JP6107800B2 - Apex seal structure of rotary piston engine - Google Patents

Description

  The present invention belongs to a technical field related to an apex seal structure of a rotary piston engine.

  Conventionally, in a rotary piston engine, it is well known that an apex seal is provided in a seal groove formed at the top of a rotor. The apex seal is attached to the seal groove in a state where the spring is biased toward the trochoidal surface of the rotor housing.

  In Patent Document 1, the cross-sectional shape of the apex seal is changed to a keystone shape, and thus the apex seal is displaced by the displacement of the rotor (displacement away from the trochoidal surface) due to the internal pressure at the initial stage of explosion combustion near the compression top dead center. When the amount of relative protrusion from the rotor increases, the gap between the side wall surface of the seal groove and the side surface of the apex seal expands, and gas pressure tends to act on the back surface (base side surface) of the apex seal. Thus, it is disclosed that the gas backup force is increased and the gas sealability between the apex seal top and the trochoidal surface of the rotor housing is improved.

JP 2008-8199 A

  However, when the rotary piston engine is increased in power by, for example, installing a turbocharger, the gas backup force that presses the apex seal toward the trochoid surface side will increase excessively. The pressing force against the trochoidal surface becomes too large, causing a problem that the wear on the apex seal increases.

  Here, the apex seal has a sliding surface in sliding contact with the trochoidal surface, and the sliding surface has a central portion in the apex seal width direction protruding toward the trochoidal surface from both ends. The apex seal is in line contact with the trochoid surface. As a result, a gap is formed between the portion of the sliding surface of the apex seal other than the contact point with the trochoidal surface and the trochoidal surface. For this reason, it is located on the trailing side and the leading side (the trailing side and the leading side in the rotor rotation direction) of the working chamber (referred to as the combustion working chamber) where explosion combustion has occurred, which is located near the compression top dead center with the rotor rotation Of the two apex seals, the sliding surface of the trailing apex seal (the portion closer to the combustion operation chamber than the contact point) is placed on the bottom side of the seal groove almost simultaneously with the start of explosion combustion. The gas pressure that pushes the apex seal acts on the back surface (base side surface) of the apex seal, and the gas pressure that pushes the apex seal against the trochoidal surface side (gas backup force) acts on the back surface of the apex seal. The gas pressure acts after the gas has passed through the narrow gap between the side surface of the apex seal and the side wall surface of the seal groove. The gas pressure lags action will act in. For this reason, in the initial stage of explosion combustion, the pressing force against the trochoidal surface of the apex seal becomes considerably small (in some cases, a negative value), and thereafter, the pressing force becomes large due to the gas backup force. The same applies to the apex seal on the leading side of the combustion working chamber located near the compression top dead center as the rotor rotates.

  As described above, since the pressing force against the trochoidal surface of the apex seal becomes small at the early stage of explosion combustion, the gas sealing performance at that time becomes a problem, and then the pressing force against the trochoidal surface of the apex seal increases due to the gas backup force. If it passes, wear of the apex seal will become a problem as described above.

  The present invention has been made in view of such a point, and the object of the present invention is to improve the gas sealability at the initial stage of explosive combustion, and thereafter, the pressing force against the trochoidal surface of the apex seal becomes too large. There is in trying to prevent.

  In order to achieve the above object, the present invention includes an apex seal that is mounted in a spring groove toward the trochoidal surface of the rotor housing in a seal groove formed at the top of the rotor in the rotary piston engine. In the apex seal structure of a rotary piston engine, the apex of the apex seal is a sliding surface that is in sliding contact with the trochoid surface, and the central portion of the sliding surface in the width direction of the apex seal is more than the both ends. A sliding surface formed in a curved shape is provided so as to protrude toward the trochoidal surface side, and the apex seal is positioned on the base side with respect to the top side seal portion including the sliding surface and the top side seal portion. It is divided into a base side seal part, and the top side seal part and the base side seal part can be separated from each other. A gap between the side surface of the top side seal portion and the side wall surface of the seal groove portion facing the side surface, the width of the top side seal portion being smaller than the width of the base side seal portion. However, it is set to be larger than the gap between the side surface of the base side seal portion and the side wall surface of the seal groove portion facing the side surface.

  With the above configuration, since the width of the top seal portion is smaller than the width of the base seal portion, the area of the sliding surface can be reduced. As a result, the area of the combustion working chamber side portion from the contact point with the trochoidal surface of the sliding surface of the apex seal on the trailing side and leading side of the combustion working chamber located near the compression top dead center as the rotor rotates is reduced. Can be reduced. As a result, it is possible to reduce the pressing force that acts on the sliding surface in the early stage of explosion combustion and presses the apex seal toward the bottom of the seal groove. Further, the gap between the side surface of the top side seal portion and the side wall surface of the seal groove portion facing the side surface is made larger than the gap between the side surface of the base side seal portion and the side wall surface of the seal groove portion facing the side surface. Therefore, in the apex seal on the trailing side, gas pressure is likely to act on the leading side portion of the top side surface of the base side seal portion almost simultaneously with the start of explosion combustion, and in the apex seal on the leading side, Almost simultaneously with the start of explosion combustion, the gas pressure is likely to act on the trailing side portion of the top side surface of the base side seal portion. As a result, a gap is easily generated between the base side surface of the top side seal portion and the top side surface of the base side seal portion in the trailing and leading apex seals (the top side seal portion and the base portion). The side seal part is easily separated from each other), and gas enters the gap, thereby pressing the top side seal part against the trochoidal surface side against the base side surface of the top side seal part in the early stage of explosion combustion. The gas pressure will act early.

  The separation between the top side seal portion and the base side seal portion is likely to occur particularly when the engine speed is high (when the gas pressure is high), and when the engine speed is low (when the gas pressure is low), The top side seal part and the base side seal part behave integrally, but at this low rotation, the gas pressure acting on the sliding surface, that is, the pressing force pressing the apex seal toward the bottom side of the seal groove part is small, Gas passes between the side surface of the top side seal portion and the base side seal portion on the combustion working chamber side and the side wall surface of the seal groove portion on the combustion working chamber side, and relatively smoothly toward the bottom side of the seal groove portion of the base side seal portion. Easy to enter. Accordingly, it is possible to improve the gas sealability at the early stage of explosion combustion by suppressing the pressing force against the trochoidal surface of the apex seal at the early stage of explosion combustion.

  On the other hand, as the area of the sliding surface is reduced, the area of the base side surface of the top side seal part is also reduced, so that the top side seal part that acts on the top side seal part after the initial stage of explosion combustion The pressing force to be pressed to the trochoidal surface side does not become excessively large, and the gap between the side surface of the base side seal portion and the side wall surface of the seal groove portion is small, so that the gas flows into the base side seal portion particularly at high rotation. It becomes difficult to enter the bottom side of the seal groove. During low rotation, the gas relatively easily enters the bottom side of the seal groove portion of the base side seal portion, but the gas pressure acting on the back surface of the base side seal portion is small. Therefore, it is possible to prevent the pressing force on the trochoidal surface of the apex seal from becoming excessively large while improving the gas sealing property at the early stage of explosion combustion.

  In the apex seal structure of the rotary piston engine, the surface on the base side of the top seal portion is formed in a curved shape so that the central portion in the apex seal width direction on the surface protrudes to the base side from both ends. It is preferable.

  As a result, the gas pressure that presses the top seal portion against the trochoidal surface can be applied to the base side surface of the top seal portion at an early stage of explosion combustion, and the explosion combustion initial stage In addition, it is possible to effectively suppress the pressing force of the apex seal against the trochoidal surface.

  As described above, according to the apex seal structure of the rotary piston engine of the present invention, the apex seal is divided into a top side seal part and a base side seal part, and the top side seal part and the base side seal part are divided. Are attached to the seal groove part so as to be separable from each other, the width of the top side seal part is made smaller than the width of the base side seal part, and the side face of the top side seal part and the seal facing the side face The gap between the side wall surface of the groove is made larger than the gap between the side surface of the base side seal portion and the side wall surface of the seal groove portion facing the side surface, thereby improving gas sealing performance at the initial stage of explosion combustion. However, it is possible to prevent the pressing force against the trochoidal surface of the apex seal from becoming excessively large thereafter, and to suppress wear of the sliding surface of the apex seal.

It is the figure seen from the direction of the axis of rotation of an eccentric shaft in the state where the side housing was removed showing the rotary piston engine to which the apex seal structure concerning the embodiment of the present invention was applied. It is a disassembled perspective view which shows the vicinity of one top part of the rotor in a rotary piston engine. FIG. 3 is a view in the direction of arrow III in FIG. 2. It is the expanded sectional view cut | disconnected in the width direction center of this rotor which shows the vicinity of one top part of a rotor. It is the expanded sectional view cut | disconnected in the width direction center of the rotor which shows the apex seal by the side of the trailing of the combustion working chamber located in the vicinity of a compression top dead center with rotor rotation, and its periphery. FIG. 5 is an enlarged cross-sectional view taken along the center in the width direction of the rotor, showing the apex seal on the leading side of the combustion working chamber located in the vicinity of the compression top dead center with the rotation of the rotor and its periphery.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a rotary piston engine 1 (hereinafter simply referred to as an engine 1) to which an apex seal structure according to an embodiment of the present invention is applied. This engine 1 is a two-rotor type (two-cylinder engine) having two rotors 2 (only one is shown in FIG. 1), and two rotor housings 3 (see FIG. 1) arranged in a direction perpendicular to the plane of FIG. In FIG. 1, only one is shown), and the intermediate housing 4 is sandwiched between them, and the two side housings (not shown) are sandwiched from both sides so as to be integrated. . That is, each rotor housing 3 is sandwiched between the intermediate housing 4 and the side housing adjacent to each other on both sides thereof.

  In FIG. 1, the intermediate housing 4 is visible on the back side of the paper with respect to the rotor 2, and the two side housings are disposed on the front side of the paper with respect to the rotor 2 and the rotor housing 3 illustrated in FIG. 1. One of the side housings is arranged. Further, another rotor housing 3 and the other side housing are arranged in this order on the further inner side of the sheet of FIG. 1 is a rotational axis of the eccentric shaft 6 serving as an output shaft, and hereinafter this is simply referred to as a rotational axis X.

  The rotor housing chambers 7 (cylinders) are defined by the rotor housings 3 and the intermediate housings 4 and the side surfaces of the side housings adjacent to both sides of the rotor housings 3. The rotors 2 are respectively housed in the rotor housing chambers 7. ing. It can be said that the intermediate housing 4 is a side housing common to the two rotor housing chambers 7.

  The inner peripheral surface of the rotor housing 3 is a trochoidal surface 3a drawn by a parallel trochoidal curve, and the rotor accommodating chamber 7 is like a ridge when viewed from the direction of the rotation axis X (the direction perpendicular to the paper surface of FIG. 1). Substantially elliptical shape (substantially elliptical shape defined by a major axis Y and a minor axis Z orthogonal to each other).

  The rotor 2 is composed of a substantially triangular block body in which the central part of each side bulges outward as viewed from the direction of the rotational axis X, and three substantially rectangular flank is provided between the apexes on the outer peripheral surface thereof. A surface 2a (an outer peripheral surface in contact with each working chamber 8 described later) is provided. Recesses 2b are formed at the center of each flank surface 2a.

  Further, as will be described in detail later, the rotor 2 has apex seals 51 (see FIGS. 2 to 6 (not shown in FIG. 1)) at the apexes of the triangles, and these apex seals 51 are rotor housings. 3 is in sliding contact with the trochoidal surface 3a. The side surfaces of the intermediate housing 4 and the side housing adjacent to both sides of the rotor housing 3, the trochoidal surface 3 a of the rotor housing 3, and the flank surface 2 a of the rotor 2, the interior of the rotor housing chamber 7 (the flank surface of the rotor 2). 2 a and the trochoidal surface 3 a of the rotor housing 3), three working chambers 8 are respectively defined. Each apex seal 51 seals between two adjacent working chambers 8.

  Although not shown in the figure, the rotor 2 includes an intermediate housing 4 and a side gear while an internal gear (rotor gear) provided on the inner side of the rotor 2 and an external gear (fixed gear) provided on the side housing are engaged with each other. The eccentric shaft 6 passing through the housing is supported so as to make a planetary rotational movement.

  That is, the rotational motion of the rotor 2 is defined by the meshing of the internal gear and the external gear. The rotor 2 has three apex seals that are in sliding contact with the trochoidal surface 3a of the rotor housing 3, and the eccentric wheel 6a of the eccentric shaft 6 While rotating around, it revolves around the rotation axis X in the same direction as the rotation (including rotation and revolution, simply called rotation of the rotor 2 in a broad sense). Then, the three working chambers 8 move in the circumferential direction while the rotor 2 makes one rotation, and intake, compression, expansion, and exhaust strokes are performed in each of them, and the rotational force generated thereby is transmitted through the rotor 2. And output from the eccentric shaft 6. In addition, during one rotation of the rotor 2, the eccentric shaft 6 rotates three times, and during this time, the three working chambers 8 each perform a combustion cycle once. For this reason, one combustion cycle is performed for one rotation of the eccentric shaft 6.

  More specifically, in FIG. 1, the rotor 2 rotates in the clockwise direction, as indicated by an arrow, and is separated from the major axis Y of the rotor accommodation chamber 7 passing through the rotation axis X as a boundary. The left side of 7 is a region for intake and exhaust strokes, and the right side is a region for compression and expansion strokes.

  When attention is paid to the upper left working chamber 8 in FIG. 1, this working chamber 8 is in an intake stroke in which an air-fuel mixture is formed by intake air and fuel injected from an injector 15 (fuel injection valve). When the working chamber 8 located in is shifted to the compression stroke as the rotor 2 rotates, the air-fuel mixture is compressed therein. Thereafter, as in the working chamber 8 shown on the right side of FIG. 1 (in FIG. 1, this working chamber 8 is at the compression top dead center (TDC)), at a predetermined timing from the latter stage of the compression stroke to the expansion stroke. It is ignited by first and second spark plugs 21 and 22, which will be described later, and an expansion stroke is performed. Then, when the exhaust stroke such as the lower left working chamber 8 in FIG. 1 is finally reached, the combustion gas is exhausted from the exhaust port 10 and then returns to the intake stroke to repeat the above steps. .

  The injector 15 is attached on the long axis Y of the rotor housing 3. The injector 15 is disposed facing the working chamber 8 in the intake stroke or the compression stroke, and directly injects fuel into the working chamber 8.

  A plurality (three in the present embodiment) of intake ports 11 communicate with the working chamber 8 in the intake stroke. In this embodiment, one of these three intake ports 11 opens on the side of the intermediate housing 4 facing the working chamber 8 in the intake stroke (see FIG. 1), and the remaining two (not shown). Is open on the side surface of the side housing facing the working chamber 8 in the intake stroke so as to face the opening of the intake port 11 of the intermediate housing 4. The openings of the intake ports 11 are located near the short axis Z in the outer peripheral side portion of the rotor accommodating chamber 7 when viewed from the direction of the rotation axis X.

  In the rotor housing 3, the first spark plug 21 and the leading side (advance side) and the trailing side (delay side) of the rotor rotation direction across the short axis Z (near the short axis Z) are respectively A second spark plug 22 is attached. These two spark plugs 21 and 22 are used for the first spark plug 21 and the second spark plug 22 to burn the air-fuel mixture in the working chamber 8 in the compression or expansion stroke (the air-fuel mixture compressed in the compression stroke). Ignite in order. In the present embodiment, both the spark plugs 21 and 22 are ignited near the compression top dead center. Hereinafter, the working chamber 8 in which explosion combustion has occurred by this ignition is referred to as a combustion working chamber 8a. The working chamber 8 at the compression top dead center shown on the right side of FIG. 1 is a combustion working chamber 8a.

  The first spark plug 21 is opposed to the leading side of the recess 2b at the compression top dead center in the rotor rotation direction with respect to the leading side in the rotor rotation direction, and the second spark plug 22 is further than the short axis Z of the recess 2b. Opposite the trailing side of the rotor rotation direction. Thus, the recess 2b has a length longer than the distance between the spark plugs 21 and 22. Moreover, both the spark plugs 21 and 22 are located on the center line of the rotor 2 in the width direction (width direction of the flank surface 2a). The width direction of the rotor 2 is the central axis direction of the rotor 2 and also the direction of the rotation axis X.

  A plurality (two in this embodiment) of exhaust ports 10 communicate with the working chamber 8 in the exhaust stroke. In the present embodiment, one of these two exhaust ports 10 opens on the side of the intermediate housing 4 facing the working chamber 8 in the exhaust stroke (see FIG. 1), and the remaining one (not shown). Are open on the side surface of the side housing facing the working chamber 8 in the exhaust stroke so as to face the opening of the exhaust port 10 of the intermediate housing 4. The openings of the exhaust ports 10 are located near the short axis Z of the outer peripheral side portion of the rotor accommodating chamber 7 when viewed from the direction of the rotation axis X (on the opposite side of the short axis Z from the intake port 11). It is located in the position. In the present embodiment, the opening position and the opening shape of the exhaust port 10 are set so that the opening timing of the intake port 11 and the opening timing of the exhaust port 10 do not overlap.

  As shown in FIGS. 2 and 3, a seal groove portion 25 is formed at each top portion of the rotor 2 so as to extend in the width direction of the rotor 2. The apex seal 51 is mounted in the seal groove 25 in a state where the spring is urged toward the trochoidal surface 3a of the rotor housing 3 by two leaf springs 55 and 56 extending in the width direction of the rotor 2. The seal groove portion 25 is a line L (see FIG. 3) connecting the top portion of the rotor 2 where the seal groove portion 25 is formed and the center of the rotor 2 when viewed from the center axis direction of the rotor 2 (direction of the rotation axis X). Reference) is formed. That is, both side wall surfaces of the seal groove portion 25 extend along the line L on both sides of the line L when viewed from the central axis direction of the rotor 2. The apex seal 51 is mounted in the seal groove portion 25 so as to be movable along the line L (along the side wall surfaces of the seal groove portion 25) when viewed from the central axis direction of the rotor 2.

  At both ends of the seal groove 25 in the width direction of the rotor 2 (in the vicinity of both side surfaces of the rotor 2 of the seal groove 25), both ends of the apex seal 51 in the width direction of the rotor 2 (both ends in the longitudinal direction of the apex seal 51) Circular corner seals 31 each having a recessed portion 31e to be fitted are provided. Each corner seal 31 is composed of an inner portion 31b and an outer portion 31c surrounding the inner portion 31b, and the outer portion 31c has a substantially C shape with a part in the circumferential direction cut off. The cut portion 31a and the groove 31d formed in the inner portion 31b constitute the recess 31e. Each corner seal 31 is biased to the outside in the width direction of the rotor 2 by a substantially C-shaped corner seal spring 32 from which a part in the circumferential direction is cut, and is in sliding contact with the side surface of the intermediate housing 4 or the side housing. It is made like that.

  The corner seal 31 includes a side seal 35 and an apex seal that are attached to side groove portions 27 (see FIG. 2 and FIG. 3 (not shown in FIG. 1)) formed on outer peripheral edge portions on both side surfaces of the rotor 2 in the width direction. 51 has the role of a seam. The side seal 35 is slidably brought into contact with the intermediate housing 4 or the side surface of the side housing by a corrugated side seal seal spring 36 (see FIG. 2).

  As shown in FIG. 2, the apex seal 51 is divided into two parts, a first part 51a and a second part 51b, in the width direction of the rotor 2. The first part and the second parts 51a, 51b They are in contact with each other on opposite surfaces that face each other in the width direction. These opposing surfaces are located in the recess 31e into which one end of both ends of the apex seal 51 in the width direction of the rotor 2 is fitted, and the length of the second portion 51b is the length of the first portion 51a. It is considerably shorter than that. The opposing surface is inclined from the base side of the apex seal 51 (bottom side of the seal groove 25) to the second side 51b from the top side (trochoid surface 3a side). Thereby, even if a force acts on the apex seal 51 in the longitudinal direction, the first portion and the second portion 51a, 51b can be absorbed by the displacement from each other along the facing surface.

  The second portion 51b is biased toward the trochoidal surface 3a by one end of the leaf spring 56, and the first portion 51a is moved toward the trochoidal surface 3a by the other end of the leaf spring 56 and both ends of the leaf spring 55. Be energized. The apex seal 51 is not necessarily divided into the first part 51a and the second part 51b.

  On the apex of the apex seal 51, there is formed a sliding surface 51c that is in sliding contact with the trochoidal surface 3a. As shown in FIGS. 3 to 6, the sliding surface 51 c has a central portion of the sliding surface 51 c in the width direction of the apex seal 51 (circumferential direction of the rotor 2) so as to protrude toward the trochoidal surface 3 a side from both ends. The apex seal 51 is in point contact with the trochoid surface 3a (point contact in contact with the contact point Q in the cross-sectional views of FIGS. 5 and 6). A gap is generated between a portion of the sliding surface 51c of the apex seal 51 other than the contact point Q with the trochoidal surface 3a and the trochoidal surface 3a (see FIGS. 5 and 6). The contact point Q moves in the width direction of the apex seal 51 on the sliding surface 51 c depending on the rotational position of the rotor 2.

  As shown in FIGS. 2 and 4, the apex seal 51 (first portion 51a) includes a top side seal portion 51d including the sliding surface 51c, and a base side (seal groove portion 25) than the top side seal portion 51d. The base side seal part 51e is located on the bottom side of the base part, and the top side seal part 51d and the base side seal part 51e are attached to the seal groove part 25 so as to be detachable from each other. In FIG. 4 to FIG. 6, the leaf springs 55 and 56 are not shown.

  And the width | variety of the said top part side seal part 25d is made smaller than the width | variety of the said base part side seal part 51e. The width of the seal groove 25 is constant over the entire area from the opening facing the trochoidal surface 3a to the bottom. Thereby, the gap between the side surface of the top seal portion 51d and the side wall surface of the seal groove portion 25 facing the side surface is larger than the gap between the side surface of the base side seal portion 51e and the side wall surface of the seal groove portion 25 facing the side surface. Has also been enlarged. 4 to 6, the gap between the side surface of the top side seal portion 51 d and the side wall surface of the seal groove portion 25 facing the side surface, and the side surface of the base side seal portion 51 e and the seal groove portion 25 facing the side surface. The gap with the side wall surface is exaggerated.

  When the apex seal 51 (the top-side seal portion 51d and the base-side seal portion 51e) is brought close to one side in the width direction of the apex seal 51 (the width direction of the seal groove 25), the apex seal 51 of the top-side seal portion 51d. The gap between the side surface on the other side in the width direction and the side wall surface on the other side in the width direction of the seal groove portion 25 is larger than 70 μm and not more than 110 μm, and the apex seal 51 of the base side seal portion 51e in the width direction. The gap between the side surface on the other side and the side wall surface on the other side in the width direction of the seal groove portion 25 is preferably 40 μm and 70 μm or less. Even when the apex seal 51 is brought close to the other side in the width direction of the apex seal 51, the one side surface in the width direction of the apex seal 51 in the width direction of the apex seal 51 and the one side in the width direction of the seal groove portion 25 are also included. The gap with the side wall surface on the side is larger than 70 μm and not more than 110 μm, and the one side surface in the width direction of the apex seal 51 of the base side seal portion 51 e and the one side side in the width direction of the seal groove portion 25. The gap with the wall surface is preferably 40 μm and 70 μm or less.

  Further, in the present embodiment, the base side surface of the top side seal portion 51d is formed in a curved shape so that the central portion of the apex seal 51 in the width direction protrudes to the base side from both ends. On the other hand, the top side surface of the base side seal portion 51e is formed in a flat shape.

  Here, as shown in FIG. 5, there is a gap between the portion of the sliding surface 51c of the apex seal 51 other than the contact point Q and the trochoidal surface 3a as described above due to the shape of the sliding surface 51c. Therefore, two apex seals located on the trailing side and the leading side of the combustion working chamber 8a located near the compression top dead center (in the present embodiment, near the compression top dead center) as the rotor 2 rotates. 51 of the trailing apex seal 51A (reference numeral 51A as shown in FIG. 5) on the sliding surface 51c (the portion closer to the combustion working chamber 8a than the contact point Q) At substantially the same time, the gas pressure P1 that presses the apex seal 51A toward the bottom side of the seal groove 25 acts. At this time, the apex seal 51A is brought closer to the side opposite to the combustion working chamber 8a in the width direction. Temporarily, the apex seal 51A is not a divided structure of the top side seal portion 25d and the base side seal portion 51e, and the gap between the side surface of the apex seal 51A and the side wall surface of the seal groove portion 25 does not leak gas. In the case of a gap, the gas pressure (gas backup force) that presses the apex seal 51A toward the trochoidal surface 3a is applied to the back surface (base side surface) of the apex seal 51A. Acts later than. For this reason, in the initial stage of the explosion combustion, the pressing force against the trochoidal surface 3a of the apex seal 51A is considerably reduced, and thereafter, the pressing force is increased by the gas backup force (in this embodiment, the combustion working chamber 8a is compressed and dead. When the point is reached, the pressing force is the largest). In particular, when the engine 1 has a high output, this pressing force may become too large. The above also applies to the apex seal 51B on the leading side of the combustion working chamber 8a located near the compression top dead center with the rotation of the rotor 2 shown in FIG. 6 (reference numeral 51B as shown in FIG. 6). It is. 5 and 6, the rotation direction of the rotor 2 is the clockwise direction.

  However, in this embodiment, since the width of the top side seal portion 51d is smaller than the width of the base side seal portion 51e, the area of the sliding surface 51c can be reduced. As a result, the combustion operation is performed more than the contact point between the sliding surface 51c of the trailing side and leading side apex seals 51A and 51B of the combustion working chamber 8a located near the compression top dead center with the rotation of the rotor 2 than the trochoidal surface 3a. The area of the portion on the chamber 8a side can be reduced. As a result, it is possible to reduce the pressing force that presses the apex seals 51A and 51B to the bottom side of the seal groove 25, which acts on the sliding surface 51c in the early stage of explosion combustion. Further, the gap between the side surface of the top side seal portion 51d and the side wall surface of the seal groove portion 25 facing the side surface is larger than the gap between the side surface of the base side seal portion 51e and the side wall surface of the seal groove portion 25 facing the side surface. In the trailing apex seal 51A, gas pressure is likely to act on the leading side portion of the top side surface of the base side seal portion 51e substantially simultaneously with the start of explosion combustion. In the apex seal 51B, gas pressure easily acts on the trailing side portion of the top side surface of the base side seal portion 51e substantially simultaneously with the start of explosion combustion. Accordingly, a gap is likely to be generated between the base side surface of the top side seal portion 51d and the top side surface of the base side seal portion 51e (the top side seal portion 51d and the base side seal portion 51e are separated from each other). The gas enters the gap (exaggerated in FIGS. 5 and 6). As a result, as shown in FIGS. 5 and 6, apex seals 51A and 51B are formed at the initial stage of explosion combustion. The gas pressure P2 that presses the top seal portion 51d toward the trochoidal surface 3a acts on the base side surface of the top seal portion 51d at an early stage. In particular, as in this embodiment, the base side surface of the top seal portion 51d is formed in a curved shape so that the central portion of the apex seal 51 in the width direction protrudes to the base side from both ends. As a result, it becomes easier for gas to enter between the base-side surface of the top-side seal portion 51d and the top-side surface of the base-side seal portion 51e, and the base portion of the top-side seal portion 51d at the initial stage of explosive combustion. The gas pressure P2 acts on the side surface even earlier.

  The separation between the top seal portion 51d and the base seal portion 51e is likely to occur particularly when the engine speed is high (when the gas pressure is high), and when the engine speed is low (when the gas pressure is low). The top-side seal portion 51d and the base-side seal portion 51e behave integrally. At this low rotation, the gas pressure acting on the sliding surface 51c, that is, the apex seals 51A and 51B is moved to the bottom side of the seal groove portion 25. The pressing force to be pressed is small, and the gas passes between the side surface on the combustion working chamber 8a side of the top side seal portion 51d and the base side sealing portion 51e and the side wall surface on the combustion working chamber 8a side of the seal groove 25 in the base portion. It is easy to enter the seal groove part 25 bottom side of the side seal part 25 relatively smoothly. Therefore, it is possible to improve the gas sealability at the early stage of the explosion combustion by suppressing the pressing force of the apex seals 51A, 51B against the trochoid surface 3a at the early stage of the explosion combustion.

  On the other hand, since the area of the base side surface of the top side seal portion 51d is also reduced in the same manner as the area of the sliding surface 51c is reduced, the top side acting on the top side seal portion 51d after the initial stage of explosion combustion. The pressing force for pressing the seal portion 51d toward the trochoidal surface 3a is not excessively large, and the gap between the side surface of the base-side seal portion 51e and the side wall surface of the seal groove portion 25 is small, particularly at high rotations. It becomes difficult for gas to enter the seal groove portion 25 bottom side of the base side seal portion 51e. During low rotation, the gas relatively easily enters the bottom side of the seal groove portion 25 of the base side seal portion 51e, but the gas pressure acting on the back surface of the base side seal portion 51e (the surface facing the bottom portion of the seal groove portion 25) is small. . Accordingly, it is possible to prevent the pressing force of the apex seals 51A and 51B against the trochoidal surface 3a from becoming excessively large while improving the gas sealability at the early stage of explosion combustion.

  The present invention is not limited to the embodiment described above, and can be substituted without departing from the spirit of the claims.

  For example, in the above-described embodiment, the base-side surface of the top-side seal portion 51d is formed in a curved shape so that the central portion of the apex seal 51 in the width direction protrudes to the base side from both ends. The base side surface of the top side seal portion 51d may be flat so as to contact the entire top side surface of the base side seal portion 51e. Alternatively, the base-side surface of the top-side seal portion 51d is curved or flat as in the above embodiment, and the top-side surface of the base-side seal portion 51e is the apex seal on the surface. The central part in the 51 width direction may be formed in a curved shape so as to protrude from the both ends to the top side.

  The above-described embodiments are merely examples, and the scope of the present invention should not be interpreted in a limited manner. The scope of the present invention is defined by the scope of the claims, and all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  The present invention provides an apex seal structure for a rotary piston engine, comprising an apex seal that is mounted in a seal groove formed on the top of a rotor in a rotary piston engine in a spring-biased state toward the trochoidal surface of the rotor housing. This is particularly useful when the rotary piston engine has a high output, for example, by installing a turbocharger.

DESCRIPTION OF SYMBOLS 1 Rotary piston engine 2 Rotor 3 Rotor housing 3a Trochoid surface 8 Working chamber 8a Combustion working chamber 25 Seal groove part 51 Apex seal 51c Sliding surface 51d Top side seal part 51e Base side seal part

Claims (2)

An apex seal structure for a rotary piston engine comprising an apex seal mounted in a spring groove toward the trochoidal surface of the rotor housing in a seal groove formed on the top of the rotor in the rotary piston engine,
At the top of the apex seal, it is a sliding surface that is in sliding contact with the trochoid surface, and is formed in a curved shape so that the central portion of the sliding surface in the apex seal width direction protrudes toward the trochoidal surface from both ends. Provided with a sliding surface,
The apex seal is divided into a top-side seal portion including the sliding surface and a base-side seal portion located on the base side with respect to the top-side seal portion, and the top-side seal portion and the base-side seal Are attached to the seal groove so as to be separable from each other,
The width of the top side seal portion is smaller than the width of the base side seal portion, and the gap between the side surface of the top side seal portion and the side wall surface of the seal groove portion facing the side surface is the base side seal portion. An apex seal structure for a rotary piston engine, wherein the apex seal structure is larger than a clearance between the side surface of the seal groove and the side wall surface of the seal groove facing the side surface. In the apex seal structure of the rotary piston engine according to claim 1,
A surface of the top side seal portion on the base side is formed in a curved shape so that a central portion of the surface in the apex seal width direction protrudes to the base side from both ends. Apex seal structure.

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