JP2021071065A - Oil supply and drainage mechanism - Google Patents

Abstract

To properly supply and drain oil in a sliding body.SOLUTION: An oil supply and drainage mechanism 34L includes: a check valve portion 34La having a piston port 501a (sliding body port) that is formed on one side in a sliding direction of a piston (sliding body) sliding in the predetermined sliding direction, and a piston check valve 502 (sliding body check valve) for closing the piston port 501a; and an oil supply/drainage portion 34Lb provided on one side in the sliding direction with respect to the piston. The oil supply/drainage portion 34Lb has a housing 511, an oil supply/drainage portion hydraulic chamber 514 that is formed in the housing 511 and communicates with a supply oil passage or a drainage oil passage, a hydraulic chamber opening 517 formed on the other side in the sliding direction in the oil supply/drainage portion hydraulic chamber 514, and an extension member 512 that includes an oil supply/drainage portion valve element 512b, which is urged in a direction from the oil supply/drainage portion hydraulic chamber 514 to the hydraulic chamber opening 517 to close the hydraulic chamber opening 517 from the oil supply/drainage portion hydraulic chamber 514 side, and that is insertable into the piston port 501a.SELECTED DRAWING: Figure 5

Description

The present disclosure relates to an oil supply / drainage mechanism.

Sliding bodies may be used in various devices. For example, as disclosed in Patent Document 1, in a trunk piston type engine used for a ship or the like, the piston slides in the cylinder. The energy of the reciprocating motion of the piston is converted into rotational energy and transmitted to the crankshaft via the connecting rod.

Japanese Unexamined Patent Publication No. 2011-074822

By the way, when a sliding body such as an engine piston is provided with a mechanism that operates by flood control, it is necessary to supply hydraulic oil to the sliding body and discharge hydraulic oil from the sliding body. However, refueling (ie, refueling and draining) of sliding bodies is generally more difficult than refueling and draining of non-moving equipment. For example, it is conceivable to supply and drain oil from the sliding body by using a mechanism that expands and contracts as the sliding body slides. However, in this case, the device may become large.

In view of the above problems, an object of the present disclosure is to provide an oil supply / drainage mechanism capable of appropriately supplying / draining oil to a sliding body.

In order to solve the above problems, the oil supply / drainage mechanism according to one aspect of the present disclosure communicates with the oil-using portion in the sliding body that slides in the predetermined sliding direction, and one side of the sliding direction in the sliding body ( Specifically, in each embodiment described later, a check valve having a sliding body port formed on the bottom dead point side of the piston and a sliding body check valve including a sliding body valve body that closes the sliding body port. A valve portion and an oil supply / drainage portion provided on one side in the sliding direction with respect to the sliding body are provided, and the oil supply / drainage portion is formed in a housing and a supply oil passage or a discharge oil passage. A hydraulic chamber opening formed on the other side of the sliding direction in the oil supply / drainage section hydraulic chamber and the oil supply / drainage section hydraulic chamber (specifically, the top dead point side of the piston in each embodiment described later). The oil supply / drainage section valve body is urged in the direction from the oil supply / drainage section hydraulic chamber to the hydraulic chamber opening and closes the hydraulic chamber opening from the oil supply / drainage section hydraulic chamber side. It has an existing member.

The housing includes an outer tubular portion and an inner tubular portion that slides in the outer tubular portion in a sliding direction, and the inner tubular portion is attached in a direction from one side to the other in the sliding direction. The end of the inner tubular portion on the other side of the sliding direction is located on the other side of the sliding direction of the outer tubular portion on the other side of the sliding direction. The chamber is defined by one side of the inner tubular portion in the sliding direction and the inner peripheral portion of the outer tubular portion, and the hydraulic chamber opening is formed on one side of the inner tubular portion in the sliding direction and extends. The existing member may extend to the outside of the housing through an opening on the other side in the sliding direction in the inner tubular portion.

A sealing member may be provided on the other side of the inner tubular portion in the sliding direction.

It may have a switching valve for switching the oil passage communicating with the oil supply / drainage unit hydraulic chamber between the supply oil passage and the discharge oil passage.

According to the oil supply / drainage mechanism of the present disclosure, oil supply / drainage of the sliding body can be appropriately performed.

It is a schematic diagram which shows the schematic structure of the engine which concerns on 1st Embodiment of this disclosure. It is a perspective view which shows the piston which concerns on 1st Embodiment of this disclosure. It is sectional drawing which shows the piston in the case of the low compression ratio which concerns on 1st Embodiment of this disclosure. It is sectional drawing which shows the piston in the case of the high compression ratio which concerns on 1st Embodiment of this disclosure. It is sectional drawing which shows the mode that the oil supply / drainage mechanism which concerns on 1st Embodiment of this disclosure operates as an oil supply mechanism. It is sectional drawing which shows the mode that the oil supply / drainage mechanism which concerns on 1st Embodiment of this disclosure operates as an oil drainage mechanism. It is sectional drawing which shows the piston in the case of the low compression ratio which concerns on the 2nd Embodiment of this disclosure. It is sectional drawing which shows the piston in the case of the high compression ratio which concerns on the 2nd Embodiment of this disclosure. It is sectional drawing which shows the piston crown which concerns on 2nd Embodiment of this disclosure. It is a bottom view which shows the piston crown which concerns on 2nd Embodiment of this disclosure. It is a top view which shows the piston skirt which concerns on the 2nd Embodiment of this disclosure. It is sectional drawing which shows the piston skirt which concerns on 2nd Embodiment of this disclosure.

The embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding, and the present disclosure is not limited unless otherwise specified. In the present specification and the drawings, elements having substantially the same function and configuration are designated by the same reference numerals, so that duplicate description will be omitted. In addition, elements not directly related to the present disclosure are not shown.

<First embodiment>
The first embodiment of the present disclosure will be described with reference to FIGS. 1 to 6.

FIG. 1 is a schematic diagram showing a schematic configuration of an engine 1 according to the first embodiment of the present disclosure. The engine 1 is a trunk piston type engine, specifically, an engine for driving an engine or a generator mounted on a ship. As shown in FIG. 1, in the engine 1, a cylinder 12 is provided above the crankcase 11. The outer circumference of the upper part of the cylinder 12 is covered with the jacket 13. A cylinder cover 14 is provided at the upper end of the cylinder 12. An intake flow path (not shown) and an exhaust flow path (not shown) are connected to the cylinder cover 14.

A piston 15 is provided in the cylinder 12. The piston 15 is slidable in the cylinder 12. The piston 15 has a piston crown 15a and a piston skirt 15b. The piston skirt 15b is connected to one end of the small end portion 17a of the connecting rod 17 via the piston pin 16. The small end 17a of the connecting rod 17 is rotatable relative to the piston skirt 15b around the central axis of the piston pin 16.

A large end 17b is provided at the other end of the connecting rod 17. The large end 17b is connected to the crank pin 18a of the crankshaft 18. The large end 17b is rotatable relative to the crankshaft 18 around the central axis of the crankpin 18a. The crank journal 18b of the crankshaft 18 is pivotally supported by a bearing member provided on the crankcase 11. A balance weight 19 is provided on the side of the crankshaft 18 opposite to the crank pin 18a side with respect to the crank journal 18b. When the piston 15 reciprocates, the crankshaft 18 rotates. The energy of the reciprocating motion of the piston 15 is converted into rotational energy and transmitted to the crankshaft 18 via the connecting rod 17.

The crankcase 11 extends in the axial direction of the crankshaft 18. Although only one cylinder 12 is shown in FIG. 1, a plurality of cylinders 12 are provided side by side in the axial direction of the crankshaft 18 on the upper part of the crankcase 11. An oil pan 20 is connected to the lower part of the crankcase 11. The oil (hydraulic oil, lubricating oil, etc.) used in the crankcase 11 is stored in the oil pan 20.

In the engine 1, the combustion chamber 21 is defined by the cylinder 12, the cylinder cover 14, and the piston 15. Intake air is supplied to the combustion chamber 21 via the cylinder cover 14. Exhaust gas is discharged from the combustion chamber 21 through the cylinder cover 14. In FIG. 1, the state in which the piston 15 is located at the top dead center is shown by a solid line, and the state in which the piston 15 is located at the bottom dead center is shown by a two-dot chain line. The compression ratio ε of the engine 1 is expressed by the following equation (1).

ε = (Vh + Vc) / Vc ・ ・ ・ (1)

As shown in FIG. 1, Vh in the equation (1) corresponds to the difference in volume of the combustion chamber 21 when the piston 15 is located at the top dead center and when it is located at the bottom dead center. The stroke volume is shown, and Vc in the formula (1) indicates the gap volume which is the volume of the combustion chamber 21 when the piston 15 is located at the top dead center.

The sliding direction of the piston 15 coincides with the axial direction of the cylinder 12. Hereinafter, the top dead center side is referred to as the upper side, the bottom dead center side is referred to as the lower side, and the sliding direction of the piston 15 is also referred to as a vertical direction.

FIG. 2 is a perspective view showing a piston 15 according to the first embodiment of the present disclosure. The piston crown 15a is connected to the upper portion of the piston skirt 15b. Specifically, the piston crown 15a is fitted with the outer peripheral portion of the upper portion of the piston skirt 15b. As shown in FIG. 2, a fire contact surface 101 is formed on the upper portion of the piston crown 15a. The fire contact surface 101 defines the lower surface of the combustion chamber 21. A ring groove 102 into which the piston ring is fitted is formed on the side portion of the piston crown 15a. A pin hole 103 through which the piston pin 16 penetrates is formed on the side portion of the piston skirt 15b. The axial direction of the pin hole 103 is orthogonal to the axial direction of the piston 15.

FIG. 3 is a cross-sectional view showing a piston 15 in the case of a low compression ratio according to the first embodiment of the present disclosure. FIG. 4 is a cross-sectional view showing a piston 15 in the case of a high compression ratio according to the first embodiment of the present disclosure.

As shown in FIG. 3, a recessed portion 104 recessed downward is formed in the upper portion of the piston skirt 15b. For example, the recessed portion 104 is an annular shape coaxial with the central axis of the piston 15. A protrusion 105 that fits with the recess 104 is formed in the lower portion of the piston crown 15a. For example, the protrusion 105 is an annular shape coaxial with the central axis of the piston 15. The protrusion 105 is movable in the vertical direction relative to the recess 104. Therefore, the piston crown 15a can move relative to the piston skirt 15b in the vertical direction.

The piston hydraulic chamber 106 is defined by the recess 104 and the protrusion 105. Specifically, the piston hydraulic chamber 106 is defined by the inner side surface and the bottom surface of the recessed portion 104 and the lower surface of the protruding portion 105. For example, the piston hydraulic chamber 106 is an annular shape coaxial with the central axis of the piston 15. As will be described later, by adjusting the oil pressure in the piston hydraulic chamber 106, the vertical position of the piston crown 15a with respect to the piston skirt 15b is adjusted. As a result, the compression ratio of the engine 1 changes.

A hole 107 extending in the vertical direction is formed in the piston skirt 15b. The hole 107 is provided below the recess 104 and has an opening at the lower end. For example, the hole portion 107 has a cylindrical shape, and a plurality of hole portions 107 are provided at intervals in the circumferential direction of the piston 15. A bolt 108 is connected to the piston crown 15a as a penetrating member that penetrates the piston skirt 15b and extends to the hole 107. The upper end of the bolt 108 is screwed into the protrusion 105 of the piston crown 15a. The bolt 108 extends from the upper side through the piston hydraulic chamber 106 and the recess 104 to the hole 107. The bolt 108 is provided with a sliding member 109 that can slide in the hole 107. For example, the sliding member 109 has a cylindrical shape. A nut 110 is screwed below the sliding member 109 of the bolt 108. The upper surface of the nut 110 comes into contact with the lower surface of the sliding member 109. As a result, the sliding member 109 is restricted from rotating relative to the bolt 108.

The piston skirt hydraulic chamber 111 is defined by the inner peripheral portion of the hole portion 107 and the sliding member 109. Specifically, the piston skirt hydraulic chamber 111 is defined by the inner side surface and the bottom surface of the hole portion 107 and the upper surface surface of the sliding member 109. For example, the piston skirt hydraulic chamber 111 has a cylindrical shape. As will be described later, when the piston skirt hydraulic chamber 111 is pressurized, a downward force acts on the piston crown 15a via the sliding member 109 and the bolt 108.

A compression spring 112 is provided in the piston skirt hydraulic chamber 111. The compression spring 112 corresponds to an example of an urging member that urges the piston crown 15a in the bottom dead center direction. The compression spring 112 is provided between the bottom surface of the hole 107 and the top surface of the sliding member 109 in a posture in which the expansion and contraction direction of the compression spring 112 is in the vertical direction. Due to the restoring force of the compression spring 112, a downward force acts on the piston crown 15a via the sliding member 109 and the bolt 108.

The oil supply / drainage mechanism 34L and the oil supply / drainage mechanism 34R are provided as the oil supply / drainage mechanism connected to the piston hydraulic chamber 106. The oil supply / drainage mechanism is a mechanism for supplying hydraulic oil to a target hydraulic chamber or discharging hydraulic oil from the hydraulic chamber. The oil supply / drainage mechanism 34L and the oil supply / drainage mechanism 34R have similar components to each other. In the following, when the oil supply / drainage mechanism 34L and the oil supply / drainage mechanism 34R are not particularly distinguished, they are also referred to as the oil supply / discharge mechanism 34. The oil supply / drainage mechanism 34L includes a check valve portion 34La provided at the lower part of the piston 15 and an oil supply / drainage portion 34Lb provided below the check valve portion 34La outside the piston 15. The oil supply / drainage mechanism 34R includes a check valve portion 34Ra provided at the lower part of the piston 15 and an oil supply / drainage portion 34Rb provided below the check valve portion 34Ra outside the piston 15.

The oil supply / drainage mechanism 34L has an oil supply function (that is, a function of supplying hydraulic oil), and the oil supply / discharge mechanism 34R has an oil discharge function (that is, a function of discharging hydraulic oil). When the oil supply / discharge mechanism 34L operates as shown in FIG. 5, which will be described later, oil is supplied to the piston hydraulic chamber 106. When the oil supply / drainage mechanism 34R operates as shown in FIG. 6, which will be described later, oil is drained from the piston hydraulic chamber 106.

The piston hydraulic chamber 106 and the piston skirt hydraulic chamber 111 are connected to the oil supply / drainage mechanism 34L and the oil supply / drainage mechanism 34R as common oil supply / drainage mechanisms. Therefore, the oil supply / drainage of the piston skirt hydraulic chamber 111 is also performed by the oil supply / discharge mechanism 34L and the oil supply / discharge mechanism 34R, similarly to the piston hydraulic chamber 106. The details of the oil supply / drainage mechanism 34L and the oil supply / drainage mechanism 34R will be described later.

The oil supply / drainage unit 34Lb and the oil supply / discharge unit 34Rb are provided on a support base 41 located below the piston 15. A cylinder portion 42 extending upward is provided below the check valve portion 34La on the support base 41. The oil supply / drainage portion 34Lb fits with the cylinder portion 42. A port 42a that communicates the inside and the outside of the cylinder portion 42 is provided on the side portion of the cylinder portion 42. A cylinder portion 43 extending upward is provided below the check valve portion 34Ra on the support base 41. The oil supply / drainage portion 34Rb fits with the cylinder portion 43. A port 43a that communicates the inside and the outside of the cylinder portion 43 is provided on the side portion of the cylinder portion 43.

The support base 41 is formed with an oil passage 41a that communicates the internal space of the cylinder portion 42 with the switching valve 44. The oil passage 41a is connected to the internal space of the cylinder portion 42 at the bottom of the cylinder portion 42. The support base 41 is formed with an oil passage 41b that communicates the internal space of the cylinder portion 43 with the switching valve 45. The oil passage 41b is connected to the internal space of the cylinder portion 43 at the bottom of the cylinder portion 43.

The switching valve 44 and the switching valve 45 are connected to the hydraulic pump 46. By controlling the operation of the switching valve 44, the oil passage 41a is sent from the hydraulic pump 46 to the internal space of the cylinder portion 42 (specifically, the space between the bottom of the cylinder portion 42 and the bottom of the oil supply / drainage portion 34Lb). It is possible to switch between a state in which the hydraulic oil is supplied via the cylinder portion 42 and a state in which the hydraulic oil is discharged from the internal space of the cylinder portion 42 via the oil passage 41a. By controlling the operation of the switching valve 45, the oil passage 41b is sent from the hydraulic pump 46 to the internal space of the cylinder portion 43 (specifically, the space between the bottom of the cylinder portion 43 and the bottom of the oil supply / drainage portion 34Rb). It is possible to switch between a state in which the hydraulic oil is supplied via the cylinder portion 43 and a state in which the hydraulic oil is discharged from the internal space of the cylinder portion 43 via the oil passage 41b.

When hydraulic oil is supplied to the internal space of the cylinder portion 42, the oil supply / drainage portion 34Lb rises. When the hydraulic oil is discharged from the internal space of the cylinder portion 42, the oil supply / drainage portion 34Lb is lowered. When hydraulic oil is supplied to the internal space of the cylinder portion 43, the oil supply / drainage portion 34Rb rises. When the hydraulic oil is discharged from the internal space of the cylinder portion 43, the oil supply / drainage portion 34Rb is lowered. By adjusting the vertical positions of the oil supply / drainage unit 34Lb and the oil supply / discharge unit 34Rb, each oil supply / discharge mechanism 34 can be switched between an operable state and a non-operational state.

Specifically, when the internal space of the oil supply / drainage section 34Lb communicates with the port 42a of the cylinder section 42, the oil supply / drainage mechanism 34L becomes operable, and the internal space of the oil supply / drainage section 34Lb becomes the port 42a of the cylinder section 42. If it does not communicate with, the oil supply / drainage mechanism 34L becomes inactive. When the internal space of the oil supply / drainage section 34Rb communicates with the port 43a of the cylinder section 43, the oil supply / drainage mechanism 34R becomes operable, and when the internal space of the oil supply / drainage section 34Rb does not communicate with the port 43a of the cylinder section 43, The oil supply / drainage mechanism 34R becomes inactive.

3 and 4 show a state in which the oil supply / drainage mechanism 34L is operable and the oil supply / drainage mechanism 34R is inactive. In this state, the oil supply / discharge mechanism 34L can be operated to supply oil to the piston hydraulic chamber 106. On the other hand, in a state where the oil supply / drainage mechanism 34L is inactive and the oil supply / discharge mechanism 34R can be operated, the oil supply / discharge mechanism 34R can be operated to drain oil from the piston hydraulic chamber 106.

The hydraulic pump 46 is connected to the port 42a on the side of the cylinder portion 42 via a switching valve 47. Therefore, as shown in FIG. 3, in a state where the oil supply / drainage mechanism 34L can be operated, hydraulic oil is supplied from the hydraulic pump 46 to the oil supply / discharge unit 34Lb via the port 42a as a supply oil passage. When the oil supply / drainage mechanism 34L is activated, the internal space of the oil supply / discharge unit 34Lb and the internal space of the check valve portion 34La communicate with each other, as will be described later. The check valve portion 34La is connected to one end of the oil passage 114 via the oil passage 113. The oil passage 114 is connected to the piston hydraulic chamber 106 and the piston skirt hydraulic chamber 111 via the oil passage 115. For example, a plurality of oil passages 115 are provided at intervals in the circumferential direction of the piston 15, and each oil passage 115 is provided above one piston skirt hydraulic chamber 111 and the piston skirt hydraulic chamber 111 in the piston hydraulic chamber 106. The part is connected to. Pressurized hydraulic oil is sent from the oil supply / drainage mechanism 34L to the piston hydraulic chamber 106 and the piston skirt hydraulic chamber 111 via the oil passage 113, the oil passage 114, and the oil passage 115.

The pressurized hydraulic oil is sent from the oil supply / drainage mechanism 34L to the piston hydraulic chamber 106, so that the piston hydraulic chamber 106 is pressurized. As a result, an upward force acts on the piston crown 15a. The pressurized hydraulic oil is sent from the oil supply / drainage mechanism 34L to the piston skirt hydraulic chamber 111, so that the piston skirt hydraulic chamber 111 is pressurized. As a result, a downward force acts on the piston crown 15a.

Here, the area of the hydraulic action surface of the piston hydraulic chamber 106 (specifically, the area of the lower surface of the protrusion 105 of the piston crown 15a) is the area of the hydraulic action surface of each piston skirt hydraulic chamber 111 (specifically, the area of the hydraulic action surface of each piston skirt hydraulic chamber 111). , The area of the upper surface of the sliding member 109) is larger than the total. Therefore, the upward force acted by the hydraulic pressure of the piston hydraulic chamber 106 is larger than the downward force acted by the hydraulic pressure of the piston skirt hydraulic chamber 111. Therefore, the piston crown 15a moves upward. By repeatedly pressurizing the piston hydraulic chamber 106 in this way, as shown in FIG. 4, the piston crown 15a can be moved upward with respect to the vertical position in FIG. 3, and the compression ratio can be increased.

As described above, the hydraulic pressure of the piston skirt hydraulic chamber 111 exerts a downward force on the piston crown 15a. Further, the restoring force of the compression spring 112 also exerts a downward force on the piston crown 15a. These forces cancel the upward force acting on the piston crown 15a due to the inertia of the reciprocating motion of the piston 15. As a result, the piston crown 15a moves relatively stably with respect to the piston skirt 15b.

Note that FIG. 3 shows an example in which a plurality of oil passages 115 are branched from the oil passages 114, and each oil passage 115 is further branched toward each of the piston hydraulic chamber 106 and the piston skirt hydraulic chamber 111. However, the routes of the oil passage 114 and the oil passage 115 (specifically, the method of branching the oil passage) are not particularly limited.

The check valve portion 34Ra is connected to the other end of the oil passage 114 via the oil passage 116. When the oil supply / drainage mechanism 34R is activated, the internal space of the oil supply / discharge unit 34Rb and the internal space of the check valve portion 34Ra communicate with each other, as will be described later. Therefore, in a state in which the oil supply / drainage mechanism 34R can be operated, hydraulic oil is supplied to the oil supply / discharge unit 34Rb from the piston hydraulic chamber 106 and the piston skirt hydraulic chamber 111 via the oil passage 115, the oil passage 114, and the oil passage 116. Sent. When the oil supply / drainage mechanism 34R can be operated, the internal space of the oil supply / discharge unit 34Rb is connected to the port 43a of the cylinder unit 43. Therefore, the hydraulic oil sent to the oil supply / drainage unit 34Rb is discharged into the crankcase 11 in FIG. 1 via the port 43a as the oil discharge passage.

The piston hydraulic chamber 106 and the piston skirt hydraulic chamber 111 are depressurized by the discharge of hydraulic oil by the oil supply / drainage mechanism 34R. As a result, a downward force acts on the piston crown 15a due to the pressure in the cylinder 12, the inertia due to the reciprocating motion of the piston 15, and the restoring force of the compression spring 112. Therefore, the piston crown 15a moves downward. By repeatedly depressurizing the piston hydraulic chamber 106 in this way, as shown in FIG. 3, the piston crown 15a is moved downward to lower the compression ratio (that is, return to the compression ratio of FIG. 3). Can be done.

FIG. 5 is a cross-sectional view showing how the oil supply / drainage mechanism 34L according to the first embodiment of the present disclosure operates as an oil supply mechanism. The upper side in FIG. 5 is the top dead center side, and the lower side in FIG. 5 is the bottom dead center side.

As shown in FIG. 5, the check valve portion 34La includes a port member 501 including a piston port 501a formed in the lower part of the piston 15 and a piston check valve 502 including a piston valve body 502a that closes the piston port 501a. Has.

The port member 501 is provided below the piston 15. For example, the port member 501 is cylindrical with an opening at the top and a bottom at the bottom. The lower portion of the port member 501 extends below the lower end of the piston 15. The upper opening of the port member 501 is covered by the cover 503. A piston port 501a that communicates the inside and the outside of the port member 501 is formed at the bottom of the port member 501. The piston port 501a extends in the vertical direction. A contact surface 501b with the oil supply / drainage portion 34Lb is formed at the lower end of the port member 501. For example, the contact surface 501b has a spherical shape.

The port part hydraulic chamber 504 is defined by the port member 501 and the cover 503. A port 501c is formed on the side of the port member 501 to communicate the port hydraulic chamber 504 and the oil passage 113 in FIG. Therefore, the piston port 501a communicates with the piston hydraulic chamber 106 via the port portion hydraulic chamber 504, the port 501c, and the oil passage 113.

The piston check valve 502 is provided in the port hydraulic chamber 504. The piston check valve 502 limits the flow of hydraulic oil from the inside of the piston 15 to the outside of the piston 15 through the piston port 501a. The piston check valve 502 includes a piston valve body 502a and a compression spring 502b. The compression spring 502b comes into contact with the piston valve body 502a in a posture in which the compression direction of the compression spring 502b is in the vertical direction. The piston valve body 502a is urged by a compression spring 502b from the inside of the piston 15 (specifically, from the port hydraulic chamber 504) toward the piston port 501a, and closes the piston port 501a from the inside of the piston 15. The lift amount of the piston valve body 502a is limited by the protrusion 503a extending downward from the lower part of the cover 503.

The oil supply / drainage unit 34Lb has a housing 511 and an extending member 512 that is movable in the housing 511 and extends in the vertical direction. The housing 511 includes a bottom portion 511a, an outer tubular portion 511b, and an inner tubular portion 511c. For example, the outer tubular portion 511b and the inner tubular portion 511c are cylindrical. The outer tubular portion 511b extends in the vertical direction. The lower opening of the outer tubular portion 511b is closed by the bottom portion 511a. The inner tubular portion 511c fits into the inner peripheral portion of the outer tubular portion 511b. The inner tubular portion 511c slides in the outer tubular portion 511b in the vertical direction (that is, the sliding direction of the piston 15).

A compression spring 513 is provided inside the outer tubular portion 511b. The compression spring 513 comes into contact with the lower portion of the inner tubular portion 511c in a posture in which the compression direction of the compression spring 513 is in the vertical direction. The inner tubular portion 511c is urged upward by the restoring force of the compression spring 513. The upper end of the inner tubular portion 511c is located above the upper end of the outer tubular portion 511b. The inner tubular portion 511c is locked by the upper end portion of the outer tubular portion 511b so as not to come out upward with respect to the outer tubular portion 511b.

In the housing 511, an oil supply / drainage unit hydraulic chamber 514 communicating with the port 42a as a supply oil passage in FIG. 3 is formed. Specifically, the oil supply / drainage unit hydraulic chamber 514 is defined by the lower portion of the inner tubular portion 511c, the inner peripheral portion of the outer tubular portion 511b, and the upper portion of the bottom portion 511a. An oil passage 515 connecting the oil supply / drainage unit hydraulic chamber 514 and the port 42a is formed in the bottom portion 511a. A tubular portion 516 extending upward is formed on the upper portion of the bottom portion 511a. The oil passage 515 passes through the cylinder portion 516 and is connected to the oil supply / drainage unit hydraulic chamber 514.

A hydraulic chamber opening 517 is formed above the oil supply / drainage unit hydraulic chamber 514. Specifically, a valve seat 518 is provided below the inner tubular portion 511c. The hydraulic chamber opening 517 is defined by a valve seat 518. That is, the hydraulic chamber opening 517 is formed in the lower part of the inner tubular portion 511c.

A compression spring 519 is provided inside the inner tubular portion 511c. The compression spring 519 comes into contact with the lower portion of the enlarged diameter portion 512a of the extending member 512 in a posture in which the compression direction of the compression spring 519 is in the vertical direction. The extending member 512 is urged upward by the restoring force of the compression spring 519. The extending member 512 passes through the upper opening of the inner tubular portion 511c and extends to the outside of the housing 511. The extending member 512 is locked by the upper end portion of the inner tubular portion 511c so as not to come out upward with respect to the inner tubular portion 511c. A sealing member 520 is provided at the upper end of the inner tubular portion 511c.

An oil supply / drainage part valve body 512b is provided at the lower end of the extending member 512. The oil supply / drainage section valve body 512b is located below the valve seat 518, and closes the hydraulic chamber opening 517 from the oil supply / drainage section hydraulic chamber 514 side. The oil supply / drainage part valve body 512b is urged upward by the restoring force of the compression spring 519. Therefore, the oil supply / drainage section valve body 512b limits the flow of hydraulic oil from the inside of the oil supply / drainage section hydraulic chamber 514 to the outside of the oil supply / drainage section hydraulic chamber 514 through the hydraulic chamber opening 517.

The oil supply / drainage mechanism 34L operates when the oil supply / drainage portion 34Lb is pressed downward by the check valve portion 34La. In the example shown in FIG. 5, at time T11, the piston 15 is lowered, but the check valve portion 34La is not in contact with the oil supply / drainage portion 34Lb. At this time, since the piston check valve 502 is in a closed state (that is, a state in which the flow of hydraulic oil is blocked), the oil pressure in the port portion hydraulic chamber 504 is maintained. Further, the hydraulic chamber opening 517 is closed by the oil supply / drainage part valve body 512b.

At time T12 after time T11, the check valve portion 34La comes into contact with the oil supply / drainage portion 34Lb. At this time, the contact surface 501b of the port member 501 comes into contact with the sealing member 520 of the inner tubular portion 511c, and the upper end of the extending member 512 and the piston valve body 502a of the piston check valve 502 come into contact with each other and push each other. Fit. As a result, the piston check valve 502 rises relative to the piston port 501a, so that the piston check valve 502 is in an open state (that is, a state in which hydraulic oil flows). Further, since the extending member 512 descends relative to the hydraulic chamber opening 517, the hydraulic chamber opening 517 is opened by the oil supply / drainage unit valve body 512b. Therefore, the oil passage 113 and the port 42a communicate with each other.

In the state where the oil passage 113 and the port 42a communicate with each other in this way, the check valve portion 34La separates from the oil supply / drainage portion 34Lb after the time T12 and the time T13 when the piston 15 reaches the bottom dead center. The piston 15 is maintained until the time T14 when the piston 15 rises to the position (where it does not come into contact with the oil supply / drainage portion 34Lb). Therefore, by controlling the switching valve 47 so that the port 42a and the hydraulic pump 46 are connected between the time T12 and the time T14, the pressurized hydraulic oil is released from the oil supply / drainage mechanism 34L to the oil passage 113. Will be sent to. As a result, the piston hydraulic chamber 106 in FIG. 3 is pressurized, so that the piston crown 15a moves upward.

FIG. 6 is a cross-sectional view showing how the oil supply / drainage mechanism 34R according to the first embodiment of the present disclosure operates as an oil drainage mechanism. The upper side in FIG. 6 is the top dead center side, and the lower side in FIG. 6 is the bottom dead center side.

As described above, the configuration of the oil supply / drainage mechanism 34R is the same as the configuration of the oil supply / discharge mechanism 34L. However, in the oil supply / drainage mechanism 34R, the port 501c of the check valve portion 34Ra communicates with the oil passage 116 in FIG. Therefore, the piston port 501a communicates with the piston hydraulic chamber 106 via the port hydraulic chamber 504, the port 501c, and the oil passage 116. Further, the oil supply / drainage unit hydraulic chamber 514 formed in the housing 511 of the oil supply / discharge unit 34Rb communicates with the port 43a as the oil discharge passage in FIG. Specifically, the oil passage 515 formed in the bottom portion 511a of the housing 511 connects the oil supply / drainage unit hydraulic chamber 514 and the port 43a.

The oil supply / drainage mechanism 34R operates when the oil supply / drainage portion 34Rb is pressed downward by the check valve portion 34Ra. In the example shown in FIG. 6, at time T21, although the piston 15 is lowered, the check valve portion 34Ra is not in contact with the oil supply / drainage portion 34Rb. At this time, since the piston check valve 502 is in the closed state, the flood pressure of the port portion hydraulic chamber 504 is maintained. Further, the hydraulic chamber opening 517 is closed by the oil supply / drainage part valve body 512b.

At time T22 after time T21, the check valve portion 34Ra comes into contact with the oil supply / drainage portion 34Rb. At this time, the contact surface 501b of the port member 501 comes into contact with the sealing member 520 of the inner tubular portion 511c, and the upper end of the extending member 512 and the piston valve body 502a of the piston check valve 502 come into contact with each other and push each other. Fit. As a result, the piston check valve 502 rises relative to the piston port 501a, so that the piston check valve 502 is opened. Further, since the extending member 512 descends relative to the hydraulic chamber opening 517, the hydraulic chamber opening 517 is opened by the oil supply / drainage unit valve body 512b. Therefore, the oil passage 116 and the port 43a communicate with each other.

In the state where the oil passage 116 and the port 43a are in communication with each other in this way, the check valve portion 34Ra separates from the oil supply / drainage portion 34Rb after the time T22 and the time T23 when the piston 15 reaches the bottom dead center. The piston 15 is maintained until the time T24 when the piston 15 rises to the position (where it does not come into contact with the oil supply / drainage unit 34Rb). Therefore, from the time T22 to the time T24, the hydraulic oil is sent from the oil passage 116 to the port 43a via the oil supply / drainage mechanism 34R and discharged through the port 43a. As a result, the piston hydraulic chamber 106 in FIG. 3 is depressurized, so that the piston crown 15a moves downward.

As described above, in the piston 15, a recessed portion 104 recessed in the sliding direction of the piston 15 is formed on the top dead center side of the piston skirt 15b. A protrusion 105 is formed on the bottom dead center side of the piston crown 15a so as to be aligned with the recess 104. The piston hydraulic chamber 106 is defined by a recess 104 and a protrusion 105. As a result, the position of the piston crown 15a in the sliding direction with respect to the piston skirt 15b can be adjusted by adjusting the oil pressure in the piston hydraulic chamber 106. Thereby, the compression ratio of the engine 1 can be changed.

The recessed portion recessed in the sliding direction of the piston 15 may be formed on the bottom dead center side of the piston crown 15a. In that case, the protrusion that meets the recess is formed on the top dead center side of the piston skirt 15b.

As described above, in the piston 15, the piston hydraulic chamber 106 is provided between the piston skirt 15b and the piston crown 15a. However, the piston hydraulic chamber may be provided on the piston skirt 15b or may be provided on the piston crown 15a, as long as it is a hydraulic chamber in which a hydraulic force for applying a force toward the top dead center is generated on the piston crown 15a. .. For example, when the piston hydraulic chamber is provided in the piston skirt 15b, the piston hydraulic chamber can be defined by the bottom dead center side surface of the member connected to the piston crown 15a and the piston skirt 15b. Further, for example, when the piston hydraulic chamber is provided on the piston crown 15a, the piston hydraulic chamber can be defined by the surface on the top dead center side of the member connected to the piston skirt 15b and the piston crown 15a.

Further, as described above, the piston 15 is provided with a compression spring 112 as an urging member for urging the piston crown 15a in the bottom dead center direction. Therefore, the restoring force of the compression spring 112 exerts a downward force on the piston crown 15a. By this force, the upward force acting on the piston crown 15a due to the inertia due to the reciprocating motion of the piston 15 is canceled. Thereby, when the compression ratio of the engine 1 is changed, the piston crown 15a can be moved relatively stably with respect to the piston skirt 15b.

Further, as described above, the piston 15 has a hole 107 formed in the piston skirt 15b and extending in the sliding direction of the piston 15. The piston 15 is connected to the piston crown 15a and has a bolt 108 as a penetrating member that penetrates the piston skirt 15b and extends to the hole 107. The piston 15 is provided on the bolt 108 and has a sliding member 109 that can slide in the hole 107. The piston 15 has a piston skirt hydraulic chamber 111 defined by an inner peripheral portion of a hole 107 and a sliding member 109. Therefore, the hydraulic pressure of the piston skirt hydraulic chamber 111 exerts a downward force on the piston crown 15a. By this force, the upward force acting on the piston crown 15a due to the inertia due to the reciprocating motion of the piston 15 is canceled. Thereby, when the compression ratio of the engine 1 is changed, the piston crown 15a can be moved relatively stably with respect to the piston skirt 15b.

Further, as described above, in the piston 15, the piston hydraulic chamber 106 and the piston skirt hydraulic chamber 111 are connected to a common oil supply / drainage mechanism (specifically, the oil supply / drainage mechanism 34L and the oil supply / drainage mechanism 34R). The oil. As a result, it is possible to prevent the oil pressure of the piston hydraulic chamber 106 from deviating from the oil pressure of the piston skirt hydraulic chamber 111. Therefore, for example, it is possible to suppress a situation in which the oil pressure of the piston skirt hydraulic chamber 111 becomes excessively high with respect to the oil pressure of the piston hydraulic chamber 106, so that the compression ratio of the engine 1 can be changed more stably.

As described above, the piston 15 corresponds to an example of a sliding body that slides in a predetermined sliding direction, and the piston hydraulic chamber 106 is an oil-using portion (that is, a portion where oil is used) in the sliding body. Corresponds to one example. Further, the piston port 501a corresponds to an example of a sliding body port communicating with the hydraulic chamber in the sliding body, and the piston valve body 502a corresponds to an example of a sliding body valve body that closes the sliding body port from the inside of the sliding body. The piston check valve 502 corresponds to an example of a sliding body check valve including a sliding body valve body. The oil supply / drainage mechanism connected to the piston hydraulic chamber 106 is the oil supply / drainage mechanism 34. The oil supply / drainage mechanism 34 has a check valve portion (specifically, a check valve portion) having a piston port 501a communicating with the piston hydraulic chamber 106 and a piston check valve 502 including a piston valve body 502a that closes the piston port 501a. It is provided with valve portions 34La, 34Ra). Further, the oil supply / drainage mechanism 34 includes a housing 511, an oil supply / drainage section hydraulic chamber 514 formed in the housing 511, a hydraulic chamber opening 517 formed in the oil supply / drainage section hydraulic chamber 514, and a hydraulic chamber opening 517. The oil supply / drainage section (specifically, the oil supply / drainage section 34Lb) including the oil supply / drainage section valve body 512b that closes the oil supply / drainage section from the hydraulic chamber 514 side and has an extension member 512 that can be inserted into the piston port 501a. , 34Rb). Therefore, the oil supply / drainage mechanism is used to supply oil to the sliding body (for example, the piston 15) from an external oil supply source (for example, the hydraulic pump 46) and to discharge oil from the sliding body (for example, the piston 15) to the outside. It can be done via 34. Therefore, oil supply / drainage (that is, oil supply and oil discharge) of the sliding body (for example, the piston 15) can be appropriately performed.

Here, for example, by using an oil supply / drainage mechanism (for example, a mechanism including a telescopic pipe) that expands and contracts as the sliding body slides, oil can be supplied to the sliding body from an external oil supply source, and the sliding body can be supplied. It is conceivable to drain the oil from the outside. However, in this case, the entire device may become large. By using the oil supply / drainage mechanism 34 as the oil supply / drainage mechanism of the sliding body, the increase in size of the entire device is suppressed. Further, by using the oil supply / drainage mechanism 34 as the oil supply / drainage mechanism of the sliding body, it is possible to reduce the sliding portion between the parts in the oil supply / drainage mechanism.

Further, in the oil supply / drainage mechanism 34, the housing has an outer tubular portion 511b and an inner tubular portion that slides in the outer tubular portion 511b in the sliding direction (specifically, in the vertical direction) of the piston 15. Includes 511c. The inner tubular portion 511c is urged in a direction from one side (specifically, the lower side) to the other side (specifically, the upper side) in the sliding direction. The other end of the inner tubular portion 511c in the sliding direction is located on the other side of the sliding direction than the other end of the outer tubular portion 511b in the sliding direction. The oil supply / drainage unit hydraulic chamber 514 is defined by one side of the inner tubular portion 511c in the sliding direction and the inner peripheral portion of the outer tubular portion 511b. The hydraulic chamber opening 517 is formed on one side of the inner tubular portion 511c in the sliding direction. The extending member 512 passes through the opening on the other side in the sliding direction in the inner tubular portion 511c and extends to the outside of the housing 511. As a result, the piston check valve 502 and the hydraulic chamber opening 517 are opened by the upper end of the extending member 512 and the piston valve body 502a coming into contact with each other and pushing each other, and the inner tubular portion 511c has an outer tubular shape. It can be continued while sliding in the portion 511b (for example, between time T12 and time T14 in FIG. 3 or between time T22 and time T24 in FIG. 4). Therefore, it is possible to more appropriately supply oil to the sliding body from an external oil supply source and drain oil from the sliding body to the outside.

Further, in the oil supply / drainage mechanism 34, a sealing member 520 is provided on the other side of the inner tubular portion 511c in the sliding direction. As a result, in the contact between the check valve portion and the oil supply / drainage portion (for example, the contact between the check valve portion 34La and the oil supply / drainage portion 34Lb or the contact between the check valve portion 34Ra and the oil supply / drainage portion 34Rb). It is possible to prevent damage to the check valve portion or the oil supply / drainage portion.

The oil supply / drainage mechanism 34 preferably has a switching valve for switching the oil passage communicating with the oil supply / discharge unit hydraulic chamber 514 between the supply oil passage and the discharge oil passage. For example, by controlling the operation of the switching valve 47 in FIG. 3, the oil passage communicating with the oil supply / drainage section hydraulic chamber 514 of the oil supply / drainage section 34Lb can be switched between the supply oil passage and the discharge oil passage. It may be. As a result, one oil supply / discharge mechanism 34 can cover the oil supply function and the oil discharge function, so that the number of parts can be reduced.

<Second embodiment>
A second embodiment of the present disclosure will be described with reference to FIGS. 7-12.

FIG. 7 is a cross-sectional view showing a piston 25 in the case of a low compression ratio according to the second embodiment of the present disclosure. FIG. 8 is a cross-sectional view showing a piston 25 in the case of a high compression ratio according to the second embodiment of the present disclosure. The piston 25 can slide in the cylinder 12 of the engine 1 in the same manner as the piston 15 described above. The piston 25 includes a piston crown 25a and a piston skirt 25b. The piston crown 25a is fitted with the outer peripheral portion of the upper portion of the piston skirt 25b. A fire contact surface 201 is formed on the upper portion of the piston crown 25a. The fire contact surface 201 defines the lower surface of the combustion chamber 21. A ring groove 202 into which the piston ring is fitted is formed on the side portion of the piston crown 25a. A pin hole 203 through which the piston pin 16 penetrates is formed on the side portion of the piston skirt 25b. The axial direction of the pin hole 203 is orthogonal to the axial direction of the piston 25.

In the piston 25, similarly to the piston 15 described above, the vertical position of the piston crown 25a with respect to the piston skirt 25b is adjusted by using hydraulic pressure. Further, similarly to the piston 15 described above, the oil supply / drainage mechanism 34L and the oil supply / drainage mechanism 34R are used as the oil supply / drainage mechanism. However, in the piston 25, the structures of the piston crown 25a and the piston skirt 25b for changing the vertical position of the piston crown 25a with respect to the piston skirt 25b are different from those of the piston 15 described above.

As shown in FIG. 7, a groove portion 204 inclined with respect to the circumferential direction of the piston 25 is formed on the outer peripheral portion of the upper portion of the piston skirt 25b. A plurality of groove portions 204 are provided at intervals in the circumferential direction of the piston 25. The groove 204 inclines upward as it goes counterclockwise when viewed from above. For example, the cross-sectional shape of the internal space of the groove 204 is rectangular. FIG. 7 shows the width h of the groove portion 204 and the inclination angle θ of the groove portion 204 with respect to the circumferential direction of the piston 25. A protrusion 205 that fits with the groove 204 is formed on the inner peripheral portion of the lower portion of the piston crown 25a. A plurality of protrusions 205 are provided at intervals in the circumferential direction of the piston 25. The protrusion 205 extends parallel to the groove 204. For example, the cross-sectional shape of the protrusion 205 is rectangular.

The protrusion 205 is slidable in the groove 204 in the extending direction of the groove 204. The protrusion 205 rises as it advances counterclockwise in the groove 204 when viewed from above, and descends as it advances clockwise in the groove 204 when viewed from above. Therefore, when the piston crown 25a rotates with respect to the piston skirt 25b around the central axis of the piston 25, the vertical position of the piston crown 25a with respect to the piston skirt 25b changes.

The upper piston hydraulic chamber 206 is defined by the top dead center side (that is, the counterclockwise side when viewed from above) and the protrusion 205 of the groove 204 with respect to the protrusion 205. The lower piston hydraulic chamber 207 is defined by the bottom dead center side (that is, the clockwise side when viewed from above) and the protrusion 205 of the groove 204 with respect to the protrusion 205.

Specifically, the end of the inner portion of the groove 204 on the bottom dead center side is closed, and the end of the inner peripheral portion of the groove 204 on the top dead center side is open. The lower piston hydraulic chamber 207 is defined by an inner surface of the groove 204, a protrusion 205, and an inner surface of the piston crown 25a. The penetrating member 208 crosses and penetrates the top dead center side of the groove portion 204 with respect to the protrusion 205. For example, the penetrating member 208 is a rod-shaped member extending in the vertical direction. The upper piston hydraulic chamber 206 is defined by an inner surface of the groove 204, a protrusion 205, an inner surface of the piston crown 25a, and a penetrating member 208.

As will be described later, the vertical position of the piston crown 25a with respect to the piston skirt 25b is adjusted by adjusting the oil pressure in the upper piston hydraulic chamber 206 and the hydraulic pressure in the lower piston hydraulic chamber 207. As a result, the compression ratio of the engine 1 changes.

An upward inclined surface 209 parallel to the groove 204 is formed on the upper portion of the piston skirt 25b. The inclination angle of the upward inclined surface 209 with respect to the circumferential direction of the piston 25 coincides with the inclination angle θ of the groove portion 204 with respect to the circumferential direction of the piston 25. The upper inclined surface 209 comes into contact with the lower inclined surface 214 (specifically, a surface parallel to the upper inclined surface 209) described later of the piston crown 25a. As a result, the pressure in the combustion chamber 21 input to the piston crown 25a can be received by the piston skirt 25b.

An oil supply / drainage mechanism 34L is connected to the lower piston hydraulic chamber 207. An oil supply / drainage mechanism 34R is connected to the upper piston hydraulic chamber 206. Each oil supply / discharge mechanism 34 has both an oil supply function and an oil discharge function. 7 and 8 illustrate a state in which the oil supply / drainage mechanism 34L operates as an oil supply mechanism and the oil supply / discharge mechanism 34R operates as an oil discharge mechanism. In this state, when the oil supply / discharge mechanism 34L is activated, oil is supplied to the lower piston hydraulic chamber 207. When the oil supply / drainage mechanism 34R is activated, oil is drained from the upper piston hydraulic chamber 206. In the second embodiment, the upper piston hydraulic chamber 206 and the lower piston hydraulic chamber 207 correspond to an example of an oil-using portion (that is, a portion where oil is used) in the sliding body.

The oil supply / drainage section 34Lb and the oil supply / drainage section 34Rb are provided on a support base 51 located below the piston 25. A cylinder portion 52 extending upward is provided below the check valve portion 34La on the support base 51. The oil supply / drainage portion 34Lb fits with the cylinder portion 52. A port 52a that communicates the inside and the outside of the cylinder portion 52 is provided on the side portion of the cylinder portion 52. A cylinder portion 53 extending upward is provided below the check valve portion 34Ra on the support base 51. The oil supply / drainage portion 34Rb fits with the cylinder portion 53. A port 53a that communicates the inside and the outside of the cylinder portion 53 is provided on the side portion of the cylinder portion 53.

The support base 51 is formed with an oil passage 51a that communicates the internal space of the cylinder portion 52 and the internal space of the cylinder portion 53 with the switching valve 54. The oil passage 51a is connected to the internal space of the cylinder portion 52 at the bottom of the cylinder portion 52, and is connected to the internal space of the cylinder portion 53 at the bottom of the cylinder portion 53.

The switching valve 54 is connected to the hydraulic pump 55. By controlling the operation of the switching valve 54, the internal space from the hydraulic pump 55 to the cylinder portion 52 (specifically, the space between the bottom of the cylinder portion 52 and the bottom of the oil supply / drainage portion 34Lb) and the cylinder portion 53. The hydraulic oil is supplied to the internal space of the cylinder portion 53 (specifically, the space between the bottom portion of the cylinder portion 53 and the bottom portion of the oil supply / drainage portion 34Rb) via the oil passage 51a, and the internal space of the cylinder portion 52. And the state where the hydraulic oil is discharged from the internal space of the cylinder portion 53 through the oil passage 51a can be switched.

When hydraulic oil is supplied to the internal space of the cylinder portion 52 and the internal space of the cylinder portion 53, the oil supply / drainage unit 34Lb and the oil supply / discharge unit 34Rb rise. When the hydraulic oil is discharged from the internal space of the cylinder portion 52 and the internal space of the cylinder portion 53, the oil supply / drainage unit 34Lb and the oil supply / discharge unit 34Rb are lowered. By adjusting the vertical positions of the oil supply / drainage section 34Lb and the oil supply / drainage section 34Rb, the oil supply / drainage mechanism 34L and the oil supply / drainage mechanism 34R can be switched between an operable state and a non-operational state. Can be done.

Specifically, when the internal spaces of the oil supply / drainage section 34Lb and the oil supply / drainage section 34Rb communicate with the port 52a of the cylinder section 52 and the port 53a of the cylinder section 53, respectively, the oil supply / drainage mechanism 34L and the oil supply / drainage mechanism 34R Can be operated. If the internal spaces of the oil supply / drainage section 34Lb and the oil supply / drainage section 34Rb do not communicate with the port 52a of the cylinder section 52 and the port 53a of the cylinder section 53, respectively, the oil supply / drainage mechanism 34L and the oil supply / drainage mechanism 34R are inoperable. .. 7 and 8 show a state in which the oil supply / drainage mechanism 34L and the oil supply / drainage mechanism 34R are operable.

The port 52a of the cylinder portion 52 and the port 53a of the cylinder portion 53 are connected to the hydraulic pump 55 via a switching valve 56. By controlling the operation of the switching valve 56, the port 52a is connected to the hydraulic pump 55 and the port 53a is connected to the discharge port, and the port 53a is connected to the hydraulic pump 55 and the port 52a is connected to the discharge port. You can switch between states. 7 and 8 show a state in which the port 52a is connected to the hydraulic pump 55 and the port 53a is connected to the discharge port. In this state, the oil supply / discharge mechanism 34L operates as the oil supply mechanism, and the oil supply / discharge mechanism 34R operates as the oil discharge mechanism.

In the state shown in FIG. 7, the oil passage 515 communicating the inside and the outside of the oil supply / drainage portion 34Lb is connected to the port 52a of the cylinder portion 52. Therefore, hydraulic oil is supplied from the hydraulic pump 55 to the oil supply / drainage unit 34Lb via the port 52a as a supply oil passage. When the oil supply / drainage mechanism 34L is operated, as described above, the internal space of the oil supply / discharge unit 34Lb and the internal space of the check valve portion 34La communicate with each other. The port 501c of the check valve portion 34La is connected to the lower piston hydraulic chamber 207 via the oil passage 210. Pressurized hydraulic oil is sent from the oil supply / drainage mechanism 34L to the lower piston hydraulic chamber 207 via the oil passage 210. The pressurized hydraulic oil is sent from the oil supply / drainage mechanism 34L to the lower piston hydraulic chamber 207, so that the lower piston hydraulic chamber 207 is pressurized. The state in which the oil supply / drainage mechanism 34L operates as the oil supply mechanism is that the oil passage 113 in FIG. 5 is replaced with the oil passage 210.

When the oil supply / drainage mechanism 34R is activated, as described above, the internal space of the oil supply / discharge unit 34Rb and the internal space of the check valve portion 34Ra communicate with each other. The port 501c of the check valve portion 34Ra is connected to the upper piston hydraulic chamber 206 via the oil passage 211. Hydraulic oil is sent from the upper piston hydraulic chamber 206 to the oil supply / drainage unit 34Rb via the oil passage 211. The oil passage 515 that communicates the inside and the outside of the oil supply / drainage portion 34Rb is connected to the port 53a of the cylinder portion 53. Therefore, the hydraulic oil sent to the oil supply / drainage unit 34Rb is discharged through the port 53a as a drainage oil passage. As a result, the pressure in the upper piston hydraulic chamber 206 is reduced. The state in which the oil supply / drainage mechanism 34R operates as the oil drainage mechanism is that the oil passage 116 in FIG. 6 is replaced with the oil passage 211.

As described above, the lower piston hydraulic chamber 207 is pressurized and the upper piston hydraulic chamber 206 is depressurized, so that the direction from the lower piston hydraulic chamber 207 toward the upper piston hydraulic chamber 206 (that is, counterclockwise when viewed from above). A force (in the circumferential direction) acts on the protrusion 205 of the piston crown 25a. Therefore, the piston crown 25a rotates in the counterclockwise direction when viewed from above, and the piston crown 25a moves upward. By repeatedly pressurizing the lower piston hydraulic chamber 207 and depressurizing the upper piston hydraulic chamber 206, the piston crown 25a is moved upward with respect to the vertical position in FIG. 7, as shown in FIG. The compression ratio can be increased.

Unlike the state shown in FIGS. 7 and 8, when the operation of the switching valve 56 is controlled so that the port 53a is connected to the hydraulic pump 55 and the port 52a is connected to the discharge port, the oil supply / drainage mechanism 34L Operates as an oil draining mechanism, and the oil supply / drainage mechanism 34R operates as an oil supply mechanism. That is, in this case, the oil supply / drainage mechanism 34L drains oil from the lower piston hydraulic chamber 207, and the oil supply / drainage mechanism 34R supplies oil to the upper piston hydraulic chamber 206. As a result, a force in the direction from the upper piston hydraulic chamber 206 toward the lower piston hydraulic chamber 207 (that is, in the clockwise direction when viewed from above) acts on the protrusion 205 of the piston crown 25a. Therefore, the piston crown 25a rotates clockwise when viewed from above, and the piston crown 25a moves downward. By repeatedly pressurizing the upper piston hydraulic chamber 206 and depressurizing the lower piston hydraulic chamber 207, the piston crown 25a is moved downward and the compression ratio is lowered (that is, as shown in FIG. 7). , The compression ratio in FIG. 7 can be restored.

FIG. 9 is a cross-sectional view showing a piston crown 25a according to the second embodiment of the present disclosure. FIG. 10 is a bottom view showing the piston crown 25a according to the second embodiment of the present disclosure.

As shown in FIGS. 9 and 10, a first inner peripheral portion 212 and a second inner peripheral portion 213 are formed in this order from the bottom in the lower portion of the piston crown 25a. The central axes of the first inner peripheral portion 212 and the second inner peripheral portion 213 are coaxial with the central axis of the piston 25. The inner diameter of the first inner peripheral portion 212 is larger than the inner diameter of the second inner peripheral portion 213. The protrusion 205 is provided on the first inner peripheral portion 212. The width of the protrusion 205 coincides with the width h of the groove 204. The inclination angle of the protrusion 205 with respect to the circumferential direction of the piston 25 coincides with the inclination angle θ of the groove 204 with respect to the circumferential direction of the piston 25. In the example of FIG. 10, four protrusions 205 are provided at equal intervals in the circumferential direction of the piston 25.

A downward inclined surface 214 parallel to the groove 204 is formed in the lower portion of the piston crown 25a. The lower inclined surface 214 is formed at a stepped portion between the first inner peripheral portion 212 and the second inner peripheral portion 213. The downward inclined surface 214 has a shape obtained by removing the region inside the second inner peripheral portion 213 from the fan shape coaxial with the central axis of the piston 25 in bottom view. The lower inclined surface 214 is located above the protrusion 205. The inclination angle of the downward inclined surface 214 with respect to the circumferential direction of the piston 25 coincides with the inclination angle θ of the groove portion 204 with respect to the circumferential direction of the piston 25. A plurality of lower inclined surfaces 214 are provided at intervals in the circumferential direction of the piston 25. In the example of FIG. 10, four downwardly inclined surfaces 214 are provided at equal intervals in the circumferential direction of the piston 25.

FIG. 11 is a top view showing the piston skirt 25b according to the second embodiment of the present disclosure. FIG. 12 is a cross-sectional view showing a piston skirt 25b according to a second embodiment of the present disclosure.

As shown in FIGS. 11 and 12, a cylindrical portion 215 coaxial with the central axis of the piston 25 is formed on the upper portion of the piston skirt 25b so as to extend upward. On the outside of the cylindrical portion 215 at the upper part of the piston skirt 25b, a protruding portion 216 is formed so as to project upward from other portions on the outside of the cylindrical portion 215. A plurality of protrusions 216 are provided at intervals in the circumferential direction of the piston 25. In the example of FIG. 11, four protrusions 216 are provided at equal intervals in the circumferential direction of the piston 25. The protruding portion 216 has a shape obtained by removing the region inside the outer peripheral surface of the cylindrical portion 215 from the fan shape coaxial with the central axis of the piston 25 when viewed from above. The groove portion 204 is formed on the outer peripheral surface of the protruding portion 216 (that is, the side surface along the circumferential direction of the piston 25). The upper inclined surface 209 is formed on the upper portion of the protrusion 216.

The cylindrical portion 215 of the piston skirt 25b fits into the second inner peripheral portion 213 of the piston crown 25a. Therefore, the inner diameter φd of the second inner peripheral portion 213 is larger than the outer diameter φd1 of the cylindrical portion 215. The outer peripheral surface of the protruding portion 216 of the piston skirt 25b is aligned with the first inner peripheral portion 212 of the piston crown 25a. Therefore, the inner diameter φD of the first inner peripheral portion 212 is larger than the outer diameter φD1 of the protruding portion 216 (that is, the diameter of the outer peripheral surface of the protruding portion 216). The upper inclined surface 209 of the piston skirt 25b and the lower inclined surface 214 of the piston crown 25a come into contact with each other.

The angle β formed by the adjacent protrusions 216 of the piston skirt 25b is larger than the central angle α of the lower inclined surface 214 of the piston crown 25a. As a result, the protrusion 205 of the piston crown 25a can be fitted into the groove 204 of the piston skirt 25b in a state where the upper inclined surface 209 of the piston skirt 25b and the lower inclined surface 214 of the piston crown 25a are in contact with each other. In a state where the protrusion 205 of the piston crown 25a is fitted into the groove 204 of the piston skirt 25b, the penetrating member 208 is attached to the top dead center side of the protrusion 205 in the groove 204. As a result, the upper piston hydraulic chamber 206 and the lower piston hydraulic chamber 207 are formed. As described above, the piston is provided so that the upper piston hydraulic chamber 206 and the lower piston hydraulic chamber 207 are formed by providing the penetrating member 208 that penetrates across the top dead center side of the protrusion 205 in the groove portion 204. Assembling the crown 25a to the piston skirt 25b is appropriately realized.

At the lower part of the piston skirt 25b, a hole portion 217 with which the check valve portion 34La is aligned and a hole portion 218 with which the check valve portion 34Ra is aligned are formed. The hole portion 217 and the hole portion 218 are formed so as to extend upward from the lower end of the piston skirt 25b.

As described above, in the piston 25, a groove portion 204 inclined with respect to the circumferential direction of the piston 25 is formed on the outer peripheral portion of the piston skirt 25b on the top dead center side. A protrusion 205 that fits with the groove 204 is formed on the inner peripheral portion of the piston crown 25a on the bottom dead center side. The upper piston hydraulic chamber 206 is defined by the top dead center side and the protrusion 205 with respect to the protrusion 205 in the groove 204. The lower piston hydraulic chamber 207 is defined by the bottom dead center side and the protrusion 205 with respect to the protrusion 205 in the groove 204. Thereby, the position of the piston crown 25a in the sliding direction with respect to the piston skirt 25b can be adjusted by adjusting the oil pressure in the upper piston hydraulic chamber 206 and the oil pressure in the lower piston hydraulic chamber 207. Therefore, the compression ratio of the engine 1 can be changed.

The groove portion that is inclined with respect to the circumferential direction of the piston 25 may be formed in the inner peripheral portion on the bottom dead center side of the piston crown 25a. In that case, the protruding portion that meets the groove portion is formed on the outer peripheral portion on the top dead center side of the piston skirt 25b. Further, in that case, the penetrating member that penetrates across the groove can penetrate across the bottom dead center side of the protrusion in the groove. As a result, the piston crown 25a is formed so that the upper piston hydraulic chamber and the lower piston hydraulic chamber are formed by attaching the penetrating member to the groove portion in a state where the groove portion of the piston crown 25a is fitted to the protrusion portion of the piston skirt 25b. Assembling to the piston skirt 25b is properly realized.

Although the embodiments have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to the above embodiments. It is clear to those skilled in the art that various modifications or modifications can be conceived within the scope of the claims, and it is understood that they also naturally belong to the technical scope of the present disclosure. Will be done.

In the above, the oil supply / drainage mechanism 34 used for oil supply / drainage of the pistons 15 and 25 has been described. However, the target of oil supply / drainage by the oil supply / drainage mechanism according to the present disclosure may be a sliding body having a mechanism operated by flood control, and includes various sliding bodies other than the pistons 15 and 25.

In the above, the shape and arrangement of each component have been described with reference to each drawing, but the shape and arrangement of each component is not particularly limited to the above example. For example, each member of the oil supply / drainage mechanism 34 may be formed of a plurality of members. Further, for example, the members connected to each other in the oil supply / drainage mechanism 34 may be integrally formed. Further, for example, the shapes of the recessed portion 104, the protruding portion 105, and the piston hydraulic chamber 106 may be shapes other than an annulus (for example, a circle, an ellipse, a polygon, or a combination thereof). Further, for example, the cross-sectional shape of the internal space of the groove portion 204 and the cross-sectional shape of the protrusion 205 may be a shape other than a rectangle (for example, a circle, an ellipse, a polygon, or a combination thereof). Further, for example, the groove portion 204 may be inclined upward as it goes clockwise when viewed from above. Further, for example, the number of the protrusion 205 and the downward inclined surface 214 is not particularly limited to the above example. Further, for example, the number of the groove portion 204, the upper inclined surface 209, and the protruding portion 216 is not particularly limited to the above example.

The present disclosure can be used for the oil supply / drainage mechanism.

1: Engine 12: Cylinder 15, 25: Piston (sliding body) 15a, 25a: Piston crown 15b, 25b: Piston skirt 16: Piston pin 17: Conrod 21: Combustion chamber 34, 34L, 34R: Oil supply / drainage mechanism 34La, 34Ra: Check valve part 34Lb, 34Rb: Oil supply / drainage part 101: Fire touch surface 102: Ring groove 103: Pin hole 104: Depression part 105: Protrusion part 106: Piston hydraulic chamber (oil use part) 107: Hole part 108 : Bolt 109: Sliding member 110: Nut 111: Piston skirt hydraulic chamber 112: Compression spring 201: Fire touch surface 202: Ring groove 203: Pin hole 204: Groove part 205: Protrusion part 206: Upper piston hydraulic chamber (oil use part) 207: Lower piston hydraulic chamber (oil-using part) 208: Penetration member 209: Upper inclined surface 214: Lower inclined surface 501: Port member 501a: Piston port (sliding body port) 501b: Contact surface 501c: Port 502: Piston reverse Stop valve (sliding body check valve) 502a: Piston valve body 502b (sliding body valve body): Compression spring 503: Cover 503a: Protrusion 504: Port hydraulic chamber 511: Housing 511a: Bottom 511b: Outer tubular part 511c : Inner tubular part 512: Extension member 512a: Enlarged part 512b: Oil supply / drainage part valve body 513: Compression spring 514: Oil supply / drainage part hydraulic chamber 515: Oil passage 516: Tube part 517: Hydraulic chamber opening 518: Valve seat 519: Compression spring 520: Sealing member

Claims (4)

A sliding body port that communicates with an oil-using portion in a sliding body that slides in a predetermined sliding direction and is formed on one side of the sliding body in the sliding direction, and a sliding body valve body that closes the sliding body port. A check valve portion having a sliding body check valve including
An oil supply / drainage unit provided on one side of the sliding body in the sliding direction,
With
The oil supply / drainage section is
With the housing
An oil supply / drainage unit hydraulic chamber formed in the housing and communicating with a supply oil passage or a discharge oil passage,
A hydraulic chamber opening formed on the other side of the sliding direction in the oil supply / drainage hydraulic chamber,
The oil supply / drainage section valve body is urged in the direction from the oil supply / drainage section hydraulic chamber toward the hydraulic chamber opening and closes the hydraulic chamber opening from the oil supply / drainage section hydraulic chamber side, and is inserted into the sliding body port. With possible extension members
Have,
Oil supply and drainage mechanism. The housing includes an outer tubular portion and an inner tubular portion that slides in the outer tubular portion in the sliding direction.
The inner tubular portion is urged in a direction from one side in the sliding direction toward the other side.
The other end of the inner tubular portion in the sliding direction is located on the other side of the sliding direction than the other end of the outer tubular portion in the sliding direction.
The oil supply / drainage section hydraulic chamber is defined by one side of the inner tubular portion in the sliding direction and the inner peripheral portion of the outer tubular portion.
The hydraulic chamber opening is formed on one side of the inner tubular portion in the sliding direction.
The extending member passes through an opening on the other side of the sliding direction in the inner tubular portion and extends to the outside of the housing.
The oil supply / drainage mechanism according to claim 1. A sealing member is provided on the other side of the inner tubular portion in the sliding direction.
The oil supply / drainage mechanism according to claim 2. It has a switching valve for switching the oil passage communicating with the oil supply / drainage unit hydraulic chamber between the supply oil passage and the discharge oil passage.
The oil supply / drainage mechanism according to any one of claims 1 to 3.

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