JP2005188327A - Vehicle cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle cooling device for stably performing an accurate control of a refrigerant temperature. <P>SOLUTION: The vehicle cooling device 1 comprises: a thermostat 20 for changing distribution of a flow rate of refrigerant flowing from a radiator 10 and a flow rate of refrigerant flowing from an engine 2 and bypassing the radiator 10 by using a thermoelement 30 as a driving source; a heater 41 heating the thermoelement 30; and an ECU 43 determining electric energy supplied to the heater 41. The ECU 43 determines the electric energy P supplied to the heater 41 based on a temperature Te of the thermoelement 30. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vehicle cooling device.

  The vehicle cooling device includes a cooling circuit having a heat exchanger and circulation means for circulating cooling water as a refrigerant in the cooling circuit, and passes the cooling water that has passed through the engine as a heat source to the radiator. The amount of heat stored in is released to the outside air.

  In general, such a vehicle cooling apparatus is provided with a bypass path that bypasses the radiator, and the connection point between the exhaust heat path provided with the radiator and the bypass path includes a flow rate of cooling water flowing from the radiator. A thermostat is provided for distributing the flow rate with the flow rate of the cooling water flowing around the radiator. The temperature of the cooling water introduced into the engine is maintained within the engine control range by the operation of the thermostat.

  2. Description of the Related Art Conventionally, there is a thermosensitive thermostat that varies a valve opening degree by using a thermoelement (wax or the like) that expands according to the temperature of cooling water as a drive source. In recent years, a vehicle cooling device has been proposed in which a heater capable of electrically heating the thermo element is provided in the vicinity of the thermo element to control the operation of the thermostat through energization of the heater.

For example, Patent Document 1 discloses vehicle cooling that determines whether or not the heater is energized according to the engine operating state quantity / ambient state quantity (engine throttle opening, engine speed, engine water temperature, vehicle speed, intake air temperature, etc.). Patent Document 2 discloses a vehicle cooling device that can change a heating output by a heater. And if such a vehicle cooling device is employ | adopted, more precise water temperature control according to a vehicle state can be performed.
Japanese Patent No. 2662187 JP-A-11-62584

  However, the amount of heat that needs to be applied to the thermoelement to operate the valve of the thermostat increases when the difference between the temperature of the thermoelement and the valve opening temperature is large, and decreases when the difference is small. The temperature of the thermo element changes greatly depending on the cooling water temperature, and the amount of heat released to the outside air around the thermo element always changes. Therefore, the heating output from the heater and the valve opening in the thermostat do not necessarily have a fixed relationship.

  However, in the above conventional vehicle cooling device, the temperature of the thermo element as a drive source is not taken into consideration at all, and therefore, excessive or insufficient heating output by the heater is likely to occur. As a result, when the heating output is excessive, hunting of the coolant temperature occurs due to excessive valve opening, or when the heating output is insufficient, there is a problem that the valve opening hardly changes, resulting in deterioration of fuel consumption or knocking. There is a risk of occurrence.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a vehicle cooling apparatus capable of stably performing precise control of the refrigerant temperature.

  In order to solve the above problems, the invention according to claim 1 is directed to a flow rate of refrigerant flowing from a radiator using a thermoelement that expands according to the temperature of the refrigerant as a drive source, and a flow rate of refrigerant flowing from a heat source bypassing the radiator. The vehicle cooling device includes: a thermostat that changes the flow distribution of the heater; a heater that heats the thermo element; and a control unit that determines an amount of electric power to be supplied to the heater. The gist is to determine the amount of power supplied to the heater based on at least the temperature of the thermo element.

  According to a second aspect of the present invention, the control unit includes an estimation unit that estimates a temperature of the thermo element based on a vehicle state quantity, and the power amount to be supplied is calculated based on the estimated temperature of the thermo element. The gist is to decide.

  The gist of the invention described in claim 3 is that the estimating means estimates the temperature of the thermo element based on at least the refrigerant temperature at the heat source outlet, the refrigerant temperature at the radiator outlet, or the outside air temperature.

(Function and effect)
According to the first aspect of the present invention, it becomes possible to supply an amount of electric power corresponding to the temperature of the thermo element to the heater, and it is possible to prevent the heating output by the heater from being excessive or insufficient. That is, the thermostat can be stably controlled even if the temperature of the thermo element changes with the change of the vehicle state, the occurrence of refrigerant temperature hunting due to excessive valve opening, non-response of the valve opening, etc. Can be prevented. As a result, it is possible to stably perform precise control of the refrigerant temperature while preventing deterioration of fuel consumption and occurrence of knocking.

  According to the invention described in claim 2, since it is not necessary to newly provide a temperature sensor for detecting the temperature of the thermo element, a conventional thermostat with a built-in heater can be used. Therefore, precise control of the refrigerant temperature can be stably performed without increasing the manufacturing cost.

  According to the third aspect of the present invention, since the temperature of the thermo element is estimated based on the control parameter used for controlling the conventional vehicle cooling device, it is possible to accurately adjust the refrigerant temperature without causing an increase in manufacturing cost. Control can be performed.

  ADVANTAGE OF THE INVENTION According to this invention, the vehicle cooling device which can perform precise control of refrigerant | coolant temperature stably can be provided.

Hereinafter, an embodiment in which the present invention is embodied in a vehicle cooling device will be described with reference to the drawings.
As shown in FIG. 1, a vehicle cooling device 1 includes a cooling circuit 3 in which cooling water (refrigerant) that has passed through an engine 2 as a heat source is circulated, and a water pump (W that circulates cooling water in the cooling circuit 3). / P) 4.

  In the present embodiment, the W / P 4 is provided in the vicinity of the inlet 2 a for introducing cooling water into the engine 2. W / P 4 is a mechanically driven water pump driven by the engine 2, and pumps cooling water circulated through the cooling circuit 3 into the engine 2 from the inlet 2 a. Then, the cooling water heated when passing through the engine 2 is circulated again into the cooling circuit 3 from the engine outlet 2b.

  The cooling circuit 3 includes an exhaust heat path 11 provided with a radiator 10 that releases heat stored in the cooling water to the outside air by heat exchange with the outside air. The exhaust heat path 11 includes an engine outlet 2b and the radiator 10. It has the 1st flow path 13 to connect, and the 2nd flow path 15 which connects the radiator 10 and the inlet 2a. The cooling water heated by the engine 2 is cooled by passing through the radiator 10 and flows into the second flow path 15.

  The cooling circuit 3 has a bypass path 17 that bypasses the radiator 10 and connects the first flow path 13 and the second flow path 15, and a connection point between the bypass path 17 and the second flow path 15. Is provided with a thermostat 20.

  As shown in FIG. 2, the thermostat 20 includes a main flow path 21 into which cooling water that has passed through the radiator 10 flows, a bypass flow path 22 into which cooling water that has bypassed the radiator 10 via the bypass path 17 flows, A main valve 25 and a bypass valve 26 capable of opening and closing the main channel 21 and the bypass channel 22 are provided.

  The thermostat 20 of the present embodiment is a thermosensitive thermostat having a thermo element 30 that expands according to the temperature of the cooling water, and the main valve 25 and the bypass valve 26 are driven by the thermo element 30. As a result, the valve opening varies. The thermostat 20 is introduced from the outflow passage 28 by distributing the flow rate of the cooling water flowing from the radiator 10 and the cooling water flowing around the radiator 10 by the main valve 25 and the bypass valve 26. The temperature of the cooling water flowing out to the port 2a is maintained within a predetermined control temperature range.

  More specifically, in this embodiment, wax is used as the thermo element 30, and the thermo element 30 is enclosed in a wax case 31. The wax case 31 is provided with a piston 34 that reciprocates along the axial direction by expansion or contraction of the thermo element 30, and the tip of the piston 34 is supplied with cooling water from the main flow path 21 and the bypass flow path 22. Is protruded into the valve chamber 35 into which the gas flows. A main shaft 36 to which the main valve 25 and the bypass valve 26 are fixed is connected to the tip of the piston 34.

  Further, the thermostat 20 has a temperature sensitive flow path 37 connected to the bypass path 17, and a part of the wax case 31 is exposed in the temperature sensitive flow path 37. That is, the thermo element 30 expands as the temperature of the cooling water flowing from the engine outlet 2b bypasses the radiator 10 and rises. The piston 34 moves in a direction protruding into the valve chamber 35 due to the expansion of the thermo element 30, and the main shaft 36 moves in the valve chamber 35 when pressed by the piston 34.

  The main valve 25 is fixed to the main shaft 36 so as to close the outlet 21 a of the main flow path 21 in a state where the thermo element 30 is contracted. The main valve 25 and the main shaft 36 are discharged by the elastic force of the coil spring 38. It is biased toward the 21a side.

  In the present embodiment, the elastic force of the coil spring 38 is the thermo element 30 when the temperature of the cooling water in the temperature-sensitive flow path 37 is at the lower limit of the predetermined control temperature range in consideration of the pressure of the cooling water. Is set equal to the force with which the piston 34 presses the main shaft 36.

  That is, the thermostat 20 is closed when the temperature of the cooling water in the temperature sensing flow path 37 is lower than the lower limit of the predetermined control temperature range, and when the main valve 25 is closed and higher than the lower limit. The main valve 25 is opened when the main shaft 36 moves against the elastic force of the coil spring 38. Thereby, when the main valve 25 is in the closed state, the low-temperature cooling water that has passed through the radiator 10 does not flow into the valve chamber 35. On the other hand, when the main valve 25 is in the open state, the low-temperature cooling water that has passed through the radiator 10 flows into the valve chamber 35. The flow rate of the low-temperature cooling water flowing from the main channel 21 into the valve chamber 35 is increased by increasing the valve opening according to the temperature rise of the cooling water.

  On the other hand, the bypass valve 26 is fixed to the main shaft 36 so as to close the outlet 22a of the bypass passage 22 when the temperature of the cooling water in the temperature sensitive passage 37 reaches the upper limit of the predetermined control temperature range. Has been. That is, the bypass valve 26 is set so that the valve opening degree decreases as the temperature of the cooling water in the temperature-sensitive flow path 37 approaches the upper limit. The flow rate of the high-temperature cooling water flowing from the bypass valve 26 into the valve chamber 35 is reduced.

  In the thermostat 20 of the present embodiment, a heater 41 for heating the thermo element 30 is provided at one end of the wax case 31. Then, by energizing the heater 41 via the connector 42, the valve opening of the main valve 25 can be positively increased.

  As shown in FIG. 1, the heater 41 is connected to an ECU 43 serving as a control unit and an estimation unit via a power supply wiring (not shown) connected to a connector 42 (see FIG. 2). The ECU 43 sequentially detects a plurality of vehicle state quantities, and monitors the vehicle state based on the detected vehicle state quantities. The ECU 43 controls the operation of the thermostat 20 so that the temperature of the cooling water introduced into the engine 2 from the inlet 2a becomes an optimum value by supplying power to the heater 41 according to the vehicle state. Yes.

  More specifically, water temperature sensors 45 and 46 are provided in the vicinity of the engine outlet 2b of the first flow path 13 and in the vicinity of the radiator outlet 10b of the second flow path 15, respectively. It is connected to the. The ECU 43 detects the engine outlet water temperature Tew and the radiator outlet water temperature Trw based on signals input from the water temperature sensors 45 and 46. The ECU 43 is connected to an engine control ECU (not shown), and vehicle state quantities related to the control of the engine 2 are sequentially input from the engine control ECU. Specifically, the throttle opening Rth, the rotational speed NE, the intake air temperature Tia, the vehicle speed V, and the idle signal Si are input.

  The ECU 43 determines the vehicle state (during cold start, high load, etc.) based on these vehicle state quantities, and determines the optimum coolant temperature corresponding to the vehicle state, that is, the target coolant temperature Twt. Then, by supplying electric power to the heater 41, the thermostat 20 is controlled so that the temperature of the cooling water introduced into the engine 2 becomes the target cooling water temperature Twt.

  More specifically, in the vehicle cooling device 1 of the present embodiment, the above-described control temperature range of the thermostat 20 has no heating means in order to reduce the sliding resistance of the engine 2 at normal time (partial load). It is set higher (for example, 100 ° C. to 110 ° C.) than in the case of a thermosensitive thermostat (for example, 80 ° C. to 90 ° C.).

  When it is determined that the engine 2 is in a high load state, the ECU 43 determines a target cooling water temperature Twt that is lower than normal (for example, about 80 ° C.). Then, the thermostat 20 is controlled so that the valve opening degree of the main valve 25 is increased by supplying power to the heater 41 and heating the thermoelement 30 with the heater 41. Then, the distribution ratio of the cooling water that has passed through the radiator 10 is increased to lower the temperature of the cooling water introduced into the engine 2, thereby preventing the occurrence of knocking and improving the output of the engine 2.

  In the present embodiment, the ECU 43 determines the amount of electric power P supplied to the heater 41 based on the temperature Tte of the thermo element 30. Specifically, the ECU 43 estimates the temperature Tte of the thermo element 30 based on the vehicle state quantity. Then, based on the estimated temperature Tte of the thermoelement 30, the amount of electric power P supplied to the heater 41 is determined.

  More specifically, the ECU 43 estimates the temperature Tte of the thermo element 30 based on the engine outlet water temperature Tew, the radiator outlet water temperature Trw, and the intake air temperature Tia detected as vehicle state quantities. In this embodiment, the intake air temperature Tia is used as a surrogate parameter for the outside air temperature. The “outside air temperature” is the temperature of the air surrounding the thermostat 20, that is, the temperature in the engine room where the thermostat 20 is disposed. .

  As shown in FIG. 3, the ECU 43 includes a memory 47, in which the detected engine outlet water temperature Tew, radiator outlet water temperature Trw, intake air temperature Tia, and temperature Tte of the thermo element 30 are related. The attached map 48 is stored. The relationship between the engine outlet water temperature Tew, the radiator outlet water temperature Trw and the intake air temperature Tia and the temperature Tte of the thermo element 30 is obtained in advance by experiments, simulations, etc. and stored in the map 48. The ECU 43 estimates the temperature Tte of the thermo element 30 by referring to this map 48.

  Then, the ECU 43 determines the amount of electric power P supplied to the heater 41 based on the estimated temperature Tte of the thermo element 30. Specifically, the power amount P is decreased as the estimated temperature Tte of the thermo element 30 is higher, and the power amount P is increased as the temperature Tte of the thermo element 30 is lower. Then, the ECU 43 controls the operation of the thermostat 20 by supplying the determined electric energy P to the heater 41.

  The relationship between the temperature Tte of the thermo element 30 and the amount of power P supplied to the heater 41 is stored in the memory 47 in the same map format as the map 48, and the ECU 43 refers to the map to determine the power. The quantity P is determined. In the present embodiment, the ECU 43 varies the amount of power P supplied to the heater 41 by varying the current DUTY at a constant voltage. However, other methods such as varying the voltage at a constant current may be used.

Next, the control aspect of the thermostat 20 by ECU43 is demonstrated.
As shown in FIG. 4, first, the ECU 43 detects the engine outlet water temperature Tew, the radiator outlet water temperature Trw, and the intake air temperature Tia based on signals input from the water temperature sensors 45 and 46 and inputs from the engine control ECU. (Step 101). Next, the ECU 43 estimates the temperature Tte of the thermo-element 30 by referring to the engine outlet water temperature Tew, the radiator outlet water temperature Trw, the intake air temperature Tia and the map 48 detected in step 101 (step 102). Then, the ECU 43 determines the amount of power P to be supplied to the heater 41 based on the temperature Tte of the thermoelement 30 estimated in step 102 (step 103), and supplies the determined amount of power P to the heater 41. Thus, the operation of the thermostat 20 is controlled (step 104).

As described above, according to the present embodiment, the following features can be obtained.
(1) The vehicle cooling device 1 includes a thermostat 20 that changes a flow distribution between a refrigerant flow rate that flows from the radiator 10 and a refrigerant flow rate that flows around the radiator 10 from the engine 2 using the thermoelement 30 as a drive source, and a thermoelement 30 includes a heater 41 that heats 30 and an ECU 43 that determines the amount of power supplied to the heater 41. Then, the ECU 43 determines the amount of electric power P supplied to the heater 41 based on the temperature Tte of the thermo element 30.

  With such a configuration, it becomes possible to supply the heater 41 with the amount of electric power P corresponding to the temperature Tte of the thermoelement 30, and it is possible to prevent the heating output by the heater 41 from being excessive or insufficient. it can. That is, it becomes possible to stably control the thermostat 20 even if the temperature of the thermo element 30 changes with the change of the vehicle state, and the occurrence of hunting of the cooling water temperature due to the excessive valve opening and the insufficiency of the valve opening. Responses can be prevented. As a result, it is possible to stably perform precise control of the refrigerant temperature while preventing deterioration of fuel consumption and occurrence of knocking.

  (2) The ECU 43 estimates the temperature Tte of the thermo element 30 based on the detected vehicle state quantity. With such a configuration, it is not necessary to provide the wax case 31 with a temperature sensor for detecting the temperature Tte of the thermoelement 30, so that a conventional thermostat with a built-in heater can be used. Therefore, precise control of the cooling water temperature can be stably performed without causing an increase in manufacturing cost.

  (3) The ECU 43 estimates the temperature Tte of the thermo element 30 based on the engine outlet water temperature Tew, the radiator outlet water temperature Trw, and the intake air temperature Tia detected as vehicle state quantities. That is, the temperature Tte of the thermo element 30 is estimated based on the control parameters used for controlling the conventional vehicle cooling device. Therefore, precise control of the cooling water temperature can be stably performed without causing an increase in manufacturing cost.

In addition, you may change each said embodiment as follows.
In the present embodiment, the ECU 43 estimates the temperature Tte of the thermo element 30 based on the vehicle state quantity. However, the temperature sensor may directly detect the temperature Tte of the thermo element 30.

In the present embodiment, the intake air temperature Tia is used as a surrogate parameter for the outside air temperature, but an outside air temperature sensor may be provided to directly detect the outside air temperature.
In the present embodiment, the ECU 43 estimates the temperature Tte of the thermo element 30 based on the engine outlet water temperature Tew, the radiator outlet water temperature Trw, and the intake air temperature Tia detected as vehicle state quantities. However, the present invention is not limited to this, and based on at least the engine outlet water temperature Tew, the radiator outlet water temperature Trw, or the intake air temperature Tia, that is, at least one of these parameters and other parameters (rotational speed NE or The temperature Tte of the thermo element 30 may be estimated in combination with the vehicle speed V or the like.

  In the present embodiment, the memory 47 stores a map 48 in which the engine outlet water temperature Tew, the radiator outlet water temperature Trw, the intake air temperature Tia, and the temperature Tte of the thermo element 30 are related, and the ECU 43 refers to this map 48. Thus, the temperature Tte of the thermo element 30 was estimated. However, the present invention is not limited to this, and the configuration may be such that the amount of heat received and received in the thermo element 30 is calculated based on the detected vehicle state quantity, and the temperature Tte of the thermo element 30 is estimated based on the amount of heat received and received.

  For example, as shown in FIG. 5, after detecting the vehicle state quantity (step 201), the ECU first determines the engine outlet water temperature Tew and the flow rate of the cooling water (the rotational speed NE of the engine 2 × the coefficient α). A first heat exchange amount Q1 between the thermo element and the refrigerant is calculated (step 202). Next, the second heat exchange amount Q2 between the thermo element 30 and the outside air is calculated based on the outside air temperature (intake air temperature Tia) and the vehicle speed V (step 203). Then, the sum of the first heat exchange amount Q1 and the second heat exchange amount Q2 calculated in the above steps 202 and 203 is set as the heat release / reception amount Q0 in the thermo element 30 (step 204), and the thermoreaction is performed based on the heat release / reception amount Q0. The temperature Tte of the element 30 may be estimated (step 205).

Next, technical ideas other than the claims that can be grasped from the above embodiments will be described below.
(A) In the vehicle cooling device according to claim 2, the estimation unit includes a calculation unit that calculates a heat release / reception amount in the thermo element based on the vehicle state quantity, and based on the calculated heat release / reception amount. And estimating the temperature of the thermo element.

  (B) In the vehicle cooling device according to (A), the calculation means includes a first heat exchange amount between the thermo element and the refrigerant, and a second heat exchange amount between the thermo element and the outside air. A vehicle cooling device characterized in that a heat exchange amount is calculated, and the sum of the first heat exchange amount and the second heat exchange amount is set as the heat receiving / receiving heat amount.

  (C) The vehicle cooling apparatus according to (b), wherein the calculation unit calculates the first heat exchange amount based on a refrigerant temperature at the outlet of the heat source and a flow rate of the refrigerant. Vehicle cooling device.

  (D) The vehicle cooling device according to (b), wherein the estimating means calculates the second heat exchange amount based on the outside air temperature and the vehicle speed.

The schematic block diagram of the vehicle cooling device of this embodiment. Sectional drawing of the thermostat of this embodiment. Explanatory drawing of the map memorize | stored in memory. The flowchart explaining the control aspect of the thermostat by ECU. The flowchart explaining the temperature estimation method of the thermo element of another example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vehicle cooling device, 2 ... Engine, 10 ... Radiator, 11 ... Exhaust heat path, 20 ... Thermostat, 30 ... Thermo element, 41 ... Heater, 43 ... ECU, Tte ... Temperature of thermo element, Tew ... Engine outlet water temperature, Trw: Radiator outlet water temperature, Tia: Intake air temperature, P: Electricity supplied to the heater.

Claims (3)

A thermostat that changes a flow distribution between a refrigerant flow rate that flows from a radiator and a refrigerant flow rate that flows around the radiator from a heat source by using a thermoelement that expands according to the temperature of the refrigerant as a drive source; and a heater that heats the thermoelement A vehicle cooling device comprising a control means for determining the amount of electric power supplied to the heater,
The said control means determines the electric power supplied to the said heater based on the temperature of the said thermo element at least, The vehicle cooling device characterized by the above-mentioned. The vehicle cooling device according to claim 1,
The control unit includes an estimation unit that estimates a temperature of the thermo element based on a vehicle state quantity, and determines the power to be supplied based on the estimated temperature of the thermo element. apparatus. The vehicle cooling device according to claim 2, wherein
The estimating means estimates the temperature of the thermo element based on at least the refrigerant temperature at the heat source outlet, the refrigerant temperature at the radiator outlet, or the outside air temperature;
The vehicle cooling device characterized by this.

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