This application is based on and claims the benefit of priority from the prior Japanese Patent Application No. 2005-156694, filed on May 30, 2005; the entire contents of which are incorporated herein by reference.
1. Field of Invention
The present invention relates to an air tool of an air impact driver, an air impact wrench or a power source of a motor driven by compressed air, particularly relates to an air tool which can be connected to a high pressure air compressing apparatus supplying high pressure air.
2. Description of Related Art
Generally, according to an air tool of a nailing machine, an air impact driver, an air duster or the like, two kinds of a low pressure specification constituting a range of use by compressed air in a normal pressure (low pressure) region having an upper limit pressure up to 0.98 MPa and a high pressure specification constituting a range of use by compressed air in a high pressure region of 1 through 2.48 MPa with object of promotion of a function or small-sized and light-weighted formation of an air tool have been reduced into practice. Particularly, a tool of a high pressure specification is fabricated by a structure of capable of ensuring to withstand high pressure air in comparison with a tool of a low pressure specification from a view point of breakage and safety of an apparatus. There is a case in which the two kinds of air tools having different specifications of compressed air are simultaneously used at an operation site of the same construction site or the like.
Therefore, one piece of a high pressure air compressing machine (high pressure air compressor) constituting a drive source of the air tools is generally provided with two pieces of take out ports for taking out compressed air of the high pressure specification and compressed air of the low pressure specification independently from each other by aiming at a reduction in installation cost and promotion of a way of use. However, in this case, when an interchangeability is provided to modes of connecting an air hose including a socket member, a plug member and a hose member of the high pressure air take out port and the low pressure air take out port, for example, there is a concern of connecting an air tool of the low pressure specification to the high pressure air take out port, conversely, connecting an air tool of the high pressure specification to the low pressure air take out port, in the former case, there poses a problem of destructing the air hose or a seal member of the tool and in the latter case, there poses a problem that an inherent function cannot be achieved. In order to prevent the problems, air hoses without the interchangeability are respectively used by constituting the modes of connecting the air hose to the high pressure air take out port and the low pressure air take out port by respectively exclusive shapes, or constituting structures of portions of connecting the plug members or the like of the air hoses by inverse screw structures. Such a well-known technology is disclosed in, for example, JP-A-2003-161302.
On the other hand, as shown by JP-A-2004-230553, there is well known a technology of including a pressure reducing valve at a handle housing portion of the air tool of a low pressure specification and operating the air tool by reducing a pressure of high pressure air supplied from a high pressure air compressor to a pressure of compressed air at a low pressure region by the pressure reducing valve of the air tool per se. According to the technology, the above-described low pressure air take out port from the high pressure compressor is dispensed with and also the modes of connecting the air hoses can be unified to one mode exclusive for the high pressure air take out port. Thereby, a way of use of the high pressure air compressor and the connecting air hose at an operation site is promoted, also the installation cost of the air compressor can be reduced to cost of one piece of the high pressure air compressor and the above-described problems of the related art can be resolved.
However, according to the related art, although the pressure is reduced to that of compressed air of the low pressure specification by the pressure reducing valve provided at one end portion of the handle housing portion of the air tool, since substantially a total of the handle housing portion is used as an accumulating chamber of compressed air, in order to ensure pressure withstanding performance of the total of the handle housing, a thickness (wall thickness) of a handle member needs to be thickened. Therefore, it is difficult to achieve thin-walled formation, that is, light-weighted formation of the handle member requested for the air tool for carrying out operation while grabbing the handle housing portion.
Further, according to the air tool constituting the power source by the air motor, it is requested to accelerate a speed of rotating the air motor by promoting an efficiency of exhausting compressed air used in the air motor by widely ensuring a flow path area of an exhaust chamber communicating with an exhaust port of the air motor. However, it is difficult to ensure the wide exhaust chamber by the mode of arranging the pressure reducing valve of the air tool of the related art.
Further, according to the air tool using the air motor, it is requested to promote operability of a trigger for making ON or OFF rotation of the air motor (rotor). Particularly, according to the air tool, it is preferable to lighten a tool pull load for operating the trigger in the beginning of trigger operation and improve operability of controlling the speed of the air motor initially.
Therefore, it is an object of the invention to provide an air tool including a pressure reducing valve which can be connected to a high pressure air compressing apparatus.
It is another object of the invention to provide a structure of arranging an air tool mounted with an air motor mechanism portion, a trigger valve mechanism portion and a pressure reducing valve mechanism portion at inside of a housing.
It is still another object of the invention to provide an air tool promoting an operability of a trigger of a trigger valve mechanism portion.
According to an aspect of the invention, there is provided an air tool comprising an air motor mechanism portion having an air supply port and an exhaust port of compressed air for generating a rotational force by the compressed air, an exhaust chamber which is an exhaust chamber for discharging the compressed air exhausted from the exhaust port of the air motor mechanism portion to the atmosphere having an exhaust hole communicating with the atmosphere at a portion of the exhaust chamber, an air joint portion capable of being connected to a high pressure air supply source, a pressure reducing valve mechanism portion including a primary pressure side port (high pressure air side port) connected to a side of the air joint portion, a secondary pressure side port (normal pressure air side port) connected to the air supply port of the air motor mechanism portion, an opening/closing valve arranged between the primary pressure side port and the secondary pressure side port for opening/closing a flow path of the compressed air flowing from the primary pressure side port to the secondary pressure side port, a pressure control spring for generating an urge force in a direction of opening the opening/closing valve, a closing direction pressure receiving face for receiving the compressed air operated in a direction of closing the opening/closing valve, and an opening direction pressure receiving face for receiving the compressed air operated to the opening/closing valve in a direction the same as the direction of the urge force of the pressure control spring, and a trigger valve mechanism portion including a valve member for opening/closing a flow path between the secondary pressure side port of the pressure reducing valve mechanism portion and the air supply port of the air motor mechanism portion, a trigger for controlling to open/close the valve member, and a pressing member for pressing in a direction reverse to a direction of operating the trigger for opening the valve member in correspondence with an amount of operating the trigger to drive the air motor mechanism portion, wherein when the air motor is driven by opening the valve member by operating the trigger of the trigger valve mechanism portion, a pressure of air exhausted from the exhaust port of the air motor mechanism portion to the exhaust chamber is added to the urge force of the pressure control spring by being received by the opening direction pressure receiving face of the pressure reducing valve mechanism portion.
According to another aspect of the invention, the air motor further comprising a body housing portion extended from one end portion to other end portion thereof along a horizontal axis line, and a handle housing portion hung from the body housing portion, wherein the air motor mechanism portion is mounted to the one end portion of the body housing portion, the pressure reducing valve mechanism portion is mounted to substantially a center portion of the handle housing portion, the exhaust chamber is mounted to the handle housing portion to surround the pressure reducing valve mechanism portion contiguously to the pressure reducing valve mechanism portion, and the trigger valve mechanism portion is mounted to a side of an upper end portion of the handle housing portion connected with the body housing.
According to still another characteristic of the invention, the air joint portion and the exhaust hole of the exhaust chamber are mounted to a side of a lower end portion of the handle housing portion.
According to still yet another aspect of the invention, the pressure control spring of the pressure reducing valve mechanism portion engages with the opening direction pressure receiving face at inside of a hermetically closed chamber of the pressure reducing valve mechanism portion, and the hermetically closed chamber is communicated with the exhaust chamber by way of a relief hole.
According to another aspect of the invention, the exhaust chamber is arranged contiguously to an outer peripheral portion of the pressure reducing valve mechanism portion.
According to the above-aspects, in an initial state (transient state) of operating the air tool by applying a trigger load, a pressure of the compressed air at the secondary pressure side port of the pressure reducing valve mechanism portion is determined in correspondence with the urge force of the pressure control spring and therefore, the trigger load necessary at an initial stage of operating the tool can be reduced, by reducing the trigger load, the load of pulling the trigger can be alleviated, further, an operability of initially controlling a speed of the air motor can be promoted. In a state of applying the trigger load after operating the air tool (ON state of trigger), by making air exhausted from the exhaust port of the air motor mechanism portion to the exhaust chamber flow into the hermetically closed chamber and receiving air by the opening direction pressure receiving face of the pressure reducing valve mechanism portion, the pressure of the air is added to the urge force of the pressure control spring and therefore, the pressure of compressed air at the secondary pressure side port of the pressure reducing valve mechanism portion can be increased to a predetermined value necessary for rotating the rotor of the air motor mechanism portion at high speed. That is, in an initial state of operating the trigger for operating the air tool, the pressure of the secondary pressure side port of the pressure reducing valve mechanism portion can previously be set to a low pressure, the trigger valve can initially be made to be easy to be operated.
According to the above-aspects, the pressure of compressed air is reduced to the compressed air of the low pressure specification by the pressure reducing valve mechanism portion mounted to be proximate to the air supply port of the air motor mechanism portion and therefore, a predetermined air pressure can stably be supplied to the air motor mechanism portion without being influenced by a connection mode of a length, a structure or the like of the air hose connected to the high pressure air supply source.
According to the above-aspects, the pressure reducing valve mechanism portion is arranged substantially at the center portion in the handle housing portion, the exhaust chamber for exhausting compressed air having a comparatively low pressure is constituted at the outer peripheral portion surrounding the pressure reducing valve mechanism portion and therefore, pressure withstanding performance requested for the handle housing member can be reduced. Therefore, a thickness of the handle housing member can be thinned, or material of the handle housing member can be changed from a metal material to a material of a synthetic resin of plastic or the like and therefore, light-weighted formation of the air tool can be achieved.
According to the above-aspects, a total of the handle housing excluding the space of the pressure reducing valve mechanism portion can be constituted by the exhaust chamber and therefore, the efficiency of exhausting the air motor mechanism portion can be promoted and the speed of rotating the rotor of the air motor mechanism portion can be accelerated.
The above-described aspects and objects of the invention will become further apparent from the description and the attached drawings of the specification as follows.
These and other objects and advantages of this invention will become more fully apparent from the following detailed description taken with the accompanying drawings in which:
An embodiment of the invention will be explained in details in reference to the drawings as follows. Further, in all of the drawings for explaining the embodiment, members having the same functions are attached with the same notations and a repeated explanation thereof will be omitted.
As shown by
One end portion of the body housing portion 2 is mounted with the air motor mechanism portion 10 constituting a source of driving an impact driver. The air motor mechanism portion 10 is designed by a so-to-speak low pressure specification constituting a range of use by a low pressure (normal pressure) up to about 0.98 MPa, including an air motor main body including a cylinder bush 12 in a cylindrical shape fixed to inside of the housing, a rotor 11 supported by a pair of bearing portions 15 and 16, a blade 14, and a blade groove 13 inserted with the blade 14 for making compressed air flow, and the air motor memory includes an air supply port 17 for supplying compressed air to the air motor main body and an exhaust port 18 for exhausting compressed air from the air motor main body. By receiving compressed air supplied from the air supply port 17 by the blade 14, the rotor 11 is exerted with a rotational force in a predetermined direction. Compressed air which has driven the blade 14 is exhausted from the exhaust port 18.
A rotational output of the rotor 11 of the air motor mechanism portion 10 is transmitted to a power transmitting mechanism portion 20 including a rotational striking force mechanism portion (not illustrated) including a hammer frame 21 arranged at other end portion of the body housing portion 2 and an anvil 22 for receiving a rotational striking force from the rotational striking mechanism portion. The anvil 22 is attachably and detachably inserted with a driver bit (not illustrated) constituting a front end tool from a front end face 22a thereof along the direction of the rotating shaft X and the driver bit is fixed by a bit drawout stopping portion 23. As the front end tool, a bit for a bolt fastening hexagonal hole can also be used other than the driver bit.
As shown by
As shown by enlarged sectional views of
As shown by
When the operator grabs the trigger 37 to pull from left to right in the direction of the center axis of the valve rod 37b against a load of pulling the trigger 37 by the pressing force of the urge spring 34 and the pressure P21 (refer to
Further, when the trigger 37 is completely pulled back to a pull back limit against the urge force of the urge spring 34 as shown by
In the case of the embodiment, in the state of slightly pulling the trigger 37 as shown by
In reference to
There is mounted the pressure reducing valve mechanism portion 50 in the cylindrical shape extended from the air joint portion 60 at the lower end portion of the handle housing portion 3 to the trigger valve mechanism portion 30 of the handle housing portion 3. The pressure reducing valve mechanism portion 50 is for reducing high pressure of air supplied to the air joint portion 60 to low pressure of air suitable for the air motor mechanism portion 10 of the low pressure specification. For example, according to the embodiment, a pressure of high pressure air supplied to the air joint portion 60 is 2.3 MPa, the pressure of the high pressure air is reduced by the pressure reducing valve mechanism portion 50 and compressed air of 0.8 MPa constituting the low pressure specification is supplied to the supply port 17 of the air motor mechanism portion 10 by way of the trigger valve mechanism portion 30. The pressure reducing valve mechanism portion 50 is extended from a lower end portion to an upper end portion particularly at a center portion of the handle housing portion 3.
According to the invention, a housing member 3a is provided by surrounding an outer peripheral portion of the pressure reducing valve mechanism portion 50 and the exhaust chamber (expanding chamber) 40 for communicating with the exhaust port 18 of the air motor mechanism portion 10 is formed by the housing member 3a. The exhaust chamber 40 expands compressed air exhausted from the exhaust port 18 of the air motor mechanism portion 10 to exhaust into the atmosphere from an exhaust hole 41 disposed at the lower end portion of the handle housing portion 3 by way of a noise reduction muffler 42. In operating the air motor mechanism portion 10, an exhaust pressure of the exhaust chamber 40 becomes, for example, about 0.2 MPa. According to an arrangement structure of the invention, the exhaust chamber 40 can occupy substantially a total of the handle housing portion 3 excluding the pressure reducing valve mechanism portion 50 and therefore, a wide space in correspondence with a shape of hanging the handle housing portion 3 can be ensured. As a result, an exhaust efficiency of the air motor mechanism portion 10 can be promoted, and a rotational speed of the air motor mechanism portion 10 can be accelerated. Further, the housing member 3a partitioning the exhaust chamber 40 may be made to be able to ensure a rupture strength against air at low pressure near to the atmospheric pressure and therefore, a thickness of the housing member 3a can be formed to be thin. Particularly, in a case of using a metal material as the housing member, light-weighted formation of the air tool can be achieved by thin-walled formation of the handle housing member 3a.
As shown by enlarged sectional views of
The valve piston 54 includes a pressure receiving face (closing direction pressure receiving face) S2 for receiving pressure P21 or P22 for compressed air operated to the valve piston (opening/closing valve) 54 in the closing direction, and a pressure receiving face (opening direction pressure receiving face) S1 for receiving pressure P1 of compressed air operated to the valve piston (opening/closing valve) 54 in the opening direction. Further, the hermetically closed space 59a installed with the pressure control spring 56 includes an opening direction pressure receiving face S3 at which exhaust air pressure P3 of the exhaust chamber 40 is operated to the valve piston 54 in the opening direction as shown by
As shown by
Next, in a transient state in which the air hose 61 from the high pressure air supply source is connected to the plug 60 (refer to
After connecting the air source, as shown by
As shown by
Operation of the total of the air tool 1 according to the invention will be explained. As shown by
On the other hand, as shown by
As is apparent from the above-described explanation, according to the invention, in the initial state (transient state) of operating the air tool by applying the trigger load to the trigger 37, pressure P21 of compressed air at the secondary pressure side port 52 of the pressure reducing valve mechanism portion 50 is set in correspondence with the urge force F of the pressure control spring 56 and therefore, the trigger load applied to the trigger 37 can be reduced at an initial stage of operating the tool. By reducing the trigger load, the operability of the trigger 37 can be promoted. In the state of applying the trigger load after operating the air tool (ON state of the trigger), air pressure P3 (for example, 0.2 MPa) exhausted from the exhaust port 18 of the air motor to the exhaust chamber 40 is received by or fed back to the opening direction pressure receiving face S3 of the pressure reducing valve mechanism portion 50. Thereby, air pressure P3 of the exhaust chamber 40 is added to urge force F of the pressure control spring 56 and therefore, pressure P22 of compressed air at the secondary pressure side port 52 of the pressure reducing valve mechanism portion 50 can be increased to a predetermined value. That is, in the initial state of operation of the trigger 37, the trigger 37 can be made to be easy to be operated in the state of reducing the pressure P1 at the secondary pressure side port 52 of the pressure reducing valve mechanism portion 50 and after operating the air tool, the pressure at the secondary pressure side port 52 of the pressure reducing valve mechanism portion 50 can be increased to the predetermined value P22.
Further, according to the invention, the pressure reducing valve mechanism portion 50 is arranged substantially at the center portion of the handle housing portion 3, the exhaust chamber 40 for exhausting compressed air at a comparatively low pressure is arranged at the outer peripheral portion of surrounding the pressure reducing valve mechanism portion 50 and therefore, pressure reducing performance requested for the handle housing member 3a can be reduced. The thickness of the handle housing 3a can be thinned, or a material of the handle housing member 3a can be changed from a metal material to a material of a synthetic resin of plastic or the like.
Furthermore, according to the invention, the total of the handle housing portion 3 excluding the space of the pressure reducing valve mechanism portion 50 can constitute the exhaust chamber 40 and therefore, the efficiency of exhausting the air motor mechanism portion 10 is promoted and the speed of rotating the air motor can be accelerated. Further, as described above, the pressure of compressed air of the high pressure specification is reduced to pressure of the low pressure specification by the pressure reducing valve mechanism portion 50 installed in the handle housing portion 3 and therefore, always stable air pressure can be supplied to the air motor.
Although according to the above-described embodiment, an explanation has been given of the impact driver tool, the invention is widely applicable to other air tool using the air motor.
Although the invention carried out by the inventors has been specifically explained based on the embodiment as described above, the invention is not limited to the embodiment but can variously be changed within a range not deviated from a gist thereof.
Number | Date | Country | Kind |
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P2005-156694 | May 2005 | JP | national |
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Number | Date | Country |
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2003-161302 | Jun 2003 | JP |
2004-230533 | Aug 2004 | JP |
Number | Date | Country | |
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20060278416 A1 | Dec 2006 | US |