JP2006214280A - Cooling device of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the fuel cost and emission at the cold time by promoting warming-up of an engine as much as possible while restraining a local temperature rise in the periphery of cylinders s1 to s4 and partial boiling of cooling water due to such temperature rise by controlling flow of cooling water in water jackets 4, 5 in an engine body part 1 after the start of cooling. <P>SOLUTION: A motor-driven pump 9 is provided instead of a crankshaft drive water pump. The pump is stopped during a predetermined period after the start of cooling the engine, thereby stopping circulation of cooling water in the water jackets 4, 5, and after that, the pump is operated in a pulse control mode, thereby intermittently circulating the cooling water in the water jackets 4, 5. Thus, while radiation of heat from the engine is reduced remarkably, a local temperature rise in the periphery of the cylinders s1 to s4 is restrained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cooling device that changes the flow state of cooling water in accordance with the state of an engine.

  In general, in a cooling system for a water-cooled engine, a water pump is mechanically driven by a crankshaft to distribute cooling water to a water jacket (cooling water passage in the engine body) of a cylinder block or a cylinder head. , It is circulated with the radiator. In addition, a thermostat is disposed in the cooling water flow path between the engine body and the radiator, and when the engine is cooled after the engine is started, the flow of the cooling water between the engine body and the radiator is interrupted. It is designed to promote warm-up.

  In such a combination of a mechanical pump and a thermostat, the water pump operates with the rotation of the crankshaft while the engine is running. For example, in the case of a vehicle, cooling with a heater core for heating the passenger compartment, etc. The water circulates and the amount of heat released from the engine increases accordingly, and it is inevitable that the warm-up is delayed, and there is a problem that the deterioration of fuel consumption and emission during cold-down cannot be sufficiently suppressed.

Therefore, it has been proposed to use an electric water pump instead of a mechanical pump or a thermostat so that the circulation state of the cooling water in the water jacket can be changed regardless of the operating state of the engine (for example, patents). Reference 1). In this proposal, an electric pump is disposed between the engine main body and the radiator, and when the engine is cold, the pump is not operated to stop the circulation of the cooling water between the radiator and the cooling water in the water jacket. The distribution itself is also stopped.
JP 2002-161748 A

  However, when the cooling water flow of the water jacket is stopped when the engine is cold as in the above-mentioned proposal, the water temperature rises locally around the cylinder, resulting in abnormal noise due to partial boiling of the cooling water. Or an excessive temperature rise at a specific part may cause a decrease in reliability.

  In order to prevent the occurrence of such problems, the electric pump must be operated so that the cooling water flows before the temperature of the cooling water becomes too high. In the end, however, it cannot be said that engine warm-up can be sufficiently promoted, and there remains room for improvement in fuel efficiency and emissions when the engine is cold.

  Although it is possible to minimize the heat dissipation of the engine by taking advantage of the features of the electric pump that can be controlled regardless of the operating state of the engine and operating it at the lowest possible speed to reduce the flow of cooling water. In general, water pumps are required to secure a maximum flow rate that can handle a large amount of heat generated during high-load operation of the engine. It is difficult to squeeze.

  The present invention has been made in view of such a point, and the object of the present invention is to devise control of the flow of cooling water in the engine body during cold operation to increase local temperature around the cylinder. Thus, while suppressing the partial boiling of the cooling water, the engine warm-up is promoted as much as possible to further improve the fuel efficiency and emission during the cool-down.

  In order to achieve the above object, the main solution of the present invention is to promote the warm-up by substantially stopping the circulation of the cooling water in the cooling water passage in the engine body when the engine is cold. The local temperature rise around the cylinder was suppressed by shaking and slightly stirring.

  That is, according to the first aspect of the present invention, an engine cooling device provided with a flow variable means capable of changing the flow state of the cooling water in the cooling water passage in the engine body is used as a target for cooling water in the cooling water passage when the engine is cooled. It is characterized by comprising control means for operating the flow variable means so as to flow intermittently.

  With the above configuration, when the engine is cold, the control of the flow variable means by the control means is performed so that the cooling water flows intermittently in the cooling water passage in the main body. Here, intermittent circulation means that the cooling water does not continuously move from the inlet to the outlet of the cooling water passage, but repeatedly moves and stops for a short time in the cooling water passage. In other words, it means a circulation state in which the entire cooling water in the cooling water passage is shaken and slightly stirred.

  The engine is just like stopping the movement of the cooling water while suppressing the local temperature rise around the cylinder by shaking the cooling water in the cooling water passage in the engine body and stirring it slightly. The amount of heat released can be reduced and the warm-up can be promoted sufficiently. Therefore, the fuel consumption and emission when the engine is cold can be further improved than before.

  As a more specific configuration of the cooling device, the flow variable means may include an electric pump for flowing cooling water, and the control means may operate the electric pump intermittently ( Invention of Claim 2). In this way, the flow variable means can be easily configured by taking advantage of the electric pump that can be controlled regardless of the operating state of the engine.

  In this case, if the control means can control the amount of power supplied to the electric pump (invention of claim 3), the operating state of the electric pump can be finely and precisely controlled. In addition, it is possible to minimize the heat radiation amount of the engine while more surely suppressing the local temperature rise around the cylinder.

  Further, since the flow state of the cooling water can be freely changed by controlling the electric pump as described above, the switching of the flow and shut-off of the cooling water with the radiator is performed by a conventionally known mechanical thermostat. This is sufficient, and a thermostat that mechanically opens and closes according to a change in the temperature of the cooling water may be provided in the communication passage that connects the cooling water passage in the engine body and the passage in the radiator. Item 8). That is, an electric thermostat is unnecessary, and the cost can be reduced accordingly.

  Further, as another specific configuration of the cooling device according to the present invention, the flow variable means switches the flow of the cooling water circulated by the mechanical pump to either the cooling water passage or the bypass passage in the engine body. A valve may be provided, and the control means may switch and operate the switching valve (invention of claim 4). In this way, the distribution variable means can be configured more easily and at a lower cost without using an electric pump.

  In the cooling device having the above-described configuration, a sensor for detecting the temperature of the cooling water is provided, and the stop time of the circulation time of the coolant that circulates intermittently as the cooling water temperature detected by the sensor increases. It is preferable to operate the flow variable means by the control means so that the ratio to the ratio becomes large (invention of claim 5).

  In this way, in a situation where the cooling water temperature is relatively low and local excessive temperature rise is unlikely to occur, the cooling water circulation time can be shortened to further reduce the heat dissipation of the engine. If the temperature rises, the excessive temperature rise can be more reliably suppressed by lengthening the circulation time of the cooling water accordingly. In other words, by changing the ratio of the circulation time of the coolant that circulates intermittently according to the change in the coolant temperature, the contradictory requirements of the suppression of problems caused by temperature rise and the rapid warm-up of the engine are higher. Can be compatible.

  Alternatively, the flow variable means is operated so that the flow of the cooling water in the cooling water passage in the engine body stops during a predetermined period after the engine is started, and after the predetermined period, the cooling water flows in the cooling water passage. You may make it operate | move a distribution variable means so that it may distribute | circulate intermittently (invention of Claim 6). That is, after a cold start of the engine, the heat dissipation of the engine can be minimized by stopping the circulation of the cooling water during a predetermined period in which the cooling water temperature is low and local excessive temperature rise cannot occur.

  Further, as described above, not only the cooling water flow is stopped during cooling, but the cooling water is not allowed to flow intermittently, but the cooling water is intermittent until the cooling water temperature reaches a predetermined high temperature even after the engine is warmed up. The flow variable means may be operated so as to be circulated, and the flow variable means may be operated so that the cooling water continuously flows after the cooling water temperature reaches a predetermined high temperature state. 7 invention). In this way, it is possible to increase the thermal efficiency and reduce the fuel consumption by maintaining the warmed-up engine at a higher temperature than before.

  Next, in the invention of claim 9, as in the invention of claim 1, the engine cooling device provided with the flow variable means capable of changing the flow state of the cooling water in the cooling water passage in the engine body is targeted. A switching valve for switching the flow of the cooling water circulated by the mechanical pump to either the cooling water passage or the bypass passage, and a capacity smaller than that of the mechanical pump, and the flow variable means in the cooling water passage An electric pump arranged to circulate the cooling water, and when the engine is cold, the switching valve is operated so that the flow of the cooling water by the mechanical pump is switched to the bypass passage, and Control means for operating the electric pump so that the cooling water flows through a predetermined minute flow rate in the cooling water passage is provided.

  According to this configuration, when the engine is cold, the flow of the cooling water circulated by the crankshaft driven mechanical pump is switched to the bypass passage by the switching valve, and the operation of the electric pump having a smaller capacity than the mechanical pump, The cooling water flows through the cooling water passage in the engine body by a predetermined minute flow rate. And the circulation of the minute flow rate of the cooling water can suppress a local temperature rise around the cylinder and the like while reducing the heat radiation amount of the engine.

  In other words, the mechanical pump can secure the maximum flow rate corresponding to a large amount of heat generated during high-load operation of the engine, and the flow rate of cooling water can be extremely reduced by a separate small-capacity electric pump. Thus, as in the invention of claim 1, the engine can be rapidly warmed up while suppressing problems caused by a local temperature rise, and the fuel efficiency and Emissions can be improved.

  As described above, according to the engine cooling apparatus according to the first to eighth aspects of the present invention, for example, when the engine is cooled immediately after a cold start, the cooling water is intermittently supplied in the cooling water passage in the main body. By circulating, it is possible to suppress the local temperature rise around the cylinder, etc., while reducing the amount of heat released from the engine in the same way as when cooling water is stopped, thereby promoting engine warm-up. Thus, fuel consumption and emission can be improved.

  At that time, the intermittent circulation time ratio of the cooling water is changed according to the change of the cooling water temperature (the invention of claim 5), or the circulation of the cooling water is stopped for a predetermined period after the engine is started. (Invention of claim 6) makes it possible to minimize the heat dissipation from the engine, thereby satisfying the conflicting demands of suppressing the malfunction due to local temperature rise and rapid engine warm-up at a high level. it can.

  Furthermore, if the coolant temperature is allowed to flow intermittently when the water temperature is relatively low even after the engine is warmed up (invention of claim 7), the thermal efficiency of the engine is increased by maintaining the temperature higher than before. Thus, fuel consumption can be reduced.

According to the engine cooling device of the ninth aspect of the invention, a small-capacity electric pump is provided separately from the mechanical pump, and the cooling water is circulated by a minute flow rate in the cooling water passage in the engine body when cold. Thus, the same effect as in the first aspect of the invention can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

(Embodiment 1)
FIG. 1 schematically shows a configuration of an engine cooling device A according to Embodiment 1 of the present invention. The cooling device A includes water jackets 4 and 5 as cooling water passages formed in a cylinder block 2 and a cylinder head 3 constituting the main body 1 of the engine, and a front portion of the vehicle for cooling the cooling water by outside air. A radiator 6 disposed in the upper and lower hoses 7 and 8 constituting a flow path for circulating cooling water between the radiator 6 and the engine body 1, and a water jacket 4 of the cylinder block 2. And an electric water pump (hereinafter simply referred to as an electric pump) 9 for supplying cooling water.

  The water jacket 4 of the cylinder block 2 is formed over the entire longitudinal direction of the cylinder block 2 (hereinafter also referred to as the engine longitudinal direction) so as to surround the outer periphery of the four cylinders s1 to s4 in the example shown in the figure, and its front end It communicates with the discharge side of the electric pump 9 through an introduction path 4a that opens to the intake side (lower side in the figure) of the part. Further, a bypass passage 10 for returning the cooling water to the suction side of the electric pump 9 is opened in the vicinity of the opening of the introduction path 4a, and the first cylinder s1 to the cylinder block 2 are adjacent to the opening. A partition wall 4b is formed up to the side wall.

  Therefore, the cooling water discharged from the electric pump 9 and flowing into the front end portion of the water jacket 4 from the introduction path 4a is formed in the water jacket 4 as shown by an arrow in the figure if the bypass passage 10 is closed. After flowing on the exhaust side (upper side in the figure) toward the rear of the engine and turning back at the rear end, this time, the air flows on the intake side toward the front of the engine. On the other hand, if the bypass passage 10 is opened, the cooling water mainly flows into the bypass passage 10 and is returned to the suction side of the electric pump 9.

  The water jacket 4 of the cylinder block 2 is connected to the cylinder block 2 through a plurality of holes formed in the top deck of the cylinder block 2 and a plurality of holes formed in the bottom deck of the cylinder head 3. The cooling water flowing through the water jacket 4 of the cylinder block 2 as described above is sequentially communicated with the water jacket 5 of the cylinder head 3 as shown by the arrows in the drawing. It comes to circulate.

  The water jacket 5 of the cylinder head 3 is formed over the entire longitudinal direction of the cylinder head 3 so as to wrap around the outer periphery of the intake / exhaust ports and plug holes (not shown) of the cylinders s1 to s4. It communicates with the flow path in the upper hose 7 via a lead-out path 5a that opens to the section. In addition, a flow path in the heater hose 12 that circulates the cooling water between the lead-out path 5a and the heater core 11 of the vehicle air conditioner is also communicated. As a result, the relatively high-temperature cooling water that has circulated through the water jacket 5 of the cylinder head 3 flows out from the outlet path 5a to the flow paths in the upper hose 7 and the heater hose 12.

  The downstream end of the upper hose 7 is connected to the upper tank of the radiator 6, and the relatively high-temperature cooling water flowing through the upper hose 7 as described above is cooled by heat exchange with the outside air in the radiator 6. Afterwards, it flows out into the flow path in the lower hose 8 connected to the lower tank of the radiator 6, flows through the lower hose 8, and returns to the suction side of the electric pump 9. Similarly, the relatively high-temperature cooling water flowing through the heater hose 12 is returned to the suction side of the electric pump 9 after exchanging heat with air-conditioning air in the heater core 11.

  More specifically, in this embodiment, the housing 13a of the thermostat 13 is provided on the side wall of the cylinder block 2 adjacent to the suction side of the electric pump 9, and the lower hose 8 and the heater hose 12 are provided in the housing 13a. Each downstream end is connected to each other. The flow path in the lower hose 8 communicates with the suction port of the electric pump 9 via the valve body 13b of the thermostat 13 so as to be openable and closable, while the flow path in the heater hose 12 passes through the valve body 13b of the thermostat 13. Instead, it communicates directly with the suction port of the electric pump 9 through a space (valve chamber) in the housing 13a that accommodates it.

  Further, the bypass passage 10 is opened facing the valve chamber of the thermostat 13, and the bypass passage 10 communicates with the suction port of the electric pump 9 through the valve chamber. A throttle valve 15 (hereinafter referred to as a bypass flow rate adjusting valve) for adjusting the flow rate of the cooling water in the bypass passage 10 is provided integrally with the valve body 13b of the thermostat 13 so that the thermostat 13 can be opened and closed. In conjunction with this, the bypass passage 10 is opened and closed.

  That is, when the thermostat 13 is fully closed as shown in the figure, the bypass flow rate adjusting valve 15 opens the bypass passage 10 fully, while the thermostat 13 starts to open and the valve body 13b moves to the lower side of the drawing, The flow rate adjusting valve 15 also moves downward to throttle the bypass passage 10, and further, when the thermostat 13 is fully opened, the bypass passage 10 is fully closed.

  The electric pump 9 is, for example, a well-known centrifugal type that sends cooling water by rotating the impeller, and the operation of the electric motor connected to the shaft of the impeller is controlled by an engine control unit 20 (hereinafter referred to as a control means). ECU). In other words, the electric pump 9 is controlled by the ECU 20 so as to constitute a flow variable means capable of changing the flow state of the cooling water in the water jackets 4 and 5 in the engine body 1.

  The overall flow of the cooling water in the engine cooling device A configured as described above is schematically shown in FIG. FIG. 5A shows the flow when the thermostat 13 is closed by arrows. Most of the cooling water sent to the water jacket 4 of the cylinder block 2 by the electric pump 9 is supplied by the bypass passage 10 to the electric pump 9. And a part of the cooling water also flows into the water jacket 5 of the cylinder head 3, flows through the flow path in the heater hose 12, and returns to the suction side of the electric pump 9. At this time, since the thermostat 13 is closed, the cooling water does not flow with the radiator 6.

  On the other hand, when the thermostat 13 is fully open, the bypass passage 10 is closed by the bypass flow rate adjusting valve 15, so that the coolant from the electric pump 9 flows into the cylinder block as shown by the arrow in FIG. After flowing through the water jackets 4 and 5 of the cylinder head 3 and the cylinder head 3, they flow out into the flow paths in the upper hose 7 and the heater hose 12, and then return to the suction side of the electric pump 9. Of course, if the electric pump 9 does not operate, the flow of the cooling water as described above does not occur, and the cooling water substantially stops except for the flow by convection.

(Operation control of electric pump)
Next, operation control of the electric pump 9 by the ECU 20 will be described. As is well known, the ECU 20 includes a CPU, a memory, an I / O interface circuit, a driver circuit, and the like, and performs fuel injection control and ignition timing control for each of the cylinders s1 to s4 for engine operation control. However, in addition to this, in this embodiment, the operation of the electric pump 9 is controlled mainly in accordance with the temperature and load of the engine or the rotational speed.

  That is, in this embodiment, the ECU 20 includes at least a signal from a sensor 16 (for example, an accelerator opening sensor or an airflow sensor of a vehicle, hereinafter referred to as a load state sensor) for detecting a load state of the engine. Then, a signal from the engine speed sensor 17 and a signal from the water temperature sensor 18 arranged facing the cooling water lead-out path 5a at the rear end of the cylinder head 2 of the engine are input, thereby determining the state of the engine. And according to this, the output voltage to the electric pump 9 is controlled.

  The control of the output voltage is so-called duty control in which the magnitude of the output voltage is adjusted by changing the duty ratio. By changing the control duty ratio in the range of 0 to 100%, the output voltage is changed to, for example, 0.5 to The rotational speed of the electric pump 9 can be finely controlled with high accuracy by changing it approximately linearly within a predetermined range of about 12V.

  Further, as a characteristic part of the present invention, the ECU 20 switches the control duty ratio at a preset time interval and supplies a voltage to the electric pump 9 in a pulsed manner, thereby causing the electric pump 9 to have a constant cycle. It can be operated instantaneously, that is, intermittently, and the pulse control mode for operating the electric pump 9 as described above, and while the electric pump 9 is operated continuously as described above, The operating state of the electric pump 9 is controlled by switching to the normal control mode in which the rotational speed is changed according to the state of the engine.

  More specifically, in the normal control mode, the rotational speed of the electric pump 9 is controlled based on a control map as shown in FIG. This control map is a three-dimensional map in which the basic control rotation speed of the electric pump 9 is preset according to the engine load and rotation speed, and the pump rotation speed is relatively high on a relatively high load or high rotation side. Thus, while ensuring the flow rate of cooling water corresponding to the large amount of heat generated by the engine, the pump speed is lowered on the relatively low load or low rotation side to prevent overcooling of the engine, thereby reducing fuel consumption. It comes to reduce.

  On the other hand, the pulse control mode is performed mainly when the engine is cold, such as after a cold start of the engine, and the water jacket 4 in the engine main body 1 is operated by intermittently operating the electric pump 9 at a low frequency. , 5, the circulation of the cooling water can be almost stopped and the warm-up can be promoted, and when the electric pump 9 is operated, the entire cooling water in the water jackets 4, 5 is shaken and slightly stirred. The local temperature rise around the cylinders s1 to s4 can be suppressed.

  4 (a) and 4 (b) show an engine having the same configuration as that of this embodiment, for example, in which a temperature sensor is provided at each of the cylinder liner of the third cylinder s3 and a predetermined portion of the water jacket 5 in the vicinity thereof, and The experimental result which measured the temperature rise after a long start is shown. A graph indicated by a broken line in the figure shows an increase in the water temperature when the electric pump 9 is operated at a rotational speed proportional to the engine rotational speed as in the case of a conventional mechanical pump. The solid line graph shows the case where the electric pump 9 is intermittently operated in the pulse control mode.

  As shown in FIG. 5A, the temperature rise of the cylinder liner is the fastest when the electric pump 9 is stopped and the slowest when the electric pump 9 is operated in the same manner as the conventional mechanical pump. Thus, when the electric pump 9 is intermittently operated, the temperature of the cylinder liner rises as early as when the electric pump 9 is stopped, and it is understood that the engine can be warmed up rapidly.

  On the other hand, as shown in FIG. 5B, when the electric pump 9 is stopped, the water temperature at the predetermined location of the water jacket 5 is rapidly increased and decreased, and the partial boiling due to the cooling water being stopped. Is considered to have occurred. On the other hand, when the electric pump 9 is operated in the same manner as the conventional mechanical pump and continuously circulated, not only when the electric pump 9 is intermittently operated as in this embodiment, the water temperature as described above is obtained. Abrupt fluctuations are not observed, and it can be seen from this that local temperature rise can be suppressed by intermittently circulating cooling water as described above.

-Control procedure when engine is cold-
Hereinafter, the operation control procedure of the electric pump 9 performed by the ECU 20 will be described with reference to FIGS. 6 to 10 mainly based on the flowchart of FIG. First, in step S1 after the start of the flow of FIG. 5, signals from each sensor of the engine control system including at least the load state sensor 16, the engine speed sensor 17, the water temperature sensor 18 and the like are input, and the memory is also input. Read the stored control parameter values.

  Subsequently, in step S2, a time T1 from the engine start to the start of control of the electric pump 9 is read from a preset table. For example, as schematically shown in FIG. 6, this table shows the first set time T1 from the engine start to the start of the electric pump control according to the engine water temperature at the start, and the electric pump 9 from the pulse control mode. The second set time T2 until switching to the control mode is determined based on experiments and the like. In the example in the figure, when the engine water temperature at the start is equal to or lower than a predetermined value, the engine after the start is for a while. The first and second set times T1 and T2 are lengthened as the temperature of the starting water is lower, assuming that the engine is in the cold state.

  In step S3, it is first determined whether or not the first set time T1 has elapsed after the engine is started. If not (NO), the process returns. That is, the electric pump 9 is not operated until the first set time T1 elapses after the cold start of the engine, and the flow of the cooling water in the water jackets 4 and 5 in the engine main body 1 is stopped to thereby warm the engine. Maximize the opportunity.

  On the other hand, if the first set time T1 has elapsed from the start (YES), the process proceeds to step S4, where it is determined whether or not the second set time T2 has elapsed. If the determination result is NO and the second set time T2 has not elapsed, the process proceeds to steps S6 and S7 described later to operate the electric pump 9 in the pulse control mode, while the determination result is YES and the second set time T2 has elapsed. If so, the process proceeds to step S5, where it is determined whether the execution condition of the pulse control mode after engine warm-up is satisfied.

  That is, in this embodiment, the electric pump 9 is operated in the pulse control mode until the engine water temperature reaches a predetermined high temperature state even after the engine is warmed up as will be described later. It is assumed that the engine is not more than a predetermined value and the engine is in a relatively low load or low speed operation state. This is because the amount of heat generated by the engine increases when the load or the rotational speed is high, and therefore it is preferable to continuously flow the cooling water regardless of the engine water temperature after the engine is warmed up.

  More specifically, for example, as schematically shown in FIG. 7, a table in which a threshold value of the engine load is set according to the engine speed as an execution condition of the pulse control mode after warm-up is based on an experiment or the like in advance. This is created and stored in the memory of the ECU 20. When the engine load is lower than the predetermined value when the engine load is lower than the threshold value read from the table according to the engine speed, it is determined that the execution condition for the pulse control mode is satisfied.

  In order to prevent hunting, it is preferable to add hysteresis to the execution condition of the pulse control mode. For example, for the engine water temperature, the control start condition is set to 93 ° C or lower, while the control end condition is set to 95 ° C. That is all. The engine load threshold value may be set such that the control start condition is lower than the end condition if the engine speed is the same.

  If it is determined in step S5 that the execution condition of the pulse control mode is not satisfied (NO), the process proceeds to steps S8 to S12 described later to operate the electric pump 9 in the normal control mode, while in the pulse control mode. If it is determined that the execution condition is satisfied (YES), the electric pump 9 is operated in the pulse control mode in steps S6 and S7 described below.

  Specifically, first, in step S6, the intermittent operation cycle of the electric pump 9 and the control duty ratio at the time of operation are read from preset tables. In this table, for example, as schematically shown in FIG. 8, the optimum operation cycle and duty ratio of the electric pump 9 are determined based on experiments, respectively, according to the engine water temperature. The duty cycle is set so as not to change much while the operation cycle becomes shorter as the engine water temperature becomes higher, but instead or in addition to this, the duty ratio becomes larger as the engine water temperature becomes higher. It may be set.

  In the subsequent step S7, an output voltage is applied in a pulsed manner to the motor of the electric pump 9 by a control signal corresponding to the operation cycle and duty ratio, and this is operated intermittently, and then the process returns. When the electric pump 9 is operated instantaneously, that is, intermittently at a preset period, the cooling water in the water jackets 4 and 5 of the cylinder block 2 and the cylinder head 3 is continuously operated by the electric pump 9. Instead of continuously moving from the inlet side to the outlet side as in the case of time, it is repeatedly stopped immediately after being moved small by an instantaneous pump operation.

  In other words, the intermittent operation of the electric pump 9 causes the entire cooling water of the water jackets 4 and 5 to oscillate periodically and circulate intermittently so as to be slightly agitated. The local temperature rise around the cylinders s1 to s4 of the engine is suppressed, and the amount of heat released from the engine is reduced in the same manner as when the cooling water is stopped, so that warming up of the engine is sufficiently promoted. Will be.

  The time chart of FIG. 9 shows the relationship between the operating state of the electric pump 9 after the cold start as described above and the increase in the engine water temperature in comparison with an engine having a conventional mechanical water pump. First, until the first set time T1 elapses after the cold start (0 to t1 = T1), the control duty ratio of the electric pump 9 is set to 0% and the pump is maintained in the stopped state (step S1). (Return in S3), thereby minimizing heat dissipation from the engine. At this time, as shown by the solid line in the figure, the increase in the engine water temperature is apparently delayed because the electric pump 9 is stopped and the cooling water of the water jackets 4 and 5 does not flow. This is because the heated cooling water around s4 does not reach the water temperature sensor 18.

  Then, when the cooling water heated as described above reaches the water temperature sensor 18 by convection, the detected value of the sensor rapidly rises as shown in the figure, and overtakes that of the comparative example (shown by a broken line). When the first set time T1 has elapsed from the start (time t1), pulse control is started (steps S4 → S6), and the electric pump 9 operates intermittently as described above. The intermittent operation of the electric pump 9 causes the cooling water in the water jackets 4 and 5 to intermittently flow and be slightly agitated, so that the local temperature rise around the cylinders s1 to s4 and the like. Is suppressed.

  When the thermostat 13 is opened while the electric pump 9 is operating intermittently, low-temperature (substantially outside temperature) cooling water flows from the radiator 6 side (time t2). Since the electric pump 9 is intermittently operated as described above, the low-temperature cooling water does not flow into the water jacket 4 at a stretch, but only when the electric pump 9 is momentarily operated. Therefore, although the water temperature detection value temporarily decreases as shown in the figure, the degree of the decrease is not so large.

  In addition, in this embodiment, the period of intermittent operation of the electric pump 9 is changed to be longer in response to the decrease in the water temperature (step S6). For example, the ratio of the intermittent operation time of the electric pump 9 to the stop time is changed. Is smaller than 1/10, the inflow of low-temperature cooling water from the radiator 6 side becomes very small, and the drop in water temperature is sufficiently suppressed.

  That is, if the electric pump 9 is not operated intermittently as described above, when the thermostat 13 is opened, low-temperature cooling water flows in from the radiator 6 side, and the cooling water temperature of the water jackets 4 and 5 is As shown by the phantom line, it is thought that the engine will suddenly fall, and not only the engine warm-up will be delayed, but there is also a possibility that the combustion will be temporarily deteriorated. By intermittently operating the pump 9, the cooling water temperature fluctuations in the water jackets 4, 5 can be sufficiently suppressed by making the inflow of the low-temperature cooling water into the water jackets 4, 5 very small.

  That is, according to the engine cooling device A of this embodiment, the electric water pump 9 is stopped for a predetermined time after the engine is cold-started, and then intermittently operated to suppress problems such as local excessive temperature rise. However, the warm-up of the engine can be promoted as much as possible, and the cooling water temperature drop due to the opening of the thermostat 13 can be suppressed to further improve the fuel economy and emission during the cold-cooling. .

  In particular, in this embodiment, the cycle of the intermittent operation of the electric pump 9 is changed according to the change in the engine water temperature, thereby changing the ratio of the circulation time of the coolant that circulates intermittently to the stop time. Therefore, it is possible to finely and accurately adjust the temperature state of the cooling water, and to satisfy the conflicting demands of suppression of problems caused by the rise in the water temperature and rapid warm-up of the engine at a higher level.

-Control procedure after warm-up-
As described above, the warm-up of the engine is promoted as much as possible, and when the second set time T2 elapses from the cold start, the entire cooling water of the water jackets 4 and 5 becomes about 90 ° C., Although the engine warm-up is completed, in this embodiment, the pulse control mode of the electric pump 9 is continued even after the warm-up. Then, when the engine water temperature further rises and the detected value by the water temperature sensor 18 becomes equal to or higher than a predetermined value (95 ° C. in this example) that is the end condition of the pulse control mode (time t3), the flow of the flow shown in FIG. In step S5, it is determined that the execution condition of the pulse control mode is not satisfied (NO), and the process proceeds to steps S8 to S12 to operate the electric pump 9 in the normal control mode.

  Specifically, first, in step S8, the basic control target rotation speed of the electric pump 9 is read from the control map as shown in FIG. 3, and the water temperature is corrected in the subsequent step S9. That is, for example, a correction coefficient set in advance according to the engine water temperature is read from a table schematically shown in FIG. 10, and this water temperature correction coefficient is multiplied by the basic control rotation speed. Subsequently, in step S10, acceleration correction is performed. For example, the acceleration operation of the engine is determined when the accelerator opening increases by 2% or more in 5 milliseconds, or the pump rotational speed is corrected to 1.2 times during a predetermined time. That's it.

  Subsequently, in step S11, the control target rotation speed of the electric pump 9 corrected as described above is converted into a control duty ratio with reference to a preset conversion table, and the duty ratio thus determined is a predetermined upper limit. After confirming that the value is within the range of the value and the lower limit value in subsequent step S12, the process proceeds to step S7. Then, an output voltage is applied to the motor of the electric pump 9 by a control signal corresponding to the duty ratio, this is continuously operated, and then the process returns.

  In this way, the voltage supplied to the electric pump 9 can be changed substantially linearly by changing the control duty ratio, so that the rotation speed can be finely controlled with high accuracy according to the engine load and rotation speed. it can.

  However, since the electric pump 9 is required to secure a maximum flow rate corresponding to a large amount of heat generated during high-load operation of the engine, no matter how low the rotation is performed, for example, the low load of the engine While the operation continues and the amount of heat generated is small, the engine temperature may be relatively low when the outside air temperature is low and the temperature of the cooling water tends to decrease. If this happens, the heat loss increases accordingly, and at this time, the pulse control mode is started again.

  That is, when the engine is in a relatively low load and low speed operation range and the value detected by the water temperature sensor 18 falls below 93 ° C., the pulse control mode after engine warm-up in step S5 of the flow of FIG. It is determined that the execution condition is satisfied, and the electric pump 9 is intermittently operated by the ECU 20 in steps S6 and S7. As a result, the cooling water in the water jackets 4 and 5 temporarily flows intermittently, the temperature rises quickly, and the normal control mode is restored again.

  In this way, even after the engine is warmed up, the electric pump 9 is intermittently operated according to the engine load, rotation speed, engine water temperature, and the like, so that the engine water temperature is higher than that in the past (eg, 93 ° C. or higher). The heat efficiency can be increased and the fuel consumption can be reduced.

  As shown in steps S3, S4 → S6, S7 of the flow of FIG. 5, the ECU 20 (control means) of this embodiment is electrically operated until the first set time T1 elapses after the engine is cold started. The pump 9 (distribution variable means) is maintained in a stopped state, the circulation of the cooling water in the water jackets 4 and 5 is stopped, and further, the cooling water is cooled until the second set time T2 elapses from the start (during cooling). The electric pump 9 is operated in the pulse control mode so that is intermittently distributed.

  When the electric pump 9 is operated in the pulse control mode as described above, the thermostat 13 is opened in response to the increase in the engine water temperature, so that the ECU 20 at least includes the water jackets 4 and 5 in the engine body 1. The electric pump 9 is also operated so that the cooling water is intermittently circulated in the water jackets 4 and 5 when the circulation of the cooling water between the radiator 6 and the radiator 6 starts.

  Further, as shown in steps S5 to S6 and S7 in the flow, the ECU 20 intermittently operates the electric pump 9 until the engine water temperature reaches a predetermined high temperature state even after warming up. As shown in the table of FIG. 8, the higher the engine water temperature, the shorter the pump operation cycle, that is, the ratio of the circulation time of the coolant that circulates intermittently to the stop time increases. 9 is controlled.

  Therefore, according to the engine cooling device A according to the first embodiment described above, the electric pump 9 is provided instead of the conventional crankshaft driven water pump, and the electric pump 9 is the first after the engine is cold-started. By stopping the set time T1 and stopping the flow of the cooling water in the water jackets 4 and 5 in the cylinder block 2 and the cylinder head 3, the heat radiation from the engine is minimized and the warm-up is promoted to the maximum. can do.

  Then, after the first set time T1 has elapsed, the electric pump 9 is operated in the pulse control mode, and the cooling water is intermittently circulated in the water jackets 4 and 5, thereby greatly reducing heat dissipation from the engine. However, a local temperature rise around the cylinders s1 to s4 can be suppressed, and thus warming up of the engine can be promoted.

  Moreover, in the pulse control mode, the time average circulation amount of the cooling water in the water jackets 4 and 5 is changed by changing the intermittent operation cycle of the electric pump 9 based on the detected value of the engine water temperature by the water temperature sensor 18. Can be reduced to the minimum amount necessary to suppress problems caused by local temperature rise, which makes the conflicting demands of suppressing problems caused by temperature rise and rapid engine warm-up extremely high. It can be compatible at a high level.

  Further, when the electric pump 9 is operated in the pulse control mode as described above, the electric pump 9 is also pulsed as described above when the thermostat 13 is opened and the circulation of the low-temperature cooling water starts from the radiator 6 side. By operating in the control mode, the cooling water is made to flow into the water jacket 4 very little by little, thereby suppressing the cooling water temperature from dropping in the water jackets 4 and 5 and preventing the deterioration of the combustion. Can be promoted.

  In addition, in this embodiment, even after the engine is warmed up, when the water temperature is equal to or lower than a predetermined value, the cooling water is intermittently circulated to suppress heat dissipation from the engine. Maintaining a high temperature state can increase thermal efficiency and reduce fuel consumption.

(Embodiment 2)
FIG. 11 shows an overall flow of the cooling water in the cooling device A according to the second embodiment of the present invention. The second embodiment is a mechanical type that is conventionally known instead of the electric pump 9 of the first embodiment. A water pump 30 is provided, and an electromagnetically operated switching valve 31 for switching the flow of cooling water from the mechanical pump 30 to one of the water jackets 4 and 5 and the bypass passage 10 is provided. The switching operation is performed by the ECU 20. Since the configuration of the second embodiment is the same as that of the first embodiment except for the water pump 30 and the switching valve 31, the same members are denoted by the same reference numerals and the description thereof is omitted.

  More specifically, for example, in the first embodiment, the bypass flow rate control valve 15 (see FIG. 1) is selectively connected to the valve chamber of the thermostat 13 through either the bypass passage 10 or the flow path in the heater hose 12. The bypass flow rate control valve 15 is constituted by an electromagnetic valve that is electromagnetically operated without being interlocked with the thermostat 13, and is referred to as the switching valve 31.

  When the thermostat 13 is closed, the switching valve 31 allows the bypass passage 10 to communicate with the valve chamber of the thermostat 13 while the valve chamber and the flow path in the heater hose 12 are closed. In this case (hereinafter referred to as a bypass position), as schematically shown in FIG. 11A, the cooling water sent to the water jacket 4 of the cylinder block 2 by the mechanical pump 30 flows through the bypass passage 10 and passes through the machine. It is returned to the suction side of the pump 30. That is, since the lower hose 8 is closed by the valve body 13 b of the thermostat 13 and the heater hose 12 is closed by the switching valve 31, cooling water is supplied to the water jackets 4 and 5 of the cylinder block 2 and the cylinder head 3. In the water jackets 4 and 5, the cooling water substantially stops except for the flow due to the convection.

  On the other hand, the flow path in the heater hose 12 is communicated with the valve chamber of the thermostat 13 by the switching valve 31 while the space between the valve chamber and the bypass passage 10 is closed (hereinafter referred to as heater circulation position). The cooling water discharged from the mechanical pump 30 circulates from the water jacket 4 of the cylinder block 2 to the water jacket 5 of the cylinder head 2 as shown schematically in FIG. 12 is returned to the suction side of the mechanical pump 30 through the flow path in the inside.

  Therefore, according to the engine cooling device A according to the second embodiment, the ECU 20 operates the switching valve 31 and switches the position between the bypass position and the heater circulation position in the first embodiment. As in the case of intermittently operating 9, the cooling water can be intermittently circulated in the water jackets 4 and 5, thereby suppressing a local temperature rise around the cylinders s 1 to s 4. However, engine warm-up can be promoted as much as possible to improve fuel consumption and emissions.

  In addition, since the bypass flow rate adjusting valve 15 that has been integrated with the valve body 13b of the thermostat 13 conventionally only needs to be an independent electromagnetically operated type without using an electric pump as in the first embodiment. It can be simpler and less expensive.

(Embodiment 3)
FIG. 12 shows the overall flow of the cooling water in the cooling device A according to the third embodiment of the present invention. The third embodiment is similar to the second embodiment in that the cooling from the mechanical pump 30 is performed. The water flow is switched to one of the water jackets 4 and 5 and the bypass passage 10 by the switching valve 31, and a small-capacity electric pump 32 is provided separately. When the engine is cold, the water jacket 4 is only driven by the electric pump 32. , 5 is made to circulate cooling water. The configuration of the third embodiment is the same as that of the second embodiment except that the small-capacity electric pump 32 is added. Therefore, the same members are denoted by the same reference numerals and the description thereof is omitted. To do.

  In the illustrated example, the suction side of the electric pump 32 is branched and connected to the heater hose 12 upstream of the switching valve 31, while the discharge side communicates with the valve chamber of the thermostat 13 to connect the valve body 13 b to the heater hose 12. It communicates directly with the suction port of the mechanical pump 30 without intervention. That is, the electric pump 32 is arranged in parallel with the switching valve 31 so that the cooling water can be circulated to the water jackets 4 and 5 through the heater hose 12 even when the switching valve 31 is closed. It has become.

  Then, when the thermostat 13 is closed, the switching valve 31 is switched to the bypass position to close the space between the valve chamber and the flow path in the heater hose 12, as in the second embodiment, Since the cooling water discharged from the mechanical pump 30 flows through the bypass passage 10 and returns to the suction side of the mechanical pump 30, if the electric pump 32 is stopped at this time, the water jacket 4, No cooling water flows through 5.

  Further, when the electric pump 32 is operated, the coolant that is sucked into the electric pump 32 from the flow path in the heater hose 12 flows from the water jacket 4 of the cylinder block 2 to the water jacket 5 of the cylinder head 3. As a result, a minute flow rate is generated in the water jackets 4 and 5. And by the circulation of the minute flow rate of the cooling water, it is possible to suppress a local temperature rise around the cylinders s1 to s4 while suppressing heat dissipation from the engine.

  That is, as in the first and second embodiments, in order to suppress the heat dissipation from the engine and promote the warm-up, the discharge flow rate of the electric pump 32 must be very small. In an engine, for example, it is necessary to use a small-capacity electric pump capable of minute flow control of about 0.5 liters per minute or less.

  Furthermore, if the switching valve 31 is switched to the heater circulation position so that the flow path in the heater hose 12 communicates with the valve chamber of the thermostat 13, while the valve chamber and the bypass passage 10 are closed, As schematically shown in FIG. 12 (b), the cooling water discharged from the mechanical pump 30 flows from the water jacket 4 of the cylinder block 2 to the water jacket 5 of the cylinder head 2, and further in the heater hose 12. This flow is returned to the suction side of the mechanical pump 30.

  Therefore, according to the engine cooling apparatus A according to the third embodiment, the mechanical pump 30 ensures the maximum flow rate corresponding to a large amount of heat generated during high-load operation of the engine, while the small-capacity electric pump 32 is separated from the maximum flow rate. As a result, the circulation amount of the cooling water can be reduced so as to be very small, thereby suppressing the local temperature rise around the cylinders s1 to s4 as in the first and second embodiments. The engine warm-up can be promoted as much as possible to improve fuel consumption and emissions.

  In the first to third embodiments, the flow of the cooling water in the water jackets 4 and 5 is stopped during a predetermined period (first set time T1) immediately after the cold start of the engine. Instead, the cooling water may be intermittently circulated immediately after startup.

  In each of the above embodiments, the thermostat 13 is disposed on the cooling water inlet side to the water jackets 4, 5. However, the present invention is not limited to this, and the present invention does not limit the thermostat 13 to the water jackets 4, 5. Even when the cooling water is disposed on the outlet side of the cooling water, it is applicable.

  Furthermore, although each said embodiment has shown about the case where the cooling device A of this invention is applied to an in-line 4 cylinder engine, the structure of an engine is not limited to it.

  As described above, the engine cooling apparatus A according to the present invention is characterized by the flow control of the cooling water during cooling, and suppresses local temperature rise and partial boiling of the cooling water in the water jacket. However, the engine warm-up can be promoted as much as possible to improve the fuel efficiency and emission during cold operation, and therefore, it is particularly suitable for an automobile engine that is frequently driven and stopped.

It is a mimetic diagram showing a schematic structure of an engine cooling device concerning Embodiment 1 of the present invention. FIG. 3 is a schematic diagram showing a flow of cooling water in the first embodiment. It is a schematic diagram which shows an example of the rotation speed control map of an electric pump. It is a graph which shows a mode that water temperature etc. rise at the time of intermittent operation | movement of an electric pump compared with the time of a pump's continuous operation | movement and a stop. It is a flowchart figure which shows the control procedure of an electric pump. It is the schematic diagram of the table which matched the 1st and 2nd setting time after cold start corresponding to the water temperature at the time of start. It is a schematic diagram of the table which set the threshold value of the engine load according to the engine speed as an execution condition of the pulse control mode after warming up. It is the schematic diagram of the table which set the operating cycle and duty ratio of the electric pump in pulse control mode according to engine water temperature. It is a time chart which shows the relationship between the operating state of the electric pump after a cold start, and a raise of engine water temperature. It is a schematic diagram of the table which set the water temperature correction coefficient of the pump rotation speed in normal control mode. FIG. 3 is a view corresponding to FIG. 2 of an engine cooling device according to a second embodiment. FIG. 6 is a view corresponding to FIG. 2 illustrating an engine cooling device according to a third embodiment.

Explanation of symbols

A Engine cooling device 1 Engine body 4, 5 Water jacket (cooling water passage)
7 Upper hose (communication path)
8 Lower hose (communication passage)
9 Electric pump (distribution variable means)
10 Bypass passage 13 Thermostat 15 Bypass flow adjustment valve (switching valve)
18 Water temperature sensor (sensor)
20 Engine control unit (ECU: Control means)
30 Mechanical pump (distribution variable means)
31 Switching valve 32 Electric pump with small capacity

Claims (9)

A cooling device provided with flow variable means capable of changing the flow state of the cooling water in the cooling water passage in the engine body,
An engine cooling apparatus comprising: control means for operating the flow variable means so that the cooling water flows intermittently in the cooling water passage when the engine is cold. The cooling device according to claim 1, wherein
The distribution variable means includes an electric pump for circulating cooling water,
The engine cooling device characterized in that the control means operates the electric pump intermittently. The cooling device according to claim 2, wherein
The engine cooling device is characterized in that the control means is configured to be able to perform duty control on the amount of electric power supplied to the electric pump. The cooling device according to claim 1, wherein
The distribution variable means includes a switching valve that switches the flow of the cooling water distributed by the mechanical pump to either the cooling water passage or the bypass passage in the engine body,
The engine cooling device characterized in that the control means switches and operates the switching valve. In the cooling device according to any one of claims 1 to 4,
Equipped with a sensor to detect the temperature of the cooling water,
The control means operates the flow variable means so that the ratio of the circulation time of the coolant flowing intermittently to the stop time increases as the coolant temperature detected by the sensor increases. The engine cooling device. In the cooling device according to any one of claims 1 to 5,
The control means circulates so that the cooling water flow in the cooling water passage in the engine body stops for a predetermined period after the engine is started, and the cooling water flows intermittently in the cooling water passage after the predetermined period. An engine cooling apparatus for operating a variable means. The cooling device according to claim 6, wherein
The control means operates the flow variable means so that the cooling water circulates intermittently until the cooling water temperature reaches a predetermined high temperature state after the engine is warmed up, and thereafter the cooling water circulates continuously. A cooling device for an engine characterized by being. In the cooling device according to any one of claims 1 to 7,
A cooling device for an engine characterized in that a thermostat that mechanically opens and closes in response to a temperature change of the cooling water is disposed in the communication passage that connects the cooling water passage in the engine body and the passage in the radiator. . A cooling device provided with flow variable means capable of changing the flow state of the cooling water in the cooling water passage in the engine body,
The flow variable means has a switching valve for switching the flow of the cooling water circulated by the mechanical pump to either the cooling water passage or the bypass passage, and has a capacity smaller than that of the mechanical pump, and is connected to the cooling water passage. An electric pump arranged to circulate the cooling water,
When the engine is cold, the switching valve is operated so that the flow of cooling water from the mechanical pump is switched to the bypass passage, and the electric pump is operated so that the cooling water flows through the cooling water passage by a predetermined minute flow rate. An engine cooling apparatus comprising control means for operating the engine.

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