JP5879946B2 - Engine cooling system - Google Patents

Description

  The present invention relates to an engine cooling apparatus.

  In engines, it is known that deposits adhere to intake valves and exhaust valves. In this regard, for example, Patent Document 1 or 2 discloses a technique that is considered to be related to the present invention in that it discloses a technique for suppressing deposit adhesion to an intake valve or an exhaust valve. In addition, on the aspect of cooling using oil or cooling water, technologies considered to be related to the present invention are disclosed in Patent Documents 3 to 6, for example. Further, for example, Patent Document 7 or 8 discloses a technique considered to be related to the present invention in that the valve characteristic of the intake valve is changed in consideration of temperature.

Japanese Utility Model Publication No. 1-149901 JP 2006-348867 A JP 2007-32306 A JP 63-108512 A JP 2006-242078 A Japanese Utility Model Publication No. 2-19807 JP 2002-235593 A JP 2006-283632 A

  FIG. 9 is a diagram showing an example of the deposit amount according to the temperature. The vertical axis represents the amount of deposit deposited, and the horizontal axis represents the temperature of the valve umbrella. As shown in FIG. 9, in this example, it can be seen that the deposit amount starts to increase rapidly around 200 ° C., reaches a maximum around 250 ° C., and then decreases. In this regard, the intake valve can be used near a temperature at which the amount of deposit is maximized. For this reason, in the intake valve, deposit adhesion can be suppressed by raising the temperature above the temperature at which the amount of deposit accumulation becomes maximum. However, an increase in the temperature of the intake valve also causes an increase in the intake air temperature. For this reason, if the temperature of the intake valve is raised above the temperature at which the amount of deposits is maximized, engine performance may be degraded.

  In view of the above problems, an object of the present invention is to provide an engine cooling device that can suppress a decrease in engine performance even when the temperature of an intake valve is raised above the temperature at which the amount of deposit accumulation becomes maximum.

The present invention is provided in an engine provided with an intake valve capable of raising the temperature higher than the temperature at which the amount of deposit is maximized, and when the degree of output demand for the engine is larger than a predetermined degree, the intake valve A cooling device for an engine that lowers the temperature.

The present invention is provided corresponding to a stem guide of the intake valve and includes a passage portion for circulating cooling water, and the cooling water is circulated through the passage portion when the degree of output demand for the engine is larger than a predetermined degree. It can be set as the structure made to do.

The present invention includes a passage portion that is provided in correspondence with a seat portion on which the intake valve is seated, and that circulates cooling water. When the degree of output demand for the engine is greater than a predetermined degree , the cooling water is provided in the passage portion. Can be configured to circulate.

The present invention includes an oil supply unit capable of supplying oil to a stem guide of the intake valve or an umbrella portion of the intake valve, and when the degree of output demand for the engine is greater than a predetermined level, the oil supply unit It can be set as the structure which supplies.

The present invention includes a variable valve mechanism that can change a lift amount of the intake valve, and is configured to increase the lift amount of the intake valve when a degree of output request to the engine is larger than a predetermined degree. it can.

  According to the present invention, it is possible to suppress a decrease in engine performance even when the temperature of the intake valve is set higher than the temperature at which the amount of deposit accumulation becomes maximum.

It is a figure which shows the principal part of the engine of Example 1. FIG. It is a figure which shows the umbrella part of an intake valve. FIG. 3 is a diagram illustrating a control operation according to the first embodiment. It is a figure which shows the principal part of the engine of Example 2. FIG. It is a figure which shows the principal part of the engine of Example 3. FIG. FIG. 10 is a diagram illustrating a control operation of Example 3. It is a figure which shows the principal part of the engine of Example 4. FIG. FIG. 10 is a diagram illustrating a control operation according to a fourth embodiment. It is a figure which shows an example of the deposit accumulation amount according to temperature.

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

  FIG. 1 is a view showing a main part of the engine 50A. The engine 50A includes a cylinder head 51A, an intake valve 52, an exhaust valve 53, stem guides 54 and 55, and seat portions 56 and 57. The engine 50A is provided with a water pump (hereinafter referred to as W / P) 1, a control valve 2, a radiator 3, and an ECU 70A.

  The cylinder head 51A forms a combustion chamber E together with a cylinder block and a piston (not shown). An intake port 51a and an exhaust port 51b are formed in the cylinder head 51A. The intake port 51 a introduces intake air into the combustion chamber E, and the exhaust port 51 b exhausts gas from the combustion chamber E. The intake valve 52, the exhaust valve 53, the stem guides 54 and 55, and the seat portions 56 and 57 are provided in the cylinder head 51A.

  The intake valve 52 opens and closes the intake port 51a, and the exhaust valve 53 opens and closes the exhaust port 51b. The stem guide 54 is provided for the stem portion of the intake valve 52, and the stem guide 55 is provided for the stem portion of the exhaust valve 53. The stem guides 54 and 55 guide the corresponding intake and exhaust valves 52 and 53. The seat portion 56 is provided for the intake valve 52, and the seat portion 57 is provided for the exhaust valve 53. The corresponding intake / exhaust valves 52 and 53 contact the seat portions 56 and 57 when the valves are closed.

  The cylinder head 51A is provided with passage portions WJ1 and WJ2. The passage portions WJ1 and WJ2 are water jackets, and circulate cooling water. The passage portion WJ1 is provided corresponding to a spark plug (not shown). The passage portion WJ2 is provided corresponding to the stem guide 54. Specifically, the passage portion WJ2 is a passage portion including a portion provided around the stem guides 54 and 55, and is thereby provided corresponding to the stem guide 54. The passage portion WJ2 is provided so as to be able to control the circulation of the cooling water independently of the passage portion WJ1 which is another passage portion.

  W / P1 pumps the cooling water to the engine 50A. W / P1 is a mechanical W / P driven by the output of the engine 50A. W / P1 may be an electric W / P. The cooling water pumped by W / P1 is supplied to the passage portion WJ2 via the control valve 2. The cooling water pumped by W / P1 is also supplied to the passage portion WJ1. The control valve 2 permits and prohibits the flow of the cooling water in the passage portion WJ2. The cooling water supplied to the passage portion WJ2 flows through the passage portion WJ2, and then returns to W / P1 via the radiator 3. The radiator 3 performs heat exchange between the circulating cooling water and the air to cool the cooling water. Specifically, for example, a flow control valve or a switching valve can be applied to the control valve 2.

  FIG. 2 is a view showing the umbrella portion 52 a of the intake valve 52. The umbrella part 52a has a shape in which the wall part forming the slope part is thinned by providing the umbrella back part exposed to the combustion chamber E in a concave shape according to the slope part. The intake valve 52 is provided with such an umbrella portion 52a, so that a structure capable of raising the temperature at a slope portion of the umbrella portion 52a can be set higher than the temperature at which the deposit amount is maximum (for example, 250 ° C.). It is an intake valve. Further, by providing such a structure, the intake valve is capable of raising the temperature higher than the temperature at which the amount of deposits is maximized. The intake valve 52 can suppress adhesion of deposits to the slope portion of the umbrella portion 52a by raising the temperature of the slope portion of the umbrella portion 52a to a temperature at which the amount of deposit deposition becomes maximum.

  The ECU 70A shown in FIG. 1 is an electronic control device, and the control valve 2 is electrically connected to the ECU 70A as a control target. A sensor group 60 for detecting the operating state of the engine 50A is electrically connected. The sensor group 60 includes, for example, an exhaust temperature sensor that can detect the exhaust temperature of the engine 50A, an air-fuel ratio sensor that can detect the exhaust air-fuel ratio, a crank angle sensor that can detect the rotational speed NE of the engine 50A, and an acceleration for the engine 50A. It includes an accelerator opening sensor that can detect the amount of depression of the accelerator pedal (accelerator opening) for making a request, and a water temperature sensor that can detect the cooling water temperature of the engine 50A.

  In the ECU 70A, various functional units are realized by executing processing while the CPU uses a temporary storage area of the RAM as required based on a program stored in the ROM. In this regard, in the ECU 70A, for example, the following control unit is functionally realized.

  The control unit reduces the temperature of the intake valve 52 when a predetermined condition is satisfied. The predetermined condition is whether or not the exhaust gas temperature is higher than a predetermined value α. However, the predetermined condition is not limited to this, for example, whether the fuel injection amount is larger than a predetermined value, whether the exhaust air-fuel ratio is smaller than a predetermined value, or the load of the engine 50A is a predetermined value. Or larger than that. In this regard, the predetermined condition can be a condition that can determine whether or not the degree of the output request to the engine 50A is larger than the predetermined degree. Thereby, the temperature of the intake valve 52 can be lowered when a high output is required.

  Specifically, the control unit causes the cooling water to flow through the passage portion WJ2 when a predetermined condition is satisfied. When circulating the cooling water through the passage portion WJ2, the control unit specifically controls the control valve 2 to permit the circulation of the cooling water in the passage portion WJ2 (ie, opens the control valve 2). In this embodiment, an engine cooling device (hereinafter referred to as a cooling device) including the control valve 2, the passage portion WJ2, and the ECU 70A is realized.

  Next, the control operation of the cooling device of this embodiment performed by the ECU 70A will be described with reference to the flowchart shown in FIG. The ECU 70A detects various signals output from the sensor group 60 (step S1). And it is determined whether exhaust temperature is higher than predetermined value (alpha) (step S2). If a negative determination is made, the process returns to step S1. If the determination is affirmative, the ECU 70A opens the control valve 2 (step S3). And thereby, a cooling water is distribute | circulated to the channel | path part WJ2. After step S3, the process returns to step S1.

  Next, the effect of the cooling device of the present embodiment will be described. The cooling device of this embodiment reduces the temperature of the intake valve 52 when a predetermined condition is satisfied. As a result, as a result of increasing the temperature of the intake valve 52 above the temperature at which the amount of deposit is maximized, the intake air temperature can be lowered if a predetermined condition is satisfied even if the intake air temperature rises. . For this reason, the cooling device of the present embodiment can suppress the deterioration of the engine performance when the temperature of the intake valve 52 is raised above the temperature at which the deposit accumulation amount becomes maximum.

  Specifically, the cooling device of the present embodiment can reduce the temperature of the stem portion of the intake valve 52 via the stem guide 54 by flowing cooling water through the passage portion WJ2 when a predetermined condition is satisfied. it can. Thus, by promoting the movement of heat from the umbrella portion 52a to the stem portion, the temperature of the slope portion of the umbrella portion 52a, which is increased in temperature when suppressing deposit adhesion, can also be lowered.

  The cooling device of this embodiment is provided with a passage portion WJ2 so that the flow of the cooling water can be controlled independently of the other passage portions, so that the cooling water is circulated individually to the passage portion WJ2 when a predetermined condition is satisfied. It is possible to make it. In this regard, the cooling device of the present embodiment may prohibit the circulation of the cooling water in the passage portion WJ2 when the engine 50A is warmed up. As a result, even when the temperature of the intake valve 52 is set higher than the temperature at which the accumulated amount of deposit is maximized, priority is given to the promotion of warm-up when the engine 50A is warmed up, which is desired to be completed quickly from the viewpoint of improving fuel efficiency. You can also In this case, the emission of unburned HC can be reduced by improving the atomization of the fuel.

  FIG. 4 is a view showing a main part of the engine 50B. Engine 50B is substantially the same as engine 50A, except that cylinder head 51B is provided instead of cylinder head 51A. The cylinder head 51B is substantially the same as the cylinder head 51A except that a passage portion WJ3 is provided instead of the passage portion WJ2.

  The passage portion WJ3 is a water jacket for circulating cooling water, and is provided corresponding to the seat portion 56. Specifically, the passage portion WJ3 is provided in the cylinder head 51B so as to correspond to the seat portion 56 by being provided close to the seat portion 56 at a portion closer to the cylinder block than the intake port 51a. The passage portion WJ3 is provided so as to be able to control the flow of the cooling water independently of the passage portion WJ1 which is another passage portion.

  The engine 50B is provided with W / P1, a control valve 2, a radiator 3, and an ECU 70B. In the engine 50B, the cooling water pumped by W / P1 is supplied to the passage portion WJ3 via the control valve 2, flows through the passage portion WJ3, and then returns to W / P1 via the radiator 3. Therefore, in the engine 50B, the control valve 2 is provided so as to permit or prohibit the circulation of the cooling water in the passage portion WJ3.

  The ECU 70B is substantially the same as the ECU 70A, except that the control unit is realized so that the cooling water flows through the passage portion WJ3 when a predetermined condition is satisfied. In the present embodiment, a cooling device including the control valve 2, the passage portion WJ3, and the ECU 70B is realized. Note that the control operation itself of the cooling device according to the present embodiment is the same as the control operation of the cooling device according to the first embodiment, and is omitted here.

  Next, the effect of the cooling device of the present embodiment will be described. The cooling device of the present embodiment can lower the temperature of the intake valve 52 via the seat portion 56 by circulating the cooling water through the passage portion WJ3 when a predetermined condition is satisfied. Then, by reducing the intake air temperature, it is possible to suppress a decrease in engine performance when the temperature of the intake valve 52 is increased above the temperature at which the deposit amount is maximum.

  In this regard, the cooling device of the present embodiment can directly reduce the temperature of the slope portion of the umbrella portion 52 a by reducing the temperature of the intake valve 52 via the seat portion 56. For this reason, the cooling device according to the present embodiment is suitable for the case where the temperature is higher than the temperature at which the deposition amount of the deposit is maximized on the slope portion of the umbrella portion 52a.

FIG. 5 is a view showing a main part of the engine 50C. The engine 50C is substantially the same as the engine 50A except that the engine 50C includes a cylinder head 51C instead of the cylinder head 51A, and further includes an oil jet 58. The cylinder head 51C is substantially the same as the cylinder head 51B except that the oil jet 58 is provided. The engine 50C is provided with an electric pump 5 and an ECU 70C.

  The electric pump 5 supplies oil to an oil passage (not shown) formed in the cylinder head 51C. The oil jet 58 is connected to the oil passage, and supplies oil to the stem guide 54 by injecting oil toward the stem guide 54. The oil jet 58 corresponds to an oil supply unit. The oil supply unit may be, for example, a shower pipe capable of supplying oil to the stem guide 54, or a sheet portion made of a porous material capable of supplying oil to the umbrella portion 52a of the intake valve 52.

  The ECU 70C is substantially the same as the ECU 70A except that the electric pump 5 is electrically connected as a control target instead of the control valve 2 and the control unit is realized as described below. In the ECU 70C, the control unit supplies oil from the oil jet 58 when a predetermined condition is satisfied. Specifically, the controller supplies oil from the oil jet 58 by operating the electric pump 5. In this embodiment, a cooling device including the electric pump 5, the oil jet 58, and the ECU 70C is realized.

  Next, the control operation of the cooling device of the present embodiment performed by the ECU 70C will be described using the flowchart shown in FIG. The ECU 70C detects various signals output from the sensor group 60 (step S11). And it is determined whether exhaust temperature is higher than predetermined value (alpha) (step S12). If a negative determination is made, the process returns to step S11. If the determination is affirmative, the ECU 70C operates the electric pump 5 (step S13). As a result, oil is supplied from the oil jet 58 to the stem guide 54. After step S13, the process returns to step S11.

  Next, the effect of the cooling device of the present embodiment will be described. The cooling device of the present embodiment can reduce the temperature of the intake valve 52 via the stem guide 54 by supplying oil from the oil jet 58 to the stem guide 54 when a predetermined condition is satisfied. Then, by reducing the intake air temperature, it is possible to suppress a decrease in engine performance when the temperature of the intake valve 52 is increased above the temperature at which the deposit amount is maximum.

  The cooling device according to the present embodiment may include an oil supply unit that supplies oil to the umbrella portion 52 a of the intake valve 52 instead of the oil jet 58. In this case, since the temperature of the slope part of the umbrella part 52a can be directly reduced, it is suitable when the temperature is raised above the temperature at which the amount of deposit deposition becomes maximum on the slope part of the umbrella part 52a.

FIG. 7 is a view showing a main part of the engine 50D. The engine 50D is substantially the same as the engine 50A except that it further includes a variable valve mechanism 59 and a cylinder head 51D instead of the cylinder head 51A. The cylinder head 51D is substantially the same as the cylinder head 51B except that the variable valve mechanism 59 is provided.

  The variable valve mechanism 59 makes the valve characteristic of the intake valve 52 variable. Specifically, the variable valve mechanism 59 is a variable lift mechanism that can change the lift amount of the intake valve 52. For example, the variable valve mechanism 59 may be a mechanism in which a variable valve timing mechanism capable of changing the valve timing of the intake valve 52 and a variable lift mechanism are combined. For example, the variable valve timing mechanism can be a cam shift mechanism that can select a cam that drives the intake valve 52 from a plurality of cams that are provided for the intake valve 52 and have different cam profiles.

  An ECU 70D is provided for the engine 50D. The ECU 70D is substantially the same as the ECU 70A except that the variable valve mechanism 59 is electrically connected as a control target instead of the control valve 2 and the control unit is realized as described below. . In the ECU 70D, the control unit increases the lift amount of the intake valve 52 when a predetermined condition is satisfied. Specifically, the control unit controls the variable valve mechanism 59 to increase the lift amount of the intake valve 52. In the present embodiment, a cooling device is realized by the variable valve mechanism 59 and the ECU 70D.

  Next, the control operation of the cooling device of this embodiment performed by the ECU 70D will be described with reference to the flowchart shown in FIG. The ECU 70D detects various signals output from the sensor group 60 (step S21). Then, it is determined whether or not the fuel injection amount is larger than a predetermined value β (step S22). That is, in this embodiment, a predetermined condition is whether or not the fuel injection amount is larger than the predetermined value β. If a negative determination is made, the process returns to step S21. If the determination is affirmative, the ECU 70D controls the variable valve mechanism 59 so as to increase the lift amount (step S23). After step S23, the process returns to step S21.

  Next, the effect of the cooling device of the present embodiment will be described. The cooling device of the present embodiment increases the lift amount of the intake valve 52 when a predetermined condition is satisfied. As a result, it is possible to suppress an increase in the intake air temperature due to heat received from the intake valve 52 by suppressing the intake valve 52 from becoming an intake flow resistance. For this reason, the cooling device of the present embodiment can suppress the deterioration of the engine performance when the temperature of the intake valve 52 is raised above the temperature at which the deposit accumulation amount becomes maximum.

  When the variable valve mechanism 59 is a mechanism in which a variable lift mechanism and a variable valve timing mechanism are combined, the cooling device provides valve timing of the intake valve 52 so that the volume efficiency of the engine 50D is increased when a predetermined condition is satisfied. By changing the above, it is possible to suppress a decrease in engine performance. This is the same even when the variable valve mechanism 59 is a variable valve timing mechanism capable of changing the valve timing of the intake valve 52.

  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 intake valve is heated by a heating element via a stem guide, that is, by providing a configuration capable of raising the temperature higher than the temperature at which the deposit accumulation amount is maximized, the deposit accumulation amount is maximized. It may be possible to raise the temperature above that.

W / P 1
Control valve 2
Engine 50A, 50B, 50C, 50D
Intake valve 52
Stem guide 54, 55
Seat part 56, 57
Oil jet 58
Variable valve mechanism 59
ECU 70A, 70B, 70C, 70D

Claims (5)

It is provided in an engine equipped with an intake valve that can raise the temperature above the temperature at which the amount of deposit accumulation becomes maximum,
An engine cooling device for lowering the temperature of the intake valve when the degree of output demand for the engine is greater than a predetermined degree . The engine cooling device according to claim 1,
Provided corresponding to the stem guide of the intake valve, and provided with a passage portion for circulating cooling water,
An engine cooling apparatus for circulating cooling water through the passage when the degree of output request to the engine is larger than a predetermined degree . The engine cooling device according to claim 1,
Provided corresponding to the seat portion on which the intake valve is seated, and provided with a passage portion for circulating cooling water;
An engine cooling apparatus for circulating cooling water through the passage when the degree of output request to the engine is larger than a predetermined degree . The engine cooling device according to claim 1,
An oil supply unit capable of supplying oil to a stem guide of the intake valve or an umbrella part of the intake valve;
An engine cooling apparatus that supplies oil from the oil supply unit when a degree of output request to the engine is larger than a predetermined degree . The engine cooling device according to claim 1,
A variable valve mechanism capable of changing the lift amount of the intake valve;
An engine cooling apparatus for increasing a lift amount of the intake valve when a degree of output request to the engine is larger than a predetermined degree .

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