JP5974619B2 - Control device and control method for engine cooling system - Google Patents

Description

  The present invention relates to a control device and a control method for controlling an engine cooling system mounted on a vehicle.

  In order to control the amount of cooling water supplied to the radiator mounted on the vehicle, instead of the conventional wax-type thermostat, for example, as disclosed in Patent Document 1, the cooling water is used using an electric actuator such as a motor. An electronic control valve is used to control the flow rate.

JP 2005-90480 A

  In the conventional example disclosed in Patent Document 1 described above, until the temperature of the engine cooling water reaches a predetermined temperature or higher, the electronic control valve is fully closed to promote warm-up, so that the radiator and other radiators are connected. The amount of cooling water is reduced. However, since it does not consider that the pressure of the cooling water increases when the engine speed increases, when the engine speed increases with the cooling water temperature being low, the cooling water is supplied to the cooling circuit or the like. There is a risk of load due to pressure.

  The present invention has been made to solve such a conventional problem. The object of the present invention is to suppress a decrease in the warm-up efficiency of the engine and to apply a large water pressure to the piping of the cooling system. An object of the present invention is to provide a control device for an engine cooling system and a control method for the engine cooling system that can prevent the occurrence of the above.

In order to achieve the above object, the present invention acquires an engine speed, and has a first threshold value for the engine speed, a second threshold value greater than the first threshold value, and a second threshold value. A large third threshold is set. When the engine speed is equal to or lower than the first threshold and the temperature measured by the temperature measuring means is equal to or lower than the predetermined temperature, the first branch valve, the second branch valve, and the third branch valve are closed, When the engine speed exceeds the first threshold, either the second branch valve or the third branch valve is opened, and when the engine speed exceeds the second threshold, Both the 2-branch valve and the third branch valve are opened, and when the engine speed exceeds the third threshold value, the first branch valve, the second branch valve, and the third branch valve are all opened. Control.

  In the present invention, when the engine speed increases or is expected to increase, the electronic control valve is opened to circulate the cooling water regardless of the temperature of the cooling water. It is possible to prevent the cooling water circuit from being burdened while suppressing the above.

It is a block diagram which shows the structure of the engine cooling system which concerns on one Embodiment of this invention, and a control apparatus. FIG. 2 is a block diagram showing a detailed configuration of an electronic control valve 4 shown in FIG. 1 according to one embodiment of the present invention. FIG. 6 is a characteristic diagram illustrating a relationship between an engine speed and a coolant pressure in an embodiment of the present invention. FIG. 6 is a characteristic diagram illustrating a relationship between an engine speed and a coolant pressure in an embodiment of the present invention. FIG. 6 is a characteristic diagram illustrating a relationship between an engine speed and a water flow resistance coefficient according to an embodiment of the present invention. It is a flowchart which shows the process sequence of the control apparatus of the engine cooling system which concerns on one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram schematically showing the configuration of a control device for an engine cooling system according to an embodiment of the present invention. As shown in FIG. 1, this engine cooling system includes a water pump 8 that circulates cooling water, a cooling water circuit 3 that is connected to the output side of the water pump 8 and is provided in the engine 1 to cool the engine 1. An electronic control valve 4 provided near the engine outlet of the cooling water circuit 3 and branching the cooling water circuit 3 into three systems, and a water temperature provided near the engine outlet of the cooling water circuit 3 for measuring the temperature of the cooling water A sensor (temperature measuring means) 14.

  As shown in FIG. 2, the electronic control valve 4 includes a first branch valve 4a, a second branch valve 4b, and a third branch valve 4c, and adjusts the opening degree of each of the branch valves 4a to 4c. Thus, the cooling water sent from the cooling water circuit 3 is branched into three systems and sent out.

  The system branched by the first branch valve 4 a passes through the radiator 5 via the first coolant circuit 3 a (branch coolant circuit) and is connected to the inlet side of the water pump 8. That is, the radiator 5 can be cooled by flowing cooling water into the first cooling water circuit 3a.

  The system branched by the second branch valve 4b passes through the heater 9 and the EGR (Exhaust Gas Recirculation) cooler 10 via the second cooling water circuit 3b (branch cooling water circuit), and enters the inlet side of the water pump 8. It is connected. That is, the heater 9 and the EGR cooler can be cooled by flowing the cooling water into the second cooling water circuit 3b.

  The system branched by the third branch valve 4c passes through the engine oil cooler 6 and the transmission oil cooler 7 via the third coolant circuit 3c (branch coolant circuit) and is connected to the inlet side of the water pump 8. ing. That is, the engine oil cooler 6 and the transmission oil cooler 7 can be cooled by flowing the cooling water into the third cooling water circuit 3c.

  Further, the outlet of the cooling water circuit 3 is connected to the cooling water circuit 3d at the engine outlet, and the cooling water circuit 3d passes through the turbocharger 11 and the throttle chamber 12 and is connected to the EGR valve 13. Yes. The EGR valve 13 is connected to the inlet side of the water pump 8. Therefore, the amount of cooling water flowing into the cooling water circuit 3d can be adjusted by adjusting the opening degree of the EGR valve 13.

  Further, a valve control device (valve control means) 21 is provided to adjust the opening degree of each branch valve 4 a to 4 c provided in the electronic control valve 4. The valve control device 21 is connected to the electronic control valve 4 and the water temperature sensor 14.

  The valve control device 21 includes a valve position detection unit 22 that detects the opening degree of each branch valve 4a to 4c, and a traveling state of the vehicle (information on the rotational speed of the engine 1 and information on whether the ignition is turned on). And the water pressure prediction unit 23 for predicting the pressure of the cooling water circulating in the cooling water circuit 3 based on the travel state data and the opening states of the branch valves 4a to 4c, and the water pressure prediction A valve opening degree control unit 24 that adjusts the opening degree of each branch valve 4a to 4c based on the water pressure predicted by the unit 23 and the cooling water temperature measured by the water temperature sensor 14.

  The valve control device 21 can be configured as an integrated computer including a central processing unit (CPU) and storage means such as a RAM, a ROM, and a hard disk.

  Here, in a vehicle equipped with a belt-driven mechanical water pump, when the rotational speed of the engine 1 increases, the rotational speed of the water pump 8 increases accordingly, and the cooling water circulating in the cooling water circuit 3 is increased. Water pressure rises. Further, when the electronic control valve 4 is closed for warming up (when 4a to 4c are fully closed), the water pressure further increases. As a specific example, as shown in FIG. 3, when the electronic control valve 4 is fully open, the water pressure of the cooling water changes as shown by the curve q2 as the rotational speed of the engine 1 increases. When the electronic control valve 4 is fully closed, the water pressure changes as shown by the curve q1 as the rotational speed of the engine 1 increases. That is, when the electronic control valve 4 is fully closed, the water pressure changes so as to be greatly increased as compared with the fully open case. Therefore, in the present embodiment, when the number of revolutions of the engine 1 is increased and the cooling water pressure is expected to increase to exceed the allowable value of the water pressure, the branch valves 4a to 4c are appropriately set. By opening, control is performed so as to suppress an excessive increase in water pressure.

  For example, a case where the allowable value of the water pressure is 350 [KPa] is taken as an example. When all the branch valves 4a to 4c are fully closed, the water pressure exceeds the allowable value when the rotational speed of the engine 1 reaches 4800 [rpm]. This characteristic changes as shown by a curve q1 in FIG. 4 (same as q1 in FIG. 3).

  Further, when only the second branch valve 4b is fully opened and the first branch valve 4a and the third branch valve 4c are fully closed, the water pressure reaches an allowable value when the rotational speed of the engine 1 reaches 4900 [rpm]. Exceed. This characteristic changes as shown by a curve q3 in FIG.

  Further, when only the third branch valve 4c is fully opened and the first branch valve 4a and the second branch valve 4b are fully closed, the water pressure reaches an allowable value when the rotational speed of the engine 1 reaches 4900 [rpm]. Exceed. This change changes as shown by a curve q3 in FIG. The characteristics when only the second branch valve 4b is fully open and when only the third branch valve 4c is fully open are not the same, but are almost the same. Therefore, it is shown as the same curve q3.

  Further, when both the second branch valve 4b and the third branch valve 4c are fully opened and the first branch valve 4a is fully closed, the water pressure reaches an allowable value when the rotational speed of the engine 1 reaches 5000 [rpm]. Exceed. This characteristic changes as shown by a curve q4 in FIG.

  Accordingly, after the engine 1 is started, when the engine speed is expected to be less than 4800 [rpm], all the branch valves 4a to 4c are fully closed. If the engine speed is expected to exceed 4800 [rpm], either the second branch valve 4b or the third branch valve 4c is fully opened. When the engine speed is expected to exceed 4900 [rpm], both the second branch valve 4b and the third branch valve 4c are fully opened. Further, when the engine speed is expected to exceed 5000 [rpm], in addition to the second and third branch valves 4b and 4c, the first branch valve 4a is opened.

  When opening the first branch valve 4a, the relationship between the engine speed and the opening degree of the first branch valve 4a is set in advance so that the first branch valve 4a has an appropriate opening degree. To control. For example, as shown in FIG. 5, a map showing the relationship between the engine speed and the water flow resistance coefficient is prepared in advance, and the relationship between the water flow resistance coefficient and the opening of the first branch valve 4a is set in advance. . When the engine speed is predicted, the opening degree of the first branch valve 4a is obtained based on the predicted engine speed, and the opening degree of the first branch valve 4a is adjusted so as to be the opening degree. Just do it.

  In this way, even when the water pressure of the cooling water circulating in the cooling water circuit 3 increases as the rotational speed of the engine 1 increases, the water pressure is adjusted to be an allowable value (for example, 350 [KPa]) or less. can do.

  Next, with reference to the flowchart shown in FIG. 6, the process procedure by the control apparatus of the engine cooling system which concerns on this embodiment is demonstrated. In addition, the process shown below has shown the process operation | movement in case the temperature of the cooling water detected by the water temperature sensor 14 is below the preset threshold temperature.

  First, in step S11, the valve control device 21 detects that the accelerator opening of the vehicle is larger than a predetermined value based on the traveling state detection signal. That is, as the accelerator opening increases, the engine speed increases accordingly. Therefore, the engine speed is estimated based on the accelerator opening, and it is detected that the engine speed has increased. The reason for using the accelerator opening without directly detecting the engine speed is that a delay occurs in response to subsequent processing after the increase in the engine speed is detected. Further, the estimation of the engine speed can be executed by using, for example, a map showing a correspondence relationship between the accelerator opening and the engine speed.

  In step S <b> 12, the valve position detector 22 detects the opening degree of each branch valve 4 a to 4 c provided in the electronic control valve 4. Thereby, the present opening degree of each branch valve 4a-4c can be recognized.

In step S13, the valve control device 21 determines whether any of the branch valves 4a to 4c needs to be opened. Specifically, whether or not the water pressure of the cooling water reaches a preset threshold pressure (for example, 35 0 [KPa]) based on the relationship between the opening degree of each branch valve 4a to 4c and the estimated engine speed. Determine whether. As described above, this determination can be made based on whether or not the engine speed reaches 4800 [rpm] (first threshold; predetermined speed). If it is determined that the threshold pressure is reached, the process proceeds to step S14. If it is determined that the threshold pressure is not reached, the process is terminated.

  In step S14, the valve control device 21 predicts the engine speed again according to the change in the accelerator opening. In step S15, one of the second branch valve 4b and the third branch valve 4c is opened. By this operation, the cooling water flows through either the second cooling water circuit 3b or the third cooling water circuit 3c, so that the water pressure generated in the cooling water circuit 3 can be reduced.

  Thereafter, in step S16, the valve control device 21 determines whether it is necessary to open both the second branch valve 4b and the third branch valve 4c. Specifically, as described above, it is determined whether or not the engine speed exceeds 4900 [rpm] (second threshold).

  And when it is judged that it exceeds (YES in Step S16), in Step S17, valve opening control part 24 opens both the 2nd branch valve 4b and the 3rd branch valve 4c. Specifically, when the second branch valve 4b is opened in the process of step S15, in addition to this, the third branch valve 4c is opened, and when the third branch valve 4c is opened. In addition, the second branch valve 4b is opened. Thereby, the raise of the water pressure accompanying the raise of the rotation speed of an engine can be reduced.

  Next, in step S18, the valve control device 21 determines whether or not it is necessary to open the first branch valve 4a. Specifically, as described above, it is determined whether or not the engine speed exceeds 5000 [rpm] (third threshold value). And when it is judged that it exceeds (YES in Step S18), since it is necessary to flow the cooling water to the first cooling water circuit 3a, in Step S19, based on the characteristic curve shown in FIG. The opening degree of the first branch valve 4a is calculated.

  In step S20, the valve opening degree control unit 24 controls the opening degree of the first branch valve 4a to be the opening degree calculated in the process of step S19. As a result, the cooling water flows in the first cooling water circuit 3a in addition to the second and third cooling water circuits 3b and 3c, and the water pressure of the cooling water is further reduced. Reaching a threshold (for example, 350 [KPa]) can be prevented.

  In the above-described embodiment, the example in which the second branch valve 4b and the third branch valve 4c are fully opened or fully closed according to the engine speed has been described. It is also possible to control the opening of the valves 4b and 4c to be large.

Thus, in the engine cooling system control apparatus and the engine cooling system cooling method according to the present embodiment, when the engine speed exceeds or is expected to exceed the predetermined value, the electronic control valve Since at least one of the branch valves 4a to 4c provided in 4 is opened and the cooling water flows, it is assumed in advance that the water pressure in the cooling water circuit 3 exceeds an allowable value (for example, 35 0 [KPa]). It is possible to prevent the load on the cooling water circuit 3 from being reduced. In addition, it is possible to avoid a rapid decrease in engine warm-up efficiency.

  Also, by controlling the opening degree to increase as the engine speed increases, the water pressure of the cooling water can be finely adjusted so that the allowable value of the water pressure is at the limit, thereby reducing the engine warm-up efficiency. While suppressing, it can suppress that a big water pressure is applied to piping of a cooling system.

  Furthermore, since it has several branch valve 4a-4c and the opening degree of each branch valve 4a-4c is suitably controlled according to an engine speed, appropriate valve control according to an engine speed is attained.

  When the engine speed exceeds the first threshold value based on the detected or estimated engine speed, one of the second branch valve 4b and the third branch valve 4c is opened, and the engine When the rotational speed exceeds the second threshold, both the second branch valve 4b and the third branch valve 4c are opened, and when the engine rotational speed exceeds the third threshold, all branches are opened. Since the valves 4a to 4c are controlled to be opened, it is possible to perform appropriate valve opening / closing control in accordance with the engine speed, and it is possible to suppress an increase in water pressure while suppressing the warm-up efficiency of the engine.

  As mentioned above, although the control apparatus and control method of the engine cooling system of this invention were demonstrated based on embodiment of illustration, this invention is not limited to this, The structure of each part is the arbitrary which has the same function. It can be replaced with that of the configuration.

  For example, in the above-described embodiment, it has been described that the electronic control valve 4 is provided with the three branch valves 4a, 4b, and 4c. However, the present invention is not limited to this, and one, two, Alternatively, the present invention can be applied to a case where four or more branch valves are provided.

  The present invention can be used to suppress an increase in the water pressure of engine cooling water.

DESCRIPTION OF SYMBOLS 1 Engine 3 Cooling water circuit 3a 1st cooling water circuit 3b 2nd cooling water circuit 3c 3rd cooling water circuit 4 Electronic control valve 4a 1st branch valve 4b 2nd branch valve 4c 3rd branch valve 5 Radiator 6 Engine oil cooler 7 Transmission oil cooler 8 Water pump 9 Heater 10 Cooler 11 Turbocharger 12 Throttle chamber 13 EGR valve 14 Water temperature sensor 21 Valve controller 22 Valve position detection unit 23 Water pressure prediction unit 23 Water pressure prediction unit 24 Valve opening control unit

Claims (3)

A water pump driven by an engine and circulating cooling water ;
A temperature measuring means for measuring the temperature of the pre-Symbol cooling water,
A first branch valve that adjusts the flow rate of the cooling water sent to the radiator and the flow rate of the cooling water sent to the heater are provided in a cooling water circuit that branches and flows the cooling water sent from the water pump and passed through the engine. An electronic control valve having a second branch valve for adjusting and a third branch valve for adjusting a flow rate of cooling water sent to the oil cooler;
Valve control means for controlling the electronic control valve,
The valve control means includes
Obtaining an engine speed, and setting a first threshold value of the engine speed, a second threshold value greater than the first threshold value, and a third threshold value greater than the second threshold value,
When the engine speed is equal to or lower than the first threshold and the temperature measured by the temperature measuring means is equal to or lower than a predetermined temperature, the first branch valve, the second branch valve, and the third branch valve Is closed,
When the engine speed exceeds the first threshold, either one of the second branch valve or the third branch valve is opened,
When the engine speed exceeds the second threshold, both the second branch valve and the third branch valve are opened,
When the engine speed exceeds the third threshold, control is performed so that the first branch valve, the second branch valve, and the third branch valve are all opened. . The valve control means controls to increase an opening degree of at least one of the second branch valve and the third branch valve according to an increase in the rotational speed of the engine. The control device for the engine cooling system according to claim 1. A water pump driven by the engine to circulate the cooling water, a temperature measuring means for measuring the temperature of the cooling water,
A first branch valve that adjusts the flow rate of the cooling water sent to the radiator and the flow rate of the cooling water sent to the heater are provided in a cooling water circuit that branches and flows the cooling water sent from the water pump and passed through the engine. An engine cooling system comprising: an electronic control valve having a second branch valve that controls the flow rate of cooling water sent to the oil cooler; and a valve control means that controls the electronic control valve. A control method for controlling,
Obtaining an engine speed, and setting a first threshold value of the engine speed, a second threshold value greater than the first threshold value, and a third threshold value greater than the second threshold value,
When the engine speed is equal to or lower than the first threshold and the temperature measured by the temperature measuring means is equal to or lower than a predetermined temperature, the first branch valve, the second branch valve, and the third branch valve Is closed,
When the engine speed exceeds the first threshold, either one of the second branch valve or the third branch valve is opened,
When the engine speed exceeds the second threshold, both the second branch valve and the third branch valve are opened,
When the engine speed exceeds the third threshold, control is performed so that the first branch valve, the second branch valve, and the third branch valve are all opened.
A method for controlling an engine cooling system.

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