JP2023078692A - rotary engine - Google Patents

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

The technology disclosed herein relates to rotary engines.

In a rotary engine, a combustion chamber is formed between a rotor housing having a trochoidal inner peripheral surface and a rotor. A recess (dent) 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.

Specifically, in Patent Document 1, the volume of the leading side recess extending forward in the rotor rotation direction from the center in the longitudinal direction of the outer peripheral surface is larger than the volume of the trailing side recess extending forward in the rotor rotation direction. It is stated to be enlarged. The recess described in Patent Document 1 increases the volume of the leading side concave portion to promote the growth of the flame, making it possible to shorten the advance ignition and the ignition delay period, and improve the thermal efficiency by advancing the combustion center of gravity. is aimed at.

Japanese Patent Application Laid-Open No. 2020-12410

However, the accelerated flame growth hastened the combustion of the air-fuel mixture, which can lead to rapid heat generation. Therefore, there are concerns about combustion noise, gas leakage, and the like, and the cooling loss worsens, which is disadvantageous in terms of improving fuel efficiency.

The present disclosure has been made in view of this point, and an object thereof is to improve the fuel efficiency of a rotary engine.

A first aspect of the present disclosure includes a rotor housing having a substantially elliptical trochoidal inner peripheral surface, side housings arranged on both sides of the rotor housing to form a rotor housing chamber together with the rotor housing, and the rotor housing. It is housed in a rotor housing chamber and partitions three working chambers in the rotor housing chamber, and while each working chamber is moved in the circumferential direction by rotation, each stroke of intake, compression, expansion and exhaust is sequentially performed in each working chamber. a substantially triangular rotor that allows the rotor to move, spark plugs provided in the rotor housing, and a control unit that controls the operation of the spark plugs; related to the rotary engine.

In the above rotary engine, the recess in the outer peripheral surface of the rotor includes a first concave portion arranged forward in the rotational direction of the rotor relative to the center in the longitudinal direction of the outer peripheral surface and extending forward; a second recess that is continuous with the recess and extends forward; and a third recess that is continuous with the first recess and extends from the center to a front side in the rotational direction; Each of the second recess and the third recess has a bottom surface having a predetermined length in the longitudinal direction of the outer peripheral surface.

According to the first aspect of the present disclosure, the cross-sectional area of the recess when crossing the recess with a plane perpendicular to the rotation direction and passing through the rotation axis of the rotor is Assuming that the cross-sectional area of the bottom surface is the first cross-sectional area, the cross-sectional area of the bottom surface of the second recess is the second cross-sectional area, and the cross-sectional area of the bottom surface of the third recess is the third cross-sectional area,
Satisfying the relationship of first cross-sectional area>second cross-sectional area>third cross-sectional area, the control unit determines that the timing before the top dead center of the compression stroke is the ignition timing when the spark plug faces the bottom surface of the second recess. The operation of the spark plug is controlled so that

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

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 ignition plug toward the L side.

As the rotor rotates, the air-fuel mixture is supplied to the flame from the first recess located on the T side with respect to the second recess, and the flame grows by burning the air-fuel mixture. After that, the air-fuel mixture is supplied through the third recess located further on the T side than the first recess, and the air-fuel mixture is burned out, thereby completing one cycle of combustion in one working chamber.

Here, the first concave portion having a relatively large cross-sectional area is not only positioned on the L side of the third concave portion, but also positioned on the L side of the center of the outer peripheral surface. Therefore, the first recess can supply the air-fuel mixture to the flame at timing before TDC, that is, timing in the first half of combustion immediately after ignition.

In general, as the TDC is approached, the gap between the center of the outer peripheral surface and the rotor housing becomes narrower. However, by forming the cross-sectional area of the first recess relatively large, a larger amount of air-fuel mixture is supplied to the flame while ensuring the fluidity of the unburned air-fuel mixture, compared to the case where the first recess is formed small. can do. During timing just after ignition, more of the mixture can be burned.

In addition, by relatively increasing the cross-sectional area of the first recess, the flow of the squish flow of the air-fuel mixture can be weakened and the flow velocity can be suppressed. That is, it is possible to allow the combustion to progress slowly while a large amount of air-fuel mixture is being burned in the first half of the combustion. As a result, it is possible to suppress abrupt heat generation, thereby suppressing combustion noise, gas leakage, deterioration of fuel consumption performance due to an increase in cooling loss, and the like.

Further, 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 has a higher pressure than the air-fuel mixture near the first recess. As a result, the ignitability of the unburned air-fuel mixture can be enhanced.

In addition, by making the cross-sectional area of the third recess relatively small, it is possible to strengthen the flow of the squish flow pushed out from the third recess toward the L side and increase the flow velocity. This makes it possible to smoothly supply the remaining air-fuel mixture to the flame and burn it efficiently during the latter half of combustion after TDC. By smoothly advancing the supply of the unburned air-fuel mixture, it is possible to suppress the occurrence or scale of so-called two-stage combustion, and consequently suppress the cooling loss.

Further, increasing the cross-sectional area of the first recess is equivalent to relatively decreasing the cross-sectional areas of the second and third recesses. As a result, the geometric compression ratio of the engine can be maintained and the thermal efficiency can be ensured while slowing down the combustion.

As described above, according to the first aspect, while a large amount of air-fuel mixture is supplied from the first recess, the combustion proceeds slowly, thereby suppressing combustion noise, gas leakage, etc., and cooling loss. can be suppressed to improve fuel efficiency. Further, setting the cross-sectional areas of the second recess and the third recess as described above is more advantageous for improving the fuel efficiency.

Further, according to the second aspect of the present disclosure, the length of the bottom surface of the first recess may be shorter than the length of the bottom surface of the second recess.

According to the second aspect, the bottom surface (second bottom surface) of the second recess configured to face the spark plug during ignition is longer than the bottom surface (first bottom surface) of the first recess adjacent thereto. It will be. According to this, even if the ignition timing changes according to the operating state of the engine such as the introduction of EGR, the spark plug and the second bottom surface do not face the position outside the second bottom surface during ignition. will be able to face each other. As a result, it becomes possible to allow changes in ignition timing and to secure a path for air-fuel mixture to reach the plug position.

Further, according to the third aspect of the present disclosure, the length of the bottom surface of the first recess is the length from the center in the longitudinal direction of the outer peripheral surface (the center of the outer peripheral surface) to the front end of the outer peripheral surface. 2/10 or more and 4/10 or less of .

Hereinafter, the front end of the outer peripheral surface may be referred to as the "L side recess end".

According to the third aspect, the length of the bottom surface of the first recess is set to 2/10 or more of the length of the L-side recess end. This is advantageous in increasing the volume of the first recess and weakening the flow velocity of the squish flow of the air-fuel mixture. Further, by setting the length of the bottom surface of the first recess to 4/10 or less of the length of the L-side recess end, the minimum length of the bottom surface of the second recess is secured, and the spark plug is placed in the second recess. The range of the rotation angle of the rotor that can be ignited in the state of facing to widens, which is advantageous for advancing the ignition timing.

Further, according to the fourth aspect of the present disclosure, the length of the bottom surface of the third recess may be shorter than the sum of the lengths of the bottom surfaces of the first recess and the second recess.

According to the fourth 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 with respect to the center of the outer peripheral surface. Become.

Further, according to the fifth aspect of the present disclosure, the length of the bottom surface of the third recess is 2/10 or more of the length from the center in the longitudinal direction of the outer peripheral surface to the front end of the recess. /10 or less. This makes it possible to greatly advance the ignition timing while suppressing two-stage combustion and combustion noise.

Further, according to the sixth aspect of the present disclosure, the length from the longitudinal center of the outer peripheral surface to the front end of the recess is the length from the longitudinal center of the outer peripheral surface to the front side of the outer peripheral surface. 7/10 or more and 9/10 or less of the length to the end of the . As a result, the range of rotation angles of the rotor that can be ignited with the spark plug facing the second recess is widened, which is advantageous for advancing the ignition timing.

Further, according to a seventh aspect of the present disclosure, the spark plug is arranged at a position on the front side of the rotor housing with respect to the short axis of the rotor housing, and the control unit is arranged at the compression stroke top dead center. The operation of the spark plug may be controlled so that the ignition timing is within the range of 55° forward or less.

As described above, according to the present disclosure, it is possible to improve the fuel efficiency of a rotary engine.

BRIEF DESCRIPTION OF THE DRAWINGS The perspective view which shows the outline|summary of the rotary engine which concerns on embodiment of this invention. The front view which shows the rotor and rotor housing of the engine. The top view which shows the outer peripheral surface of the same rotor. FIG. 2 is a longitudinal sectional view of the same rotor; Sectional drawing which shows the magnitude|size of the clearance gap of a rotor and a rotor housing in TDC. 4 is a graph showing changes in recess cross-sectional area; FIG. 4 is a cross-sectional view showing the relationship between the rotor and the rotor housing at ignition timing before TDC; FIG. 4 is a cross-sectional view showing the relationship between the rotor and the rotor housing in the first half of combustion before TDC; FIG. 5 is a cross-sectional view showing the relationship between the rotor and the rotor housing in the latter half of combustion after TDC;

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated based on drawing. The following description of preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its applications or uses.

<Overall Configuration of 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. 2 is a front view showing the rotor 2 and rotor housing 3 of the engine 1. FIG.

An engine 1 shown in FIG. 1 is mounted on a vehicle and includes one or more rotors 2 (two rotors in the example shown). An intermediate housing 4 is provided between two rotor housings 3 each containing 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 positioned as a side housing that forms a rotor housing chamber 31 together with the rotor housing 3 and the side housing 5. .

In FIG. 1, a portion of the front side (right side in FIG. 1) of the engine 1 is cut away to show the inside of the engine. showing. Symbol X in the drawing is the rotational axis of the eccentric shaft as the output shaft.

As shown in FIG. 2, the rotor housing 3 has a trochoidal inner peripheral surface 3a that is substantially elliptical (barrel-shaped) when viewed from the direction of the rotation axis X drawn by parallel trochoidal curves. As shown in FIG. 1, the inner peripheral surface of the rotor housing 3, the inner side surfaces 4a on both sides of the intermediate housing 4, and the inner side surfaces 5a of the side housing 5 form a rotor housing chamber 31. The rotor housing chamber 31 accommodates the rotor 2. is accommodated. The rotor housing chambers 31 on both sides of the intermediate housing 4 have the same configuration except that the rotors 2 have different rotational phases.

The rotor 2 has a substantially triangular shape in which the central portion of each side bulges outward when viewed from the direction of the rotation axis X, and a recess 7 is formed in the substantially rectangular outer peripheral surface 2a between the tops of the triangle. there is Apex seals 14 provided on the triangular tops of the rotor 2 slide against the trochoidal inner peripheral surface 3a of the rotor housing 3 as the rotor 2 rotates (the apex seals 14 are shown only in FIG. 6). The rotor 2 partitions the interior of the rotor housing chamber 31 into three working chambers 8, as shown in FIG.

The rotor 2 is supported by the eccentric ring 6a of the eccentric shaft 6, and while rotating, revolves around the rotation axis X in the same direction as the rotation (including this rotation and revolution, in a broad sense, simply the rotor 2 rotation). During one rotation of the rotor 2, the three working chambers 8 move in the circumferential direction, and respective strokes of intake, compression, expansion (combustion), and exhaust are performed. The rotational force generated thereby is output from the eccentric shaft 6 via the rotor 2 .

In FIG. 2, the rotor 2 rotates clockwise as indicated by an arrow, and the left side of the rotor housing chamber 31 divided by the long axis Y passing through the rotation axis X is generally the intake stroke and the exhaust stroke. The area on the right side is generally the area for the compression stroke and the expansion stroke.

As shown in FIG. 1, intake ports 11 to 13 and an exhaust port 10 are opened at portions of the inner surface 4a of the intermediate housing 4 and the inner surface 5a of the side housing 5 corresponding to the areas of the intake stroke and the exhaust stroke. ing. Although not shown, a fuel injection valve for injecting fuel into the working chamber 8 during the intake stroke or compression stroke is provided at the top of the rotor housing 3 .

As shown in FIG. 2, the L side of the rotor housing 3 in the direction of rotation of the rotor 2 across the short axis Z of the rotor housing chamber 31 that passes through the rotation axis X (hereinafter referred to as the "rotational direction of the rotor"). , the spark plug 9 is attached with its electrode portion exposed to the rotor housing chamber 31 side. Note that the long axis Y and the short axis Z are orthogonal to each other.

Although not shown, the engine 1 includes an EGR device that recirculates part of the exhaust gas to the intake passage, and the recirculation of the exhaust gas is performed according to the operating state of the engine 1 .

The engine 1 also includes a control unit as a control section for controlling the operations of the engine 1 including the operations of the intake throttle valve, the fuel injection valve, the spark plug 9 and the EGR device.

<About control unit>
The control unit is based on a microcomputer, and includes a central processing unit (CPU) that executes programs, a memory that stores programs and data, for example, RAM and ROM, and a signal input/output (I /O) bus. The control unit receives signals of various information from a vehicle accelerator opening sensor, vehicle speed sensor, engine rotation angle sensor, air-fuel ratio sensor, engine coolant temperature sensor, air flow sensor, and the like.

The control unit determines the operating state of the engine 1 based on input signals from various sensors. The control unit controls the opening of the throttle valve, the EGR rate by the EGR device, the ignition timing by the spark plug 9 in each working chamber 8, the fuel injection amount by the fuel injection valve, and the fuel injection timing according to the determined operating state. I do.

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

The ignition timing is controlled according to the EGR rate so that the combustion center of gravity is positioned at an appropriate position of 10° to 30° after top dead center (ATDC) of the compression stroke with high thermal efficiency. 2, when one of the apexes of the rotor 2 is positioned on the opposite side of the spark plug 9 on the minor axis Z, the working chamber 8 located on the opposite side of the apex is at TDC. It's becoming

The higher the EGR rate, the longer the ignition delay period and the more retarded the center of gravity of combustion. Therefore, the ignition delay period is set according to the EGR rate, and the target heat generation start timing (apparent heat generation start target timing) is set according to the EGR rate. Then, the ignition timing of the ignition plug 9 is set to the timing advanced by the ignition delay period from the target heat generation start timing.

<Regarding the rotor recess>
FIG. 3 is a plan view showing the outer peripheral surface 2a of the rotor 2. FIG. 4 is a longitudinal sectional view of the rotor 2, and FIG. 5 is a 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 changes in recess cross-sectional area.

Here, FIG. 4 corresponds to the IV-IV section of FIG. The aa cross section of the second recess 72 in FIG. 4 corresponds to the upper diagram (a) of FIG. 5, and the bb cross section of the first recess 71 corresponds to the central diagram (b) of FIG. A cc cross section of the third concave portion 73 corresponds to the lower part (c) of FIG.

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 positional coordinates (unit: mm) with the center of the rotor outer peripheral surface 2a in the longitudinal direction as the origin (0), the L side being plus and the T side being minus. More precisely, the length position measured on a straight line connecting the apex seals 14 positioned at both ends of the rotor outer peripheral surface 2a corresponds to the position coordinates here. 6, reference numeral 9a denotes a plug hole of the spark plug 9. As shown in FIG.

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

As a result, the length Ll from the center C of the outer peripheral surface to the L-side end of the recess 7 (hereinafter referred to as "L-side recess end") 7l is It is longer than the length Lt up to 7t (hereinafter referred to as "T side recess end") (Ll>Lt). In addition, the "length" here means the length measured along the rotor outer peripheral surface 2a. The same is true for the various "lengths" that appear below, unless otherwise stated. Further, the “outer peripheral surface center C7” refers to a portion having a spread of about 4 to 8 degrees in terms of the central angle of the rotor 2 .

Specifically, 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 length Ll of the latter is preferably two to five times the length Lt of the former), more preferably approximately 1/4.

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

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

Here, the first recess 71 is arranged on the L side relative to the center C of the outer peripheral surface and extends to the L side. The second recess 72 is continuous with the first recess 71 and extends to the L side. The third recess 73 is continuous with the first recess 71 and extends from the center C of the outer peripheral surface to the T side.

These three recesses 71 to 73 respectively have bottom surfaces 71a to 73a 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 size relationship of each length will be described later.

As shown in FIG. 4 , the first recessed portion 71 is recessed deeper than the second recessed portion 72 and the third recessed portion 73 . For example, in the present 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). Further, as shown in FIGS. 4 to 5 and FIG. 6 described later, the depth D2 of the second bottom surface 72a is deeper than the depth D3 of the third bottom surface 73a.

The term "depth" used herein refers to the depth measured along a straight line perpendicular to the rotor outer peripheral surface 2a and extending toward the rotation axis X. As shown in FIG. Especially in this embodiment, among the depths measured along such a straight line, the maximum depth in the rotor width direction is regarded as the "depth".

Specifically, the depth D2 of the second bottom surface 72a can be 1/3 or more and 1/2 or less of the depth D1 of the first bottom surface 71a, and the depth D3 of the third bottom surface 73a can be the depth D3 of the second bottom surface. It can be 1/3 or more and 1/2 or less of the depth D2 of 72a.

Further, as shown in FIG. 3, the first recess 71 is wider than the second recess 72 and the third recess 73 in the lateral 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 substantially equal to the width W3 of the third recess 73. As shown in FIG. The term "width" used herein refers to the depth measured along the lateral direction of the rotor outer peripheral surface 2a.

Thus, when the bottom surfaces 71a, 72a, 73a of the first recess 71, the second recess 72, and the third recess 73 are compared, the first bottom surface 71a of the first recess 71 is larger than the bottom surfaces of the other recesses. , wide and deep. 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 formed deeper.

As shown in FIG. 5, the first bottom surface 71a, the second bottom surface 72a, and the third bottom surface 73a extend flat in the width direction of the rotor, and both sides rise in an arc shape. Therefore, the cross-sectional area of the recess 7 when crossing the recess 7 with a plane perpendicular to the longitudinal direction of the rotor outer peripheral surface 2 a and passing through the center of the rotor 2 has a size substantially corresponding to the depth of the recess 7 .

Therefore, in view of the size relationship between the width and the depth described above, the cross-sectional area of the first bottom surface 71a is the first cross-sectional area, the cross-sectional area of the second bottom surface 72a is the second cross-sectional area, and the cross-sectional area of the third bottom surface 73a is the cross-sectional area. is the third cross-sectional area, the cross-sectional area of the recess 7 according to the present embodiment is
First cross-sectional area>Second cross-sectional area>Third cross-sectional area (A)
will satisfy the relationship of

As shown in FIG. 6, the second cross-sectional area (see range R2 in FIG. 6) can be 1/3 or more and 1/2 or less of the first cross-sectional area (see range R2 in FIG. 6), The third cross-sectional area (see range R3 in FIG. 6) can be 1/3 or more and 1/2 or less of the second cross-sectional area.

(Details of the first concave portion)
Among the three concave portions 71 to 73, the first concave portion 71 further includes a first connecting surface 71b connecting the first and second bottom surfaces 71a and 72a and a second connecting surface 71b connecting the first and third bottom surfaces 71a and 73a. and a connecting surface 71c. 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.

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 formed 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 formed as an inclined surface that gradually becomes shallower and narrower from the first bottom surface 71a toward the third bottom surface 73a.

The first bottom surface 71a forms a flat plane compared to the first connection surface 71b and the second connection surface 71c. This is equivalent to the cross-sectional area at the first bottom surface 71a changing more gently than the cross-sectional areas at the first connecting surface 71b and the second connecting surface 71c.

For example, as shown in FIG. 6, the cross-sectional area of the recess 7 is substantially constant in a first range R1 corresponding to the first bottom surface 71a, and the range corresponding to the first connecting surface 71b and the second connecting surface 71c (first range In the range adjacent to the left and right of R1 on the paper), it decreases relatively sharply.

Further, 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, as shown in FIG. 3, the first length L1 is shorter than the length range (second length L2) of the second bottom surface 72a, and the first connecting surface 71b and It is longer than the length of the second connecting surface 71c.

Specifically, the first length L1 is preferably 4/10 or more and 8/10 or less of the second length L2, and more preferably approximately 2/3. The first length L1 is preferably 2/10 or more and 4/10 or less of the length La from the outer peripheral surface center C to the L-side end of the rotor outer peripheral surface 2a, more preferably approximately 1/3. is.

(Details of the second recess)
On the other hand, in addition to the second bottom surface 72a, the second recess 72 has a third connecting surface 72b that connects the second bottom surface 72a to the L-side recess end portion 7l. 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 toward the L side.

The third connecting surface 72b is formed as an inclined surface that is gradually shallowed from the second bottom surface 72a toward the L-side recess end portion 7l. On the other hand, the second bottom surface 72a forms a flat plane compared to the third connecting surface 72b. This is equivalent to the cross-sectional area at the second bottom surface 72a changing more slowly than the cross-sectional area at the third connecting surface 72b.

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

In addition, as described above, the second bottom surface 72a extends over a predetermined length range (second length L2) along the longitudinal direction of the rotor outer peripheral surface 2a. The second length L2 is longer than the first length L1, the third length L3 and the length of the third connecting surface 72b, as shown in FIG.

The second length L2 is longer than the median value (=Ll/2) when the length Ll from the outer peripheral surface center C to the L side recess end portion 7l is divided into two (L2>Ll/2). The position of the first connecting surface 71b indicating the boundary between the first concave portion 71 and the second concave portion 72 is set closer to the center C of the outer peripheral surface than the above-described median value.

(Details of the third recess)
In addition to the third bottom surface 73a, the third recess 73 has a fourth connecting surface 73b that connects the third bottom surface 73a and the T-side recess end portion 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 toward the T side.

The fourth connecting surface 73b is formed as an inclined surface that gradually becomes shallower from the third bottom surface 73a toward the T-side recess end portion 7t. On the other hand, the third bottom surface 73a forms a flat plane compared to the fourth connecting surface 73b. This is equivalent to the cross-sectional area of the third bottom surface 73a changing more gently than the cross-sectional area of the fourth connecting surface 73b.

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

Further, as described above, the third bottom surface 73a extends over a predetermined length range (third length L3) along the longitudinal direction of the rotor outer peripheral surface 2a. As shown in FIG. 3, the 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 is longer than the second connecting surface 71c and the fourth connecting surface 73b. too long.

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

(further details of the cross-sectional area)
Thus, the first bottom surface 71a, the second bottom surface 72a and the third bottom surface 73a according to the present embodiment are connected to each other by the first connection surface 71b, the second connection surface 71c, the third connection surface 72b and the fourth connection surface 72b. Since they are formed flatter than the connecting surfaces 73b and the like, they each have a substantially constant cross-sectional area compared to the first connecting surfaces 71b and the like.

Therefore, the relationship (A) described above is satisfied in substantially the entire length of the first bottom surface 71a, the second bottom surface 72a, and the third bottom surface 73a in the longitudinal direction. More specifically, the recess cross-sectional area is the largest in the first range R1 (the range of +10 to +30 mm on the L side from the origin 0) corresponding to the first bottom surface 71a. From this range to about 1/4 of the total length of the first recess 71 toward the L side, the recess cross-sectional area is 1/3 or more and 1/2 or less of the recess cross-sectional area in the first range R1. is gradually decreasing. From there, the recess cross-sectional area remains substantially constant at 1/3 or more and 1/2 or less of the recess cross-sectional area in the first range R1 until it passes through the second range R2 toward the L side, After that, the L-side recess end portion 7l is reached at a distance of about 1/5 of the total length of the second range R2, and the recess cross-sectional area becomes zero.

Also, on the T side, since the third recess 73 is positioned on the T side of the first recess 71, the recess cross-sectional area is the same as that in the first range R1 until the third range R3 is passed. It remains substantially constant at 1/9 or more and 1/4 or less, and after passing through the third range R3, it gradually and continuously decreases until reaching the T-side recess end portion 7t.

<Effect>
FIG. 7 is a sectional view showing the relationship between the rotor 2 and the rotor housing 3 at ignition timing before TDC. 8 is a 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 sectional view showing the relationship between the rotor 2 and the rotor housing 3 in the latter half of combustion after TDC. It is a diagram.

During operation of the engine 1, 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 ignition plug 9 toward the L side.

After that, as the rotor 2 rotates, the air-fuel mixture is supplied to the flame from the first recess 71 located on the T side with respect to the second recess 72, and the flame grows by burning the air-fuel mixture. (See Figure 8).

After that, the air-fuel mixture is supplied through the third recess 73 located further on the T side than the first recess 71, and by burning the air-fuel mixture, one cycle of combustion in one working chamber 8 is completed (Fig. 9).

Here, as described with reference to FIG. 5 and the like, 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 is positioned closer to the center C of the outer peripheral surface. is also located on the L side. Therefore, the first recess 71 can supply the air-fuel mixture to the flame at timing before TDC, that is, timing in the first half of combustion immediately after ignition.

As can be seen from the comparison between (a) and (b) in FIG. 5 and the comparison between (b) and (c) in FIG. It's getting narrower. However, by forming the cross-sectional area of the first recess 71 to be relatively large as in the above embodiment, a larger amount of unburned air-fuel mixture can be obtained while ensuring the fluidity of the unburned air-fuel mixture, compared to the case where the cross-sectional area is formed small. of mixture can be supplied to the flame. During timing just after ignition, more of the mixture can be burned.

In addition, by relatively increasing the cross-sectional area of the first recess 71, the flow of the squish flow of the air-fuel mixture can be weakened and the flow velocity can be suppressed. That is, it is possible to allow the combustion to progress slowly while a large amount of air-fuel mixture is being burned in the first half of the combustion. As a result, it is possible to suppress abrupt heat generation, thereby suppressing combustion noise, gas leakage, deterioration of fuel consumption performance due to an increase in cooling loss, and the like.

Further, 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 has a higher pressure than the air-fuel mixture near the first recess 71 . As a result, the ignitability of the unburned air-fuel mixture can be enhanced.

In addition, 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 the flow velocity can be increased. This makes it possible to smoothly supply the remaining air-fuel mixture to the flame and burn it efficiently during the latter half of combustion after TDC. By smoothly advancing the supply of the unburned air-fuel mixture, it is possible to suppress the occurrence or scale of so-called two-stage combustion, and consequently suppress the cooling loss.

Further, increasing the cross-sectional area of the first recess 71 is equivalent to relatively decreasing the cross-sectional areas of the second recess 72 and the third recess 73 . As a result, the geometric compression ratio of the engine 1 can be maintained and the thermal efficiency can be ensured while slowing down the combustion.

As described above, according to the above-described embodiment, while supplying a large amount of air-fuel mixture from the first recess 71, the combustion of the air-fuel mixture is allowed to progress slowly, thereby suppressing combustion noise, gas leakage, etc., and reducing cooling loss. can be suppressed to improve fuel efficiency. Further, setting the cross-sectional areas of the second recessed portion 72 and the third recessed portion 73 as described above is more advantageous for improving the fuel efficiency.

Further, as shown in FIG. 3 and the like, the second bottom surface 72a configured to face the spark plug 9 when ignited is extended longer than the first bottom surface 71a continuous on the T side thereof. According to this, even if the ignition timing changes according to the operating state of the engine 1 such as the introduction of EGR, the spark plug 9 does not face the position outside the second bottom surface 72a, and the It becomes possible to face the second bottom surface 72a. As a result, it becomes possible to allow changes in the ignition timing and to ensure a path for the air-fuel mixture to reach the plug position.

More specifically, the length L1 of the first bottom surface 71a is set to 2/10 or more of the length Ll of the L-side recess end portion 7l. This is advantageous in increasing the volume of the first recess 71 and weakening the flow velocity of the squish flow of the air-fuel mixture. In addition, by setting the length of the first bottom surface 71a to 4/10 or less of the length Ll of the L-side recess end portion 7l, the length of the second bottom surface 72a is ensured at a minimum, and the spark plug 9 is positioned at the second bottom surface 71a. The range of the rotation angle of the rotor 2 that can be ignited while facing the recess 72 is widened, which is advantageous for advancing the ignition timing.

Further, as shown in FIG. 3 and the like, by making the third length L3 shorter than the sum of the first length L1 and the second length L2, and unburned air-fuel mixture can be supplied more quickly.

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

In addition, the length Ll from the center C of the outer peripheral surface to the L-side recess end 7l is set to 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. be. As a result, the range of rotation angles of the rotor 2 that can be ignited with the spark plug 9 facing the second recess 72 is widened, which is advantageous for advancing the ignition timing.

<<Other embodiments>>
In the above embodiment, the first connecting portion 71b and the second connecting portion 71c are each defined as one element of the first recess 71, but this definition is for convenience only. For example, the first connecting portion 71 b may be one element of the second recess 72 , and the second connecting portion 71 c may be one element of the third recess 73 . The above relationship (A) holds regardless of such definitions.

Also, 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 have cross-sectional areas that change relatively slowly compared to the first connecting portion 71b that connects the bottom surfaces and the third connecting surface 73b that connects the bottom surfaces to the end of the recess 7. It is good if there is

1 rotary engine 2 rotor 2a rotor outer peripheral surface 3 rotor housing 3a trochoid inner peripheral surface 4, 5 side housing 7 recess 71 first recess 71a first bottom 72 second recess 72a second bottom 73 third recess 73a third bottom 7l L Side recess edge (front edge of outer peripheral surface)
7t T-side recess edge (edge on the front side of the outer peripheral surface)
8 working chamber 9 spark plug 31 rotor housing chamber L1 first length (length of the bottom surface of the first recess)
L2 second length (length of the bottom surface of the second recess)
L3 third length (length of the bottom surface of the third recess)
C Center of outer peripheral surface (center of outer peripheral surface in longitudinal direction)
X Rotation axis Z Minor axis

Claims (7)

a rotor housing having a substantially elliptical trochoidal inner peripheral surface; side housings arranged on both sides of the rotor housing to form a rotor housing chamber together with the rotor housing; a substantially triangular rotor that partitions the chamber into three working chambers, moves the working chambers in the circumferential direction by rotation, and sequentially performs intake, compression, expansion and exhaust strokes in each working chamber; A rotary engine comprising: a spark plug provided in a rotor housing;
The recess in the outer peripheral surface of the rotor includes a first recess disposed forward in the rotational direction of the rotor relative to the center in the longitudinal direction of the outer peripheral surface and extending forward; a second recess extending forward; and a third recess continuous with the first recess and extending from the center to the front side in the rotation direction, the first recess, the second recess, and the Each of the third recesses has a bottom surface having a predetermined length in the longitudinal direction of the outer peripheral surface,
The cross-sectional area of the recess when crossing the recess on a plane perpendicular to the direction of rotation and passing through the rotational axis of the rotor is defined as the cross-sectional area of the bottom surface of the first recess, and the second cross-sectional area of the recess. Assuming that the cross-sectional area of the bottom surface of the second recess is the second cross-sectional area and the cross-sectional area of the bottom surface of the third recess is the third cross-sectional area,
Satisfying the relationship of first cross-sectional area>second cross-sectional area>third cross-sectional area,
The rotary engine, wherein the control unit controls the operation of the spark plug so that the spark plug faces the bottom surface of the second recess and the timing before the top dead center of the compression stroke becomes the ignition timing. A rotary engine as claimed in claim 1,
The rotary engine, wherein the length of the bottom surface of the first recess is shorter than the length of the bottom surface of the second recess. A rotary engine according to claim 2,
The length of the bottom surface of the first recess is 2/10 or more and 4/10 or less of the length from the center in the longitudinal direction of the outer peripheral surface to the front end of the outer peripheral surface. . In the rotary engine according to any one of claims 1 to 3,
The rotary engine, wherein the length of the bottom surface of the third recess is shorter than the sum of the lengths of the bottom surfaces of the first recess and the second recess. A rotary engine according to claim 4,
The rotary engine, wherein the length of the bottom surface of the third recess is 2/10 or more and 5/10 or less of the length from the longitudinal center of the outer peripheral surface to the front end of the recess. In the rotary engine according to any one of claims 1 to 5,
The length from the longitudinal center of the outer peripheral surface to the front end of the recess is 7/10 or more 9/ of the length from the longitudinal center of the outer peripheral surface to the front end of the outer peripheral surface. 10 or less, a rotary engine. In the rotary engine according to any one of claims 1 to 6,
The spark plug is arranged in the front side of the rotor housing across the short axis of the rotor housing,
The rotary engine, wherein the control unit controls the operation of the spark plug so that the ignition timing is within a range of 55° or less before top dead center of the compression stroke.

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