JP2016217203A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance degree of freedom to control of an in-cylinder air amount, by enabling a lift amount of an intake valve or exhaust valve to be controlled regardless of the position of a piston.SOLUTION: An internal combustion engine includes: a cylinder part 10 that includes a piston 12, a hole 11 through which the piston reciprocatively moves, and a recess 13 communicating with the upper dead point side end part of the piston 12 on the hole 11 and enlarged in an outer peripheral direction with respect to the hole 11; a combustion chamber X that is formed by the piston 12 and the recess 13, and includes an enlarged portion X2 corresponding to the recess part 13; and an intake valve 33 and an exhaust valve 34 that is opened/closed at the enlarged portion X2 of the combustion chamber X.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an internal combustion engine including a piston, an intake / exhaust valve, and a combustion chamber.

  There is known an internal combustion engine in which reciprocating movement of a piston and opening / closing operation of an intake / exhaust valve are interlocked to supply and compress a combustion chamber, combust in the combustion chamber, and discharge exhaust gas from the combustion chamber. In this internal combustion engine, since the intake valve and the exhaust valve are arranged directly above the piston, the opening / closing operation of each valve is controlled so that these valves do not collide with the piston. For example, Patent Document 1 discloses a technique for limiting the lift amount of the exhaust valve when executing the compression release brake in relation to the position of the piston.

JP 2012-202372 A

  If the lift amount of the intake valve and exhaust valve can be controlled regardless of the position of the piston, the degree of freedom in controlling the air amount in the cylinder can be increased, and as a result, the degree of freedom in various controls such as the strength of the compression release brake and the intake air amount can be increased. Can be increased.

  It is an object of the disclosed internal combustion engine to increase the degree of freedom in controlling the in-cylinder air amount by making it possible to control the lift amount of the intake valve and the exhaust valve regardless of the position of the piston.

  The disclosed internal combustion engine includes a piston, a hole part in which the piston is reciprocated, and a top dead center side end part of the piston in the hole part, and a shape that is enlarged in the outer circumferential direction than the hole part. A combustion chamber that is formed by the piston and the recess and has an enlarged portion corresponding to the recess, and an intake valve and an exhaust valve that are opened and closed at the enlarged portion of the combustion chamber.

  According to the disclosed internal combustion engine, the lift amount of the intake valve and the exhaust valve can be controlled regardless of the position of the piston, thereby increasing the degree of freedom in controlling the in-cylinder air amount.

It is a typical sectional view of an engine. It is a typical partial expanded sectional view of a combustion chamber periphery. It is a typical top view of a combustion chamber. (A) is a partially enlarged sectional view schematically illustrating the valve movable range on the intake valve side, and (B) is a partially enlarged sectional view schematically illustrating the valve movable range on the exhaust valve side. (A) is a schematic plan view of a combustion chamber of the second embodiment, and (B) is a diagram schematically illustrating an example of control of an intake valve. It is a typical partial expanded sectional view of a combustion chamber periphery explaining a modification.

  Hereinafter, a diesel engine 1 (an example of an internal combustion engine, hereinafter simply referred to as an engine 1) according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, the engine 1 includes a cylinder block 2 and a cylinder head 3. The upper half of the cylinder block 2 corresponds to the cylinder portion 10 and is formed with a circular hole 11 extending in the vertical direction. The hole 11 accommodates the piston 12 in a reciprocable state. The lower end of the hole 11 (that is, the end on the bottom dead center side of the piston 12) is connected to the crankcase portion 20. On the other hand, a recess 13 is formed in communication with the upper end of the hole 11 (that is, the end on the top dead center side of the piston 12). The recess 13 forms a combustion chamber X together with the top surface 12 a of the piston 12 and the lower surface 3 a of the cylinder head 3. The recess 13 will be described later together with the combustion chamber X.

  A crankshaft 21 is disposed in the crankcase portion 20 in a rotatable state. A lower end of a connecting rod 23 is attached to a crankpin 22 provided in the crankshaft 21 in a rotatable state. The upper end of the connecting rod 23 is attached to a piston pin 12b included in the piston 12 in a rotatable state. An oil jet 25 that injects oil supplied from the oil passage 24 upward is provided at the upper end of the crankcase portion 20. The oil jetted from the oil jet 25 flows into a cooling channel 12c (see FIG. 2) formed inside the piston 12, and is used for cooling the piston 12. A coolant channel 14 through which a coolant such as cooling water flows is provided around the recess 13 in the cylinder portion 10.

  An intake port 31 and an exhaust port 32 are formed in the cylinder head 3. The intake port 31 is a flow path for introducing fresh air, and the exhaust port 32 is a flow path for discharging exhaust gas. The outlet of the intake port 31 is opened at a position directly above the recess 13 (bottom surface 13 a) in the lower surface 3 a of the cylinder head 3. The inlet of the exhaust port 32 is opened at a position directly above the recess 13 (bottom surface 13 a) in the lower surface 3 a of the cylinder head 3, similarly to the outlet of the intake port 31.

  An intake valve 33 is disposed at the intake port 31, and an exhaust valve 34 is disposed at the exhaust port 32. Specifically, the umbrella portion of the intake valve 33 is disposed at the outlet of the intake port 31, and the umbrella portion of the exhaust valve 34 is disposed at the inlet of the exhaust port 32. An upward force is applied to the intake valve 33 and the exhaust valve 34 by valve springs 35 provided on the respective shaft portions. Further, hydraulic plungers 36 are arranged at the upper ends of the intake valve 33 and the exhaust valve 34, respectively.

  The hydraulic plunger 36 includes a pin 36 a that is moved in the vertical direction according to the hydraulic pressure, and the lower end surface of the pin 36 a is in contact with the upper end surface of the shaft portion of each valve 33, 34. When the pin 36a is moved downward against the restoring force of the valve spring 35 due to the increase in hydraulic pressure, the corresponding intake valve 33 and exhaust valve 34 are lifted in the valve opening direction. On the other hand, when the restoring force of the valve spring 35 wins due to a decrease in hydraulic pressure, the pin 36a is moved upward, and the corresponding intake valve 33 and exhaust valve 34 are moved in the valve closing direction.

  The hydraulic plunger 36 is electrically connected to an electronic control unit 50 (hereinafter referred to as ECU 50), and the operation (the amount of movement of the pin 36a) is controlled in accordance with a control signal from the ECU 50. Therefore, the combination of the hydraulic plunger 36 and the ECU 50 is an example of the intake valve control means and the exhaust valve control means of the present invention.

  An injector 41 is disposed between the intake valve 33 and the exhaust valve 34. The injector 41 is a member that injects fuel into the combustion chamber X, and a plurality of injection holes 42 are formed at the tip portion disposed in the combustion chamber X, and fuel is injected from these injection holes 42. The The number of the injection holes 42 formed can be determined as appropriate, such as 5, 7, 10 or the like.

  Next, the combustion chamber X will be described in detail. As shown in FIG. 2, the combustion chamber X is formed by a recess 13 formed in the cylinder block 2, a piston 12, and the cylinder head 3. That is, the entire space defined by the bottom surface 13 a and the side surface 13 b of the recess 13, the top surface 12 a of the piston 12 located at the top dead center, and the lower surface 3 a of the cylinder head 3 is the combustion chamber X. In the combustion chamber X, the portion located above the top surface 12a (hole 11) of the piston is the center side portion X1, and the portion located similarly above the bottom surface 13a of the recess 13 is the enlarged portion X2. The volume of the combustion chamber X is the same as the volume of a general combustion chamber formed at the upper end of the hole 11 without the recess 13. In other words, the combustion chamber X of this embodiment and the general combustion chamber have the same compression ratio.

  The recess 13 has a shape that is enlarged in the outer peripheral direction (radial direction of the hole 11) than the edge of the hole 11 where the piston 12 reciprocates, and is formed by a bottom surface 13a and a side surface (circumferential surface) 13b.

  Since the concave portion 13 that is expanded in the outer peripheral direction from the edge of the hole portion 11 is formed, as shown in FIG. 3, the distance L2 from the center of the injector 41 to the outer peripheral edge of the bottom surface 13 a is from the injector 41 to the hole portion 11. It becomes longer than the distance L1 to the inner wall surface. And the bottom face 13a is provided in the circular ring shape centering on the hole part 11 seeing from a planar direction. The intake valve 33 and the exhaust valve 34 are disposed at positions facing the bottom surface 13a.

  In this embodiment, two intake valves 33 are arranged on the left side in FIG. 3, and two exhaust valves 34 are arranged on the right side as well. The width of the bottom surface 13a (the difference between the distance L2 and the distance L1) is equal to or greater than the diameter of the umbrella portion of the intake valve 33 and the umbrella portion of the exhaust valve 34. In other words, when the diameter Dp of the piston 12, the diameter Db of each valve 33, 34, and the diameter Dc of the hole portion 11, the diameter of each part satisfies the relationship of L2−L1> Db and Dc> Dp. Determined.

  The side surface 13b is formed by a surface that rises upward from the outer peripheral edge of the bottom surface 13a. The height of the side surface 13 b is set to be equal to or greater than the maximum lift amount of the intake valve 33 and the exhaust valve 34. This is also because the intake valve 33 and the exhaust valve 34 are opened and closed at the enlarged portion X2 of the combustion chamber X.

  The bottom surface 13a is formed by an inclined surface that goes down from the inner periphery to the outer periphery. Since the top surface 12 a of the piston 12 is formed in a conical shape with a low height, the bottom surface 13 a of the recess 13 is also an inclined surface having the same inclination angle as the top surface 12 a of the piston 12. Thereby, when the piston 12 is located at the top dead center, the top surface 12a of the piston 12 and the bottom surface 13a of the recess 13 form a series of inclined surfaces (conical surfaces).

  In the engine 1 of the first embodiment having the above configuration, the intake valve 33 and the exhaust valve 34 can be opened and closed regardless of the height position of the piston 12.

  As shown in FIG. 4 (A), since the enlarged portion X2 of the combustion chamber X is formed in the outer peripheral direction with respect to the piston 12, the intake valve 33 disposed in the enlarged portion X2 has the piston 12 top dead. Even if it is located at a point, it can be freely opened and closed within the valve movable range H1. Similarly, as shown in FIG. 4B, since the intake valve 33 is also arranged in the enlarged portion X2, it can be freely opened and closed within the valve movable range H2 even if the piston 12 is located at the top dead center. it can.

  In this way, the lift amount of the intake valve 33 and the exhaust valve 34 can be determined regardless of the position of the piston 12, and the degree of freedom for controlling the in-cylinder air amount can be increased. Thereby, an in-cylinder pressure can be adjusted and the gas flow in a cylinder can be adjusted. As a result, it is possible to increase the degree of freedom for various controls such as the strength of the compression release brake and the intake air amount.

  As shown in FIG. 2, when the piston 12 is located at the top dead center, the bottom surface of the combustion chamber X (the top surface 12 a of the piston 12, the recess 13) extends from the center of the surface of the piston 12 to the outer peripheral edge of the recess 13. The bottom surface 13a) becomes a downward inclined surface. For this reason, the combustion chamber X becomes a space that becomes deeper toward the outer peripheral side. And the injector 41 injects a fuel toward the center of the height direction in the side surface 13b.

  Therefore, even if the fuel injected from the injection hole 42 spreads in the vertical direction, the amount of fuel that directly collides with the bottom surface of the combustion chamber X or the ceiling surface of the combustion chamber X (the lower surface 3a of the cylinder head 3) can be suppressed. . As a result, it becomes easy to mix the fuel and air uniformly, and the generation of an excess fuel region can be suppressed. Further, since the combustion chamber X can be made shallower than the combustion chamber having a general shape and expands in the plane direction, the flame is difficult to come into contact with the fuel being diffused, and the fuel can be burned efficiently.

  Further, since the combustion chamber X is circular when viewed in the plane direction and has a shape that becomes deeper toward the outer peripheral side, even if the fuel injected from the injection holes 42 expands in the vertical direction toward the outer peripheral side, The amount of fuel that directly collides with the ceiling surface or the bottom surface 13a can be suppressed, and the concentration of the fuel injected into the combustion chamber X can be equalized.

  Moreover, since the top surface 12a is made into the cone shape with low height regarding the piston 12, sufficient intensity | strength is securable also under high temperature and a high pressure. In addition, a refrigerant flow path 14 through which the refrigerant flows is provided around the recess 13 in the cylinder block 2. Since the cylinder block 2 is a component having a large volume in the component group constituting the engine 1, a necessary cooling capacity can be easily obtained without impairing the strength of the engine 1.

  Next, the engine 1 which concerns on 2nd Embodiment of this invention is demonstrated. In the engine 1 of the second embodiment, the number and control of the intake valves 33 and the exhaust valves 34 are different from the engine 1 of the first embodiment. For this reason, below, the part regarding a difference is demonstrated and the description about a common part is abbreviate | omitted.

  As shown in FIG. 5A, the combustion chamber X of the second embodiment also has a center side portion X1 formed above the piston 12 and an enlarged portion X2 formed above the bottom surface 13a of the recess 13. Prepare. Also in the second embodiment, the volume of the combustion chamber X is the same as the volume of a general combustion chamber.

  The engine 1 of the second embodiment includes four intake valves 33A to 33D and four exhaust valves 34A to 34D. In this example, the intake valves 33A to 33D are arranged in an arc shape in the clockwise direction from the lower side of the drawing in the left half of the drawing. Similarly, the exhaust valves 34A to 34D are arranged in an arc shape in the counterclockwise direction from the lower side of the drawing in the right half of the drawing.

  As described with reference to FIG. 1, hydraulic plungers 36 are provided corresponding to the intake valves 33 </ b> A to 33 </ b> D and the exhaust valves 34 </ b> A to 34 </ b> D, respectively. Each hydraulic plunger 36 is electrically connected to the ECU 50 and its operation is controlled independently. The intake valves 33A to 33D may be controlled in the same manner or individually. Similarly, the exhaust valves 34A to 34D may be controlled in the same manner or individually.

  Then, by individually controlling the intake valves 33A to 33D and the exhaust valves 34A to 34D, the gas flow in the cylinder can be controlled. For example, as shown in FIG. 5B, the first intake valve 33A is opened at timing t1, the second intake valve 33B is opened at timing t2, and the third intake valve 33C is opened at timing t3. By opening the third intake valve 33D at the timing t4, it becomes possible to positively generate a swirling flow in the cylinder.

  Further, with respect to each of the exhaust valves 34A to 34D, it is also possible to adjust the strength of the compression release brake by adjusting the number of exhaust valves 34 to be opened and the valve lift amount.

  The above description of the embodiment is for facilitating the understanding of the present invention, and does not limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

  For example, regarding the combustion chamber X (recessed portion 13), in each of the above-described embodiments, a circular depression is seen from the plane direction, but the shape is not limited thereto. For example, it may be an elliptical depression as viewed from the plane, or may be a fan-shaped depression.

  Furthermore, as shown in FIG. 6, the side surface (circumferential surface) 13 b of the recess 13 may be an inclined surface that rises from the outer peripheral edge of the bottom surface of the recess 13 toward the outer periphery as the distance from the bottom surface 13 a of the recess 13 increases. Thus, by making the diameter of the umbrella portion of the intake valve 33 and the exhaust valve 34 smaller than the width of the enlarged portion X2 of the combustion chamber X (the width of the bottom surface 13a), the depth of the outermost peripheral portion of the enlarged portion X2 Even if is 0, each valve 33, 34 can be operated freely.

  In each of the above-described embodiments, the opening / closing operation of the intake valve 33 and the exhaust valve 34 is controlled by the combination of the hydraulic plunger 36 and the ECU 50 (intake valve control means, exhaust valve control means). However, the present invention is not limited to this configuration. Absent. For example, a set of an intake cam, an exhaust cam, and a rocker arm may be provided in each of the intake valve 33 and the exhaust valve 34, and the opening / closing operation of each valve 33, 34 may be controlled by these. In this case, the combination of the intake cam, the exhaust cam, and the rocker arm corresponds to the intake valve control means and the exhaust valve control means of the present invention.

  Moreover, in each above-mentioned embodiment, although the engine 1 provided with the cylinder block 2 and the cylinder head 3 was illustrated, it is not limited to the engine 1 of this structure. It is sufficient if the engine includes at least a piston, a hole in which the piston is reciprocated, and a recess communicated with the hole at the upper end of the hole.

DESCRIPTION OF SYMBOLS 1 ... Diesel engine, 2 ... Cylinder block, 3 ... Cylinder head, 3a ... Lower surface of cylinder head, 10 ... Cylinder part, 11 ... Hole part, 12 ... Piston, 12a ... Top surface of piston, 12b ... Piston pin, 12c ... Cooling channel, 13 ... concave portion, 13a ... bottom surface of concave portion, 13b ... side surface of concave portion, 14 ... refrigerant flow path, 20 ... crankcase portion, 21 ... crankshaft, 22 ... crankpin, 23 ... connecting rod, 24 ... oil flow passage , 25 ... oil jet, 31 ... intake port, 32 ... exhaust port, 33 ... intake valve, 33A ... first intake valve, 33B ... second intake valve, 33C ... third intake valve, 33D ... fourth intake valve, 34 ... exhaust valve, 34A ... first exhaust valve, 34B ... second exhaust valve, 34C ... third exhaust valve, 34D ... fourth exhaust Lub, 35 ... Valve spring, 36 ... Hydraulic plunger, 36a ... Hydraulic plunger pin, 41 ... Injector, 42 ... Injection hole, 50 ... ECU, X ... Combustion chamber, X1 ... Center portion of combustion chamber, X2 ... Combustion chamber Enlarged part of

Claims (3)

A piston,
A hole portion in which the piston is reciprocally moved, and a cylinder provided with a recess having a shape that is communicated with a top dead center side end portion of the piston in the hole portion and is expanded in an outer peripheral direction from the hole portion;
A combustion chamber that is formed by the piston and the recess and includes an enlarged portion corresponding to the recess;
An internal combustion engine comprising an intake valve and an exhaust valve that are opened and closed at the enlarged portion of the combustion chamber. A plurality of the intake valves are provided for one piston,
The internal combustion engine according to claim 1, further comprising intake valve control means for individually controlling opening and closing operations of the plurality of intake valves. A plurality of the exhaust valves are provided for one piston,
The internal combustion engine according to claim 1, further comprising exhaust valve control means for individually controlling a plurality of exhaust valve opening / closing operations.

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