JP2006283642A - Reciprocating compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase compression efficiency and improve workability at a time of assembly by forming a suction valve clearance groove in a shape having a narrow intermediate part. <P>SOLUTION: A piston 10 and a suction valve 18 are arranged in a cylinder 2. The suction valve 18 is formed to gradually reduce width dimension from a base end part toward a tip side to reinforce a part which easily deforms. The piston 10 is provided with the suction valve clearance grove 15 preventing interference with the suction valve 18 at top dead center position. The suction valve clearance groove 15 is formed to have small width dimension A at a longitudinal direction intermediate part and large width direction B at both sides. Consequently, dead space in a compression chamber 11 can be reduced by matching shapes of the suction valve 18 and the suction valve clearance groove 15. Since the suction valve clearance groove 15 can be formed in symmetrical shape, directional property at a time of assembly of the piston is eliminated and assembly work can be done efficiently. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a reciprocating compressor suitably used for compressing, for example, air or a refrigerant.

  Generally, a reciprocating compressor compresses gas, such as air and a refrigerant | coolant, by reciprocating a piston within a cylinder (for example, refer patent document 1).

Japanese Utility Model Publication No. 57-136875

  As this type of reciprocating compressor according to the prior art, for example, an oil supply type compressor configured to lubricate each part of the compressor with lubricating oil accommodated in a crankcase, for example, a self-lubricating seal ring (piston) 2. Description of the Related Art An oil-free (oil-free) compressor having a structure in which a lubricating function is provided without containing lubricating oil in a crankcase by using a ring) is known.

  These compressors include a cylindrical cylinder having a cylinder head mounted at the tip thereof, a valve seat member provided between the cylinder and the cylinder head, having a suction port and a discharge port, A reciprocatingly inserted piston that defines a compression chamber between the valve seat member, a suction valve that opens and closes the suction port of the valve seat member, and opens and closes the discharge port. And a discharge valve.

  Here, in the oil supply type compressor, for example, by providing a concave valve stopper on the inner periphery of the opening end of the cylinder, when the suction valve is opened, the tip side is received by the cylinder valve stopper. Yes. In this case, the contact portion between the suction valve and the valve stopper is lubricated and protected by the lubricating oil in the crankcase.

  Further, a suction valve relief groove is provided at a position corresponding to the suction valve, for example, at the top of the piston, and the suction valve relief groove is formed as a groove extending in the diameter direction of the piston with a certain width dimension. When the piston reaches top dead center, the suction valve enters the suction valve relief groove, thereby preventing interference with the piston.

  On the other hand, in an oil-free compressor, if the suction valve is received by the cylinder valve stopper, wear or the like is likely to occur in these contact parts, so a valve plate such as a metal plate is provided at a position covering the suction valve from the outside. It is configured. In this case, the suction valve relief groove of the piston is formed as a groove having a depth into which the suction valve and the valve receiver are inserted.

  In these oil supply type and non-oil supply type compressors, the suction valve is formed by, for example, an elongated metal plate having a spring property, and its base end side is a fixed end fixed to the valve seat member. . Further, the tip end side of the suction valve is a free end that is detached from and seated on the valve seat member by being bent and deformed in the thickness direction.

  In this case, the suction valve mainly elastically deforms a portion near the base end side, and thus high strength is required for this portion. For this reason, in the prior art, the width dimension of the suction valve extending in the radial direction of the cylinder may be gradually reduced from the base end side to the tip end side, thereby forming a portion closer to the base end side wide. To ensure its strength.

  By the way, in the prior art mentioned above, there exists a request | requirement of forming the width dimension of a suction valve so that it may become small gradually toward a front end side from a base end side, and it wants to ensure durability of a suction valve. However, in this case, when the suction valve enters the suction valve relief groove at the top dead center position of the piston, a large gap is formed between the narrow end of the suction valve and the suction valve relief groove. Therefore, this gap becomes a part of the space remaining in the compression chamber when the piston reaches the top dead center, that is, the invalid space that does not contribute to the compression efficiency.

  For this reason, in the prior art, for example, when the shape of the suction valve is changed according to various conditions, the ineffective space increases and the compression efficiency tends to decrease, and it is difficult to improve the performance of the compressor. There is.

  On the other hand, for example, the shape of the suction valve relief groove is formed in substantially the same manner as the suction valve, and the width dimension is gradually reduced from one side of the length direction to the other side, whereby the suction valve and the suction valve relief groove are formed. A method of reducing the invalid space between the two is also conceivable.

  However, in this case, for example, in the assembly line of the compressor, it is difficult to determine the piston assembly position. That is, if the piston is rotated 180 ° in the cylinder, the shape of the suction valve relief groove and the suction valve will be opposite to each other, so if the piston is assembled to the cylinder at this position, It becomes a state.

  Therefore, in this method, it is necessary to pay extra attention to align the direction of the suction valve relief groove and the suction valve when the piston is assembled, which reduces work efficiency and causes incorrect assembly. There is a problem that it becomes easy.

  The present invention has been made in view of the above-described problems of the prior art, and the object of the present invention is to reduce the ineffective space in the cylinder and increase the compression efficiency without being affected by the shape or the like of the suction valve. In addition, an object of the present invention is to provide a reciprocating compressor capable of improving workability during assembly.

  In order to solve the above-described problems, the present invention provides a cylindrical cylinder having a cylinder head mounted at the tip, and a valve seat member provided between the cylinder and the cylinder head and having a suction port and a discharge port. A piston that is reciprocally inserted into the cylinder and defines a compression chamber between the valve seat member and a proximal end side that is fixed to the valve seat member and a distal end side that extends in the diameter direction of the cylinder. The present invention is applied to a reciprocating compressor including a suction valve that opens and closes a suction port and a discharge valve that is provided in the valve seat member and opens and closes the discharge port.

  A feature of the configuration adopted by the invention of claim 1 is that the top of the piston is formed in the top of the cylinder so as to extend in the diameter direction of the cylinder and to reduce the width of the intermediate portion in the length direction and to increase the width of both sides. The suction valve relief groove is formed so that the width dimension of the suction valve is smaller than the width dimension of the suction valve relief groove and gradually decreases from the proximal end side toward the distal end side, and the piston is When the vicinity of the dead center is reached, the suction valve escape groove is inserted.

  According to the invention of claim 2, the suction valve relief groove is formed symmetrically on both sides in the length direction with the axial center of the piston interposed therebetween.

  Further, according to the invention of claim 3, the suction valve relief groove is formed in a wide groove portion which is opened at the top of the piston and has a small width in the lengthwise intermediate portion and a large width on both sides, and the wide groove portion. In order to perform a no-load operation at the time of start-up, the cylinder head is formed as a two-stage stepped groove by a narrow groove part that opens with a smaller width dimension than the wide groove part and into which the suction valve enters. In addition, an unloading mechanism for opening the tip side of the suction valve to a position corresponding to the narrow groove portion is provided.

  According to the invention of claim 1, since the width dimension of the suction valve can be gradually reduced from the proximal end side toward the distal end side, the portion of the suction valve that is easily elastically deformed when opened (the portion closer to the proximal end side). Can be formed wide and the strength of the suction valve can be secured. Further, the width dimension of the suction valve relief groove in the middle in the length direction can be made small corresponding to the shape of the suction valve. For this reason, when the piston reaches top dead center, the volume of the gap formed between the suction valve relief groove and the suction valve that has entered the interior (the volume of the invalid space that does not contribute to the compression operation) is reduced. This can improve the compression efficiency.

  In addition, since the suction valve relief groove has a width dimension that decreases from both sides in the length direction toward the middle part, the groove corresponding to the suction valve can be left or right when the length direction is left or right. It can be formed as a shape. That is, both the left half groove shape and the right half groove shape of the suction valve relief groove can be matched to the shape of the wide portion of the suction valve. Moreover, since the width dimension becomes small at the front end side of the suction valve, this narrow width portion can be disposed at either the left or right position of the suction valve relief groove.

  Therefore, it is possible to form a suction valve relief groove so that the piston can be assembled in either the left or right direction. For this reason, when assembling the compressor, the assembling work can be efficiently performed without being affected by the direction of the piston or the like, and erroneous assembling can be prevented and productivity can be improved.

  According to the invention of claim 2, the suction valve relief groove can be formed in a symmetrical shape on the left and right, and the suction valve relief groove can be assembled in either the left or right direction. It can be formed with high accuracy.

  Furthermore, according to the invention of claim 3, for example, in an oil supply type compressor, when the suction valve is opened, the suction valve can be received by a part of the lubricated cylinder. There may be no valve seat or the like that determines the valve opening position. And when there is no valve seat, if the suction valve is forcibly opened by the unload mechanism, the valve opening amount tends to be larger than that during normal valve opening.

  In this case, since the suction valve relief groove has a wide groove portion and a narrow groove portion, when the tip side of the suction valve is opened larger than the normal valve opening time, the tip portion is changed from the wide groove portion to the narrow groove portion. Can be entered. Thereby, it can prevent that a suction valve contacts a piston also at the time of a no-load driving | operation, can protect a suction valve and can extend a lifetime. Moreover, since the width of the narrow groove is narrower than that of the wide groove, for example, it can be formed with a small groove width corresponding only to the tip side of the suction valve.Therefore, even in a compressor equipped with an unload mechanism, The ineffective space between the distal end side of the valve and the narrow groove portion can be reliably reduced, and high compression efficiency can be realized.

  Hereinafter, as a reciprocating compressor according to an embodiment of the present invention, an oil supply type compressor in which lubricating oil is accommodated in a crankcase, and an oil-free type using self-lubricating parts, lubricating oil-filled parts, and the like. The compressor will be described as an example, and will be described in detail with reference to the accompanying drawings.

  Here, FIG. 1 to FIG. 6 show a first embodiment. In this embodiment, an oil supply type air compressor will be described as an example.

  In the figure, reference numeral 1 denotes an oil supply type air compressor in which lubricating oil is contained in a crankcase (not shown). During operation of the air compressor 1, the lubricating oil in the crankcase is caused by rotation of the crankshaft or the like. The lubricating oil is scraped up and lubricates a cylinder 2, a valve stopper 3, a piston ring 13, an oil ring 14 and the like which will be described later.

  Reference numeral 2 denotes a cylindrical cylinder provided in the crankcase of the air compressor 1, and the cylinder 2 is formed as a cylinder bore 2A having an inner peripheral surface. Further, as shown in FIGS. 1 and 3, for example, indentations 2B and 2C are provided on both sides in the diameter direction across the axial center O of the cylinder bore 2A, as shown in FIGS. Extends outward in the radial direction of the cylinder bore 2A. And the fixed end 18A of the suction valve 18 mentioned later is arrange | positioned in one hollow part 2B among the hollow parts 2B and 2C.

  Further, the most distal end portion 18C of the suction valve 18 is inserted into the other recess portion 2C, and a part of the peripheral wall of the recess portion 2C is a valve stopper that determines the valve opening position of the suction valve 18 as shown in FIG. 3 In this case, the contact portion between the valve stopper 3 and the suction valve 18 is lubricated by supplying lubricating oil in the crankcase.

  Reference numeral 4 denotes a cylinder head mounted on the distal end side of the cylinder 2 via a valve seat member 7 which will be described later. The inside of the cylinder head 4 is defined by a suction chamber 4A and a discharge chamber 4B. The suction chamber 4A communicates with the outside via a suction port 5 drilled in the outer wall of the cylinder head 4, and the discharge chamber 4B communicates with air via a discharge port 6 drilled in the outer wall of the cylinder head 4. It is connected to a tank (not shown).

  Reference numeral 7 denotes a flat valve seat member provided between the cylinder 2 and the cylinder head 4. The valve seat member 7 is configured such that a later-described suction valve 18 and discharge valve 19 are separated from each other. As shown in FIGS. 1 and 4, the valve seat member 7 has a suction port 8 that communicates between the suction chamber 4 </ b> A of the cylinder head 4 and the inside of the cylinder 2, and a discharge that communicates between the discharge chamber 4 </ b> B and the inside of the cylinder 2. An outlet 9 is provided. In this case, the suction port 8 is formed, for example, as a long hole extending in the radial direction from the vicinity of the axial center O of the cylinder bore 2A.

  Reference numeral 10 denotes a piston slidably inserted into the cylinder 2. The piston 10 is formed by casting a metal material such as an aluminum alloy as shown in FIGS. It is a closed cylinder with a lid. Further, a circular pressure receiving surface 10A having the same axial center O as the cylinder bore 2A is provided at the top of the piston 10, and this pressure receiving surface 10A is located in the cylinder 2 and between the valve seat member 7 and A compression chamber 11 is defined.

  A piston pin 10B is provided inside the piston 10, and the piston pin 10B is connected to a crankshaft (not shown) via a connecting rod 12 or the like. Thus, for example, when the crankshaft is rotationally driven by a drive source such as a motor, the piston 10 reciprocates in the cylinder 2 and a compression operation is performed.

  Further, a piston ring 13 and, for example, two oil rings 14 and 14 are mounted on the outer peripheral side of the piston 10, and these three rings 13 and 14 are in sliding contact with the inner peripheral surface of the cylinder bore 2A. In this case, the piston ring 13 enhances the airtightness of the compression chamber 11, and each oil ring 14 performs airtight maintenance of the compression chamber 11, scraping of lubricating oil, and the like.

  Reference numeral 15 denotes a suction valve relief groove provided on the top of the piston 10 (pressure receiving surface 10A side). The suction valve relief groove 15 is formed when the piston 10 reaches top dead center as shown in FIG. When the suction valve 18 enters the suction valve relief groove 15, the suction valve 18 is released from contact with the piston 10.

  Here, as shown in FIGS. 5 and 6, the suction valve relief groove 15 is formed, for example, as a two-step step groove by a wide groove portion 16 and a narrow groove portion 17 which will be described later, and an axial center O of the piston 10 or the like is formed. It extends diametrically through. In this case, the wide groove portion 16 and the narrow groove portion 17 of the suction valve relief groove 15 are formed in symmetrical shapes on both sides in the length direction (left side and right side in FIG. ing.

  The piston 10 is formed by casting or the like, and the suction valve relief groove 15 is formed by cutting the cast piston 10 or integrally formed when the piston 10 is cast. When the suction valve relief groove 15 is integrally formed when the piston 10 is cast, productivity can be improved.

  Reference numeral 16 denotes a wide groove provided to be opened on the pressure receiving surface 10A of the piston 10, and the wide groove 16 is a concave groove that is inserted when the suction valve 18 is closed, as indicated by a solid line in FIG. The interference between the closed suction valve 18 and the piston 10 is prevented.

  Here, as shown in FIG. 5, the groove shape of the wide groove portion 16 is formed such that the width dimension A of the lengthwise intermediate portion is small and the width dimension B on both sides is large (B> A), from the lengthwise intermediate portion. The width dimension gradually decreases toward both sides. The depth dimension of the wide groove portion 16 is slightly smaller than the thickness dimension of the suction valve 18 so that the closed suction valve 18 and the bottom surface of the wide groove portion 16 do not contact each other, for example, as shown in FIGS. The width of the wide groove portion 16 is substantially constant, and the dimension value is substantially constant.

  In this way, the wide groove portion 16 reduces the groove shape of the suction valve relief groove 15 in accordance with the shape of the suction valve 18 so that the suction valve relief groove 15 and the suction valve 18 are located at the top dead center position of the piston 10. It is possible to reduce the volume of gaps formed between them (ineffective spaces that do not contribute to compression efficiency).

  Further, in the wide groove portion 16, the left half groove shape and the right half groove shape with the shaft center O interposed therebetween correspond to the shape of the root side of the suction valve 18 (free end 18B), respectively. It is formed larger by a certain dimension than the shape. Thereby, for example, even if the piston 10 in FIG. 5 is rotated 180 ° around the axis O, the suction valve 18 can enter the wide groove portion 16.

  Reference numeral 17 denotes a narrow groove provided to be opened on the bottom surface side of the wide groove 16. The narrow groove 17 is a piston in a state in which an unload mechanism 20 described later is operated, as indicated by an imaginary line in FIG. When 10 reaches the top dead center, the free end 18B side of the suction valve 18 enters.

  Here, the narrow groove portion 17 is formed as a concave groove extending in the diametrical direction of the piston 10, and an intermediate portion of its length dimension has a width dimension (width dimension A) equal to, for example, the wide groove section 16. The narrow groove portion 17 is formed so that the width dimension gradually decreases from the intermediate portion in the length direction toward the left and right sides, and the width dimension C on both the left and right sides is the width dimension of the wide groove portion 16. It is smaller than A and B (B> A> C).

  The left half groove shape and the right half groove shape across the shaft center O of the narrow groove portion 17 correspond to the shape of the tip side of the suction valve 18 (free end 18B). It is formed larger by a certain dimension than the side shape. Further, the depth dimension of the narrow groove portion 17 is formed as a substantially constant dimension value corresponding to the valve opening amount of the suction valve 18.

  As a result, the narrow groove 17 forms a deep groove into which the free end 18B side enters when the free end 18B side of the suction valve 18 is largely opened by the unload mechanism 20, for example, and the piston 10 and the suction valve 18 To prevent interference. The narrow groove portion 17 is formed between the suction valve relief groove 15 and the suction valve 18 by restricting the deep groove into which the suction valve 18 is inserted to a narrow range corresponding to the shape of the free end 18B. The invalid space is reduced as much as possible.

  On the other hand, 18 is a suction valve provided in the valve seat member 7 so as to face the inside of the cylinder 2, and the suction valve 18 is formed of, for example, an elongated metal plate having a spring property, as shown in FIGS. The suction port 8 is opened and closed by bending and deforming in the thickness direction and separating and seating on the valve seat member 7.

  Here, as shown in FIG. 3, the suction valve 18 is located on the base end side thereof and is fixed to the valve seat member 7 in the hollow portion 2B of the cylinder 2, and the cylinder bore 2A from the fixed end 18A. The free end 18B extending in the diametrical direction through the axial center O and the most distal end portion 18C formed as the most distal end portion of the free end 18B and inserted into the recessed portion 2C of the cylinder 2 are configured. ing.

  In this case, the suction valve 18 is formed so that the width dimension gradually decreases from the proximal end side toward the distal end side, and the free end 18B has a distal end side width dimension b smaller than the proximal end side width dimension a. (A> b). Thereby, the base end side of the free end 18B can be formed wide to increase the strength.

  Further, the width dimension of each part of the free end 18B is formed to be smaller than the wide groove portion 16 of the suction valve relief groove 15 by a certain dimension, and the free end 18B enters the suction valve relief groove 15 without contact. It has a configuration.

  A discharge valve 19 is provided on the valve seat member 7 so as to face the cylinder head 4. The discharge valve 19 is made of, for example, a spring-like metal plate or the like, similar to the suction valve 18. The discharge port 9 is opened and closed by being separated and seated.

  Reference numeral 20 denotes an unloading mechanism attached to the suction valve 18. The unloading mechanism 20 performs a no-load operation by forcibly holding the suction valve 18 open when the compressor is started. .

  Here, as shown in FIG. 1, the unload mechanism 20 is inserted into a cylinder portion 20A provided in the cylinder head 4, a bush 20B that closes the cylinder portion 20A from the outside, and a slidable insertion in the cylinder portion 20A. An unload piston 20C that is fitted and the front end side advances and retreats with respect to the suction valve 18, a return spring 20D that urges the unload piston 20C in the backward direction, and is defined between the unload piston 20C and the bush 20B. The air chamber 20E is supplied with air pressure from the outside.

  During normal compression operation, as indicated by the solid line in FIG. 1, the unload mechanism 20 is stopped and the unload piston 20C is held at the stop position by the return spring 20D. For this reason, the suction valve 18 can block the suction port 8 when the discharge stroke is performed.

  On the other hand, when the compressor is started, as shown by the phantom line in FIG. 1, when the air pressure is supplied to the air chamber 20E and the unload mechanism 20 is operated, the unload piston 20C is moved to the cylinder 2 side by the air pressure. It penetrates and the suction valve 18 is forcibly opened. Thereby, the compressor can be operated in a no-load state.

  In this case, when the unloading mechanism 20 is operated, the free end 18B is inserted into the narrow groove 17 of the suction valve relief groove 15 even if the suction valve 18 is opened larger than the normal valve opening. Thus, interference between the piston 10 and the suction valve 18 can be prevented.

  The oil supply type air compressor according to the present embodiment has the above-described configuration, and the operation thereof will be described next.

  First, when starting the compressor, the unload mechanism 20 is operated to start operation in a no-load state, and after the rotational speed of the drive source has increased, the unload mechanism 20 is stopped to perform normal compression operation. I do. During the compression operation, when the crankshaft is rotationally driven by a drive source such as a motor, the piston 10 reciprocates in the cylinder bore 2A, whereby the suction stroke and the compression stroke are alternately repeated.

  In this case, in the suction stroke, as shown in FIG. 2, when the piston 10 is displaced from the top dead center toward the bottom dead center, a negative pressure is generated in the compression chamber 11, and the suction valve 18 is opened by this negative pressure. At the same time, the discharge valve 19 is closed. Thereby, air is sucked into the compression chamber 11 from the suction port 5 through the suction port 8.

  Further, in the discharge stroke, the piston 10 is displaced from the bottom dead center toward the top dead center, whereby the air in the compression chamber 11 is compressed, and the suction valve 18 is closed by this pressure, and the discharge valve 19 is Open the valve. As a result, the compressed air in the compression chamber 11 is discharged from the discharge port 9 to the outside through the discharge port 6 and stored in a tank or the like.

  In this case, when the piston 10 reaches the vicinity of the top dead center, the suction valve 18 enters the wide groove portion 16 of the suction valve relief groove 15, so that interference between the piston 10 and the suction valve 18 can be prevented. . Further, in this state, only a small gap is formed between the wide groove portion 16 and the suction valve 18 having shapes corresponding to each other, so that the volume of the invalid space can be reduced.

  On the other hand, when the compressor is assembled, the connecting rod 12 is connected to the piston 10 and the piston ring 13, the oil ring 14, and the like are attached, and then the piston 10 is inserted into the cylinder 2 and assembled. In this assembling operation, for example, not only when the piston 10 is inserted into the cylinder 2 in the state shown in FIG. 3, but also within the cylinder 2 with the piston 10 rotated 180 ° around the axis O from the position of FIG. The groove shape of the suction valve relief groove 15 can be adapted to the suction valve 18 even when it is inserted into the suction valve 18.

  Thus, according to the present embodiment, on the pressure receiving surface 10A side of the piston 10, the suction valve relief groove 15 is formed in which the width dimension A of the middle portion in the longitudinal direction is reduced and the width dimension B on both sides is increased. The widths a and b of the valve 18 are configured to gradually decrease from the proximal end side toward the distal end side.

  As a result, the proximal end portion of the free end 18B of the suction valve 18 that is easily elastically deformed when the valve is opened can be formed wide, and the strength of the suction valve 18 can be ensured. Further, in the intermediate portion in the length direction of the suction valve relief groove 15, the width dimension A can be formed small corresponding to the shape of the suction valve 18.

  For this reason, when the piston 10 reaches the top dead center, the volume of the gap formed between the wide groove portion 16 of the suction valve relief groove 15 and the suction valve 18 that has entered the piston 10 is reliably reduced. It is possible to reduce the invalid space at the top dead center and improve the compression efficiency.

  In addition, since the suction valve relief groove 15 has a width dimension that decreases from both sides in the length direction toward the middle portion, it corresponds to the suction valve 18 in either the left direction or the right direction when the length direction is set to the left and right directions. It can be formed in a groove shape. That is, both the left half groove shape and the right half groove shape of the suction valve relief groove 15 can be matched with the shape of the wide portion of the suction valve 18, and the tip side of the suction valve 18 has a small width dimension. Therefore, this narrow portion can be arranged at either the left or right position of the suction valve relief groove 15.

  Accordingly, the suction valve relief groove 15 can be formed so that the piston 10 can be assembled in either the left or right direction. For this reason, when assembling the compressor, the assembly work can be efficiently performed without being affected by the orientation of the piston 10, etc., and erroneous assembly can be prevented and productivity can be improved. .

  In this case, since the suction valve relief groove 15 is formed symmetrically on the left and right with the shaft center O in between, the suction valve relief groove 15 that allows the piston 10 to be assembled in either the left or right direction is highly accurate. Can be formed.

  For example, in the oil supply type air compressor 1, when the suction valve 18 is opened, the suction valve 18 can be received by the valve stopper 3 of the lubricated cylinder 2. There are many cases where there are no valve seats or the like. When the valve receiver is not present, if the suction valve 18 is forcibly opened by the unload mechanism 20, the valve opening amount tends to be larger than that during normal valve opening.

  In this case, since the suction valve relief groove 15 includes the wide groove portion 16 and the narrow groove portion 17, when the free end 18B side of the suction valve 18 is opened larger than the normal valve opening time, the piston 10 is top dead. At the point position, the free end 18B side can be inserted into the narrow groove 17 from the wide groove 16. Thereby, it is possible to prevent the suction valve 18 from coming into contact with the piston 10 even during no-load operation, thereby protecting the suction valve 18 and extending its life.

  In addition, since the width dimension C of the narrow groove portion 17 is narrower than that of the wide groove portion 16, it can be formed to have a small groove width corresponding only to the free end 18B side of the suction valve 18, for example. Therefore, the unload mechanism 20 is mounted. Even in the oilless compressor 1, the ineffective space formed between the free end 18 </ b> B side of the suction valve 18 and the narrow groove portion 17 can be reliably reduced, and high compression efficiency can be realized. it can.

  Next, FIGS. 7 to 10 show a second embodiment according to the present invention, and the feature of this embodiment is that it is applied to an oil-free air compressor. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  21 is an oil-free air compressor, and this air compressor 21 includes a cylinder 2, a cylinder head 4, a valve seat member 7, a suction valve 18, a discharge valve 19, and substantially the same as in the first embodiment. A piston 22 and a suction valve 26, which will be described later, are roughly configured. However, the air compressor 21 is configured as a so-called oil-free compressor that does not contain lubricating oil in a crankcase (not shown).

  A covered cylindrical piston 22 is slidably inserted into the cylinder 2. The piston 22 has a pressure receiving surface 22A, a piston pin 22B, etc., as in the first embodiment. A compression chamber 11 is defined between the seat member 7 and the seat member 7. Further, on the outer peripheral side of the piston 22, for example, a piston ring 23 formed of a self-lubricating material and the like, for example, two rider rings 24 are mounted, and these rings 23, 24 slide on the cylinder bore 2A. It touches.

  Reference numeral 25 denotes a suction valve relief groove provided to open to the pressure receiving surface 22A of the piston 22. The suction valve relief groove 25 is substantially the same as the wide groove portion 16 of the first embodiment as shown in FIGS. Although it has the same planar shape, in this embodiment, it is formed as a single-step groove having no step.

  In this case, the suction valve relief groove 25 has a groove shape corresponding to a suction valve 26 and a valve receiver 27, which will be described later, and has a small width dimension A ′ in the middle portion in the longitudinal direction and a large width dimension B ′ on both sides. It is formed (B ′> A ′), and the width dimension gradually decreases from the middle in the length direction toward both sides.

  Further, in the present embodiment, as shown in FIGS. 7 and 8, a valve receiver 27 is provided outside a suction valve 26, which will be described later, and the piston 22 has a top dead center. When the pressure reaches the suction valve, the suction valve relief groove 25 is inserted. For this reason, the depth dimension of the suction valve relief groove 25 is formed as a dimension value such that the valve receiver 27 does not come into contact with the bottom surface side of the suction valve relief groove 25 when the piston 22 reaches top dead center. .

  26 is a suction valve provided in the valve seat member 7 so as to face the inside of the cylinder 2, and the suction valve 26 is made of, for example, an elongated metal plate or the like, as in the first embodiment, and has a fixed end 26A, The free end 26B and the most distal portion 26C are configured. The suction valve 26 has a leading end portion 26 </ b> C inserted into the recessed portion 2 </ b> C of the cylinder 2.

  Here, in the oil-free compressor 21, if the suction valve 26 is received by the valve stopper 3 of the cylinder 2, wear or the like tends to occur at these contact portions. For this reason, the valve seat member 7 is provided with a valve receiver 27 made of, for example, a metal plate. The valve receiver 27 covers the suction valve 26 from the piston 22 side so that when the suction valve 26 is opened, the valve opening position is determined as shown in FIG.

  Thus, in the present embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the first embodiment. And especially in this Embodiment, since it was set as the structure which the suction valve 26 and the valve receiver 27 enter in the suction valve relief groove 25, it can apply also to the oilless type air compressor 21 which has the valve receiver 27, The application range can be expanded.

  In each of the above embodiments, the suction valve relief grooves 15 and 25 are formed to have a constant groove depth. However, the present invention is not limited to this. For example, the present invention may be configured as modified examples shown in FIGS. In this case, the narrow groove portion 17 ′ of the suction valve relief groove 15 ′ is formed such that a portion on the end portion side corresponding to the fixed end 18 </ b> A side of the suction valve 18 is shallower than other portions.

  In the embodiment, the reciprocating type air compressor has been described as an example. However, the present invention is not limited thereto, and can be applied to various compressors including a refrigerant compressor, a vacuum pump, and the like. Is.

It is a longitudinal section showing an oil supply type air compressor by a 1st embodiment of the present invention. It is a longitudinal cross-sectional view which shows the state by which the air compressor became the suction stroke. It is the cross-sectional view which looked at the air compressor from the arrow III-III direction in FIG. It is the cross-sectional view which looked at the air compressor from the arrow IV-IV direction in FIG. It is the top view which looked at the piston from the upper side. It is a perspective view which shows the piston in FIG. It is a longitudinal cross-sectional view which shows the oilless type air compressor by the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view which shows the state by which the air compressor became the suction stroke. It is the top view which looked at the piston from the upper side. It is a perspective view which shows the piston in FIG. It is the longitudinal cross-sectional view which looked at the oil supply type air compressor by the modification of this invention from the same position as FIG. It is a perspective view which shows the piston in FIG.

Explanation of symbols

1,21 Air compressor (reciprocating compressor)
2 Cylinder 2A Cylinder bore 3 Valve stopper 4 Cylinder head 7 Valve seat member 8 Suction port 9 Discharge port 10, 22 Piston 10A, 22A Pressure receiving surface (head top)
11 Compression chamber 15, 15 ', 25 Suction valve relief groove 16 Wide groove portion 17, 17' Narrow groove portion 18, 26 Suction valve 18A, 26A Fixed end 18B, 26B Free end 18C, 26C Most advanced portion 19 Discharge valve 20 Unload Mechanism 27 Valve A, A ', B, B', C, a, b Width O Center of axis

Claims (3)

A cylindrical cylinder having a cylinder head mounted on the tip, a valve seat member provided between the cylinder and the cylinder head and having a suction port and a discharge port, and reciprocatingly inserted into the cylinder. A piston that defines a compression chamber between the valve seat member, a suction valve that opens and closes the suction port with a proximal end fixed to the valve seat member and a distal end extending in the diameter direction of the cylinder; In a reciprocating compressor comprising a discharge valve provided on a valve seat member for opening and closing the discharge port,
The top of the piston is provided with a suction valve relief groove that extends in the diameter direction of the cylinder and has a small width in the middle in the length direction and a large width on both sides.
The suction valve is formed to be smaller than the width dimension of the suction valve relief groove and gradually decrease from the base end side to the tip end side, and when the piston reaches the vicinity of the top dead center The reciprocating compressor is characterized in that the suction valve is inserted into the suction valve relief groove.   The reciprocating compressor according to claim 1, wherein the suction valve relief groove is formed symmetrically on both sides in the length direction with respect to the axial center of the piston.   The suction valve relief groove has a wide groove portion which is opened at the top of the piston and has a small width in the middle in the length direction and a large width on both sides, and is smaller than the wide groove on the bottom side of the wide groove. It is formed as a two-stage step groove by a narrow groove portion that opens with a width dimension and into which the suction valve enters. The cylinder head has a narrow end on the tip side of the suction valve in order to perform no-load operation at the start. The reciprocating compressor according to claim 1 or 2, further comprising an unload mechanism that opens the valve to a position corresponding to the width groove portion.

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