motor is made as low as possible, and the differential pressure between the pressure on the air supply side and the pressure on the air discharge side to the air motor is reduced. It needs to be large. For example, in Patent Document 2, an exhaust chamber is provided in the exhaust passage so that the air discharged from the air motor can be expanded to reduce the exhaust side pressure.

  Further, in the air grinder as described above, the exhaust from the air motor is blown onto the peripheral wall of the portion that houses the bevel gear device, thereby suppressing the lubricant scattered from the rotating bevel gear from adhering to the peripheral wall. In order to achieve efficient lubrication, the lubricating oil adhering to the peripheral wall is peeled off and reattached to the bevel gear. (For example, Patent Document 3)

JP 2007-98539 A JP 2001-88056 A JP 2010-188463 A

  Attempts to provide an expansion chamber in order to increase the operating efficiency of the air motor tend to increase the outer size of the air motor housing by providing the expansion chamber. With a hand-held tool such as the above-mentioned air grinder, it becomes difficult for an operator to grip the air tool, or it becomes difficult to visually recognize the work site that is the tip of the air tool, as the external size of the tool increases. For example, there is a problem that it becomes difficult to work in a narrow place such as a corner portion.

  In order to increase the lubrication efficiency by supplying exhaust gas to the bevel gear device chamber, it is conceivable that the exhaust gas from the air motor is blown directly onto the bevel gear and the lubricant oil particles accompanying the exhaust adhere to the bevel gear. Since the exhaust into the bevel gear chamber in Patent Document 3 is high-pressure and high-speed, even if it is blown onto the bevel gear, the adhesion of the lubricating oil cannot be expected much.

  An object of the present invention is to provide an expansion chamber in the exhaust passage of an air motor without increasing the outer size of the air tool, and to lubricate the bevel gear device by introducing reduced pressure exhaust into the bevel gear chamber. An object of the present invention is to provide an air tool which can be performed more efficiently.

That is, the present invention relates to a rotor that is driven to rotate about a first longitudinal axis, a cylindrical rotor casing that rotatably accommodates the rotor, and a motor output shaft that extends from one end of the rotor along the first longitudinal axis. An air motor comprising:
A tool drive shaft extending along a second longitudinal axis forming a predetermined angle with respect to the first longitudinal axis;
An annular bearing for closing the end of the rotor casing on the one end side of the rotor and bearing the motor output shaft;
A first bevel gear provided at an end portion of the motor output shaft and a first bevel gear provided at an end portion of the tool drive shaft and engaged with the first bevel gear to drive-connect the motor output shaft and the tool drive shaft. A bevel gear device having two bevel gears;
An air tool comprising the air motor, the annular bearing, the bevel gear device, and a housing that houses the tool drive shaft;
The housing is
A cylindrical motor housing portion extending along the first longitudinal axis direction, the motor housing portion housing the air motor and the end of the motor housing portion connected to the annular bearing portion and the annular bearing portion. A cylindrical motor housing portion having an output shaft storage portion for storing the extended motor output shaft;
A cylindrical tool shaft housing portion for housing the tool drive shaft;
A corner housing portion bent so as to connect the end portion of the motor housing portion and the tool shaft housing portion;
The motor storage portion has an exhaust receiving portion that extends in the circumferential direction on the outer side in the radial direction of the rotor casing and extends in the first longitudinal axis direction, and receives the exhaust discharged from the rotor casing.
The output shaft storage portion communicates with the exhaust receiving portion, communicates with the exhaust communication hole extending in the first longitudinal axis direction on the radially outer side of the annular bearing portion, and with the circumferential direction and the first 1. An expansion chamber extending in the longitudinal axis direction, having an expansion chamber having a curved cross-sectional area larger than the exhaust communication hole and having a volume capable of expanding the exhaust gas that has passed through the exhaust communication hole and has entered the expansion chamber. And
At least one of the corner housing part and the output shaft storage part provides an air tool having an exhaust outlet extending from the expansion chamber and communicating with the outside of the housing.

  In this air tool, an expansion chamber is provided in the output shaft storage portion. The portion where the expansion chamber of the output shaft housing portion is provided is a portion for housing the output shaft extending from the annular bearing portion, and the housing surrounding the output shaft is thick. The expansion chamber is provided in the thick portion so as to extend in the circumferential direction and the axial direction, thereby forming a large volume for receiving exhaust gas, and there is substantially no need to increase the outer size of the housing. . The exhaust gas entering the expansion chamber formed in this way is greatly decompressed here. For this reason, the pressure on the exhaust side of the air motor can be reduced, and the pressure difference from the air supply side of the air motor can be increased to increase the operating efficiency of the air motor.

  Specifically, the expansion chamber is provided away from the annular bearing portion in the first longitudinal axis direction, and the exhaust communication hole is provided between the annular bearing portion and the expansion chamber. It is possible to have two communicating hole portions extending in the direction and separated from each other in the circumferential direction.

  Further, the expansion chamber can extend in the circumferential direction within an angle range of 150 ° to 180 ° around the motor output shaft.

  Further, it can be provided with an exhaust blowing hole that extends from the expansion chamber and opens in the wall surface of the chamber that houses the bevel gear device, and blows exhaust gas to the gear device.

  In this case, it is preferable to direct the exhaust air to the tooth surface facing the rotation direction of the first bevel gear in which the exhaust spray hole rotates.

  Embodiments of an air tool according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view of an air grinder as an embodiment of the present invention. FIG. 2 is a cross-sectional view when viewed downward along the longitudinal axis A of the rotor in FIG. FIG. 3 is a view taken along line III-III in FIG. 1, showing the shapes of the expansion chamber and the exhaust communication holes and their relationship, with the tool drive shaft and the like omitted, and the first bevel gear Is shown in schematic outline. FIG. 4 is a rear view of the housing when the air grinder of FIG. 1 is viewed from the rear side. It is a figure which shows one form which blows off exhaust_gas | exhaustion to a bevel gearwheel.

  As shown in the accompanying drawings, an air grinder 10 as an air tool according to the present invention has, as its basic configuration, a rotor 12 that is driven to rotate about a first longitudinal axis A, and the rotor 12 is rotatably accommodated. With respect to the first longitudinal axis A, an air motor 18 including a cylindrical rotor casing 14 and a motor output shaft 16 extending from one end (left end in the drawing) of the rotor 12 along the first longitudinal axis A A tool drive shaft 20 extending along a second longitudinal axis B that forms a substantially right angle and having a polishing disk D attached to the lower end thereof, and an annular bearing that closes the left end of the rotor casing 14 and supports the motor output shaft 16 Part 22 and the first bevel gear 24 provided at the left end of the motor output shaft 16 and the first bevel gear 24 provided at the upper end of the tool drive shaft 20 to engage with the motor. A bevel gear device 28 having a second bevel gear 26 for drivingly connecting the output shaft 16 and the tool drive shaft 20, and a housing 30 for housing the air motor 18, the annular bearing 22, the bevel gear device 28, and the tool drive shaft 20. And have. In the illustrated example, the air motor 18 is a vane motor, and 18 a is housed in a radially extending groove formed in the rotor 12, and is displaced in the radial direction as the rotor 12 rotates. The vane which slides with respect to an inner peripheral surface is shown. Denoted at 14a is exhaust ports provided so as to be scattered over substantially a half circumference of the rotor casing 14, and the compressed air that has driven the rotor 12 is discharged to the outside of the rotor casing 14 through these exhaust ports 14a. .

The housing 30 extends along the first longitudinal axis A direction and is connected to the motor housing 30a for housing the air motor 18 and the left end of the motor housing 30a, and extends to the left from the annular bearing 22 and the annular bearing 22. A cylindrical motor housing portion 30A having an output shaft storage portion 30b for storing the output motor output shaft 16, a cylindrical tool shaft housing portion 30B for storing the tool drive shaft 20, and a left end portion of the motor housing portion 30A The corner housing part 30C is bent so as to connect the upper end part of the tool shaft housing part 30B.

The motor storage portion 30a extends in the circumferential direction over 360 ° radially outside the rotor casing 14 and extends in the first longitudinal axis A direction (almost along the entire length of the rotor 12) to receive the exhaust from the exhaust hole 14a. An exhaust receiving part 32 is provided.

The output shaft storage portion 30b communicates with the exhaust receiving portion 32 and extends radially outward of the annular bearing portion 22 in the first longitudinal axis A direction, and at a position spaced forward from the annular bearing portion 22. And an expansion chamber 36 which is provided and communicated with the exhaust communication hole 34. In the illustrated example, the exhaust communication hole 34 is a first communication hole portion extending so as to pass through the support protrusion 30e engaged with the outer peripheral surface of the rotor casing 14 of the housing 30 in the first longitudinal axis A direction. 34a (for example, three first communicating hole portions 34a separated from each other in the circumferential direction), and a second communicating hole portion that communicates with the communicating hole portion 34a and extends annularly outward in the radial direction of the annular bearing portion 22. 34 b and a third communication hole portion 34 c extending from the second communication hole portion 34 b and communicating with the expansion chamber 36. In the illustrated example, as shown in FIG. 3, the expansion chamber 36 is provided so as to be bent over approximately 180 ° in the circumferential direction, and two arc-shaped third communication hole portions 34 c are formed in the expansion chamber. It communicates with both ends of 36 in the circumferential direction. The expansion chamber 36 has a cross-sectional area larger than the cross-sectional area of any of the first to third communication hole portions 34a to 34c, and the exhaust gas that has entered the expansion chamber 36 through the exhaust communication hole 34 can expand. It is made to have a volume. The expansion chamber 36 is preferably set to approximately 150 ° to approximately 180 ° according to the interval angle in the circumferential direction of the two exhaust communication holes 34. In this embodiment, as shown in FIG. Both side portions in the direction extend over an angular range of about 180 ° so as to overlap the exhaust communication hole 34.

At least one of the output shaft storage portion 30b and the corner housing portion 30C (both of them in the illustrated example) is provided with exhaust outlets 38 and 40 that communicate with the expansion chamber 36 and communicate with the outside of the housing 30. In the present invention, the expansion chamber 36 is thicker around the motor output shaft 16 extending from the annular bearing portion 22 in the output shaft housing portion 30b than the circumference of the annular bearing portion 22 of the output shaft housing portion 30b. By using the portion, the exhaust from the air motor 18 can be expanded while avoiding an increase in the peripheral size of the housing 30, and the expanded exhaust is discharged to the outside through the exhaust outlets 38 and 40. Yes. In the illustrated example, as shown in FIG. 4, the exhaust outlets 38 and 40 communicate with the outside through one large opening 42 provided on the side surface of the corner housing portion 30B so that a silencer (not shown) can be set. Has been.

  FIG. 5 shows an arrangement of an exhaust spray hole 44 that extends from the expansion chamber 36 and is opened on the wall surface of the chamber 28 a that houses the bevel gear device, and that blows the exhaust gas expanded in the expansion chamber 36 onto the first bevel gear 24. An example is shown. The exhaust spray hole 44 is configured to spray the exhaust gas entraining the lubricant oil from the air motor to the first bevel gear 24 so that the lubricant oil adheres to the first bevel gear 24. In addition, it is preferable to direct the tooth surface toward the rotation direction. This is because lubricating oil can be efficiently lubricated by adhering the lubricating oil to the surface engaged with the second bevel gear. In the present invention, exhaust gas that has been depressurized and decelerated in the expansion chamber 36 is blown, and efficient oil adhesion to the tooth surface of the first bevel gear 24 is enabled. Exhaust is blown to the first bevel gear 24 because the first bevel gear 24 has a smaller diameter (decimal number) than the second bevel gear 26 in order to transmit reduced rotation from the first bevel gear 24 to the second bevel gear 26. This is because it is easier to heat than the second bevel gear 26. In FIG. 5, an opening in the lower right is a hole 19 for mounting a spindle lock for fixing the gear and preventing the tool drive shaft 20 to which the grinding disk is attached from rotating when the grinding disk is replaced. It is.

  The embodiment of the air tool according to the present invention has been described above, but the present invention is not limited to this. For example, the air tool is not limited to an air grinder, and can be applied to other air tools such as an air sander and an air driver.

Air grinder 10;
Rotor 12;
Rotor casing 14;
Exhaust port 14a;
Motor output shaft 16;
Air motor 18;
Hole 19;
Tool drive shaft 20;
Annular bearing 22;
First bevel gear 24;
Second bevel gear 26;
Bevel gear device 28;
Chamber 28a;
Housing 30;
Motor housing part 30A;
Motor housing 30a;
Output shaft housing 30b;
Support protrusion 30e;
Tool shaft housing part 30B;
Corner housing part 30C;
Exhaust receiving part 32;
Exhaust communication hole 34;
First communication hole portion 34a;
A second communication hole portion 34b;
A third communication hole portion 34c;
Expansion chamber 36;
Exhaust outlets 38, 40
Opening 42;
Exhaust spray hole 44

Claims (5)

A rotor that is driven to rotate about a first longitudinal axis, a cylindrical rotor casing that rotatably accommodates the rotor, and an air motor that includes a motor output shaft that extends from one end of the rotor along the first longitudinal axis;
A tool drive shaft extending along a second longitudinal axis forming a predetermined angle with respect to the first longitudinal axis;
An annular bearing for closing the end of the rotor casing on the one end side of the rotor and bearing the motor output shaft;
A first bevel gear provided at an end portion of the motor output shaft and a first bevel gear provided at an end portion of the tool drive shaft and engaged with the first bevel gear to drive-connect the motor output shaft and the tool drive shaft. A bevel gear device having two bevel gears;
An air tool comprising the air motor, the annular bearing, the bevel gear device, and a housing that houses the tool drive shaft;
The housing is
A cylindrical motor housing portion extending along the first longitudinal axis direction, the motor housing portion housing the air motor and the end of the motor housing portion connected to the annular bearing portion and the annular bearing portion. A cylindrical motor housing portion having an output shaft storage portion for storing the extended motor output shaft;
A cylindrical tool shaft housing portion for housing the tool drive shaft;
A corner housing portion bent so as to connect the end portion of the motor housing portion and the tool shaft housing portion;
The motor storage portion has an exhaust receiving portion that extends in the circumferential direction on the outer side in the radial direction of the rotor casing and extends in the first longitudinal axis direction, and receives the exhaust discharged from the rotor casing.
The output shaft storage portion communicates with the exhaust receiving portion, communicates with the exhaust communication hole extending in the first longitudinal axis direction on the radially outer side of the annular bearing portion, and with the circumferential direction and the first 1. An expansion chamber extending in the longitudinal axis direction, having an expansion chamber having a curved cross-sectional area larger than the exhaust communication hole and having a volume capable of expanding the exhaust gas that has passed through the exhaust communication hole and has entered the expansion chamber. And
At least one of the corner housing part and the output shaft housing part has an exhaust outlet extending from the expansion chamber and communicating with the outside of the housing.   The expansion chamber is provided away from the annular bearing portion in the first longitudinal axis direction, and the exhaust communication hole extends between the annular bearing portion and the expansion chamber in the first longitudinal axis direction. The air tool according to claim 1, comprising two communicating hole portions separated in the circumferential direction.   The pneumatic tool according to claim 1 or 2, wherein the expansion chamber extends in the circumferential direction within an angle range of 150 ° to 180 ° around the motor output shaft.   The air tool according to any one of claims 1 to 3, further comprising an exhaust blowing hole that extends from the expansion chamber and opens in a wall surface of a chamber that houses the bevel gear device, and blows exhaust gas to the gear device. The air tool according to claim 4, wherein the exhaust spray hole is directed to spray exhaust gas on a tooth surface facing the rotation direction of the first bevel gear that rotates.

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