rotary engine

Abstract

To improve fuel combustion performance of a rotary engine.SOLUTION: A recess 7 of an outer peripheral surface 2a of a rotor 2 is equipped with a first recessed portion 71 that is disposed on an L side as compared with an outer peripheral center C and extends toward the L side, a second recessed portion 72 that extends from the first recessed portion 71 to the L side, and a third recessed portion 73 that continues to the first recessed portion and extends to a T side than the outer peripheral center C. The first recessed portion 71, the second recessed portion 72 and the third recessed portion 73 are equipped with bottom surfaces 71a, 72a, and 73a that respectively have predetermined length L1, L2, L3 in a longitudinal direction of the outer peripheral surface. Concerning a cross section of the recess 7 when traversing the recess 7 by a plane orthogonal to the longitudinal direction of the outer peripheral surface 2a and passing through a rotation axis X of the rotor 2, a cross section of the bottom surface 71a in the first recessed portion 71 becomes the largest as compared with a cross section of the bottom surface 72a in the second recessed portion 72 and a cross section of the bottom surface 73a in the third recessed portion 73.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The technology disclosed herein relates to rotary engines. [Background technology]

[0002] In a rotary engine, a combustion chamber is formed between the rotor and a rotor housing having a trochoidal inner peripheral surface. A recess (depression) that forms the combustion chamber is formed on the outer peripheral surface of the rotor. For example, Patent Document 1 describes such a rotor recess.

[0003] Specifically, Patent Document 1 discloses that the volume of the leading-side recess, which extends from the center of the longitudinal direction of the outer peripheral surface to the front side in the rotor rotation direction, is made larger than the volume of the trailing-side recess, which extends to the front side in the rotor rotation direction. The recess disclosed in Patent Document 1 aims to improve thermal efficiency by advancing the center of gravity of combustion by increasing the volume of the leading-side recess, thereby promoting flame growth and enabling advance ignition and shortening the ignition delay period. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-12410 Summary of the Invention [Problem to be solved by the invention]

[0005] However, promoting flame growth can lead to rapid heat generation due to the accelerated combustion of the air-fuel mixture, which can lead to concerns about combustion noise and gas leakage, and furthermore, the increased cooling loss can be detrimental to improving fuel efficiency.

[0006] The present disclosure has been made in consideration of the above points, and its purpose is to improve the fuel efficiency of rotary engines. [Means for solving the problem]

[0007] A first aspect of the present disclosure relates to a rotary engine comprising: a rotor housing having a substantially elliptical trochoidal inner peripheral surface; side housings arranged on either side of the rotor housing and forming a rotor accommodating chamber together with the rotor housing; a substantially triangular rotor accommodated within the rotor accommodating chamber, dividing the rotor accommodating chamber into three working chambers, and rotating to move each working chamber circumferentially, causing each working chamber to perform intake, compression, expansion, and exhaust strokes in sequence; an ignition plug provided in the rotor housing; and a control unit that controls the operation of the spark plug, wherein recesses are formed in each outer peripheral surface of the rotor that divides the working chambers.

[0008] In the rotary engine, the recess in the outer peripheral surface of the rotor is of Longitudinal direction is the midpoint of the a first recessed portion disposed on the front side of the rotor in the rotation direction relative to the center and extending toward the front side; In contrast the second recess extending forward and, Front side of the center in the direction of rotation and facing the front side and a third recess extending The first recess includes a first bottom surface having a predetermined first depth along a straight line perpendicular to the outer circumferential surface and extending toward the rotational axis of the rotor, the second recess includes a second bottom surface having a predetermined second depth formed along the straight line shallower than the first depth, and the third recess includes a third bottom surface having a predetermined third depth formed along the straight line shallower than the second depth, and the recess further includes a first connecting surface extending at an angle from the first bottom surface to the second bottom surface so as to connect the first bottom surface and the second bottom surface. and a second connecting surface extending at an angle from the first bottom surface to the third bottom surface so as to connect the first bottom surface and the third bottom surface, wherein the length of the first bottom surface is shorter than the length of the second bottom surface and longer than the lengths of the first connecting surface and the second connecting surface, the length of the first bottom surface is between 2 / 10 and 4 / 10 of the length from the center in the longitudinal direction of the outer peripheral surface to the front end of the outer peripheral surface, and the length from the center to the front end of the recess is longer than the length from the center to the front end of the recess.

[0009] According to the first aspect of the present disclosure, the cross-sectional area of ​​the recess when crossing the recess on a plane perpendicular to the rotation direction and passing through the rotation axis of the rotor is 1st bottom The cross-sectional area of ​​the above is the first cross-sectional area. 2nd bottom The cross-sectional area of ​​the above is the second cross-sectional area. 3rd bottom If the cross-sectional area of ​​is the third cross-sectional area, 1st cross-sectional area > 2nd cross-sectional area > 3rd cross-sectional area and the control unit determines whether the spark plug is 2nd bottom The operation of the spark plug is controlled so that the ignition timing is before the top dead center of the compression stroke and faces the piston. This ignites the air-fuel mixture present between the second bottom surface and the spark plug, generating a flame that is sprayed forward from the spark plug, and as the rotor rotates, the air-fuel mixture is supplied to the flame in turn from the first bottom surface and the third bottom surface.

[0010] Hereinafter, the longitudinal center of the outer peripheral surface may be simply referred to as the "center of the outer peripheral surface," the front side in the rotational direction may be referred to as the "L side (Leading side)," the near side in the rotational direction may be referred to as the "T side (Trailing side)," and the top dead center of the compression stroke may be referred to as "TDC."

[0011] According to the first aspect, the spark plug ignites the air-fuel mixture around the second recess at a timing earlier than TDC. The flame generated by this ignition blows out from the spark plug toward the L side.

[0012] As the rotor rotates, the air-fuel mixture is supplied to the flame from the first recess, which is located on the T side of the second recess, and the flame grows as the mixture is burned. After that, the air-fuel mixture is supplied through the third recess, which is located further on the T side than the first recess, and the mixture is burned up, completing one cycle of combustion in one working chamber.

[0013] Here, the first recessed portion, which has a relatively large cross-sectional area, is not only located on the L side of the third recessed portion, but also located further on the L side than the center of the outer circumferential surface. Therefore, the first recessed portion can supply the air-fuel mixture to the flame at a timing before TDC, that is, at a timing in the first half of combustion immediately after ignition.

[0014] Generally, the gap between the center of the outer peripheral surface and the rotor housing narrows as the TDC approaches. However, by making the cross-sectional area of ​​the first recess relatively large, a larger amount of the mixture can be supplied to the flame while maintaining the fluidity of the unburned mixture compared to when the cross-sectional area is made smaller. This allows a larger amount of the mixture to be burned immediately after ignition.

[0015] In addition, by relatively increasing the cross-sectional area of ​​the first recess, the squish flow of the air-fuel mixture can be weakened and its flow rate can be reduced. In other words, it is possible to burn a large amount of air-fuel mixture in the first half of combustion while allowing the combustion to proceed slowly. As a result, it is possible to suppress sudden heat generation and reduce combustion noise, gas leakage, and deterioration of fuel efficiency due to increased cooling loss.

[0016] Furthermore, by making the cross-sectional area of ​​the second recess smaller than that of the first recess, the air-fuel mixture near the second recess is under higher pressure than the air-fuel mixture near the first recess, which improves the ignition ability of the unburned air-fuel mixture when it is ignited.

[0017] Furthermore, by making the cross-sectional area of ​​the third recess relatively small, the squish flow pushed out from the third recess toward the L side can be strengthened and its flow velocity can be increased. This allows the remaining air-fuel mixture to be smoothly supplied to the flame in the latter half of combustion after TDC, enabling it to be efficiently burned up. By smoothly supplying the unburned air-fuel mixture, the occurrence or scale of so-called two-stage combustion can be suppressed, and thus cooling loss can be suppressed.

[0018] In addition, increasing the cross-sectional area of ​​the first recess is equivalent to relatively reducing the cross-sectional areas of the second and third recesses, which allows the engine's geometric compression ratio to be maintained and thermal efficiency to be ensured while slowing combustion.

[0019] Thus, according to the first aspect, while a large amount of air-fuel mixture is supplied from the first recess, the combustion thereof is allowed to proceed slowly, thereby suppressing combustion noise, gas leakage, etc., while suppressing cooling loss and improving fuel economy. Furthermore, setting the cross-sectional areas of the second recess and the third recess as described above is further advantageous in improving fuel economy.

[0020] Furthermore, the first According to this aspect, the length of the bottom surface of the first recess is shorter than the length of the bottom surface of the second recess and shorter than the lengths of the first connecting surface and the connecting surface. stomach.

[0021] the above composition According to the specification, the bottom surface (second bottom surface) of the second recess, which is configured to face the spark plug during ignition, is elongated compared to the bottom surface (first bottom surface) of the adjacent first recess. As a result, even if the ignition timing changes depending on the engine operating conditions, such as the introduction of EGR, the spark plug can be positioned to face the second bottom surface during ignition without being positioned away from the second bottom surface. This allows for changes in ignition timing and ensures a path for the air-fuel mixture to reach the plug position.

[0022] Furthermore, the first According to the embodiment, Above first bottom The length of Above center (From the center of the outer periphery) to the front end of the outer periphery, it is 2 / 10 or more and 4 / 10 or less 。

[0023] Hereinafter, the front end of the outer circumferential surface may be referred to as the "L-side recess end portion."

[0024] the above composition According to the document, the length of the bottom of the first recess is set to 2 / 10 or more of the length of the L-side recess end. This is advantageous for expanding the volume of the first recess and weakening the flow rate of the squish flow of the air-fuel mixture. Furthermore, by setting the length of the bottom of the first recess to 4 / 10 or less of the length of the L-side recess end, the length of the bottom of the second recess is kept to a minimum, widening the range of rotor rotation angles at which ignition can be achieved with the spark plug facing the second recess, which is advantageous for advancing the ignition timing.

[0025] In addition, the first aspect of the present disclosure 2 According to the embodiment, Above third bottom The length of Above first bottom and Above second bottom Each Reno It may also be shorter than the sum of the lengths.

[0026] The above item 2According to this aspect, by making the bottom surface of the third recess relatively short, the unburned air-fuel mixture can be supplied more quickly from the T side to the L side relative to the center of the outer circumferential surface.

[0027] In addition, the first aspect of the present disclosure 3 According to the embodiment, Above third bottom The length of Above center The length from the recess to the front end of the recess may be 2 / 10 or more and 5 / 10 or less of the length from the recess to the front end of the recess. This makes it possible to greatly advance the ignition timing while suppressing two-stage combustion and combustion noise.

[0028] In addition, the first aspect of the present disclosure 4 According to the embodiment, Above center The length from the front edge of the recess is Above center The distance between the first recess and the second recess may be 7 / 10 or more and 9 / 10 or less of the length from the first recess to the front end of the outer circumferential surface. This widens the range of rotor rotation angles at which ignition can be achieved with the spark plug facing the second recess, which is advantageous for advancing the ignition timing.

[0029] In addition, the first aspect of the present disclosure 5 According to this aspect, the spark plug may be arranged in the rotor housing at a position on the front side of the rotor housing across a minor axis of the rotor housing, and the control unit may control the operation of the spark plug so that the ignition timing falls within a range of 55° or less before top dead center of the compression stroke. [Effects of the Invention]

[0030] As described above, according to the present disclosure, the fuel economy performance of a rotary engine can be improved. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a perspective view showing an overview of a rotary engine according to an embodiment of the present invention. [Figure 2] FIG. 2 is a front view showing the rotor and rotor housing of the engine. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] Cross-sectional view showing the size of the gap between the rotor and rotor housing at TDC. [Figure 6] 10 is a graph showing a change in the cross-sectional area of ​​a recess. [Figure 7] FIG. 2 is a cross-sectional view showing the relationship between the rotor and the rotor housing at an ignition timing before TDC. [Figure 8] FIG. 2 is a cross-sectional view showing the relationship between the rotor and the rotor housing in the first half of combustion before TDC. [Figure 9] FIG. 2 is a cross-sectional view showing the relationship between the rotor and the rotor housing in the latter half of combustion after TDC. DETAILED DESCRIPTION OF THE INVENTION

[0032] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description of preferred embodiments is merely exemplary in nature and is not intended to limit the scope of the present invention, its applications, or uses.

[0033] <Overall structure of the rotary engine> Fig. 1 is a perspective view showing an overview of a rotary engine 1 (hereinafter simply referred to as engine 1) according to an embodiment of the present disclosure, and Fig. 2 is a front view showing a rotor 2 and a rotor housing 3 of the engine 1.

[0034] The engine 1 shown in Fig. 1 is mounted on a vehicle and has one or more rotors 2 (two in the illustrated example). An intermediate housing 4 is provided between two rotor housings 3, each housing housing a rotor 2. Side housings 5 ​​are provided on both outer sides of the two rotor housings 3. Focusing on one rotor housing 3, the intermediate housing 4 is located on one side of the rotor housing 3 and can be considered a side housing that forms a rotor accommodating chamber 31 together with the rotor housing 3 and the side housing 5.

[0035] In Figure 1, the front side (right side of Figure 1) of the engine 1 is partially cut away to show the inside of the engine, and the rear side (left side of Figure 1) of the side housing 5 is also shown separated to show the inside of the engine. The symbol X in the figure indicates the rotation axis of the eccentric shaft serving as the output shaft.

[0036] As shown in Fig. 2, the rotor housing 3 has a trochoidal inner peripheral surface 3a that is substantially elliptical (bale-shaped) when viewed from the direction of the rotation axis X, which is described by a parallel trochoid curve. As shown in Fig. 1, the inner peripheral surface of the rotor housing 3, the inner surfaces 4a on both sides of the intermediate housing 4, and the inner surface 5a of the side housing 5 form a rotor accommodating chamber 31, and the rotor 2 is accommodated in this rotor accommodating chamber 31. The rotor accommodating chambers 31 on both sides of the intermediate housing 4 have the same configuration except that the rotation phase of the rotor 2 is different.

[0037] When viewed from the direction of rotation axis X, rotor 2 has a generally triangular shape with the center of each side bulging outward, and recesses 7 are formed on the generally rectangular outer peripheral surface 2a between the apexes of the triangle. Apex seals 14 provided at each apex of the triangle of rotor 2 slide against the trochoid inner peripheral surface 3a of rotor housing 3 as rotor 2 rotates (apex seals 14 are only shown in FIG. 6). As shown in FIG. 2, this rotor 2 divides the interior of rotor accommodating chamber 31 into three working chambers 8.

[0038] The rotor 2 is supported by an eccentric ring 6a of the eccentric shaft 6, and while rotating, it revolves around the rotation axis X in the same direction as the rotation (this rotation and revolution are, in a broad sense, simply referred to as the rotation of the rotor 2). During one rotation of the rotor 2, the three working chambers 8 move circumferentially, and each chamber undergoes an intake, compression, expansion (combustion), and exhaust stroke. The rotational force generated by this movement is output from the eccentric shaft 6 via the rotor 2.

[0039] In FIG. 2, the rotor 2 rotates clockwise as indicated by the arrow, and the rotor accommodating chamber 31 is divided by the major axis Y of the rotor accommodating chamber 31, which passes through the rotation axis X. The left side of the rotor accommodating chamber 31 is generally the area for the intake stroke and exhaust stroke, and the right side is generally the area for the compression stroke and expansion stroke.

[0040] 1, intake ports 11-13 and an exhaust port 10 open at locations corresponding to the intake stroke and exhaust stroke regions on the inner surface 4a of the intermediate housing 4 and the inner surface 5a of the side housing 5. Although not shown, a fuel injection valve that injects fuel into the working chamber 8 during the intake stroke or compression stroke is provided at the top of the rotor housing 3.

[0041] 2, the spark plug 9 is attached to the side of the rotor housing 3 at a position on the L side in the direction of rotation of the rotor 2 (hereinafter referred to as the "rotor rotation direction") across the minor axis Z of the rotor accommodating chamber 31 that passes through the rotation axis X, with its electrode exposed toward the rotor accommodating chamber 31. The major axis Y and the minor axis Z are perpendicular to each other.

[0042] Although not shown, the engine 1 is provided with an EGR device that recirculates part of the exhaust gas to the intake passage, and the recirculation of the exhaust gas is performed depending on the operating state of the engine 1.

[0043] The engine 1 also includes a control unit as a control section that controls the operation of the engine 1, including the operation of the intake throttle valve, the fuel injection valve, the spark plug 9, and the EGR device.

[0044] <About the control unit> The control unit is based on a microcomputer and includes a central processing unit (CPU) that executes programs, a memory configured with, for example, RAM or ROM that stores programs and data, and a signal input / output (I / O) bus. Various information signals are input to the control unit from the vehicle's accelerator position sensor, vehicle speed sensor, engine rotation angle sensor, air-fuel ratio sensor, engine water temperature sensor, air flow sensor, etc.

[0045] Based on input signals from various sensors, the control unit determines the operating state of the engine 1. Depending on the determined operating state, the control unit controls the throttle valve opening, the EGR rate by the EGR device, the ignition timing by the spark plug 9 in each working chamber 8, and the fuel injection amount and fuel injection timing by the fuel injection valve.

[0046] The ignition timing of the spark plug 9 is set to 55° or less before top dead center (BTDC) of the compression stroke, preferably within the range of 30° to 50°, and the timing of energization of the ignition coil of the spark plug 9 is controlled based on this setting.

[0047] The ignition timing is controlled according to the EGR rate so that the center of gravity of combustion is located at an appropriate position with high thermal efficiency, between 10° and 30° after top dead center (ATDC) of the compression stroke. As shown by the dotted line in Figure 2, when one of the apexes of the rotor 2 is positioned on the minor axis Z on the opposite side of the spark plug 9, the working chamber 8 located on the opposite side of that apex is at TDC.

[0048] As the EGR rate increases, the ignition delay period becomes longer and the center of combustion gravity is retarded. Therefore, the ignition delay period is set according to the EGR rate, and the target heat generation start timing (target time for the apparent start of heat generation) is also set according to the EGR rate. Then, the ignition timing of the spark plug 9 is set to a time advanced by the ignition delay period from the target heat generation start timing.

[0049] <About the rotor recess> Fig. 3 is a plan view showing the outer peripheral surface 2a of the rotor 2. Fig. 4 is a longitudinal cross-sectional view of the rotor 2, and Fig. 5 is a cross-sectional view showing the size of the gap between the rotor 2 and the rotor housing 3 at TDC. Fig. 6 is a graph showing the change in the cross-sectional area of ​​the recess.

[0050] Here, Fig. 4 corresponds to the IV-IV cross section in Fig. 3. The aa cross section of the second recess 72 in Fig. 4 corresponds to the upper diagram (a) in Fig. 5, the bb cross section of the first recess 71 corresponds to the central diagram (b) in Fig. 5, and the cc cross section of the third recess 73 corresponds to the lower diagram (c) in Fig. 5.

[0051] FIG. 6 also shows how the recess cross-sectional area changes in the longitudinal direction of the rotor outer peripheral surface 2a. The horizontal axis of FIG. 6 represents position coordinates (unit: mm) with the origin (0) at the center of the longitudinal direction of the rotor outer peripheral surface 2a, with the L side represented as a plus and the T side represented as a minus. More precisely, the length position measured on a straight line connecting the apex seals 14 located at both ends of the rotor outer peripheral surface 2a corresponds to the position coordinates referred to here. In FIG. 6, reference numeral 9a denotes the plug hole of the spark plug 9.

[0052] (Overall structure of the recess) 3, the recess 7 formed in the outer peripheral surface 2a of the rotor 2 (hereinafter referred to as the "rotor outer peripheral surface") extends long in the rotor rotation direction. The center of the recess 7 in the rotor rotation direction is offset toward the L side from the center C in the longitudinal direction of the rotor outer peripheral surface 2a (hereinafter referred to as the "outer peripheral surface center").

[0053] As a result, the length Ll from the outer peripheral surface center C to the L-side end of the recess 7 (hereinafter referred to as the "L-side recess end") 7l is longer than the length Lt from the outer peripheral surface center C to the T-side end of the recess 7 (hereinafter referred to as the "T-side recess end") 7t (Ll > Lt). Note that "length" here refers to the length measured along the rotor outer peripheral surface 2a. Unless otherwise specified, the same applies to various "lengths" that appear below. Furthermore, the "outer peripheral surface center C7" refers to a portion having a central angle of about 4 to 8 degrees of the rotor 2.

[0054] Specifically, it is preferable that the length Lt from the center C of the outer peripheral surface to the T-side recess end 7t is 2 / 10 or more and 5 / 10 or less of the length Ll from the center C of the outer peripheral surface to the L-side recess end 7l (the latter length Ll is 2 times or more and 5 times or less of the former length Lt), and more preferably it is approximately 1 / 4.

[0055] Furthermore, the length Ll from the outer peripheral surface center C to the L-side recess end 7l (the starting position on the L side of the entire recess 7) is preferably in the range of 7 / 10 to 9 / 10, and more preferably 3 / 4, of the length La from the outer peripheral surface center C to the L-side end of the rotor outer peripheral surface 2a. On the other hand, the length Lt from the outer peripheral surface center C to the T-side recess end 7t (the starting position on the T side of the entire recess 7) is preferably in the range of 18 / 100 to 36 / 100, of the length La from the outer peripheral surface center C to the L-side end of the rotor outer peripheral surface 2a.

[0056] The recess 7 according to this embodiment includes a first recess 71 disposed on the L side relative to the center C of the outer circumferential surface, a second recess 72 disposed on the L side relative to the first recess 71, and a third recess 73 disposed on the T side relative to the first recess 71. The volume of the recess 7 is set so that the geometric compression ratio of the working chamber 8 is 9.7 or more.

[0057] Here, the first recess 71 is disposed on the L side relative to the center C of the outer circumferential surface and extends toward the L side. The second recess 72 is continuous with the first recess 71 and extends toward the L side. The third recess 73 is continuous with the first recess 71 and extends beyond the center C of the outer circumferential surface to the T side.

[0058] The three recesses 71 to 73 have bottom surfaces 71a to 73a, respectively, having predetermined lengths L1 to L3 in the longitudinal direction of the rotor outer peripheral surface 2a. Specifically, the first recess 71 has a first bottom surface 71a having a first length L1 in the longitudinal direction. The second recess 72 has a second bottom surface 72a having a second length L2 in the longitudinal direction. The third recess 73 has a third bottom surface 73a having a third length L3 in the longitudinal direction. The relationship between the lengths will be described later.

[0059] As shown in Fig. 4, the first recess 71 is recessed deeper than the second recess 72 and the third recess 73. For example, in this embodiment, the depth D1 of the first bottom surface 71a is deeper than the depth D2 of the second bottom surface 72a and the depth D3 of the third bottom surface 73a (see Fig. 5). Furthermore, as shown in Figs. 4 and 5 and Fig. 6 described below, the depth D2 of the second bottom surface 72a is deeper than the depth D3 of the third bottom surface 73a.

[0060] The "depth" here refers to the depth measured along a straight line that is perpendicular to the rotor outer peripheral surface 2a and extends toward the rotation axis X. In particular, in this embodiment, the maximum depth in the rotor width direction among the depths measured along such a straight line is considered to be the "depth."

[0061] Specifically, the depth D2 of the second bottom surface 72a can be greater than or equal to 1 / 3 and less than or equal to 1 / 2 of the depth D1 of the first bottom surface 71a, and the depth D3 of the third bottom surface 73a can be greater than or equal to 1 / 3 and less than or equal to 1 / 2 of the depth D2 of the second bottom surface 72a.

[0062] 3, the first recess 71 is wider than the second recess 72 and the third recess 73 in the short-side direction (rotor width direction) of the rotor outer peripheral surface 2a. For example, in this embodiment, the width W1 of the first recess 71 is longer than the width W2 of the second recess 72 and the width W3 of the third recess 73. As shown in FIG. 3, the width W2 of the second recess 72 is set to be approximately the same as the width W3 of the third recess 73. Note that the "width" here refers to the depth measured along the short-side direction of the rotor outer peripheral surface 2a.

[0063] Thus, when comparing the bottom surfaces 71a, 72a, 73a of the first recess 71, the second recess 72, and the third recess 73, the first bottom surface 71a of the first recess 71 is wider and deeper than the bottom surfaces of the other recesses. Also, the second bottom surface 72a of the second recess 72 has substantially the same width as the third bottom surface 73a of the third recess 73, but is deeper.

[0064] 5, the first bottom surface 71a, the second bottom surface 72a, and the third bottom surface 73a extend flat in the rotor width direction, with both side portions rising in an arc shape. Therefore, the cross-sectional area of ​​the recess 7 when crossing the recess 7 on a plane that is perpendicular to the longitudinal direction of the rotor outer peripheral surface 2a and passes through the center of the rotor 2 has a size that approximately corresponds to the depth of the recess 7.

[0065] Therefore, in consideration of the magnitude relationship between the width and the depth described above, if the cross-sectional area of ​​the first bottom surface 71a is defined as a first cross-sectional area, the cross-sectional area of ​​the second bottom surface 72a is defined as a second cross-sectional area, and the cross-sectional area of ​​the third bottom surface 73a is defined as a third cross-sectional area, the cross-sectional area of ​​the recess 7 according to this embodiment is 1st cross-sectional area > 2nd cross-sectional area > 3rd cross-sectional area…(A) This will satisfy the relationship.

[0066] As shown in FIG. 6, the second cross-sectional area (see range R2 in FIG. 6) can be greater than or equal to 1 / 3 and less than or equal to 1 / 2 of the first cross-sectional area (see range R2 in FIG. 6), and the third cross-sectional area (see range R3 in FIG. 6) can be greater than or equal to 1 / 3 and less than or equal to 1 / 2 of the second cross-sectional area.

[0067] (Details of the first recess) Of the three recesses 71 to 73, the first recess 71 further has a first connecting surface 71b connecting the first and second bottom surfaces 71a and 72a and a second connecting surface 71c connecting the first and third bottom surfaces 71a and 73a. The first connecting surface 71b, the first bottom surface 71a, and the second connecting surface 71c are continuous in this order from the L side to the T side.

[0068] As described above, the first bottom surface 71a is deeper than the second bottom surface 72a and the third bottom surface 73a and wider than the second bottom surface 72a and the third bottom surface 73a. Therefore, the first connecting surface 71b is configured as an inclined surface that gradually becomes shallower and narrower from the first bottom surface 71a toward the second bottom surface 72a. Similarly, the second connecting surface 71c is configured as an inclined surface that gradually becomes shallower and narrower from the first bottom surface 71a toward the third bottom surface 73a.

[0069] The first bottom surface 71a is flatter than the first connecting surface 71b and the second connecting surface 71c, which means that the cross-sectional area of ​​the first bottom surface 71a changes more gradually than the cross-sectional areas of the first connecting surface 71b and the second connecting surface 71c.

[0070] For example, as shown in Figure 6, the cross-sectional area of ​​the recess 7 is approximately constant in the first range R1 corresponding to the first bottom surface 71a, and decreases relatively steeply in the ranges corresponding to the first connecting surface 71b and the second connecting surface 71c (ranges adjacent to the first range R1 on the left and right sides of the paper).

[0071] As described above, the first bottom surface 71a extends over a predetermined length range (first length L1) along the longitudinal direction of the rotor outer peripheral surface 2a. When viewed along the longitudinal direction, this first length L1 is shorter than the length range (second length L2) of the second bottom surface 72a and longer than the lengths of the first connecting surface 71b and the second connecting surface 71c, as shown in FIG.

[0072] Specifically, the first length L1 is preferably 4 / 10 to 8 / 10 of the second length L2, and more preferably approximately 2 / 3.Furthermore, the first length L1 is preferably 2 / 10 to 4 / 10 of the length La from the center C of the outer circumferential surface to the L-side end of the rotor outer circumferential surface 2a, and more preferably approximately 1 / 3.

[0073] (Details of the second recess) On the other hand, the second recess 72 has, in addition to the second bottom surface 72a, a third connecting surface 72b that connects the second bottom surface 72a to the L-side recess end 71. As shown in Fig. 3, the second bottom surface 72a extends longer than the third connecting surface 72b in the rotor rotation direction. The second bottom surface 72a and the third connecting surface 72b are continuous in this order from the T side to the L side.

[0074] The third connecting surface 72b is configured as an inclined surface that gradually becomes shallower from the second bottom surface 72a toward the L-side recess end 71. Meanwhile, the second bottom surface 72a is flatter than the third connecting surface 72b. This means that the cross-sectional area of ​​the second bottom surface 72a changes more gradually than the cross-sectional area of ​​the third connecting surface 72b.

[0075] For example, as shown in Figure 6, the cross-sectional area of ​​the recess 7 is approximately constant in the second range R2 corresponding to the second bottom surface 72a, and decreases sharply in the range corresponding to the third connecting surface 72b (the range adjacent to the right side of the second range R2 on the paper).

[0076] As described above, the second bottom surface 72a extends over a predetermined length (second length L2) along the longitudinal direction of the rotor outer peripheral surface 2a. As shown in FIG. 3, the second length L2 is longer than the first length L1, the third length L3, and the length of the third connecting surface 72b.

[0077] The second length L2 is longer than the median (= Ll / 2) obtained by dividing the length Ll from the outer peripheral surface center C to the L-side recess end 7l in half (L2>Ll / 2). The position of the first connecting surface 71b, which marks the boundary between the first recess 71 and the second recess 72, is set closer to the outer peripheral surface center C than the median.

[0078] (Details of the third recess) In addition to the third bottom surface 73a, the third recess 73 has a fourth connecting surface 73b connecting the third bottom surface 73a to the T-side recess end 7t. As shown in Fig. 3, the third bottom surface 73a extends longer than the fourth connecting surface 73b in the rotor rotation direction. The third bottom surface 73a and the fourth connecting surface 73b are continuous in this order from the L side to the T side.

[0079] The fourth connecting surface 73b is configured as an inclined surface that gradually becomes shallower from the third bottom surface 73a toward the T-side recess end 7t. Meanwhile, the third bottom surface 73a is flatter than the fourth connecting surface 73b. This means that the cross-sectional area of ​​the third bottom surface 73a changes more gradually than the cross-sectional area of ​​the fourth connecting surface 73b.

[0080] For example, as shown in Figure 6, the cross-sectional area of ​​the recess 7 is approximately constant in the third range R3 corresponding to the third bottom surface 73a, and decreases sharply in the range corresponding to the fourth connecting surface 73b (the range adjacent to the left side of the third range R3 on the paper).

[0081] As described above, the third bottom surface 73a extends over a predetermined length (third length L3) along the longitudinal direction of the rotor outer peripheral surface 2a. As shown in Fig. 3, this third length L3 is shorter than the sum of the lengths of the first bottom surface 71a and the second bottom surface 72a (= L1 + L2) and longer than the lengths of the second connecting surface 71c and the fourth connecting surface 73b.

[0082] Specifically, the third length L3 is 18 / 100 or more and 36 / 100 or less of the length Ll from the outer circumferential surface center C to the L-side recess end 7l, and preferably approximately 1 / 4.

[0083] (more details on cross section) In this way, the first bottom surface 71a, the second bottom surface 72a and the third bottom surface 73a in this embodiment are configured to be flat compared to the first connecting surface 71b, the second connecting surface 71c, the third connecting surface 72b and the fourth connecting surface 73b, etc., which connect the bottom surfaces together, and therefore each have an approximately constant cross-sectional area compared to the first connecting surface 71b, etc.

[0084] Therefore, the above-described relationship (A) is satisfied over substantially the entire longitudinal areas of the first bottom surface 71a, the second bottom surface 72a, and the third bottom surface 73a. More specifically, the recess cross-sectional area is largest in a first range R1 (a range of +10 to +30 mm from the origin 0 toward the L side) corresponding to the first bottom surface 71a. From this range toward the L side, the recess cross-sectional area gradually decreases to between one-third and one-half of the recess cross-sectional area in the first range R1 up to a length of approximately one-quarter of the total length of the first recess 71. From there, the recess cross-sectional area remains substantially constant, between one-third and one-half of the recess cross-sectional area in the first range R1, until it passes through the second range R2 toward the L side. Thereafter, it reaches the L-side recess end 71 at a distance of approximately one-fifth of the total length of the second range R2, where the recess cross-sectional area becomes zero.

[0085] Furthermore, on the T side, since the third recess 73 is located on the T side of the first recess 71, the recess cross-sectional area remains approximately constant at between 1 / 9 and 1 / 4 of the recess cross-sectional area in the first range R1 until it passes through the third range R3, and after passing through the third range R3, it gradually and continuously becomes smaller up to the T-side recess end 7t.

[0086] <Action and effect> Fig. 7 is a cross-sectional view showing the relationship between the rotor 2 and the rotor housing 3 at the ignition timing before TDC, Fig. 8 is a cross-sectional view showing the relationship between the rotor 2 and the rotor housing 3 in the first half of combustion before TDC, and Fig. 9 is a cross-sectional view showing the relationship between the rotor 2 and the rotor housing 3 in the second half of combustion after TDC.

[0087] When the engine 1 is operating, the spark plug 9 ignites the air-fuel mixture around the second recess 72 at a timing earlier than TDC (see FIG. 7). The flame generated by this ignition blows out from the spark plug 9 toward the L side.

[0088] Thereafter, as the rotor 2 rotates, the mixture is supplied to the flame from the first recess 71 located on the T side relative to the second recess 72, and the flame grows as the mixture is burned (see FIG. 8).

[0089] Thereafter, the air-fuel mixture is supplied through a third recess 73 located further toward the T side than the first recess 71, and the air-fuel mixture is burned up, thereby completing one cycle of combustion in one working chamber 8 (see FIG. 9).

[0090] 5 and other figures, the first recessed portion 71 having a relatively large cross-sectional area is not only located on the L side of the third recessed portion 73, but also located further on the L side than the outer circumferential surface center C. Therefore, the first recessed portion 71 can supply the air-fuel mixture to the flame at a timing before TDC, that is, at a timing in the first half of combustion immediately after ignition.

[0091] 5(a) and 5(b) and 5(b) and 5(c), the gap between the rotor outer peripheral surface 2a and the rotor housing 3 generally narrows as the TDC approaches. However, by making the cross-sectional area of ​​the first recess 71 relatively large as in the above embodiment, a larger amount of the mixture can be supplied to the flame while ensuring the fluidity of the unburned mixture compared to when the cross-sectional area is made small. This allows a larger amount of the mixture to be burned immediately after ignition.

[0092] In addition, by relatively increasing the cross-sectional area of ​​the first recess 71, the squish flow of the air-fuel mixture can be weakened and its flow rate can be reduced. That is, while a large amount of air-fuel mixture is combusted in the first half of combustion, the combustion can be made to proceed slowly. As a result, sudden heat generation can be suppressed, and combustion noise, gas leakage, and deterioration of fuel efficiency due to increased cooling loss can be suppressed.

[0093] Furthermore, by making the cross-sectional area of ​​the second recess 72 smaller than that of the first recess 71, the air-fuel mixture near the second recess 72 is under higher pressure than the air-fuel mixture near the first recess 71. This improves the ignition ability of the unburned air-fuel mixture when it is ignited.

[0094] Furthermore, by making the cross-sectional area of ​​the third recess 73 relatively small, the squish flow pushed out from the third recess 73 toward the L side can be strengthened and its flow velocity can be increased. This makes it possible to smoothly supply the remaining air-fuel mixture to the flame in the latter half of combustion after TDC and efficiently burn it up. By smoothly supplying the unburned air-fuel mixture, the occurrence or scale of so-called two-stage combustion can be suppressed, and thus cooling loss can be suppressed.

[0095] In addition, increasing the cross-sectional area of ​​the first recess 71 is equivalent to relatively reducing the cross-sectional areas of the second recess 72 and the third recess 73. This makes it possible to maintain the geometric compression ratio of the engine 1 and ensure thermal efficiency while slowing down combustion.

[0096] As described above, according to the embodiment, a large amount of air-fuel mixture is supplied from the first recess 71, but the combustion thereof is allowed to proceed slowly, thereby suppressing combustion noise, gas leakage, etc., while suppressing cooling loss and improving fuel economy. Furthermore, setting the cross-sectional areas of the second recess 72 and the third recess 73 as described above is further advantageous in improving fuel economy.

[0097] 3 and other figures, the second bottom surface 72a, which is configured to face the spark plug 9 during ignition, is longer than the first bottom surface 71a that is continuous with the second bottom surface 72a on the T side. This allows the spark plug 9 to face the second bottom surface 72a during ignition without having to face a position that is off the second bottom surface 72a, even if the ignition timing changes depending on the operating state of the engine 1, such as the introduction of EGR. This makes it possible to allow for changes in ignition timing and ensure a path for the air-fuel mixture to reach the plug position.

[0098] More specifically, the length L1 of the first bottom surface 71a is set to be 2 / 10 or more of the length L1 of the L-side recess end 7l. This is advantageous for increasing the volume of the first recess 71 and weakening the flow velocity of the squish flow of the air-fuel mixture. Furthermore, by setting the length of the first bottom surface 71a to be 4 / 10 or less of the length L1 of the L-side recess end 7l, the length of the second bottom surface 72a is ensured to be at a minimum, widening the range of rotation angles of the rotor 2 that can ignite with the spark plug 9 facing the second recess 72, which is advantageous for advancing the ignition timing.

[0099] Furthermore, as shown in Figure 3, etc., by making the third length L3 shorter than the sum of the first length L1 and the second length L2, it becomes possible to more quickly supply the unburned mixture from the T side to the L side relative to the center C of the outer circumferential surface.

[0100] More specifically, the third length L3 is set to be 2 / 10 or more and 5 / 10 or less of the length from the outer circumferential surface center C to the L-side recess end 7l, which makes it possible to significantly advance the ignition timing while suppressing two-stage combustion and combustion noise.

[0101] Furthermore, the length Ll from the center C of the outer peripheral surface to the L-side recess end 7l is set to be 7 / 10 or more and 9 / 10 or less of the length La from the center C of the outer peripheral surface to the L-side end of the outer peripheral surface. This widens the range of rotation angles of the rotor 2 at which ignition can be achieved with the spark plug 9 facing the second recess 72, which is advantageous for advancing the ignition timing.

[0102] Other Embodiments In the above embodiment, the first connecting portion 71b and the second connecting portion 71c are each defined as an element of the first recess 71, but this definition is merely for convenience. For example, the first connecting portion 71b may be defined as an element of the second recess 72, and the second connecting portion 71c may be defined as an element of the third recess 73. The relationship (A) described above holds regardless of such definitions.

[0103] The first bottom surface 71a, the second bottom surface 72a, and the third bottom surface 73a may be inclined or curved along the rotation direction. These bottom surfaces may have a cross-sectional area that changes relatively gradually compared to the first connecting portion 71b connecting the bottom surfaces to each other and the third connecting surface 73b connecting the bottom surfaces to the ends of the recess 7. [Explanation of symbols]

[0104] 1. Rotary engine 2 rotors 2a Rotor outer surface 3 Rotor housing 3a Trochoid inner surface 4,5 Side housing 7 Recess 71 First recess 71a 1st bottom 72 Second recess 72a 2nd bottom 73 Third recess 73a 3rd bottom 7l L-side recess end (front end of outer periphery) 7t T-side recess end (near end of outer periphery) 8 Working chamber 9 Spark plugs 31 Rotor Containment Room L1 First length (length of the bottom of the first recess) L2 Second length (length of the bottom of the second recess) L3 Third length (length of the bottom of the third recess) C Center of outer periphery (center of the outer periphery in the longitudinal direction) X Rotation axis Z short axis

Claims

1. a rotor housing having a substantially elliptical trochoidal inner peripheral surface; side housings disposed on either side of the rotor housing and forming a rotor accommodating chamber together with the rotor housing; a substantially triangular rotor accommodated in the rotor accommodating chamber, dividing three working chambers within the rotor accommodating chamber, and rotating to move each working chamber circumferentially, causing each working chamber to perform intake, compression, expansion and exhaust strokes in sequence; an ignition plug provided in the rotor housing; and a control unit for controlling the operation of the ignition plug, wherein recesses are formed in each outer peripheral surface of the rotor which divides the working chambers, the recess in the outer peripheral surface of the rotor includes a first recess that is disposed forward in the rotation direction of the rotor relative to a center that is a midpoint obtained by dividing the outer peripheral surface into two equal parts in the longitudinal direction and extends toward the front side, a second recess that extends forward relative to the first recess, and a third recess that is disposed forward in the rotation direction relative to the center and extends toward the front side, the first recess includes a first bottom surface having a predetermined first depth along a straight line that is perpendicular to the outer circumferential surface and extends toward a rotation axis of the rotor; the second recess includes a second bottom surface having a second depth formed along the straight line that is shallower than the first depth; the third recess includes a third bottom surface having a predetermined third depth formed along the straight line shallower than the second depth, The recess further includes: a first connecting surface extending at an angle from the first bottom surface to the second bottom surface so as to connect the first bottom surface and the second bottom surface; a second connecting surface extending at an incline from the first bottom surface to the third bottom surface so as to connect the first bottom surface and the third bottom surface; The length of the first bottom surface is shorter than the length of the second bottom surface and longer than the lengths of the first connecting surface and the second connecting surface; a length of the first bottom surface is 2 / 10 or more and 4 / 10 or less of a length from the center in the longitudinal direction of the outer peripheral surface to the front end of the outer peripheral surface, a length from the center to the front end of the recess is longer than a length from the center to the front end of the recess; When the cross-sectional area of ​​the recess is crossed on a plane perpendicular to the rotation direction and passing through the rotation axis of the rotor, the cross-sectional area of ​​the first bottom surface is defined as a first cross-sectional area, the cross-sectional area of ​​the second bottom surface is defined as a second cross-sectional area, and the cross-sectional area of ​​the third bottom surface is defined as a third cross-sectional area. First cross-sectional area > Second cross-sectional area > Third cross-sectional area Satisfying the relationship, The control unit controls the operation of the spark plug so that the spark plug faces the second bottom surface and the ignition timing is a time before top dead center of the compression stroke, thereby igniting the air-fuel mixture present between the second bottom surface and the spark plug to generate a flame that is blown out to the front side from the spark plug, and supplies the air-fuel mixture to the flame from the first bottom surface and the third bottom surface in order as the rotor rotates. A rotary engine characterized by:

2. 2. The rotary engine according to claim 1, The length of the third bottom surface is shorter than the sum of the lengths of the first bottom surface and the second bottom surface. A rotary engine characterized by:

3. 3. The rotary engine according to claim 2, The length of the third bottom surface is 2 / 10 or more and 5 / 10 or less of the length from the center to the front end of the recess. A rotary engine characterized by:

4. 4. The rotary engine according to claim 1, The length from the center to the front end of the recess is equal to or greater than 7 / 10 and equal to or less than 9 / 10 of the length from the center to the front end of the outer circumferential surface. A rotary engine characterized by:

5. 5. The rotary engine according to claim 1, the spark plug is disposed in the rotor housing at the front position across the minor axis of the rotor housing, The control unit controls the operation of the spark plug so that the ignition timing falls within a range of 55° or less before top dead center of the compression stroke. A rotary engine characterized by:

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