JP2006348890A - Piston device for reciprocating engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an appropriate ring tension to a piston ring by using a pressure generated in a reciprocating engine, and also has a high effect of preventing the pressure used for obtaining the ring tension or gas leakage. A piston device for a reciprocating engine that can be maintained is provided.
SOLUTION: A piston main body 3 slidably inserted into a cylinder 2 and provided with a piston ring groove 8 on an outer periphery thereof, and a second ring 12 disposed in the piston ring groove 8 and capable of contacting a cylinder wall 2a, 1A, the piston body 3 is provided with a passage 15 extending from the bottom surface of the piston ring groove 8 so as to penetrate the piston body 3 and opening into the crank chamber C2. A film-like member 16 is provided at the end of the passage 15 on the groove bottom side so as to close the space between the passage 15 and the piston ring groove 8.
[Selection] Figure 1

Description

  The present invention relates to a piston device used for a reciprocating internal combustion engine or the like.

As a piston device used in a reciprocating type engine, a passage that extends from the bottom surface of the piston ring groove to penetrate the piston body and opens to the cylinder chamber is formed in the piston body, and the pressure in the cylinder chamber is passed from the passage to the piston ring groove. Piston devices for Stirling engines are known which are introduced into the space between the groove bottom surface of the piston ring and the inner periphery of the piston ring, thereby increasing the ring tension, i.e. the force pressing the piston ring against the cylinder wall (e.g. Patent Document 1). In addition, there is Patent Document 2 as a prior art document related to the present invention.
Japanese Utility Model Publication No. 64-15752 JP 2003-294141 A

  However, when the cylinder chamber and the piston ring groove are communicated with each other via a passage in the piston body, there is a high possibility that the pressure in the cylinder chamber or gas leaks or escapes to the opposite side of the piston body through the passage. .

  Therefore, the present invention can apply an appropriate ring tension to the piston ring by using the pressure generated in the reciprocating engine, and also prevents the pressure used for obtaining the ring tension or the gas leakage. An object of the present invention is to provide a piston device for a reciprocating engine that can maintain a high effect.

  The present invention comprises a piston body that is slidably inserted into a cylinder and provided with a piston ring groove on the outer periphery thereof, and a piston ring that is disposed in the piston ring groove and can contact a cylinder wall, The piston body is provided with a passage that extends from the groove bottom surface of the piston ring groove so as to penetrate the piston body and opens into a chamber on one end side in the operation direction of the piston body, and the end of the passage on the groove bottom surface side is provided. The above-described problem is solved by a piston device of a reciprocating engine in which a film-like member is provided in the section so as to close a space between the passage and the piston ring groove (Claim 1).

  According to the piston device of the present invention, the pressure generated in the chamber at one end in the operation direction of the piston body is guided from the passage to the membrane member to vibrate the membrane member, and thereby the membrane member and the inner periphery of the piston ring The ring tension in the direction toward the cylinder wall can be applied to the piston ring by vibrating the air between them. Alternatively, the membrane member can be brought into contact with the inner periphery of the piston ring to push the piston ring radially outward. Since the ring tension is obtained by utilizing the pressure generated in the reciprocating engine, the ring tension is also lowered when the pressure is low, and accordingly, the frictional resistance between the piston ring and the cylinder wall is also reduced. For this reason, there is no possibility that the frictional resistance increases more than necessary, and inconveniences such as energy loss due to friction and deterioration in fuel consumption are avoided. Since the passage for guiding the pressure is closed with respect to the piston ring groove by the membrane member, pressure or gas does not escape from the passage into the piston ring groove or from the piston ring groove to the passage.

  In one form of this invention, the inward protrusion part which protrudes toward the said film-like member may be provided in the internal peripheral surface of the said piston ring (Claim 2). According to this embodiment, by providing the inward protruding portion, the space existing between the piston ring and the membrane member can be narrowed, thereby improving the response of the change in the ring tension to the vibration of the membrane member. it can. Alternatively, the membrane member can be more easily brought into contact with the inner circumference of the piston ring to quickly and reliably convert the vibration of the membrane member into the ring tension.

  In one form of this invention, the outward protrusion part which protrudes toward the said piston ring may be provided in the outer surface facing the said piston ring of the said film-like member (Claim 3). According to this embodiment, by providing the outward projecting portion, the space existing between the piston ring and the membrane member can be narrowed, thereby improving the response of the change in the ring tension to the vibration of the membrane member. it can. Alternatively, the outward projection can be brought into contact with the inner periphery of the piston ring to quickly and reliably convert the vibration of the membrane member into the ring tension.

  In one form of the present invention, the reciprocating engine may be an internal combustion engine, and the chamber on one end side in the operation direction may be a crank chamber of the internal combustion engine. According to this embodiment, the internal pressure of the crank chamber acts on the membrane member through the passage. Therefore, when the pressure leaked from the combustion chamber to the crank chamber increases due to the wear of the piston ring, thermal expansion of the cylinder wall, or an increase in the clearance between the cylinder wall and the piston ring due to an increase in the load of the internal combustion engine, etc. The ring-shaped member vibrates and the ring tension increases, and the pressure leakage to the crank chamber is suppressed. As a result, the flow rate of blow-by gas is reduced, deterioration of oil quality and increase in oil consumption are suppressed, and reduction in output of the internal combustion engine is also avoided. On the other hand, when the wear of the piston ring is small, when the internal combustion engine is operated at a light load, or when the thermal expansion of the cylinder wall is kept small, the sealing performance by the piston ring is sufficiently secured, As a result, when the internal pressure of the crank chamber is kept small, the ring tension is also kept small, and there is no possibility that the piston ring is pressed against the cylinder wall more strongly than necessary. For this reason, an excessive increase in the frictional resistance between the piston ring and the cylinder wall can be suppressed, and inconveniences such as a reduction in output and fuel consumption due to the frictional resistance of the piston ring can be avoided. Further, since the passage is closed with respect to the piston ring groove by the film-like member, there is no possibility that pressure or gas flowing from the combustion chamber to the piston ring groove along the cylinder wall will escape to the crank chamber through the passage.

  In a mode in which a passage is opened with respect to a crank chamber of an internal combustion engine, two compression rings are attached to the piston body as the piston ring at intervals in the axial direction of the piston body, and the passage is The piston chamber may be provided so as to connect the bottom surface of the piston ring groove in which the compression ring on the side close to the crank chamber is disposed to the crank chamber. According to this embodiment, the position of the passage is made closer to the crank chamber as compared with the case where the passage is provided so as to connect the piston ring groove on the combustion chamber side and the crank chamber, thereby making the passage easier to the crank chamber. Can be opened. When the piston body wall thickness is set smaller behind the piston ring groove on the crank chamber side than behind the piston ring groove on the combustion chamber side, the piston ring groove and crank chamber on the combustion chamber side The overall length of the passage is shortened as compared with the case where the passages are connected, and as a result, the membrane member rapidly vibrates with respect to the pressure change in the crank chamber, and the response of the change in the ring tension is improved.

  In one form of the present invention, the reciprocating engine may be an internal combustion engine, and the chamber on one end side in the operation direction may be a combustion chamber of the internal combustion engine. According to this form, the pressure generated in the combustion chamber acts on the membrane member via the passage. Therefore, when the pressure in the combustion chamber rises, the ring tension can be increased to press the piston ring more strongly against the cylinder wall, and pressure leakage into the crank chamber can be suppressed. As a result, the flow rate of blow-by gas decreases, deterioration of oil quality and increase in oil consumption are suppressed, and a decrease in output of the internal combustion engine is also avoided. When the pressure in the combustion chamber is low, the ring tension is also kept small, and there is no possibility that the piston ring will be pressed more strongly than necessary against the cylinder wall. For this reason, an excessive increase in the frictional resistance between the piston ring and the cylinder wall can be suppressed, and inconveniences such as a decrease in output or a decrease in fuel consumption due to the frictional resistance of the piston ring can be avoided. Furthermore, since the passage is closed with respect to the piston ring groove by the membrane member, there is no possibility that the pressure or gas guided from the combustion chamber to the passage passes through the piston ring groove to the crank chamber.

  In a mode in which a passage is opened to a combustion chamber of an internal combustion engine, two compression rings are attached to the piston body as the piston ring at an interval in the axial direction of the piston body. A compression ring on the side close to the combustion chamber may be provided so as to connect the bottom surface of the piston ring groove and the combustion chamber. In this case, the overall length of the passage is shortened as compared with the case where the passage is provided so as to connect the piston ring groove on the crank chamber side and the combustion chamber. It vibrates quickly and the response of changes in ring tension is improved.

  As explained above, according to the piston device for an internal combustion engine of the present invention, the ring member is vibrated by causing the pressure generated in the reciprocating engine to act on the film member via the passage. Since the tension is obtained, the ring tension is increased to prevent pressure or gas leakage when the pressure rises, and the ring tension is reduced to reduce the frictional resistance between the piston ring and the cylinder wall when the pressure is lowered. This eliminates the possibility that the frictional resistance increases more than necessary, and avoids inconveniences such as energy loss due to friction and deterioration of fuel consumption. Accordingly, an appropriate ring tension corresponding to the pressure can be applied to the piston ring. Moreover, since the passage for guiding the pressure is closed with respect to the piston ring groove by the membrane member, pressure or gas does not escape from the passage into the piston ring groove or from the piston ring groove to the passage. Further, the pressure used for obtaining the ring tension, or the effect of preventing gas leakage can be kept high.

(First form)
FIG. 1 shows a first embodiment in which the present invention is applied to a piston device of a four-cycle reciprocating internal combustion engine. The piston device 1A includes a piston body 3 that is slidably inserted into a cylinder 2 of an internal combustion engine. The upper surface side of the piston body 3 faces the combustion chamber C1, and the lower surface side faces the crank chamber C2. A concave portion 3a that opens into the crank chamber C2 is formed inside the piston main body 3, and a small end 4a of the connecting rod 4 is inserted into the concave portion 3a. The small end 4a rotates with the piston main body 3 via a piston pin 5. It is connected freely. The big end 4 b of the connecting rod 4 is rotatably connected to a crankshaft (not shown) via a crankpin 6.

  The outer peripheral shape of at least the upper part of the piston main body 3 is formed in a cylindrical shape, and three annular piston ring grooves 7, 8, 9 are provided in the cylindrical portion at intervals in the axial direction of the piston main body 3. . As shown in FIG. 2, the piston ring grooves 7, 8, 9 are respectively provided with a top ring 11, a second ring 12, and an oil ring 13 as piston rings constituting a part of the piston device 1 </ b> A. Yes. The upper top ring 11 and the middle second ring 12 are provided as compression rings for preventing compression leakage. The lower oil ring 13 is provided to scrape off oil (lubricating oil) adhering to the cylinder wall 2a. Each of these rings 11 to 13 is formed in a C shape having an abutment. A coil spring-like expander 14 is provided on the inner periphery of the oil ring 13 to apply a ring tension that presses the oil ring 13 against the cylinder wall 2a. The cross-sectional dimensions of the piston ring grooves 7, 8, 9 are such that the top ring 11, the second ring 12 and the oil ring 13 are somewhat displaceable in the radial and axial directions of the piston body 3. It is set somewhat larger than.

  Further, the piston body 3 is provided with a plurality of passages 15 extending from the groove bottom surface 8 a of the piston ring groove 8 in the middle stage so as to penetrate the piston body 3 and opening in the recess 3 a with an appropriate interval in the circumferential direction of the piston body 3. Is provided. A film-like member 16 is provided at the end of each passage 15 on the groove bottom surface 8 a side so as to close the space between the passage 15 and the piston ring groove 8. That is, the end of the passage 15 on the groove bottom surface 8 a side is completely closed by the film-like member 16, and the interior of the piston ring groove 8 and the passage 15 are not communicated with each other. The membrane member 16 is vibrated by a pressure wave introduced from the crank chamber C2 through the passage 15. As such a film-like member 16, a diaphragm film or an ultrasonic vibration film can be used. For joining the film-like member 16, various joining means such as adhesion and welding may be used. However, in order to prevent pressure or gas leakage between the passage 15 and the piston ring groove 8, it is necessary to hermetically join the entire circumference of the film-like member 16 to the inner peripheral surface or the groove bottom surface 8 a of the passage 15. In addition, the groove bottom surface 8a of the piston ring groove 8 is sufficiently retracted toward the center in the radial direction with respect to the inner peripheral surface 12a (see FIG. 2) of the second ring 12, and the membrane member 16 has an inner periphery of the second ring 12. It does not contact the surface 12a.

  Next, the operation of the piston device 1A will be described. In the reciprocating internal combustion engine to which the piston device 1A of this embodiment is applied, the sealing performance of the top ring 11 and the second ring 12 may be deteriorated and the internal pressure of the crank chamber C2 may be excessively increased. For example, when the wear of both the top ring 11 and the second ring 12 is small, when the internal combustion engine is operated at a light load, or when the temperature of the internal combustion engine is low and the thermal expansion of the cylinder wall 2a is kept small. As shown in FIG. 3, when the sealing performance by the top ring 11 and the second ring 12 is sufficiently secured, the internal pressure of the crank chamber C2 is temporarily set to gauge pressure = 0 (that is, large) as shown by A in FIG. Even if the pressure rises to a positive pressure range higher than (atmospheric pressure), the average pressure Pav is maintained in the negative pressure range. However, when wear of the top ring 11 or the second ring 12 progresses, when the internal combustion engine is operated at a high load, or when the thermal expansion of the cylinder wall 2a is large, the top ring 11 or the second ring 12 When the sealing performance between the cylinder wall 2a and the cylinder wall 2a is deteriorated, the pressure leakage to the crank chamber C2 increases, and the average pressure Pav rises to the positive pressure region as shown by B in FIG. Further, as can be understood from the example of the relationship between the crank angle and the frictional torque of the piston system shown in FIG. 4, immediately after the start of combustion, the pressure in the combustion chamber C1 rises rapidly, and the friction of the piston system is accompanied accordingly. As shown by C in the figure, the torque rapidly decreases for a short time. Such a decrease in friction torque is caused by the piston rings 11 to 13 being temporarily separated from the cylinder wall 2a by the pressure in the combustion chamber C1. Also in this case, the pressure in the combustion chamber C1 is released to the crank chamber C2, and the internal pressure in the crank chamber C2 increases greatly. When such a pressure leak to the crank chamber C2 occurs, the flow rate of blow-by gas increases, the quality of oil (lubricating oil) deteriorates, the amount of oil consumption increases, or the output of the internal combustion engine decreases. Inconvenience arises.

  However, in the piston device 1A of the present embodiment, since the internal pressure of the crank chamber C2 acts on the film-like member 16 via the passage 15, the film-like member 16 vibrates as the internal pressure of the crank chamber C2 rises. Thus, the air between the groove bottom surface 8a of the piston ring groove 8 and the second ring 12 also vibrates to generate a pressure for pushing the second ring 12 from the inner peripheral side toward the cylinder wall 2a. Accordingly, as shown in FIG. 5, as the internal pressure of the crank chamber C2 increases, the ring tension increases and the second ring 12 is pressed more strongly against the cylinder wall 2a. As a result, pressure leakage to the crank chamber C2 is suppressed, whereby the flow rate of blow-by gas is reduced, deterioration of oil quality and increase in oil consumption are suppressed, and output reduction of the internal combustion engine is also avoided.

  Further, since the passage 15 communicates with the crank chamber C2 through the recess 3a, the wear of the top ring 11 and the second ring 12 is small, the internal combustion engine is operated at a light load, or the cylinder wall 2a As in the case where the thermal expansion is kept small, the sealing performance by the top ring 11 and the second ring 12 is sufficiently ensured, and as a result, when the internal pressure of the crank chamber C2 is kept small, the ring tension is also reduced. There is no possibility that the second ring 12 is pressed against the cylinder wall 2a more than necessary. For this reason, an excessive increase in the frictional resistance between the second ring 12 and the cylinder wall 2a can be suppressed, and inconveniences such as a decrease in output or a decrease in fuel consumption due to the frictional resistance of the piston ring can be avoided. Further, since the passage 15 is closed with respect to the piston ring groove 8 by the membrane member 16, the pressure or gas flowing into the piston ring groove 8 through the gap between the cylinder wall 2 a and the top ring 11 is passed through the passage 15. There is also no risk of slipping out into the crank chamber C2.

  Furthermore, since the passage 15 is provided so as to connect the piston ring groove 8 in which the lower second ring 12 is arranged and the crank chamber C2 among the upper and lower rings 11 and 12 provided as the compression ring, the upper stage Compared with the case where the passage 15 is provided so as to connect the piston ring groove 7 and the recessed portion 3a, the position of the passage 15 can be made closer to the crank chamber C2, and thereby the passage 15 can be easily opened in the recessed portion 3a. When the thickness of the piston body 3 is set smaller behind the lower piston ring groove 8 than behind the upper piston ring groove 7, the piston ring groove 7 and the recess 3 a are connected by the passage 15. Compared to the case, the total length of the passage 15 is shortened, and as a result, the membrane member 16 vibrates rapidly with respect to the pressure change in the crank chamber C2, and the response of the change in the ring tension is improved.

(Second form)
FIG. 6 is a partially enlarged cross-sectional view showing the piston ring groove 8 in the middle stage of the piston device 1B according to the second embodiment of the present invention and the second ring 12 arranged in the piston ring groove 8. In FIG. 6, parts common to the first embodiment are denoted by the same reference numerals and description thereof is omitted. In the piston device 1B of the second form, an inward projecting portion 12b that projects toward the radial center side is provided on the inner peripheral surface 12a of the second ring 12, whereby the membrane member 16 and A radial gap with the second ring 12 is narrowed. The projecting amount of the inward projecting portion 12b may be set so that the membranous member 16 and the inward projecting portion 12b come into contact when the membranous member 16 is displaced radially outward. Further, stepped portions 8b and 8c projecting along the inwardly projecting portion 12b are provided on the groove bottom surface 8a of the piston ring groove 8, whereby the volume of the space between the inner periphery of the second ring 12 and the membrane member 16 is provided. Is narrower than that of the first embodiment. Each of the inward projecting portion 12b and the step portions 8b and 8c is provided so as to make a round around the axis of the piston body 3. However, at least one of the inward projecting portion 12b, the step portion 8b, or the step portion 8c may be divided into a plurality of sections with respect to the circumferential direction of the piston ring groove 8.

  According to the above configuration, the space between the membrane member 16 and the second ring 12 is narrowed, so that the vibration of the membrane member 16 is quickly converted into the ring tension, thereby changing the pressure in the crank chamber C2. Responsiveness of the change in ring tension with respect to is improved. When the film-like member 16 and the inward projecting portion 12b can be contacted, the inward-projecting portion 12b contacts the film-like member 16 and is pushed outward in the radial direction as the film-like member 16 is displaced outward in the radial direction. It is. As a result, the pressure increase in the crank chamber C2 can be reliably and quickly converted into the ring tension.

(Third form)
FIG. 7 is a partially enlarged cross-sectional view showing the piston ring groove 8 in the middle stage of the piston device 1 </ b> C according to the third embodiment of the present invention and the second ring 12 arranged in the piston ring groove 8. In FIG. 7, the same reference numerals are given to portions common to the first form or the second form, and the description is omitted. In the piston device 1 </ b> C of the third embodiment, an outward projecting portion 17 that projects toward the second ring 12 is provided on the outer surface of the film-like member 16. The outward projecting portion 17 may be configured as a separate component from the film member 16 and may be joined to the film member 16 or may be formed integrally with the film member 16. The outward projecting portion 17 is provided so as to vibrate integrally with the film member 16. The projecting amount of the outward projecting portion 17 may be set so that the outward projecting portion 17 contacts the second ring 12 as the membrane member 16 is displaced radially outward. The outward projecting portion 17 may be provided so as to make a round around the axis of the piston body 3. A plurality of outward projecting portions 17 may be provided at intervals in the circumferential direction of the piston ring groove 8.

  According to the above configuration, the volume of the space left between the inner peripheral side of the second ring 12 and the film-like member 16 is narrowed by the outward protrusion 17, so that the film-like member 16 is the same as in the second embodiment. Is quickly converted into ring tension, thereby improving the response of the change in the ring tension to the pressure change in the crank chamber C2. When the outward projecting portion 17 and the second ring 12 can be brought into contact with each other, the outward projecting portion 17 pushes the second ring 12 outward in the radial direction as the film-like member 16 is displaced outward in the radial direction. As a result, the pressure increase in the crank chamber C2 can be reliably and quickly converted into the ring tension. In addition, in the form of FIG. 7, the inward protruding portion 12b of the second ring 12 may be omitted. Or you may provide the step parts 8b and 8c similar to FIG. 6 in the groove bottom face 8a.

(4th form)
FIG. 8 is a partially enlarged cross-sectional view showing the upper and middle piston ring grooves 7 and 8 of the piston device 1D according to the fourth embodiment of the present invention, and the top ring 11 and the second ring 12 arranged in these. In FIG. 8, the same reference numerals are given to the portions common to the first embodiment, and the description will be omitted. In the piston device 1D of the fourth embodiment, the passage and the membrane member corresponding to the piston ring groove 8 in the middle stage are omitted, and instead, the piston main body 3 passes through the groove bottom surface 7a of the piston ring groove 7 in the upper stage. A plurality of passages 18 extending so as to open to the combustion chamber C1 are provided at appropriate intervals in the circumferential direction of the piston body 3. However, only a single passage 18 is shown in FIG.

  A membrane member 16 is provided at the end of each passage 18 on the groove bottom surface 7 a side so as to close the space between the passage 18 and the piston ring groove 7. That is, the end of the passage 18 on the groove bottom surface 7 a side is completely closed by the film-like member 16, and the interior of the piston ring groove 7 and the passage 18 are not communicated with each other. The membrane member 16 is vibrated by the pressure wave introduced from the combustion chamber C1 through the passage 18. The material of the film-like member 16 and the joining method may be the same as in the first embodiment. The groove bottom surface 7 a of the piston ring groove 7 is sufficiently retracted toward the radial center with respect to the inner peripheral surface 11 a of the top ring 11, and the film-like member 16 does not contact the inner peripheral surface 11 a of the top ring 11. However, as in the second embodiment, an inward protruding portion may be provided on the inner peripheral surface of the top ring 11, or a step portion may be provided on the groove bottom surface 7a. Similarly to the third embodiment, an outward projecting portion may be provided on the outer side of the film member 16.

  According to the above configuration, the pressure wave generated in the combustion chamber C1 acts on the film-shaped member 16 via the passage 18 to vibrate the film-shaped member 16, and accordingly, the film-shaped member 16 and the top ring 11 The air in between also vibrates and generates pressure to push the top ring 11 from the inner peripheral side toward the cylinder wall 2a. Thereby, when the pressure of the combustion chamber C1 rises, the ring tension can be increased to press the top ring 11 more strongly against the cylinder wall 2a, and the pressure leakage into the crank chamber C2 can be suppressed. As a result, the flow rate of blow-by gas decreases, deterioration of oil quality and increase in oil consumption are suppressed, and a decrease in output of the internal combustion engine is also avoided.

  When the pressure in the combustion chamber C1 is small, the ring tension is also kept small, and there is no possibility that the top ring 11 is pressed more strongly than necessary against the cylinder wall 2a. For this reason, an excessive increase in the frictional resistance between the top ring 11 and the cylinder wall 2a can be suppressed, and inconveniences such as a decrease in output or a decrease in fuel consumption due to the frictional resistance of the piston ring can be avoided. Further, since the passage 18 is closed with respect to the piston ring groove 7 by the film-like member 16, there is no possibility that pressure or gas guided from the combustion chamber C1 to the passage 18 escapes to the crank chamber C2 through the piston ring groove 7. .

  Further, since the passage 18 is provided so as to connect the piston ring groove 7 in which the top ring 11 is disposed and the combustion chamber C1 among the two upper and lower rings 11 and 12 provided as the compression ring, Compared with the case where the passage 18 is provided so as to connect the piston ring groove 8 and the combustion chamber C1, the overall length of the passage 18 is shortened. As a result, the membrane member 16 vibrates rapidly with respect to the pressure change in the combustion chamber C1. In addition, the response of the change in ring tension is improved. Further, since the tension can be changed in real time with respect to the pressure in the combustion chamber of FIG. 4, gas sealing can be reliably performed.

  This invention is not limited to the form mentioned above, It can implement with a various form. For example, you may combine the channel | path 18 and the film-form member 16 which were shown to the 4th form, and the channel | path 15 and the film-form member 16 which were shown to the 1st-3rd form. In the first to third embodiments, the passage 15 may be opened at the lower end surface of the piston body 3. In the fourth embodiment, the passage 18 may be open to the upper surface or the outer peripheral surface of the piston body 3 above the piston ring groove 7. By providing the passage 15 and the membrane member 16 in the piston ring groove 9 corresponding to the oil ring 13, the ring tension of the oil ring 13 may be increased or decreased according to the pressure in the crank chamber C2.

  The present invention is not limited to the piston device of an internal combustion engine, but can be applied to various reciprocating engines as long as a piston ring is used. For example, you may apply this invention with respect to piston apparatuses, such as an external combustion engine, a compressor, and a piston pump. In these cases, the passage provided in the piston body can be opened in various chambers such as a cylinder chamber, a working chamber, and a pressure chamber provided on one end side in the operation direction of the piston body.

Sectional drawing which shows the whole structure of the piston apparatus which concerns on the 1st form of this invention. The partial expanded sectional view which shows the piston ring groove | channel of the piston apparatus which concerns on a 1st form, and the piston ring arrange | positioned at these. The figure which shows an example of the time change of the internal pressure of a crank chamber. The figure which shows an example of the relationship between a crank angle and the friction torque of a piston system. The figure which shows an example of the relationship between the internal pressure of a crank chamber, and ring tension. The partial expanded sectional view which shows the piston ring groove of the middle step of the piston apparatus which concerns on the 2nd form of this invention, and the second ring arrange | positioned at this. The partial expanded sectional view which shows the piston ring groove of the middle stage of the piston apparatus which concerns on the 3rd form of this invention, and the second ring arrange | positioned at this. The partial expanded sectional view which shows the upper ring of the piston apparatus which concerns on the 4th form of this invention, and the piston ring groove of the middle stage, and the top ring and second ring which are arrange | positioned at these.

Explanation of symbols

1A, 1B, 1C, 1D Piston device 2 Cylinder 2a Cylinder wall 3 Piston body 7, 8, 9 Piston ring groove 7a, 8a Groove bottom 8b, 8c Step 11 Top ring 12 Second ring 12b Inward projecting part 13 Oil ring 15 Passage 16 Membrane member 17 Outward projecting portion 18 Passage C1 Combustion chamber C2 Crank chamber

Claims (7)

  A piston body slidably inserted into the cylinder and provided with a piston ring groove on an outer periphery; and a piston ring disposed in the piston ring groove and capable of contacting the cylinder wall. , A passage extending from the bottom surface of the piston ring groove so as to penetrate the piston main body and opening in a chamber on one end side in the operation direction of the piston main body is provided, and at the end of the passage on the groove bottom surface side, A piston device for a reciprocating engine, wherein a membrane member is provided so as to close between the passage and the piston ring groove.   2. The piston device according to claim 1, wherein an inward protruding portion that protrudes toward the film-like member is provided on an inner peripheral surface of the piston ring.   3. The piston device according to claim 1, wherein an outward projecting portion projecting toward the piston ring is provided on an outer surface of the film-like member facing the piston ring.   The piston device according to any one of claims 1 to 3, wherein the reciprocating engine is an internal combustion engine, and the chamber on one end side in the operation direction is a crank chamber of the internal combustion engine.   Two compression rings are attached to the piston body as the piston ring with an interval in the axial direction of the piston body, and the passage is provided with a piston ring groove in which a compression ring on the side close to the crank chamber is disposed. The piston device according to claim 4, wherein the piston device is provided so as to connect a bottom surface of the groove and the crank chamber.   The piston device according to any one of claims 1 to 3, wherein the reciprocating engine is an internal combustion engine, and the chamber on one end side in the operation direction is a combustion chamber of the internal combustion engine.   Two compression rings are attached to the piston body as the piston ring with an interval in the axial direction of the piston body, and a piston ring groove in which the compression ring on the side close to the combustion chamber is disposed in the passage The piston device according to claim 6, wherein the piston device is provided to connect a bottom surface of the groove and the combustion chamber.

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