JP6011123B2 - Cooling device for internal combustion engine - Google Patents

Description

  The present invention relates to a cooling device for an internal combustion engine.

  General engine cooling is performed using a belt-driven water pump mechanically connected to a crankshaft of the engine via a belt or the like. In recent years, an electric water pump or a belt-driven water pump with an electromagnetic clutch may be used to improve the fuel consumption of the engine (see, for example, Patent Document 1).

  In this case, generally, the water pump is controlled based on the coolant temperature in the vicinity of the engine cylinder head outlet or in the cylinder head. Further, the water pump may be controlled based on the cooling water temperature in any part of the cooling water system, such as inside the cylinder block of the engine.

  When the water pump is an electric water pump, the rotation speed of the water pump is controlled such that the cooling water temperature at any of the above-described locations in the cooling water system is constant at a predetermined temperature (set temperature). On the other hand, when the water pump is a water pump with an electromagnetic clutch, the water pump is controlled by connecting / disconnecting the electromagnetic clutch so that the cooling water temperature in any one of the above-described locations in the cooling water system is within a predetermined temperature range (set temperature range). Is switched between operation and stop.

JP 2011-236780 A

  A disadvantage that can occur due to an excessive rise in the cooling water temperature is that the lower surface of the cylinder head (particularly between the exhaust valves and between the exhaust valves and the injectors) is cut and cracks occur.

  Although the temperature of the lower surface of the cylinder head rises and the local portion tends to expand, the peripheral portion of the local portion does not expand so much, and the local portion undergoes plastic deformation due to compression. Thereafter, when the temperature of the entire cylinder head decreases due to the stop of the operation of the engine, the entire cylinder head contracts (the amount of thermal expansion returns to its original state), and a large tensile stress is generated in the local portion that has undergone plastic deformation during compression. Such repeated plastic deformation and generation of tensile stress may break the local portion of the lower surface of the cylinder head and cause a crack.

  However, since the specific heat capacity of water is larger than that of iron and aluminum, even if the local temperature on the lower surface of the cylinder head increases, the cooling water temperature does not increase immediately.

  Therefore, in order to further improve the fuel efficiency of the engine, the number of revolutions of the water pump is reduced (when the water pump is an electric water pump), or the frequency of stopping the water pump is increased (the water pump is a water pump with an electromagnetic clutch). In this case, it is desirable to keep the cooling water temperature higher. However, as long as the water pump is controlled based on the cooling water temperature, a large margin is required, and the cooling water temperature cannot be raised to the limit.

  Therefore, an object of the present invention is to provide a cooling device that can more appropriately control the flow rate of cooling water supplied to an internal combustion engine by a water pump.

  In order to achieve the above object, a cooling apparatus for an internal combustion engine according to the present invention is provided in a cooling water circulation passage of the internal combustion engine and circulates the cooling water, and the cylinder head of the internal combustion engine or the cylinder head And a pump control means for controlling the water pump based on a detection value by the temperature detection means.

  The metal part may be a cam cap that holds a camshaft of the internal combustion engine.

  The temperature detecting means may detect the temperature of the cam cap using a temperature sensor, and the cam cap may have a boss portion to which the temperature sensor is attached.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an outstanding effect that the cooling device which can control more appropriately the flow volume of the cooling water supplied to an internal combustion engine with a water pump can be provided.

It is a block diagram of the cooling device of the internal combustion engine which concerns on one Embodiment of this invention. It is AA arrow sectional drawing of FIG. It is a figure which shows an example of the time change of the local temperature of the lower surface of a cylinder head, a cam cap temperature, and a cooling water temperature.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, a cooling device 10 according to the present embodiment includes a water pump 13 provided in a cooling water circulation passage 12 of a diesel engine (hereinafter simply referred to as an engine) 11 as an internal combustion engine, and an electronic control unit (hereinafter referred to as an electronic control unit). , Referred to as ECU).

  The engine 11 is mainly composed of a cylinder head 15 and a cylinder block 16, and a cooling water passage 17 for circulating cooling water is formed in the engine 11. The cylinder head 15 and the cylinder block 16 are made of, for example, iron or aluminum.

  The cooling water circulation passage 12 includes an inflow passage 19 that connects the cooling water outflow portion of the radiator 18 and the cooling water inflow portion of the lower portion of the engine 11 (cylinder block 16), and the cooling water outflow of the upper portion of the engine 11 (cylinder head 15). And an outflow passage 20 that communicates the cooling water inflow portion of the radiator 18.

  The water pump 13 is provided in the inflow passage 19 of the cooling water circulation passage 12. As the water pump 13, for example, an electric water pump or a water pump with a belt-driven electromagnetic clutch can be used. The electric water pump is driven by a motor. On the other hand, a water pump with a belt-driven electromagnetic clutch is mechanically connected to a crankshaft via an electromagnetic clutch and a belt.

  In the present embodiment, the ECU 14 uses the temperature sensor 21 to detect the temperature of the cylinder head 15 itself or a metal part (for example, iron or aluminum) that is firmly fixed to the cylinder head 15 (for example, by bolting), The water pump 13 is controlled based on the detected temperature. The portion or metal part of the cylinder head 15 to which the temperature sensor 21 is attached is not easily affected by the temperature of traveling wind (outside air), intake air flowing through the intake manifold, exhaust gas flowing through the exhaust manifold, and the like. It is desirable that the temperature be kept at a constant temperature difference with a temperature (hereinafter, referred to as a local temperature) of the local portion (for example, between the exhaust valves and between the exhaust valve and the injector).

  The ECU 14 includes a temperature detection unit 23 and a pump control unit 24 as functional elements in order to control the water pump 13. The temperature detection unit 23 and the pump control unit 24 may be provided in hardware different from the ECU 14.

  The temperature detector 23 detects the temperature of any one of the plurality of cam caps 25 (hereinafter referred to as cam cap temperature). That is, as shown in FIG. 2, the temperature sensor 21 is attached to any one of the plurality of cam caps 25. In the case of the cylinder head 15 of the engine 11 shown in FIG. 2, the mounting space for the temperature sensor 21 cannot be secured in the cylinder head 15 itself, and other parts other than the cam cap 25 are movable parts and the like. This is because it cannot be attached to any part other than the cam cap 25.

  The cam cap 25 is a metal part (for example, iron or aluminum) that holds the cam shaft of the engine 11, and is fixed to the cylinder head 15 using a bolt 26. In the case of the cylinder head 15 of the engine 11 shown in FIG. 2, the cam cap 25 is provided with a boss part 27 protruding, and the boss part 27 is provided with a screw hole 28. 21 is screwed into the screw hole 28 and attached to the cam cap 25. The temperature sensor 21 is attached to the cam cap 25 with the sensor portion 29 at the tip thereof being in close contact with the cam cap 25 (the bottom surface 30 of the screw hole 28). This is because the temperature of the cam cap is accurately detected by the temperature sensor 21.

  In the present embodiment, the temperature sensor 21 and the temperature detection unit 23 of the ECU 14 constitute the temperature detection means of the present invention.

  The pump control unit 24 controls the flow rate of the cooling water supplied to the engine 11 by the water pump 13 based on the cam cap temperature detected by the temperature detection unit 23. Specifically, when the water pump 13 is an electric water pump, the pump control unit 24, for example, the water pump 13 so that the cam cap temperature detected by the temperature detection unit 23 becomes constant at a predetermined temperature (set temperature). Control the number of revolutions. In the case where the water pump 13 is a water pump with an electromagnetic clutch, the pump control unit 24 is configured so that, for example, the electromagnetic clutch so that the cam cap temperature detected by the temperature detection unit 23 is within a predetermined temperature range (set temperature range). The water pump 13 is switched between operation and stop by the connection / disconnection control.

  The upper limit of the set temperature or set temperature range described above is, for example, the temperature at which the local portion of the lower surface 22 of the cylinder head 15 undergoes plastic deformation, and the temperature between the local temperature of the lower surface 22 of the cylinder head 15 and the cam cap temperature. Based on the difference, the temperature is set so as not to exceed the temperature at which the local portion of the lower surface 22 of the cylinder head 15 undergoes plastic deformation (see FIG. 3).

  In the present embodiment, the pump control unit 24 of the ECU 14 constitutes the pump control means of the present invention.

  Next, the effect of this embodiment is demonstrated.

  In the present embodiment, the temperature detection unit 23 of the ECU 14 detects the temperature of the cam cap 25 (cam cap temperature) fixed to the cylinder head 15 using the temperature sensor 21, and the pump control unit 24 of the ECU 14 The water pump 13 is controlled based on the cam cap temperature detected by the detector 23.

  For example, as shown in FIG. 3, consider a case where the engine load suddenly increases and the local temperature of the lower surface 22 of the cylinder head 15 rapidly increases.

  As can be seen from FIG. 3, even if the local temperature of the lower surface 22 of the cylinder head 15 exceeds the upper limit (the temperature at which the local portion undergoes compression plastic deformation), the increase in the cooling water temperature is the local temperature of the lower surface 22 of the cylinder head 15. Since the cooling water temperature is very slow compared with the increase, a rapid increase in the local temperature of the lower surface 22 of the cylinder head 15 (a rapid increase in engine load) cannot be immediately detected. Therefore, when controlling the water pump 13 based on the cooling water temperature, the cooling water temperature must be lowered with a large margin.

  On the other hand, since the thermal conductivity of iron and the thermal conductivity of aluminum are much larger than water, the local temperature of the lower surface 22 of the cylinder head 15 is immediately transmitted to the cam cap 25. Further, the cam cap temperature changes while maintaining a substantially constant temperature difference from the local temperature of the lower surface 22 of the cylinder head 15.

  That is, since the cam cap temperature rises at substantially the same speed as the local temperature of the lower surface 22 of the cylinder head 15, if the water pump 13 is controlled based on the cam cap temperature as in this embodiment, the lower surface 22 of the cylinder head 15. A sudden rise in local temperature (a sudden rise in engine load) can be detected immediately. Therefore, the cooling water temperature can be raised to the limit, and the flow rate of the cooling water supplied to the engine 11 by the water pump 13 can be controlled more appropriately.

  Further, the number of revolutions of the water pump 13 is decreased by the amount that the cooling water temperature is raised to the limit (when the water pump 13 is an electric water pump), or the frequency of stopping the water pump 13 is increased (the water pump 13 is electromagnetic). In the case of a water pump with a clutch), the fuel consumption (fuel consumption rate) of the engine 11 can be further improved.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various other embodiments can be adopted.

  For example, the engine 11 to which the cooling device 10 is applied is not limited to a diesel engine, and may be a gasoline engine or the like.

  Further, the temperature sensor 21 is not limited to the screw mounting type shown in FIG. 2, and may be another type.

  Further, the temperature sensor 21 may be attached to a metal part fixed to the cylinder head 15 other than the cylinder head 15 itself or the cam cap 25.

10 Cooling device 11 Engine (internal combustion engine)
12 Cooling water circulation passage 13 Water pump 15 Cylinder head 21 Temperature sensor (temperature detection means)
23 Temperature detection part (temperature detection means)
24 Pump control unit (pump control means)
25 Cam cap (metal parts)
27 Boss

Claims (1)

A water pump disposed in a cooling water circulation passage of the internal combustion engine for circulating the cooling water; a temperature detection means for detecting a temperature of a cylinder head of the internal combustion engine or a metal part fixed to the cylinder head; and the temperature detection means And a pump control means for controlling the water pump based on the detected value by
The metal part is a cam cap that holds a camshaft of the internal combustion engine;
The temperature detecting means detects the temperature of the cam cap using a temperature sensor, and the cam cap has a boss portion to which the temperature sensor is attached,
The temperature sensor is screwed into a screw hole formed in the boss portion, and a sensor portion provided at the tip of the temperature sensor is brought into close contact with the bottom surface of the screw hole .