JP2013208689A - Driving machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving machine capable of reducing air consumption.SOLUTION: A nail driving machine 1 includes a housing 2, a roughly cylindrical cylinder 3, a piston 4 housed in the cylinder 3, a main valve 5, and a check valve 82. In the housing 2, a pressure accumulating chamber 2a and a first expansion chamber 81a are arranged. The main valve 5 is movable between a first position for making the cylinder 3 communicate with the first expansion chamber 81a and a second position for cutting off the communication between the cylinder 3 and the first expansion chamber 81a. The check valve 82 allows flowing of air from the cylinder 3 into the first expansion chamber 81a while blocking flowing of air from the first expansion chamber 81a into the cylinder 3.

Description

  The present invention relates to a driving machine.

  A pneumatic nailing machine, which is a conventional driving machine, includes a housing provided with a pressure accumulating chamber and a return air chamber, a cylinder accommodated in the housing, and a piston that divides the cylinder into a piston upper chamber and a piston lower chamber. And a blade that protrudes downward from the piston and strikes the stopper, and a main valve that controls communication between the pressure accumulation chamber and the cylinder. An exhaust port is formed in the housing, and the compressed air in the piston upper chamber is exhausted from the exhaust port by the operation of the main valve.

  When driving the stopper, the main valve operates to cause the compressed air in the pressure accumulating chamber to flow into the piston upper chamber, and the piston is pushed down and the stopper is driven into the workpiece by the blade. At this time, the air in the piston lower chamber is stored in the return air chamber. When the main valve operates again to shut off the piston upper chamber and the pressure accumulation chamber and communicate with the piston upper chamber and the exhaust port, the air in the return air chamber flows into the piston lower chamber and returns the piston to the initial position. Such a driving machine is described in Patent Document 1, for example.

Japanese Patent No. 3346218

  When exhausting air in the cylinder, a throttle or expansion chamber may be provided for the purpose of reducing exhaust noise. In that case, since the speed at which the compressed air is discharged when passing through the throttle becomes slow, the pressure of the compressed air left in the cylinder upper chamber hinders the piston from rising. In addition, a phenomenon occurs in which part of the air once exhausted from the piston upper chamber to the expansion chamber flows back into the piston upper chamber again. If it does so, the backflowed air becomes resistance and the smooth raise of a piston is prevented. In order to return the piston to the initial position, it is necessary to increase the volume of the return air chamber in consideration of the resistance.

  When the volume of the return air chamber is increased, the amount of air consumption increases accordingly, so that the conventional nailer has room for improvement in this respect. In addition, a secondary problem such as an increase in power consumption occurred due to an increase in the operating rate of the compressor.

  In view of such a situation, the present invention intends to provide a driving machine with reduced air consumption.

  The present invention accommodates a housing, a cylinder housed in the housing, and a reciprocating movement between a top dead center and a bottom dead center in the cylinder, and the inside of the cylinder is divided into a piston upper chamber and a piston lower chamber. And a bumper received in the housing and abutted against the piston when the piston is at the bottom dead center, wherein the housing has a pressure accumulating chamber for storing compressed air. A first expansion chamber capable of communicating with the piston upper chamber is formed, and a first throttle is formed between the first expansion chamber and the piston upper chamber. A first position that defines a piston upper chamber together with the cylinder and the piston, communicates the piston upper chamber and the pressure accumulating chamber, and blocks communication between the piston upper chamber and the first expansion chamber; When communication between the upper chamber and the pressure accumulator is cut off A main valve movable between the piston upper chamber and the first expansion chamber, and a flow of air from the piston upper chamber to the first expansion chamber, And a check valve that prevents a flow of air from the first expansion chamber to the piston upper chamber.

  According to such a configuration, since the check valve is provided that allows the air flow from the piston upper chamber to the first expansion chamber and prevents the air flow from the first expansion chamber to the piston upper chamber, The backflow of air from the one expansion chamber to the piston upper chamber can be prevented. Thereby, since the resistance at the time of a piston returning to an initial position can be reduced, the usage-amount of the air for returning a piston to an initial position can be reduced.

  Moreover, it is preferable that the first expansion chamber is located radially outward of the cylinder.

  Further, the first expansion chamber and the piston upper chamber are provided adjacent to each other, and the temperature in the first expansion chamber is lowered by adiabatic expansion when compressed air is discharged, and the temperature of the piston upper chamber is lowered. preferable.

  The housing further includes a second expansion chamber communicating with the first expansion chamber via a second throttle, and the second expansion chamber preferably communicates with an exhaust port formed in the housing. .

  According to such a configuration, since the air in the piston upper chamber is expanded stepwise by the first throttle and the second throttle, the exhaust sound of the compressed air can be reduced.

  Moreover, it is preferable to further include a Peltier element disposed on the outer periphery of the cylinder for cooling the cylinder.

  According to such a configuration, since the cylinder can be cooled by the Peltier element, the pressure in the piston upper chamber can be further reduced. Thereby, since a piston can be smoothly returned to an initial position, the further reduction of air consumption can be performed.

  The check valve is an O-ring, and is preferably provided on the outer peripheral surface of the cylinder so that the axis of the O-ring coincides with the axis of the cylinder.

  According to such a configuration, the flow of air from the first expansion chamber to the piston upper chamber can be prevented with a simple configuration.

  According to the present invention, it is possible to provide a driving machine with reduced air consumption.

Overall view of a nailing machine according to an embodiment of the present invention Sectional drawing along II-II of Drawing 1 of a nailing machine of an embodiment of the invention 1 is a partial cross-sectional view taken along the line III-III of FIG. 1 of the nail driver according to the embodiment of the present invention. 3 is a partial cross-sectional view taken along the line IV-IV in FIG. 3 of the nail driver according to the embodiment of the present invention. 2 is a partial cross-sectional view taken along the line V-V in FIG. 2 of the nail driver according to the embodiment of the present invention. The elements on larger scale around the main valve when the main valve of the nail driver of the embodiment of the present invention is located at the top dead center The partial enlarged view of the periphery of the main valve when the main valve of the nailing machine of the embodiment of the present invention is located at the bottom dead center Partial enlarged view of the vicinity of the main valve when the main valve of the nail driver according to the embodiment of the present invention returns to the top dead center again. The graph showing the pressure change of the nail driver of the embodiment of the present invention The partial enlarged view of the periphery of the main valve when the main valve of the nailer of the modification of the present invention is located at the top dead center

  Embodiments of the present invention will be described below with reference to the accompanying drawings. A nail driver 1 which is an example of a driving machine according to the present invention is a tool for driving a nail which is a fastener, and uses compressed air as its power.

  As shown in FIG. 1, the nailing machine 1 includes a housing 2, a cylinder 3 accommodated in the housing 2, a piston 4 accommodated in the cylinder 3, a main valve 5 accommodated in the housing 2, and a housing 2. It is comprised from the nose part 6 extended from and the magazine 7 in which a stopper is accommodated. The housing 2 includes a handle 2 </ b> A located on one side of the housing 2. In FIG. 1, the direction in which the handle 2 </ b> A extends from the housing 2 is defined as the rear, and the opposite is defined as the front. A direction in which the nose portion 6 extends from the housing 2 is defined as a downward direction, and the opposite direction is defined as an upward direction. Further, a direction orthogonal to the front-rear direction and the up-down direction is defined as a left-right direction (the front side in FIG. 1 is the left direction, and the back side is the right direction).

  A pressure accumulating chamber 2a is formed in the handle 2A and the housing 2 in order to store compressed air from a compressor (not shown). The pressure accumulating chamber 2a is connected to the compressor via an air hose (not shown).

  At the base of the handle 2A, a trigger 12 operated by an operator, a push lever 13 extending from the lower end of the nose portion 6 to the vicinity of the protrusion trigger 12, and a switching valve that communicates with the main valve 5 to send and exhaust compressed air. , And a plunger 15 for transmitting the operation of the trigger 12 to the trigger valve unit 14. The push lever 13 is urged from the housing 2 toward the nose portion 6 and is configured to be movable in the vertical direction along the nose portion 6. A control passage 14a is formed in the housing 2, and the trigger valve portion 14 is connected to a main valve chamber 51 described later via the control passage 14a.

  As is well known, the plunger 15 of the trigger valve portion 14 is configured to be pushed up when both the pulling operation of the trigger 12 and the pressing operation of the push lever 13 against the driven material are performed.

  The cylinder 3 has a substantially cylindrical shape, and is divided into a piston upper chamber 31 (FIG. 7) and a piston lower chamber 32 by the piston 4. An exhaust cover 8 is provided above the cylinder 3 and outward in the radial direction. As shown in FIGS. 1 to 3, the exhaust cover 8 is made of metal and forms an outline of the nailing machine 1 together with the housing 2, and constitutes a first expansion chamber 81 and a third expansion chamber 84. ing. A second expansion chamber 83 is formed by the exhaust cover 8 and the housing 2. A plurality of exhaust ports 8 a are formed in the exhaust cover 8. Various materials can be used for the housing 2 and the exhaust cover 8, and for example, aluminum or magnesium alloy that is excellent in terms of light weight and strength is used.

  As shown in FIGS. 6 to 8, a seal member 3 </ b> A and a Peltier element 3 </ b> B that are slidably contactable with the main valve 5 are provided on the upper portion of the cylinder 3. When the main valve 5 is located at the bottom dead center (FIG. 7), the seal member 3A comes into contact with the main valve 5 to block communication between the piston upper chamber 31 and a first throttle 81a described later. The Peltier element 3 </ b> B is provided for cooling the cylinder 3. The Peltier element 3 </ b> B is electrically connected to a power source 71 (described later) provided in the magazine 7 by wiring 3 </ b> C formed in the cylinder 3.

  FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1 and depicts only the exhaust cover 8. A through hole 8b into which the cylinder 3 is inserted is formed at a substantially central portion of the exhaust cover 8. In the exhaust cover 8, two first throttles 81a that connect the piston upper chamber 31 and the first expansion chamber 81 are formed as counter electrodes across the through hole 8b. Two first expansion chambers 81 are formed on the outer side in the radial direction of the through hole 8b, and are formed so as to be opposite to each other across the through hole 8b. The outer wall of the first expansion chamber 81 in the radial direction is exposed to the outside.

  As shown in FIG. 1, a check valve 82 is provided in a later-described passage 51a formed in the main valve 5 so as to close an opening of the passage 51a to the first throttle 81a. The check valve 82 is an O-ring, and allows air flow from the piston upper chamber 31 to the first expansion chamber 81 and prevents air flow from the first expansion chamber 81 to the piston upper chamber 31. The center of the O-ring that is the check valve 82 is fixed to the cylinder 3 so as to coincide with the center of the cylinder 3. The check valve 82 prevents the backflow of air from the first expansion chamber 81 to the piston upper chamber 31.

  As shown in FIGS. 3 and 4, a second throttle 83 a is formed on the lower wall forming the first expansion chamber 81, and the second throttle 83 a includes the first expansion chamber 81 and the second expansion chamber 83. Are connected. Each second expansion chamber 83 is adjacent to each first expansion chamber 81 in the circumferential direction of the cylinder 3 and on the side opposite to the pressure accumulation chamber 2a.

  As shown in FIGS. 2 and 5, a third throttle 84 a is formed on the upper wall forming the second expansion chamber 83, and the third throttle 84 a includes the second expansion chamber 83, the third expansion chamber 84, and the like. Are connected. Each third expansion chamber 84 is located above each second expansion chamber 83. A plurality of exhaust ports 8 a are formed in the front wall that forms the third expansion chamber 84. The compressed air in the piston upper chamber 31 is expanded stepwise by passing through the first throttle 81a, the second throttle 83, and the third throttle 84, and is finally exhausted to the outside from the exhaust port 8a.

  A return air chamber 33 for storing compressed air for returning the piston 4 to the initial state (FIG. 1) is formed on the outer periphery of the lower portion of the cylinder 3. An air passage 3a communicating with the return air chamber 33 and an air passage 3b immediately below the air passage 3a are formed in the lower portion of the cylinder 3. Specifically, the air passage 3a is formed at a position where the piston upper chamber 31 and the return air chamber 33 communicate with each other when the piston 4 comes into contact with a later-described bumper 43 and the cylinder 3 moves to the bottom dead center. An air passage 3b is formed at a position where the piston lower chamber 32 and the return air chamber 33 communicate with each other. An O-ring 3c, which is a check valve, is provided in the air passage 3a to allow air flow from the cylinder 3 to the return air chamber 33 and to prevent air flow from the return air chamber 33 to the cylinder 3. .

  The piston 4 is slidable in the vertical direction in the cylinder 3, and a driver blade 41 extending downward is fixed. A piston ring 42 that shuts off communication between the piston upper chamber 31 and the piston lower chamber 32 is fitted to the outer periphery of the piston 4. Below the cylinder 3 is provided a bumper 43 for absorbing the surplus energy of the piston 4 after driving the stopper. The bumper 43 is an elastic body such as urethane or nitrile rubber (NBR).

  The main valve 5 is disposed on the upper side of the cylinder 3. The main valve 5 is formed with a passage 51a that communicates the piston upper chamber 31 and the first throttle 81a. A main valve chamber 51 defined by the exhaust cover 8 and the cylinder 3 is formed immediately below the main valve 5. The main valve chamber 51 is provided with a main valve spring 52 that urges the main valve 5 upward. The main valve chamber 51 communicates with the trigger valve portion 14 via the control passage 14a. In the initial state shown in FIG. 1, the main valve chamber 51 is filled with compressed air, and the main valve 5 is biased upward by the compressed air in the main valve chamber 51 and the main valve spring 52. The force with which the main valve spring 52 biases the main valve 5 upward is smaller than the force with which the compressed air in the pressure accumulating chamber 2a pushes the main valve 5 downward. Therefore, when the compressed air in the main valve chamber 51 is released and the atmospheric pressure is reached, the main valve 5 moves downward against the urging force of the main valve spring 52.

  As shown in FIG. 1, the nose portion 6 is located at the lower end of the housing 2, and a guide path 61 that guides the driver blade 41 and a nail (not shown) is formed. At the lowermost position of the guide path 61, an injection hole for injecting a nail, which is not shown, is defined. Behind the nose portion 6 is provided a magazine 7 containing a bundle of nail bundles in which a plurality of nails (not shown) are bundled and connected.

  The magazine 7 is provided with a nail feeder that sequentially feeds nails into the guide path 61. The magazine 7 is further provided with a power source 71 for supplying power to the Peltier element 3B and a controller 72 for controlling the Peltier element 3B.

  Next, the operation of the nailing machine 1 will be described.

  When an air hose (not shown) is connected, compressed air is accumulated in the pressure accumulating chamber 2a, and a part thereof flows into the main valve chamber 51 via the trigger valve portion 14 and the control passage 14a. The compressed air sent to the main valve chamber 51 pushes up the main valve 5 to prevent the compressed air from flowing into the piston upper chamber 31. Thereby, the main valve 5 is located at the top dead center. The top dead center corresponds to the second position of the present invention. At this time, the seal member 3A and the main valve 5 are separated from each other, and the piston upper chamber 31 and the first expansion chamber communicate with each other.

  When the operator pulls the trigger 12 in a state where the push lever 13 is pressed against the workpiece, the plunger 15 is pushed up, the trigger valve section 14 communicates the control passage 14a with the outside air, and the main valve chamber 51 is at atmospheric pressure. It becomes. The main valve 5 moves downward by the differential pressure between the compressed air stored in the pressure accumulating chamber 2a and the main valve chamber 51. As a result, as indicated by an arrow A in FIG. 7, the compressed air stored in the pressure accumulating chamber 2a flows into the piston upper chamber 31 and pushes down the piston 4, so that the state shown in FIG. 6 is changed to the state shown in FIG. . That is, the main valve 5 moves from the top dead center to the bottom dead center. The bottom dead center corresponds to the first position of the present invention. At this time, since the compressed air suddenly adiabatically expands in the piston upper chamber 31, the temperature of the piston upper chamber 31 rapidly decreases.

  When the piston 4 passes through the air passage 3a, the compressed air in the piston upper chamber 31 flows into the return air chamber 33 through the air passage 3a. At the same time, the air in the piston lower chamber 32 flows into the return air chamber 33 through the air passage 3b. Further, when the piston 4 descends and contacts the bumper 43, the nail is driven into the driven material.

  When the operator returns the trigger 12, the plunger 15 returns and compressed air is supplied to the main valve chamber 51 through the control passage 14a. As a result, the main valve 5 is pushed upward, and the flow of compressed air into the piston upper chamber 31 is blocked. At the same time, the seal member 3A and the main valve 5 are separated from each other, whereby the piston upper chamber 31 and the first throttle 81a communicate with each other.

  The compressed air in the piston upper chamber 31 passes through the passage 51a and the check valve 82, passes through the first throttle 81a, and is adiabatically expanded in the first expansion chamber 81 (arrow B in FIG. 8). As a result, the temperature of the first expansion chamber 81 is temporarily lower than the piston upper chamber 31, and heat transfer from the piston upper chamber 31 to the first expansion chamber 81 occurs. Here, the first expansion chamber 81 is disposed radially outward from the cylinder 3, and the outer wall of the first expansion chamber 81 is in direct contact with the outside air. Furthermore, since the exhaust cover 8 is a metal with good thermal conductivity (for example, aluminum), the first expansion chamber 81 is easily affected by the outside air temperature. Then, since the temperature of the first expansion chamber 81 rises due to the outside air temperature, a temperature reversal phenomenon that the temperature of the first expansion chamber 81 becomes higher than the piston upper chamber 31 occurs. In the conventional nailer, the air in the first expansion chamber 81 flows into the piston upper chamber 31 due to the reversal phenomenon of the temperature, preventing the piston 4 from rising. However, in the present invention, since the check valve 82 prevents the air flow from the first expansion chamber 81 to the piston upper chamber 31, the compressed air in the first expansion chamber 81 flows into the piston upper chamber 31. Can be prevented.

  Further, the controller 72 controls the Peltier element 3B to cool the cylinder 3 during or after the driving operation, thereby lowering the temperature of the cylinder 3 and reducing the pressure of the compressed air in the cylinder 3. Can do. Even if the pressure of the cylinder 3 is positively reduced by the Peltier element 3B, the air in the first expansion chamber 81 does not flow back into the piston upper chamber 31 because the check valve 82 is provided.

  FIG. 9 shows a graph of pressure changes in the piston upper chamber 31, the first expansion chamber 81, the second expansion chamber 83, and the third expansion chamber 84 from when the main valve 5 is located at the top dead center. After about 0.003 seconds, the compressed air in the piston upper chamber 31 flows into the first expansion chamber 81, and the pressure in the piston upper chamber 31 decreases and the pressure in the first expansion chamber 81 increases rapidly. Around 0.007 seconds, the pressure in the first expansion chamber 81 exceeds the pressure in the piston upper chamber 31 due to the above-described temperature reversal phenomenon. In the present embodiment, since the check valve 82 prevents the backflow of air, even if the pressure in the first expansion chamber 81 is higher than that in the piston upper chamber 31, the pressure in the piston upper chamber 31 is Stays low. In the vicinity of 0.011 seconds, the pressure in the first expansion chamber 81 and the pressure in the piston upper chamber 31 become substantially the same.

  The air in the first expansion chamber 81 adiabatically expands in the second expansion chamber 83 via the second throttle 83a, and further adiabatically expands in the third expansion chamber 84 via the third throttle 84a. Is discharged to the outside through the exhaust port 8a. Exhaust noise is reduced by providing a plurality of expansion chambers and expanding the compressed air in stages.

  The compressed air stored in the return air chamber 33 flows into the piston lower chamber 32 via the air passage 3b and pushes up the piston 4 upward, resulting in an initial state shown in FIG. In the present embodiment, the check valve 82 prevents the back flow from the first expansion chamber 81 to the piston upper chamber 31, and the pressure of the cylinder 3 is positively reduced by the Peltier element 3B. Even the amount can return to the initial position.

  In the nailing machine 1, a check valve 82 is provided that allows air flow from the piston upper chamber 31 to the first expansion chamber 81 and prevents air flow from the first expansion chamber 81 to the piston upper chamber 31. Therefore, the backflow of air from the first expansion chamber 81 to the piston upper chamber 31 can be prevented. Thereby, since the resistance when the piston 4 returns to the initial position is reduced, the capacity of the return air chamber 33 can be reduced. Thereby, air consumption can be reduced. Furthermore, the size of the nail driver 1 can be reduced.

  According to such a configuration, since the cylinder 3 can be cooled by the Peltier element 3B, the pressure in the piston upper chamber 31 can be further reduced. Thereby, since the resistance when the piston 4 returns to the initial position is reduced, the capacity of the return air chamber 33 can be further reduced. As a result, the amount of air used can be further reduced.

  According to such a configuration, since the check valve 82 is an O-ring, the backflow of air from the first expansion chamber 81 to the piston upper chamber 31 can be prevented with a simple configuration.

  The present invention is not limited to the above-described embodiments, and various improvements and modifications can be made within the scope described in the claims. For example, in the above-described embodiment, the Peltier element 3B is provided. However, as shown in FIG. 10, a structure in which no Peltier element is provided may be employed. In this case, the power source 71 of the Peltier element 3B and the controller 72 that controls the Peltier element 3B are also unnecessary. Also in this modified example, the check valve 82 can provide the same effect as that of the above-described embodiment.

  In the above-described embodiment, the first expansion chamber is provided outside the cylinder in the radial direction, but may be provided above the cylinder. Moreover, although the valve located above the cylinder is adopted as an example of the main valve, a structure in which the valve is arranged on the side surface above the cylinder may be adopted.

  In the above-described embodiment, the O-ring is used as the check valve, but the present invention is not limited to this.

  In the above-described embodiment, a plurality of expansion chambers in the exhaust path are provided. However, the number of expansion chambers may be one, or three or more. Further, in the exhaust passage, as long as the pressure downstream of the pressure exhaust passage is higher than the upstream pressure, the place where the check valve is disposed may be other than the first expansion chamber.

1 .. Nailer 2.. Housing 3. Cylinder 3A. Exhaust port 12 Trigger 14 Trigger valve portion 14 a Control passage 31 Piston upper chamber 32 Piston lower chamber 41 Driver blade 42 Bumper 51 Main valve chamber 81 First expansion Chamber 81a, first throttle 82, check valve 83, second expansion chamber 83a, second throttle 84, third expansion chamber 84a, third throttle

Claims (6)

A housing;
A cylinder housed in the housing;
A piston that is reciprocally moved between a top dead center and a bottom dead center in the cylinder, and divides the inside of the cylinder into a piston upper chamber and a piston lower chamber;
A hammer that is housed in the housing and has a bumper that abuts against the piston when the piston is at the bottom dead center;
The housing is formed with a pressure accumulation chamber for storing compressed air and a first expansion chamber capable of communicating with the piston upper chamber, and a first throttle is formed between the first expansion chamber and the piston upper chamber. Formed,
The driving machine further includes:
A first position for defining a piston upper chamber together with the cylinder and the piston, communicating the piston upper chamber and the pressure accumulating chamber and blocking communication between the piston upper chamber and the first expansion chamber; A main valve movable between a second position for blocking communication between the piston upper chamber and the pressure accumulating chamber and communicating the piston upper chamber and the first expansion chamber;
And a check valve that allows a flow of air from the piston upper chamber to the first expansion chamber and prevents air flow from the first expansion chamber to the piston upper chamber. Machine.   The driving machine according to claim 1, wherein the first expansion chamber is located radially outward of the cylinder.   The first expansion chamber and the piston upper chamber are provided adjacent to each other, and the temperature of the first expansion chamber is lowered by adiabatic expansion when compressed air is discharged, and the temperature of the piston upper chamber is lowered. The driving machine according to claim 1.   The housing further includes a second expansion chamber communicating with the first expansion chamber via a second throttle, the second expansion chamber communicating with an exhaust port formed in the housing. The driving machine according to claim 1.   The driving machine according to any one of claims 1 to 4, further comprising a Peltier element disposed on an outer periphery of the cylinder and configured to cool the cylinder.   The check valve is an O-ring, and is provided on an outer peripheral surface of the cylinder so that an axis of the O-ring and an axis of the cylinder coincide with each other. The driving machine according to any one of the above.

Images