JP2012007522A - Engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine capable of suitably reducing adhesion of fuel spray to a bore wall.SOLUTION: The engine 50 includes a fuel injection valve 58 directly injecting fuel into a cylinder 51a, and a crankshaft 59, and forms a tumble flow T in the cylinder 51a. When viewing along the extending direction of a crank axis Lc, a line connecting an end portion 58a of the fuel injection valve 58 and the center of the tumble flow T is set as a first axis L1, and a second axis L2 is set at a line having a base point at the end portion 58a and lying at a position turned to the center side of the tumble flow T by a predetermined angle α from an external tangent line Lt which is extended from a base point of the end portion 58a while aligning the extending direction with the turning direction of the tumble flow T and is externally tangent to the tumble flow T. The fuel injection valve 58 injects the fuel into a space between the first and second axes L1, L2.

Description

  The present invention relates to an engine.

  An engine that generates a tumble flow in a cylinder and directly injects fuel is known (see, for example, Patent Document 1 or 2).

JP 2009-174440 A JP 2003-220460 A

  In the engine, the fuel can be injected by matching the injection direction with the rotational direction of the tumble flow. In this case, the spray of injected fuel may adhere to the bore wall (cylinder wall) and dilute the oil that lubricates the piston. Such oil dilution may increase when the tumble ratio (the number of times the tumble flow rotates during one reciprocation of the piston) is large in a small displacement engine. The reason is as follows.

  That is, generally, the smaller the engine displacement, the smaller the bore diameter. As the bore diameter decreases, the distance between the fuel injection valve and the bore wall decreases. As a result, the spray of the fuel injected from the fuel injection valve easily reaches the bore wall before being vaporized. In addition, when the tumble ratio is large, the fuel spray rides on the tumble flow and easily reaches the bore wall. For this reason, the dilution of oil may increase.

  For example, as shown in FIG. 14, it is conceivable to inject the fuel so as to face the tumble flow T. FIG. 14 is an explanatory view of the behavior of the fuel spray F when the fuel is injected into the cylinder 51a so as to face the tumble flow T. IN indicates the intake side, and EX indicates the exhaust side. A two-dot dashed circle indicates the outer periphery of the tumble flow T. For the fuel injection valve 58, only the tip 58a indicating the tip position is shown. FIG. 14 is a view seen along the direction of extension of the crank axis.

  The first axis L1 is a line connecting the tip 58a and the center O of the tumble flow T. When the fuel is injected so as to face the tumble flow T, the fuel is injected to the bottom dead center side with respect to the first axis L1. In this case, the trajectory of the fuel spray F is deflected toward the center O side of the tumble flow T. For this reason, the oil dilution in the above-described embodiment does not occur. However, this fuel injection mode is an injection mode suitable for forming a stratified mixture near the spark plug 57, and is considered unsuitable for homogeneous combustion. That is, in this case, the fuel spray F and the tumble flow T are made to face each other, and the momentum of both is rapidly reduced. For this reason, the tumble flow T is attenuated, and it becomes difficult to improve the turbulence strength in the cylinder and the combustion speed.

  In view of the above problems, an object of the present invention is to provide an engine that can suitably reduce the adhesion of fuel spray to a bore wall.

  The present invention includes a fuel injection valve that directly injects fuel into a cylinder and a crankshaft, and generates a tumble flow in the cylinder when viewed along a direction in which the crankshaft extends along the crankshaft. The line connecting the tip of the fuel injection valve and the center of the tumble flow is the first axis, and the rotation of the tumble flow with the tip as a base when viewed along the crankshaft extending direction of the crankshaft. The center of the tumble flow by a predetermined angle within a range not exceeding the center of the tumble flow from the circumscribing line circumscribing the tumble flow, with the leading end as a base point. When the second shaft is a line positioned at a position rotated to the side, and the fuel injection valve is viewed along the crankshaft extending direction of the crankshaft, the fuel injection valve is while An engine that injects fuel into space.

  Moreover, this invention can be set as the structure further equipped with the piston which formed the top surface in the shape in alignment with the outer periphery of the said tumble flow in the said cylinder.

  The present invention further includes a determining unit that determines an acute angle formed by an injection direction of the fuel injection valve and a plane perpendicular to the central axis of the cylinder based on a required injection period of the fuel injection valve. be able to.

  The present invention may further include a first switching unit that switches the injection direction of the fuel injection valve to a direction along the outer tangent when the wall temperature of the cylinder is equal to or higher than a predetermined temperature. .

  The present invention may further include a second switching unit that switches the injection direction of the fuel injection valve to a direction along the circumscribed line when the engine load factor is less than a predetermined value.

  According to the present invention, the adhesion of fuel spray to the bore wall can be suitably reduced.

1 is a diagram illustrating a main part of an engine according to Embodiment 1. FIG. It is explanatory drawing of the injection direction of a fuel injection valve. It is explanatory drawing about the setting of angle (alpha). It is a figure which illustrates the behavior of fuel spray. It is a schematic diagram of the fuel spray by which the track | orbit was bent inside. It is explanatory drawing of the relationship between a piston top surface and a tumble flow. It is explanatory drawing about the behavior of the fuel spray which stayed near the center of the tumble flow. It is a figure which shows the principal part of the engine concerning Example 2. FIG. It is a figure which shows the change of the optimal V angle range according to the position of a piston. It is a figure which shows the determination diagram of V angle. It is a figure which shows the V angle variable mechanism of a fuel injection valve. It is a figure which shows the 1st control diagram of V angle. It is a figure which shows the 2nd control diagram of V angle. It is explanatory drawing about the behavior of the fuel spray at the time of injecting a fuel in a cylinder so as to oppose a tumble flow.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a view of the engine 50 as viewed along the extending direction of the crank axis Lc per cylinder. The engine 50 is a small displacement engine having a bore diameter between φ70 mm and φ75 mm, for example, and includes a cylinder block 51, a cylinder head 52, a piston 53, an intake valve 55, an exhaust valve 56, an ignition A plug 57, a fuel injection valve 58, and a crankshaft 59 are provided. A cylinder 51 a is formed in the cylinder block 51. A piston 53 is accommodated in the cylinder 51a. A cylinder head 52 is fixed to the upper surface of the cylinder block 51. The combustion chamber 54 is formed as a space surrounded by the cylinder block 51, the cylinder head 52 and the piston 53.

  The cylinder head 52 is formed with an intake port 52a and an exhaust port 52b. The intake port 52 a guides the intake air S to the combustion chamber 54, and the exhaust port 52 b exhausts the gas in the combustion chamber 54. The intake port 52a introduces intake air so as to generate a tumble flow T in the cylinder 51 (more specifically, in the combustion chamber 54). For this reason, the intake air S introduced into the combustion chamber 54 forms a tumble flow T. The tumble ratio of the tumble flow T is set to a high tumble ratio (for example, a value between 1.5 and 3.0 in the AVL simulation). The tumble ratio is set to be a high tumble ratio at the time of homogeneous combustion, for example. By setting the tumble ratio to a high tumble ratio, it is possible to improve the turbulence strength in the cylinder and the combustion speed during homogeneous combustion. The top surface 53a of the piston 53 is formed along the outer periphery of the tumble flow T.

  The cylinder head 52 is provided with intake and exhaust valves 55 and 56 for opening and closing the intake and exhaust ports 52a and 52b. In addition, the cylinder head 52 is provided with an ignition plug 57 and a combustion injection valve 58. The combustion injection valve 58 is provided in a portion on the intake side of the cylinder head 52, more specifically, a portion between the intake port 52 a and the cylinder block 51. The fuel injection valve 58 directly injects fuel into the cylinder 51 (more specifically, into the combustion chamber 54) from the intake side to the exhaust side. The crankshaft 59 converts the reciprocating motion of the piston 53 into a rotational motion. In the first embodiment, the engine 50 corresponds to the engine of the present invention.

  FIG. 2 is an explanatory view of the injection direction D of the fuel injection valve 58. FIG. 2 is a view of the main part of the engine 50 as seen in the extending direction of the crank axis Lc, as in FIG. IN indicates the intake side, and EX indicates the exhaust side. A two-dot dashed circle indicates the outer periphery of the tumble flow T. For the fuel injection valve 58, only the tip 58a indicating the tip position is shown. The same applies to FIGS. 3 to 7 and FIG. 9 described later.

  The first axis L1 is a line connecting the tip 58a and the center O of the tumble flow T. The circumscribing line Lt is a line that extends from the front end 58a as a base point while aligning the extending direction with the rotation direction of the tumble flow T and circumscribes the tumble flow T. The second axis L2 is located at a position rotated from the circumscribed line Lt to the center O side of the tumble flow T by a predetermined angle α within a range not exceeding the center O of the tumble flow T with the tip 58a as a base point. It is a line that is located.

  Specifically, the angle α is set as shown in FIG. The fuel injection valve 58 forms a fuel spray F that is a slit spray. When viewed along the extending direction of the crank axis Lc, the angle indicating the spread of the fuel spray F with the tip 58a as the base point is the thickness angle θc. On the other hand, the angle α is set to one half (θc / 2) of the thickness angle θc.

Returning to FIG. 2, the V angle θv is a depression angle formed by the injection direction D of the fuel injection valve 58 and the horizontal plane when the cylinder 51 a extends along the vertical direction. Therefore, the V angle θv corresponds to an acute angle formed by the injection direction D of the fuel injection valve 58 and a plane perpendicular to the central axis P of the cylinder 51a. The injection direction D of the fuel injection valve 58 is set by the V angle θv.
An angle range indicated between the first and second axes L1 and L2 with respect to the V angle θv is defined as an optimum V angle range R. Then, the V angle θv is set within the optimum V angle range R. Thereby, the injection direction D is set so that fuel is injected into the space between the first and second axes L1 and L2 (hereinafter referred to as the first space).

Next, the function and effect of the engine according to this embodiment will be described. 4A and 4B are diagrams illustrating the behavior of the fuel spray F. FIG. 4A shows the case where the V angle θv is set to 29 °, and FIG. 4B shows the case where the V angle θv is set to 39 °. Each is shown.
As shown in FIG. 4A, when the V angle θv is set to 29 °, the injection direction D is set to a direction along the circumscribed line Lt. Therefore, the fuel spray F circulates on the tumble flow T until the crank angle changes from 248 ° BTDC to 238 ° BTDC. As a result, it reaches the bore wall.
As shown in FIG. 4B, when the V angle θv is set to 39 °, the injection direction D is set so as to inject fuel into the first space. For this reason, the trajectory of the fuel spray F is bent inward by the tumble flow T until the crank angle is changed from 248 ° BTDC to 238 ° BTDC. As a result, adhesion of the fuel spray F to the bore wall surface can be reduced.

That is, in the engine according to this embodiment, as a result of injecting fuel into the first space, the trajectory of the fuel spray F is bent inward by the tumble flow T as schematically shown in FIG. As a result, even when the engine has a small displacement and the tumble ratio is set to a high tumble ratio, the adhesion of the fuel spray F to the bore wall surface can be suitably reduced.
Moreover, this engine can suppress attenuation | damping of the tumble flow T by injection by matching the injection direction D with the rotation direction of the tumble flow T, and injecting fuel. Therefore, it is particularly suitable when performing homogeneous combustion.

  In this engine, the top surface 53a of the piston 53 is formed along the outer periphery of the tumble flow T. Therefore, as shown in FIG. 6, the tumble flow T can be smoothly guided by the top surface 53a. At this time, the tumble flow T functions like an air curtain separating the fuel spray F and the top surface 53a. For this reason, this engine can also reduce adhesion of the fuel spray F to the top surface 53a.

  Further, in this engine, as a result of the trajectory of the fuel spray F being bent inward by the tumble flow T, the fuel spray F stays in the vicinity of the center O of the tumble flow T as schematically shown in FIG. On the other hand, the tumble flow T is suppressed from being attenuated by the setting of the injection direction D and the shape of the top surface 53a. For this reason, the fuel spray F staying in the vicinity of the center O diffuses to the surroundings as schematically indicated by the arrows due to the centrifugal force of the tumble flow T in which attenuation is suppressed. For this reason, the engine 50 is also suitable for performing homogeneous combustion in that the homogeneity of the air-fuel mixture can be increased in this way.

  As shown in FIG. 8, in the second embodiment, an ECU 70 </ b> A is provided for the engine 50. In the second embodiment, the engine 50 and the ECU 70A correspond to the engine of the present invention. The ECU 70A includes a microcomputer including a CPU, a ROM, a RAM, and an input / output circuit. Various sensors / SWs 80 for detecting the state of the engine 50 are electrically connected to the ECU 70A. The sensors / SWs 80 include, for example, an air flow meter that measures the intake air amount of the engine 50, a crank angle sensor that detects the crank angle of the engine 50, and a cooling water temperature sensor that detects the cooling water temperature of the engine 50. Various control objects such as the fuel injection valve 58 are electrically connected to the ECU 70A.

In the ECU 70A, various means are functionally realized by the CPU executing processing while using the temporary storage area of the RAM as necessary based on the program stored in the ROM.
For example, in the ECU 70A, a determination unit that determines the V angle θv based on the required injection period (injection amount) pe of the fuel injection valve 58 is functionally realized.
The reason for determining the V angle θv is as follows. As shown in FIG. 9, the position of the tumble flow T changes according to the position of the piston 53 exemplified by the broken line and the solid line, that is, according to the crank angle. Accordingly, the optimum V angle range R also changes according to the crank angle. For this reason, it is necessary to determine the optimum V angle θv according to the crank angle. On the other hand, the determining means determines the V angle θv as follows.

  FIG. 10 is a diagram showing a determination diagram of the V angle θv. In FIG. 10, the vertical axis represents the V angle θv, and the horizontal axis represents the crank angle. The optimum V angle range R forms a band-shaped region Rb according to the crank angle. For this reason, the determining means obtains the required injection period pe and adapts the acquired requested injection period pe to the region Rb, so that the optimum V angle θv (optimum V angle θvb) and optimum fuel injection timing t are obtained. Can be determined. The required injection period pe can be read from map data stored in advance in the ROM based on, for example, the rotational speed of the engine 50 and the intake air amount.

  On the other hand, when changing the V angle θv, the fuel injection valve 58 is specifically provided with a V angle variable mechanism shown below. FIG. 11 is a view showing a V angle variable mechanism of the fuel injection valve 58. A nozzle needle 582 is accommodated in the nozzle body 581. The nozzle needle 582 slides in the nozzle body 581. In a state where the nozzle needle 582 is separated from the seat portion 583, fuel is injected from the injection hole 584. On the other hand, fuel injection stops in a state where the nozzle needle 582 is seated on the seat portion 583.

  A chamfered portion 584 a is formed in the opening of the nozzle hole 584. The chamfered portion 584a is chamfered with a curved surface. On the other hand, a bypass passage 586 is formed in the nozzle body 581. The bypass passage 586 bypasses a part of the nozzle hole 584 from the sack portion 585 and opens toward the chamfered portion 584a. For this reason, the fuel flowing through the bypass passage 586 pushes and bends the fuel flowing through the nozzle hole 584 toward the chamfered portion 584a. The pushed and bent fuel flows along the shape of the injection hole 584 by the Coanda effect. As a result, the V angle θv can be changed.

  Further, the nozzle body 581 is slidably provided with a bypass needle 587 that can adjust the flow rate of the fuel flowing through the bypass passage 586. For this reason, by controlling the bypass needle 587, the V angle θv can be made variable. The nozzle needle 582 and the bypass needle 587 can be controlled by controlling a control valve that can control the back pressure of these 582 and 587, for example.

  Next, the function and effect of the engine according to this embodiment will be described. In the engine according to the present embodiment, the V angle θv is determined based on the required injection period of the fuel injection valve 58. Thus, the optimum V angle θv corresponding to the crank angle can be determined. For this reason, this engine can further suitably reduce the adhesion of the fuel spray F to the bore wall surface according to the crank angle.

  In the third embodiment, an ECU 70B (not shown) is provided for the engine 50. The ECU 70B is substantially the same as the ECU 70A except that the first switching means is functionally realized. The first switching means can be realized, for example, together with the determination means described above or independently. In the third embodiment, the engine 50 and the ECU 70B correspond to the engine of the present invention.

The first switching means is realized to switch the injection direction D of the fuel injection valve 58 based on the wall temperature of the cylinder 51a. Details will be described later.
The wall temperature of the bore wall located in the injection direction D can be applied to the wall temperature of the cylinder 51a. The wall temperature of the bore wall located in the injection direction D is specifically the wall temperature of the exhaust-side bore wall. Note that the wall temperature of the cylinder 51a may be detected directly using, for example, a temperature sensor, or indirectly detected by detecting the cooling water temperature near the target cylinder 51a wall and estimating it based on this ( Estimation).

  FIG. 12 is a diagram showing a first control diagram of the V angle θv. In FIG. 12, the vertical axis represents the V angle θv, and the horizontal axis represents the bore wall temperature on the exhaust side. Here, when the bore wall temperature is lower than the first predetermined temperature (here, 40 ° C.), the influence of oil dilution by the fuel spray F becomes large. Therefore, in this case, the V angle θv is set within the optimum V angle range R. On the other hand, when the bore wall temperature is equal to or higher than the first predetermined temperature, the influence of oil dilution by the fuel spray F is reduced. Therefore, in this case, the V angle θv is set so that fuel is injected into a space (hereinafter referred to as a second space) closer to the circumscribing line Lt than the second axis L2.

When fuel is injected into the second space, the V angle θv can be set as follows.
That is, when the bore wall temperature is equal to or higher than the first predetermined temperature, for example, the V angle θv can be set so that the injection direction D is in a direction along the circumscribed line Lt.
In this case, as shown in FIG. 12, when the bore wall temperature is equal to or higher than a second predetermined temperature (here, 80 ° C.) higher than the first predetermined temperature, the injection direction D is a direction along the tangent line Lt. The V angle θv can be set to be
On the other hand, when the bore wall temperature is equal to or higher than the first predetermined temperature and lower than the second predetermined temperature, the bore wall temperature is lower than the first predetermined temperature and the second predetermined temperature is higher than the second predetermined temperature. The V angle θv can be set so that the V angle θv gradually decreases as the bore wall temperature increases.

Therefore, when the wall temperature of the cylinder 51a is equal to or higher than the first predetermined temperature, the first switching means changes the fuel injection valve 58 from the state in which fuel is injected into the first space to the state in which fuel is injected into the second space. The injection direction D is switched.
The first switching means can switch the injection direction D to a direction along the circumscribed line Lt when the wall temperature of the cylinder 51a is equal to or higher than the first predetermined temperature.
In this case, the first switching means can switch the injection direction D to a direction along the circumscribed line Lt when the wall temperature of the cylinder 51a is further equal to or higher than the second predetermined temperature. On the other hand, when the wall temperature of the cylinder 51a is equal to or higher than the first predetermined temperature and lower than the second predetermined temperature, the first switching means gradually increases the tangential line in the injection direction D as the wall temperature of the cylinder 51a increases. The injection direction D can be switched so as to be in the direction along Lt.
Regarding the wall temperature of the cylinder 51a, it may be higher than the predetermined temperature when it is higher than the predetermined temperature, and may be lower than the predetermined temperature when it is lower than the predetermined temperature.

  Next, the function and effect of the engine according to this embodiment will be described. In the engine according to this embodiment, when the bore wall temperature on the exhaust side is equal to or higher than the first predetermined temperature, the fuel is injected from the state in which fuel is injected into the first space to the state in which fuel is injected into the second space. The injection direction D of the valve 58 is switched. In this case, the airflow acceleration effect of the tumble flow T by fuel injection can be enhanced. For this reason, the engine according to the present embodiment achieves both a fuel adhesion reduction effect that reduces the adhesion of the fuel spray F to the bore wall surface and an air flow acceleration effect of the tumble flow T according to the bore wall temperature on the exhaust side. Can do.

In addition, when the bore wall temperature on the exhaust side is equal to or higher than the first predetermined temperature, this engine switches the injection direction D to the direction along the outer tangent line Lt, so that the air flow acceleration effect of the tumble flow T by the fuel injection is achieved. Can be greatly increased. Further, by switching the injection direction D in this way when the temperature is equal to or higher than the second predetermined temperature, the fuel adhesion reduction effect and the airflow acceleration effect can be suitably achieved.
In addition, when the exhaust side bore wall temperature is equal to or higher than the first predetermined temperature and lower than the second predetermined temperature, the engine gradually switches the injection direction D as described above, so that the engine operating state as a whole The effect of reducing fuel adhesion and the effect of increasing the airflow can be preferably achieved.

  In the fourth embodiment, an ECU 70C (not shown) is provided for the engine 50. The ECU 70C is substantially the same as the ECU 70A except that the second switching means is functionally realized. The second switching means is realized to switch the injection direction D of the fuel injection valve 58 based on the engine load. Details will be described later. The engine load can be detected based on, for example, the rotational speed of the engine 50 and the intake air amount. The second switching means can be realized, for example, together with the determining means described above or independently. In the fourth embodiment, the engine 50 and the ECU 70C correspond to the engine of the present invention.

  FIG. 13 is a diagram showing a second control diagram of the V angle θv. In FIG. 13, the vertical axis represents the V angle θv, and the horizontal axis represents the load factor (engine load factor) of the engine 50. Here, when the load factor is equal to or greater than the first predetermined value (80% in this case), the fuel injection period becomes longer, and the penetration (penetration force) of the fuel spray F increases. For this reason, when the load factor is equal to or more than the first predetermined value, the V angle θv is set within the optimum V angle range R. On the other hand, when the load factor is less than the first predetermined value, the fuel injection period is shortened, so that the penetration of the fuel spray F also decreases. For this reason, when the load factor is less than the first predetermined value, the V angle θv is set so that fuel is injected into the second space.

When fuel is injected into the second space, the V angle θv can be set as follows.
That is, when the load factor is less than the first predetermined value, for example, the V angle θv can be set so that the injection direction D is in a direction along the circumscribed line Lt.
In this case, as shown in FIG. 13, when the load factor is further less than a second predetermined value (for example, 60%) smaller than the first predetermined value, the injection direction D becomes a direction along the circumscribed line Lt. Thus, the V angle θv can be set.
On the other hand, when the load factor is less than the first predetermined value and greater than or equal to the second predetermined value, the load factor is greater than or equal to the first predetermined value and less than the second predetermined value. Thus, the V angle θv can be set so that the V angle θv gradually decreases as the load factor decreases.

Accordingly, when the load factor is less than the first predetermined value, the second switching means causes the injection direction of the fuel injection valve 58 to change from the state in which fuel is injected into the first space to the state in which fuel is injected into the second space. Switch D.
The second switching means can switch the injection direction D to a direction along the circumscribed line Lt when the load factor is less than the first predetermined value.
In this case, the second switching means can switch the injection direction D to the direction along the circumscribed line Lt when the load factor is further less than the second predetermined value. On the other hand, when the load factor is less than the first predetermined value and greater than or equal to the second predetermined value, the second switching means causes the injection direction D to gradually move in the direction along the outer tangent line Lt as the load factor decreases. Thus, the injection direction D can be switched.
Regarding the load factor of the engine 50, when it is equal to or greater than a predetermined value, it may be greater than the predetermined value, and when it is less than the predetermined value, it may be equal to or less than the predetermined value.

  Next, the function and effect of the engine according to this embodiment will be described. In the engine according to the present embodiment, when the load factor is less than the first predetermined value, the fuel injection valve 58 injects from the state in which fuel is injected into the first space to the state in which fuel is injected into the second space. Switch direction D. In this case, the airflow acceleration effect of the tumble flow T by fuel injection can be enhanced. For this reason, the engine according to the present embodiment can achieve both the fuel adhesion reduction effect and the air flow acceleration effect of the tumble flow T according to the engine load.

In addition, when the load factor is less than the first predetermined value, this engine greatly enhances the air flow acceleration effect of the tumble flow T by the fuel injection by switching the injection direction D to the direction along the circumscribed line Lt. Can do. Moreover, when it is less than a 2nd predetermined value, the fuel adhesion reduction effect and the airflow acceleration effect can be made to make compatible suitably by switching the injection direction D in this way.
In addition, when the load factor is equal to or higher than the first predetermined value and lower than the second predetermined value, the engine gradually switches the injection direction D as described above, thereby reducing the fuel adhesion as an entire engine operating state. And the airflow speed increasing effect can be achieved in a suitable manner.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.
For example, the first switching unit and the second switching unit may be used simultaneously. In this case, for example, among the first and second switching means, the switching means that sets the acute angle formed by the injection direction of the fuel injection valve and the plane perpendicular to the central axis of the cylinder to a smaller angle, The injection direction of the fuel injection valve can be switched.

Engine 50
Cylinder block 51
Cylinder 51a
Cylinder head 52
Piston 53
Top 53a
Combustion chamber 54
Intake valve 55
Exhaust valve 56
Fuel injection valve 58
Crankshaft 59
ECU 70A, 70B, 70C

Claims (5)

A fuel injection valve for directly injecting fuel into the cylinder and a crankshaft, and generating a tumble flow in the cylinder;
When viewed along the crankshaft extending direction of the crankshaft, a line connecting the tip of the fuel injection valve and the center of the tumble flow is a first axis,
When viewed along the direction of extension of the crankshaft of the crankshaft, the tip extends from the circumscribing line circumscribing the tumble flow, extending from the tip end while aligning the extension direction with the rotation direction of the tumble flow. The second axis is a line located at a position rotated to the center side of the tumble flow by a predetermined angle within a range not exceeding the center of the tumble flow with the part as a base point,
An engine in which the fuel injection valve injects fuel into a space between the first shaft and the second shaft when viewed along the direction of extension of the crankshaft of the crankshaft. The engine according to claim 1, further comprising a piston having a top surface formed in the cylinder along the outer periphery of the tumble flow. 3. The determination unit according to claim 1, further comprising: a determination unit that determines an acute angle formed by an injection direction of the fuel injection valve and a plane perpendicular to a central axis of the cylinder based on a required injection period of the fuel injection valve. Engine. 4. The apparatus according to claim 1, further comprising a first switching unit that switches an injection direction of the fuel injection valve to a direction along the circumscribed line when a wall temperature of the cylinder is equal to or higher than a predetermined temperature. Engine. 5. The engine according to claim 1, further comprising a second switching unit that switches an injection direction of the fuel injection valve to a direction along the circumscribed line when an engine load factor is less than a predetermined value. .

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