JP2023078693A - 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 disposed at an outer peripheral surface center C, and a second recessed portion 72 that continues to the first recessed portion 71 and extends to an L side. The first recessed portion has a first bottom surface 71a that includes the outer peripheral surface center C and has a predetermined length L1 from the center toward the L side, and a first inclined surface 71b that inclines and extends from the first bottom surface to a T side recessed end portion 7t. A recess cross section when traversing the recess by a plane orthogonal to a longitudinal direction of a rotor outer peripheral surface and passing through a rotation axis X of the rotor, becomes the largest on the first bottom surface, and a border between the first bottom surface and the first inclined surface is located on a T side as compared with the center.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 recess that is arranged in the center in the longitudinal direction of the outer peripheral surface and extends along the rotational direction of the rotor, a second recess extending forward in the direction of rotation; the first recess includes a first bottom surface including the center and having a predetermined length from the center toward the front; and a first inclined surface extending from the first bottom surface to the front end of the recess while being inclined so that the depth of the first recess becomes shallower toward the recess.

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 longitudinal direction and passing through the center of rotation of the rotor is the largest at the first bottom surface. The boundary between the first bottom surface and the first inclined surface is located on the front side in the rotational direction with respect to the center, and the control unit is arranged such that the spark plug faces the second recess and is on the compression stroke. The operation of the spark plug is controlled so that the timing before the dead center is the ignition timing.

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

Here, the first bottom surface, which has a relatively large cross-sectional area, is not only positioned on the L side of the first inclined surface, but also extends from the center of the outer peripheral surface toward the L side. Therefore, the first bottom surface 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 bottom surface relatively large, compared to the case where the cross-sectional area is formed small, while ensuring the fluidity of the unburned air-fuel mixture, a larger amount of air-fuel mixture can be emitted to the flame. can be supplied to During timing just after ignition, more of the mixture can be burned.

In addition, by relatively increasing the cross-sectional area of the first bottom surface, 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.

Moreover, since the first bottom surface includes the center of the outer peripheral surface, around TDC, the supply speed of the air-fuel mixture from the T side to the flame growing on the L side of the short axis position of the rotor housing increases. This avoids the strong flow of the air-fuel mixture from the side to the L side. Therefore, the combustion speed of the main combustion after ignition does not increase, so to speak, slow combustion and sudden heat generation can be avoided. For this reason, cooling loss does not increase, which is advantageous in terms of improving fuel consumption, reducing combustion noise, and preventing gas leakage.

Moreover, making the cross-sectional area of the first bottom surface the largest is equivalent to making the cross-sectional area of the second recess relatively small. As a result, 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 increasing the cross-sectional area of the first bottom surface and relatively decreasing the cross-sectional area of the second recess, the geometric compression ratio of the engine is maintained and thermal efficiency is ensured while slowing combustion. be able to.

In addition, by providing the first inclined surface on the T side from the center of the outer peripheral surface, in the latter half of the combustion after TDC, the flow of the air-fuel mixture from the T side of the short axis position of the rotor housing to the L side where the flame exists can be controlled by this. It can be smoothly advanced through the first inclined surface. As a result, the occurrence or scale of so-called two-stage combustion can be suppressed, which is advantageous in suppressing cooling loss. At this time, the first inclined surface gradually deepens from the T-side end of the recess to the L-side first bottom surface. Gradually increasing the depth toward the L side weakens the flow velocity of the squish flow in the first concave portion, which is advantageous in terms of improving fuel efficiency by slowing combustion.

Thus, according to the first aspect, it is possible to realize slow combustion in both the first half and the second half of combustion while supplying a large amount of air-fuel mixture from the first recess. As a result, while suppressing combustion noise, gas leakage, etc., it is possible to suppress cooling loss and improve fuel efficiency. Further, setting the cross-sectional area of the second concave portion 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 first bottom surface may be longer than the length of the first inclined surface when viewed along the longitudinal direction.

According to the second aspect, the ratio of the volume defined by the first bottom surface to the total volume of the first recess can be increased. Since the volume defined by the first bottom surface is larger than the volume defined by the first inclined surface, the total volume of the first recess can be increased, slowing down combustion and, in turn, improving fuel efficiency. In addition, since the length of the first inclined surface is relatively shortened, the first inclined surface steeply becomes deeper toward the L side. As a result, the flow speed of the squish flow through the first inclined surface is weakened, which is advantageous in terms of improving fuel efficiency by slowing down combustion.

Further, according to the third aspect of the present disclosure, the length from the center in the longitudinal direction of the outer peripheral surface to the boundary between the first recess and the second recess is set from the center in the longitudinal direction of the outer peripheral surface to the outer periphery. It may be 2/10 or more and 4/10 or less of the length to the front end of the surface.

According to the third aspect, on the L side with respect to the center of the outer peripheral surface, the second recess extends longer than the first bottom surface of the first recess. 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 recess do not face the position outside the second recess 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 fourth aspect of the present disclosure, the length from the center in the longitudinal direction of the outer peripheral surface to the front end of the recess is from the center in the longitudinal direction of the outer peripheral surface to the front side of the recess. 2/10 or more and 5/10 or less of the length to the end of the . This makes it possible to greatly advance the ignition timing while suppressing two-stage combustion and combustion noise.

Further, according to the fifth 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 rotation of the outer peripheral surface. It may be 7/10 or more and 9/10 or less of the length to the front end of the direction. 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 sixth 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 falls within the range of 25° or more and 55° or less forward.

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

1 is a perspective view showing an overview of a rotary engine according to an embodiment of the present disclosure; FIG. 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 rotation 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 As the rotor 2 rotates, the apex seals 14 provided on the triangular tops of the rotor 2 come into sliding contact with the trochoidal inner peripheral surface 3a of the rotor housing 3 . 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. 4 corresponds to the upper diagram (a) in FIG. 5, and the bb cross section of the first bottom surface 71a in the first recess 71 corresponds to the central diagram (b) in FIG. ), and the cc cross section of the first inclined surface 71b in the first concave portion 71 corresponds to the lower diagram (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 at the center C of the outer peripheral surface and extending along the direction of rotation of the rotor, and a second recess 71 continuous with the first recess 71 and extending toward the L side. and a recess 72 . The volume of the recess 7 is set so that the geometric compression ratio of the working chamber 8 is 9.7 or more.

These two recesses 71-72 respectively have bottom surfaces 71a-72a having predetermined lengths L1-L2 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 in the longitudinal direction.

As shown in FIG. 4 , the first concave portion 71 is recessed deeper than the second concave portion 72 . 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 (see FIG. 5).

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 1/2 or more and 3/4 or less, preferably approximately 2/3, of the depth D1 of the first bottom surface 71a.

Further, as shown in FIG. 3, the first recess 71 is slightly wider than the second recess 72 in the lateral direction (rotor width direction) of the rotor outer peripheral surface 2a. That is, in the present embodiment, the width W1 of the first bottom surface 71a of the first recess 71 is longer than the width W2 of the second bottom surface 72a of the second recess 72. 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.

(Details of the first concave portion)
More specifically, the first recess 71 according to the present embodiment includes a first bottom surface 71a including the center C of the outer peripheral surface, a first inclined surface 71b arranged on the T side with respect to the center C, and the first recess 71 and a second inclined surface 71 c that connects the second recess 72 . The first inclined surface 71b, the first bottom surface 71a and the second inclined surface 71c are continuous in this order from the T side toward the L side.

The first bottom surface 71a extends from the center C of the outer peripheral surface toward the L side, and has a predetermined length (hereinafter referred to as "first length") L1 in the longitudinal direction. The length from the center C of the outer peripheral surface to the T-side end of the first bottom surface 71a (boundary between the first bottom surface 71a and the first inclined surface 71b) is (border with the second inclined surface 71c). The first bottom surface 71a extends perpendicularly to a straight line extending from the rotation axis X of the rotor 2 and passing through the center C of the outer peripheral surface.

The first inclined surface 71b is continuous with the T-side end of the first bottom surface 71a, and extends downward from the first bottom surface 71a to the T-side recess edge such that the depth of the first recess 71 becomes shallower toward the T-side. It extends while sloping up to 7t. The first inclined surface 71b is formed as an inclined surface that gradually becomes shallower and narrower toward the T side, and extends smoothly until the depth becomes zero. The boundary between the first bottom surface 71a and the first inclined surface 71b is located on the T side with respect to the center C of the outer peripheral surface.

On the other hand, the second inclined surface 71c is continuous with the L-side end of the first bottom surface 71a, and extends from the first bottom surface 71a to the second inclined surface 71c so that the depth of the first recessed portion 71 becomes shallower toward the L side. It extends to the concave portion 72 while being inclined. The second inclined surface 71c is formed as an inclined surface that gradually becomes shallower and narrower toward the L side, and smoothly extends to the T-side end of the second bottom surface 72a. extended.

The first bottom surface 71a forms a flat plane compared to the first inclined surface 71b and the second inclined surface 71c. This is equivalent to the cross-sectional area of the first bottom surface 71a changing more gently than the cross-sectional areas of the first inclined surface 71b and the second inclined 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 (first range R1) corresponding to the first inclined surface 71b and the second inclined surface 71c. In the range adjacent to the left and right of R1 on the paper), it decreases relatively steeply.

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, the first length L1 is approximately the same as the length range (second length L2) of the second bottom surface 72a as shown in FIG. longer than the lengths of 71b and second inclined surface 71c.

Specifically, the first length L1 is preferably 8/10 or more and 12/10 or less of the second length L2, and more preferably approximately 9/10. In addition, the length from the center C of the outer peripheral surface to the boundary between the first recess 71 and the second recess 72 (in other words, the length from the center C of the outer peripheral surface to the second inclined surface 71c) is It is 2/10 or more and 4/10 or less of the length La to the end of the surface 2a on the L side.

Also, when viewed along the longitudinal direction, the length of the first inclined surface 71b (the third length L3) is longer than the length of the second inclined surface 71c. Specifically, the third length L3 is preferably 4/10 or more and 8/10 or less of the first length L1, more preferably approximately 6/10. The length Lc from the center C of the outer peripheral surface to the boundary between the first bottom surface 71a and the first inclined surface 71b is 1/20 or more of the length La from the center C of the outer peripheral surface to the L-side end of the rotor outer peripheral surface 2a. 3/20 or less is preferable.

(Details of the second recess)
On the other hand, in addition to the second bottom surface 72a, the second recess 72 has a third inclined surface 72b connecting the second bottom surface 72a to the L-side recess end portion 7l. The second bottom surface 72a and the third inclined surface 72b are continuous in this order from the T side to the L side.

The third inclined surface 72b is formed as an inclined surface that gradually becomes shallower and narrower from the second bottom surface 72a toward the L-side recess end portion 7l. It extends smoothly until it reaches zero. On the other hand, the second bottom surface 72a forms a flat plane compared to the second bottom surface 72a. This is equivalent to the cross-sectional area at the second bottom surface 72a changing more gently than the cross-sectional area at the third inclined 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 inclined surface 72b (adjacent to the right side of the first range R1 on the paper surface). range), it decreases relatively steeply.

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. When viewed along the longitudinal direction, the second length L2 is longer than the lengths of the first inclined surface 71b and the second inclined surface 71c, similarly to the first length L1. It is also longer than the length of surface 72b.

(further details of the cross-sectional area)
Thus, when the bottom surfaces 71a and 72a of the first recess 71 and the second recess 72 are compared, the first bottom surface 71a of the first recess 71 is wider and wider than the second bottom surface 72a of the second recess 72. deeply formed.

Further, as shown in FIG. 5, the first bottom surface 71a and the second bottom surface 72a spread flatly in the rotor width direction, and both side portions 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 2a and passing through the center of the rotor 2 (hereinafter also referred to as "recess cross-sectional area") is It has a size approximately corresponding to the depth.

Therefore, in view of the size relationship between the width and the depth described above, the recess cross-sectional area according to the present embodiment is maximized at the first bottom surface 71a. Considering that the depth D1 of the first bottom surface 71a is substantially constant, it can be said that the recess cross-sectional area becomes maximum at the center C of the outer peripheral surface.

Specifically, assuming that the cross-sectional area of the first bottom surface 71a is the first cross-sectional area and the cross-sectional area of the second bottom surface 72a is the second cross-sectional area, the recess cross-sectional area is:
First cross-sectional area > Second cross-sectional area (A)
will satisfy the relationship of

In addition, as described above, the first bottom surface 71a and the second bottom surface 72a according to the present embodiment are formed flatter than the second inclined surface 71c or the like connecting the bottom surfaces. It has a constant cross-sectional area.

Therefore, the relationship (A) described above is satisfied over substantially the entire length of the first bottom surface 71a and the second bottom surface 72a in the longitudinal direction.

For example, as shown in FIG. 6, the second cross-sectional area (see range R2 in FIG. 6) can be 1/2 or more and 3/4 or less of the first cross-sectional area (see range R1 in FIG. 6). . More specifically, the recess cross-sectional area is the largest in the first range R1 corresponding to the first bottom surface 71a (range of −10 mm on the T side and +30 mm on the L side from the origin 0). From this range to about 1/6 of the total length of the first recess 71 toward the L side, the recess cross-sectional area is 1/2 or more of the recess cross-sectional area (first cross-sectional area) in the first range R1 or more 3/ It is gradually reduced to a magnitude of 4 or less. From there, the recess cross-sectional area remains substantially constant at 1/2 or more and 3/4 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 1/6 of the total length of the second range R2, and the recess cross-sectional area becomes zero.

Also, on the T side, since the first inclined surface 71b is positioned on the T side of the first bottom surface 71a, the recess cross-sectional area is gradually continuous from the first range R1 to the T-side recess end portion 7t. is smaller than

In addition, the boundary between the first bottom surface 71a and the first inclined surface 71b is located on the T side of the center C of the outer peripheral surface. That is, the first bottom surface 71a extends from the T side to the L side so as to pass through the center C of the outer peripheral surface, and has a larger volume than the first inclined surface 71b and the second bottom surface 72a. On the other hand, the first inclined surface 71b has a smaller volume than the first bottom surface 71a and the second bottom surface 72a because the length in the longitudinal direction (the third length L3) is relatively short.

<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.

Thereafter, 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, particularly from the first bottom surface 71a thereof, and the air-fuel mixture is burned. , the flame grows (see FIG. 8).

After that, the air-fuel mixture is supplied through the first inclined surface 71b located further on the T side than the first bottom surface 71a, and the air-fuel mixture is burned out, thereby completing one cycle of combustion in one working chamber 8 ( See Figure 9).

Here, as described with reference to FIG. 5 and the like, the first bottom surface 71a having a relatively large cross-sectional area is not only located on the L side of the first inclined surface 71b, but also located at the center of the outer peripheral surface. It extends from C toward the L side. Therefore, the first bottom surface 71a 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-described embodiment, compared to the case where the cross-sectional area is formed to be small, while ensuring the fluidity of the unburned air-fuel mixture, A larger amount 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 bottom surface 71a, the squish flow of the air-fuel mixture can be weakened and its 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.

Moreover, since the first bottom surface 71a crosses the center C of the outer peripheral surface, around TDC, the supply speed of the air-fuel mixture from the T side to the flame growing on the L side of the short axis position of the rotor housing 3 increases. That is, it is possible to avoid the flow of the air-fuel mixture from the T side to the L side becoming stronger. Therefore, the combustion speed of the main combustion after ignition does not increase, so to speak, slow combustion and sudden heat generation can be avoided. For this reason, cooling loss does not increase, which is advantageous in terms of improving fuel consumption, reducing combustion noise, and preventing gas leakage.

Moreover, making the cross-sectional area of the first bottom surface 71a the largest is equivalent to making the cross-sectional area of the second recess 72 relatively small. As a result, 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 increasing the cross-sectional area of the first bottom surface 71 a and relatively decreasing the cross-sectional area of the second recess 72 , the geometrical compression ratio of the engine 1 can be maintained and the thermal efficiency can be improved while slowing down the combustion. can be ensured.

Further, by providing the first inclined surface 71b on the T side of the outer peripheral surface center C, in the latter half of the combustion after TDC, the air-fuel mixture flows from the T side of the short axis position of the rotor housing 3 to the L side where the flame exists. can be smoothly advanced through this first inclined surface 71b. As a result, the occurrence or scale of so-called two-stage combustion can be suppressed, which is advantageous in suppressing cooling loss. At this time, the first inclined surface 71b gradually deepens from the T-side recess end Lt to the L-side first bottom surface 71a. Gradually increasing the depth toward the L side weakens the flow velocity of the squish flow in the first concave portion 71, which is advantageous in improving fuel efficiency by slowing combustion.

As described above, according to the above-described embodiment, it is possible to realize slow combustion in both the first half and the second half of combustion while supplying a large amount of air-fuel mixture from the first recess 71 . As a result, while suppressing combustion noise, gas leakage, etc., it is possible to suppress cooling loss and improve fuel efficiency. Further, setting the cross-sectional area of the second recess 72 as described above is more advantageous for improving the fuel efficiency.

Further, as shown in FIG. 3 and the like, by making the length of the first bottom surface 71a (first length L1) longer than the length of the first inclined surface 71b (third length L3), the first concave portion Of the total volume of 71, the proportion of the volume defined by the first bottom surface 71a can be increased. Since the volume defined by the first bottom surface 71a is larger than the volume defined by the first inclined surface 71b, the total volume of the first recess 71 can be increased to slow down combustion and improve fuel efficiency. can be done. In addition, since the length of the first inclined surface 71b is relatively shortened, the first inclined surface 71b steeply becomes deeper toward the L side. As a result, the flow speed of the squish flow through the first inclined surface 71b is weakened, which is advantageous in terms of improving the fuel consumption performance by slowing down the combustion.

The length from the center C of the outer peripheral surface to the boundary between the first recess 71 and the second recess 72 is 2/10 or more 4/2/10 or more of the length La from the center C of the outer peripheral surface to the L-side end of the rotor outer peripheral surface 2a. 10 or less.

According to this, as shown in the section of 0 mm or more in FIG. 72 will extend longer. As a result, 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 and the second recess 72 do not face the spark plug 9 at the time of ignition. 2 recesses 72 can be opposed to 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, as shown in FIG. 3, the length from the center C of the outer peripheral surface to the T-side recess end portion 7t is 2/10 or more and 5/10 or less of the length from the center C to the L-side recess end portion 7l. is set to 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>>
Although the first inclined surface 71b and the second inclined surface 71c are each defined as one element of the first concave portion 71 in the above embodiment, this definition is for convenience only. For example, the second inclined surface 71 c may be one element of the second recess 72 . The above relationship (A) holds regardless of such definitions.

Also, the first bottom surface 71a and the second bottom surface 72a may be inclined or curved along the rotation direction. These bottom surfaces have cross-sectional areas that change relatively slowly compared to the second inclined surface 71c connecting the bottom surfaces and the third inclined surface 72b connecting 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 surface 71b first inclined surface 72 second recess 72a second bottom surface 7l L side recess end part (front edge of recess)
7t T-side recess end (front end of recess)
8 working chamber 9 spark plug 31 rotor housing chamber L1 first length (length of first bottom surface)
L2 second length (length of the bottom surface of the second recess)
L3 third length (length of first inclined surface)
C Center of outer peripheral surface (center of outer peripheral surface in longitudinal direction)
X Rotation axis Z Minor axis

Claims (6)

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 that is arranged in the center of the outer peripheral surface in the longitudinal direction and extends along the rotational direction of the rotor, and a recess that is continuous with the first recess and extends forward in the rotational direction. a second recess extending along the
The first concave portion is
a first bottom surface including the center and having a predetermined length from the center toward the front side;
a first inclined surface extending from the first bottom surface to the front end of the recess while being inclined such that the depth of the first recess becomes shallower toward the front side in the rotation direction;
The cross-sectional area of the recess when the recess is traversed by a plane perpendicular to the longitudinal direction and passing through the center of rotation of the rotor is the largest at the first bottom surface. The boundary of is located on the front side in the rotational direction compared to the center,
The rotary engine, wherein the control unit controls the operation of the spark plug so that the spark plug faces the second recess and the ignition timing is before top dead center in a compression stroke. A rotary engine as claimed in claim 1,
A rotary engine, wherein the length of the first bottom surface is longer than the length of the first inclined surface when viewed along the longitudinal direction. In the rotary engine according to claim 1 or 2,
The length from the longitudinal center of the outer peripheral surface to the boundary between the first recess and the second recess is 2/2 of the length from the longitudinal center of the outer peripheral surface to the front end of the outer peripheral surface. A rotary engine characterized by being 10 or more and 4/10 or less. In the rotary engine according to any one of claims 1 to 3,
The length from the longitudinal center of the outer peripheral surface to the front end of the recess is 2/10 or more 5/5 of the length from the longitudinal center of the outer peripheral surface to the front end of the recess. 10 or less, a rotary engine. In the rotary engine according to any one of claims 1 to 4,
The length from the longitudinal center of the outer peripheral surface to the front end of the recess is 7/10 of the length from the longitudinal center of the outer peripheral surface to the front end of the outer peripheral surface in the rotation direction. A rotary engine characterized by being 9/10 or less. In the rotary engine according to any one of claims 1 to 5,
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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