JP2008267180A - Control device for variable flow rate water pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a variable flow rate water pump, controlling a flow rate of cooling water, in view of influence on the flow rate of the cooling water by opening of a thermostat. <P>SOLUTION: In the control device for a variable flow rate water pump, cooling water of the engine is circulated through the thermostat, and a thermostat valve opening calculation means and a flow rate variable water pump control means are provided. The thermostat valve opening calculation means calculates valve opening of the thermostat based on the water temperature of the cooling water in the thermostat. The flow rate variable water pump control means controls the flow rate variable water pump based on the valve opening of the thermostat. The flow rate of the cooling water is thereby adjusted to implement a required flow rate according to a pressure loss of the cooling water by opening/closing of the valve of the thermostat. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for a variable flow rate water pump that controls a variable flow rate water pump that circulates engine coolant.

  Conventionally, a technique using a variable flow rate water pump that circulates cooling water for cooling or warming up an engine has been proposed. For example, Patent Document 1 describes a technique for temporarily changing the flow rate of cooling water when the engine load changes to a flow rate corresponding to the change tendency of the engine load.

  Patent Document 2 describes a technology for controlling the flow rate of cooling water in a fuel cell cooling device in consideration of a decrease in the flow rate of cooling water due to a pressure loss of a radiator that occurs when switching the flow path of cooling water. Yes. Further, Patent Document 3 discloses a rotary flow rate by making pressure loss due to both the flow of the cooling water from the radiator port to the pump port and the flow of the cooling water from the bypass port to the pump port substantially equal. A technique for controlling the flow rate of cooling water in the radiator circuit and the bypass circuit in proportion to the valve opening of the control valve is described. Further, Patent Document 4 describes a technique for controlling the temperature of the cooling water while reducing the power consumption of the electric thermostat and the variable flow rate water pump.

JP 2006-257902 A JP 2004-178826 A JP 2000-18039 A JP 2001-32714 A

  By the way, when the opening degree of the thermostat decreases, the pressure loss increases. Therefore, when the load / rotation speed of the variable flow rate water pump is controlled to be constant, the flow rate of the cooling water cools or warms up the engine or the like. There is a risk that it will be lower than the required flow rate of the cooling water. Further, if the flow rate of the cooling water is increased uniformly, the fuel consumption may deteriorate. However, Patent Literature 1 to Patent Literature 4 do not particularly examine the influence of the opening degree of the thermostat on the flow rate of the cooling water.

  The present invention has been made to solve the above-described problems, and is capable of controlling the flow rate of cooling water in consideration of the influence of the opening degree of the thermostat on the flow rate of cooling water. It is an object of the present invention to provide a control device for a variable water pump.

  In one aspect of the present invention, a control device for a variable flow rate water pump that circulates cooling water in an engine via a thermostat is a thermostat that determines a valve opening of the thermostat based on a water temperature of the cooling water in the thermostat. Valve opening degree calculation means, and flow rate variable water pump control means for controlling the flow rate variable water pump based on the valve opening degree of the thermostat.

  The control device for the variable flow rate water pump circulates cooling water in the engine via a thermostat, and includes a thermostat valve opening degree calculation means and a variable flow rate water pump control means. The thermostat valve opening degree calculation means and the variable flow rate water pump control means are, for example, an ECU (Electric Control Unit). The thermostat valve opening calculating means obtains the valve opening of the thermostat based on the coolant temperature of the thermostat. The variable flow rate water pump control means controls the variable flow rate water pump based on the valve opening of the thermostat. Specifically, the flow rate variable water pump control means obtains a cooling water pressure loss based on the valve opening of the thermostat, and based on the cooling water pressure loss, the cooling water flow rate satisfies the required flow rate. The variable flow water pump is controlled. By doing in this way, according to the pressure loss of the cooling water by opening and closing of the valve of a thermostat, the flow volume of a cooling water can be adjusted so that a required flow volume may be satisfy | filled. Thereby, even when the valve opening degree of a thermostat is small, it can suppress that the flow volume of cooling water falls, for example.

  In another aspect of the control device for the variable flow rate water pump, the thermostat valve opening degree calculation means is configured so that the cooling of the engine is performed when the thermostat is provided on an inlet side of the cooling water of the engine. Based on the water temperature of the cooling water on the water outlet side, the flow rate of the cooling water, and the cooling loss of the engine, the water temperature of the cooling water in the thermostat is obtained. By doing so, the pressure loss of the cooling water due to the opening and closing of the thermostat valve can be obtained based on the water temperature on the outlet side of the engine cooling water, and the required flow rate is set according to the pressure loss of the cooling water. The flow rate of cooling water can be adjusted to satisfy.

  In another aspect of the control device for the flow rate variable water pump, the thermostat valve opening calculation means obtains the valve opening of the thermostat based on a response time of the valve opening of the thermostat. Thereby, the opening degree at the time of the transition which the valve of a thermostat opens and closes can be calculated | required, and the flow volume of cooling water can be adjusted so that a required flow volume may be satisfy | filled according to the opening degree at the time of the said transition time.

  Another aspect of the control device for the flow rate variable water pump is a pressure loss calculation means for obtaining a pressure loss of the cooling water based on an operating state of the flow rate variable water pump, a pressure loss of the cooling water, Thermostat operation confirmation means for confirming the operation of the thermostat based on the temperature of the cooling water in the thermostat. The pressure loss calculation unit and the thermostat operation confirmation unit are, for example, an ECU (Electric Control Unit). By doing so, it can be confirmed whether or not the thermostat is operating normally, and the accuracy of the thermostat diagnosis can be improved.

  Another aspect of the control device for the variable flow rate water pump is a pressure loss for determining a pressure loss of the cooling water based on a water temperature sensor for measuring a temperature of the cooling water and an operating state of the variable flow water pump. Water temperature sensor operation confirmation means for confirming the operation of the water temperature sensor based on the calculation means, the pressure loss of the cooling water, and the water temperature of the cooling water measured by the water temperature sensor. By doing in this way, it can be checked whether the water temperature sensor is operating normally, and the accuracy of the diagnosis of a water temperature sensor can be improved.

  Another aspect of the control device for the flow rate variable water pump is a pressure loss calculation means for obtaining a pressure loss of the cooling water based on an operating state of the flow rate variable water pump, a pressure loss of the cooling water, Cooling water specific heat calculating means for calculating the specific heat of the cooling water based on the water temperature of the cooling water. By doing in this way, the precision of a cooling water specific heat can be improved and the calculation precision of an engine cooling loss can be improved.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 is a diagram showing a schematic configuration of a cooling system 100 to which a control device for a variable flow rate water pump according to a first embodiment of the present invention is applied. In FIG. 1, solid arrows indicate the flow of cooling water (LLC: Long Life Coolant), and broken arrows indicate input / output of signals. A solid line indicated by a bold line indicates a passage (cooling water passage) through which the cooling water flows.

  The cooling system 100 according to the first embodiment cools the engine 1 using cooling water, and collects exhaust heat by exchanging heat between the cooling water and the exhaust gas. This system is used for warm-up and heater heat sources. In this case, the cooling water cools or warms up the engine 1 by passing through the cooling water passages 7a, 7b, and 7c. The exhaust heat recovery device 2 is provided on the cooling water passage 7a, the radiator 3 is provided on the cooling water passage 7b, and the variable flow water pump 5 is provided on the cooling water passage 7c. . Hereinafter, when the cooling water passages 7a to 7c are not distinguished from each other, they are simply used as the cooling water passage 7.

  The engine 1 is a device that generates power by burning a mixture of supplied fuel and air. For example, the engine 1 is configured by a gasoline engine, a diesel engine, or the like. The engine 1 is mounted on a hybrid vehicle or the like. Here, the cooling water flowing into the engine 1 passes through a water jacket (not shown) provided around a cylinder (not shown) inside the engine 1 and then flows out from the cooling water passages 7a and 7b. The cylinder is warmed up or cooled by exchanging heat with the cooling water passing through the water jacket.

  The exhaust heat recovery device 2 is provided on an exhaust passage (not shown) through which exhaust gas from the engine 1 passes. The exhaust heat recovery device 2 recovers exhaust heat by allowing cooling water to pass through and exchanging heat between the cooling water and the exhaust gas.

  In the radiator 3, the cooling water passing through the inside thereof is cooled by outside air. In this case, cooling of the cooling water in the radiator 3 is promoted by the wind introduced by the rotation of the electric fan (not shown) and the traveling wind. The flow rate variable water pump (hereinafter also referred to as “flow variable WP”) 5 includes an electric motor, and the cooling water is circulated in the cooling water passage 7 by driving the motor. . Specifically, the flow variable WP5 is supplied with electric power from a battery, and a load (or rotation speed) and the like are controlled by a control signal S5 supplied from the ECU 50.

  The thermostat 4 is configured by a valve that opens and closes according to the coolant temperature. Basically, the thermostat 4 is opened when the temperature of the coolant becomes high. In this case, the cooling water passage 7 b and the cooling water passage 7 c are connected via the thermostat 4, and the cooling water passes through the radiator 3. Thereby, a cooling water is cooled and the overheating of the engine 1 is suppressed. In contrast, when the coolant temperature is relatively low, the thermostat 4 is closed. In this case, the cooling water does not pass through the radiator 3. Thereby, since the water temperature fall of a cooling water is suppressed, the overcool of the engine 1 is suppressed.

  The water temperature sensor 6 is attached in the vicinity of the thermostat 4 in the cooling water passage 7c. The water temperature sensor 6 measures the temperature of the cooling water in the thermostat 4 and supplies a detection signal S6 corresponding to the measured cooling water temperature to the ECU 50. Since the water temperature sensor 6 is for measuring the temperature of the cooling water in the thermostat 4, the water temperature sensor 6 is located at the position shown in FIG. 1 if the water temperature is assumed to be substantially the same as the temperature of the cooling water in the thermostat 4. Needless to say, is not limited. For example, the water temperature sensor 6 may be installed at an arbitrary position on the cooling water inlet side of the engine 1, for example, the cooling water passage 7c. This is because there is no device that performs heat exchange with the cooling water on the cooling water passage 7c, and therefore, the cooling water temperature measured at an arbitrary position on the cooling water passage 7c is substantially equal to the cooling water temperature in the thermostat 4. This is because the water temperature is considered to be the same.

  The ECU (Electric Control Unit) 50 includes a CPU (Central Processing Unit) and a memory (not shown). Examples of the memory include a ROM (Read Only Memory) and a RAM (Random Access Memory). The ECU 50 controls the flow rate of the cooling water by supplying the control signal S5 to the flow variable WP5 based on the detection signal S6 supplied from the water temperature sensor 6. Below, the specific control method of flow variable WP5 is demonstrated.

(Control method for variable flow WP)
Next, a control method for the flow variable WP5 will be described. In the cooling system 100 according to the first embodiment, the ECU 50 obtains the valve opening of the thermostat 4 based on the coolant temperature, and controls the flow variable WP 5 based on the valve opening of the thermostat 4. Accordingly, the ECU 50 functions as the thermostat valve opening degree calculation means and the flow rate variable water pump control means in the present invention. The details will be described below.

  First, the ECU 50 obtains the valve opening of the thermostat based on the coolant temperature measured by the coolant temperature sensor 6. The graph shown in FIG. 2 is an example of a graph showing the relationship between the coolant temperature in the thermostat 4 and the valve opening of the thermostat 4. As can be seen from the graph shown in FIG. 2, when the temperature of the cooling water in the thermostat 4 increases, the valve opening of the thermostat 4 increases, and when the temperature of the cooling water in the thermostat 4 decreases, the valve opening of the thermostat 4 decreases. Become.

  The ECU 50 previously records the relationship between the coolant temperature in the thermostat 4 and the valve opening of the thermostat 4 in a memory as a table, as shown in the graph of FIG. Thereby, ECU50 can obtain | require the valve opening degree of the thermostat 4 using the graph of FIG. 2 based on the water temperature of a cooling water. Specifically, the ECU 50 obtains the coolant temperature of the thermostat 4 based on the detection signal S6 supplied from the coolant temperature sensor 6. Then, the ECU 50 uses a table showing the relationship between the coolant temperature in the thermostat 4 and the valve opening of the thermostat 4 as shown in the graph of FIG. 2, and the thermostat corresponding to the calculated coolant temperature. 4 is determined.

  Next, the ECU 50 controls the flow variable WP 5 based on the obtained valve opening of the thermostat 4. Specifically, the ECU 50 obtains the cooling loss of the cooling water based on the valve opening degree of the thermostat 4, and controls the flow variable WP5 based on the obtained cooling loss of the cooling water.

  The graph shown in FIG. 3 is an example of a graph showing the relationship between the valve opening of the thermostat 4 and the pressure loss of the cooling water. As can be seen from the graph shown in FIG. 3, when the valve opening of the thermostat 4 increases, the pressure loss of the cooling water decreases. This is because when the valve opening of the thermostat 4 is increased, the flow of the cooling water is not easily blocked by the valve of the thermostat 4. Moreover, if the valve opening degree of the thermostat 4 becomes small, the pressure loss of cooling water will become large. This is because when the valve opening of the thermostat 4 is reduced, the flow of the cooling water is easily blocked by the valve of the thermostat 4.

  The ECU 50 also records the relationship between the opening degree of the thermostat 4 and the pressure loss of the cooling water shown in the graph of FIG. Thereby, ECU50 can obtain | require the pressure loss of cooling water using the graph of FIG. 3 based on the valve opening degree of the thermostat 4. FIG. Specifically, the ECU 50 uses the table showing the relationship between the valve opening of the thermostat 4 and the pressure loss of the cooling water as shown in the graph of FIG. 3 to determine the valve opening of the thermostat 4 obtained previously. The pressure loss of the cooling water corresponding to is obtained.

  The ECU 50 controls the flow variable WP5 based on the calculated pressure loss of the cooling water. Specifically, the ECU 50 controls the flow variable WP5 based on the obtained cooling water pressure loss so that the flow rate of the cooling water becomes the required flow rate. This required flow rate is a flow rate of cooling water necessary for sufficiently warming up or cooling a device (for example, the engine 1 or the heater) that is warmed up or cooled by the cooling water. The ECU 50 also records the value of the required flow rate in the memory.

  Graphs 41 to 43 shown in FIG. 4 are an example of a graph showing the relationship between the required flow rate and the load (or rotational speed) of the flow variable WP5. Here, the pressure loss of the cooling water decreases in the order of the graphs 41, 42, and 43. As can be seen from the graphs 41 to 43, the load (or rotational speed) of the flow variable WP 5 that can satisfy the required flow rate increases as the pressure loss of the cooling water increases even at the same required flow rate. The smaller the pressure loss of the cooling water, the smaller the load (or rotational speed) of the variable flow WP 5 that can satisfy the required flow rate.

  The ECU 50 records the relationship between the required flow rate and the load (or rotation speed) of the flow variable WP 5 shown in graphs 41 to 43 in FIG. 4 in a memory in advance. Thus, the ECU 50 can control the flow variable WP5 so that the flow rate of the cooling water becomes the required flow rate based on the pressure loss of the cooling water. Specifically, first, the ECU 50 determines a table indicating the relationship between the required flow rate and the load (or the rotational speed) of the flow variable WP 5 corresponding to the previously determined cooling water pressure loss. For example, ECU50 determines the table which shows the graph corresponding to the pressure loss of the said cooling water from the table which shows each graph of the graphs 41-43 of FIG. Then, the ECU 50 obtains the load (or rotation speed) of the flow variable WP 5 that can satisfy the required flow rate using the determined table, and controls the flow variable WP 5 with the obtained load (or rotation speed). To do. For example, when the pressure loss of the cooling water is large, the ECU 50 obtains the load of the flow variable WP 5 corresponding to the required flow rate using the table shown in the graph 41 of FIG. 4, and controls the flow variable WP 5 with the load. .

  By doing in this way, ECU50 can adjust the flow volume of a cooling water so that a required flow volume may be satisfy | filled according to the pressure loss of the cooling water by opening and closing of the valve | bulb of the thermostat 4. FIG. Thereby, even when the valve opening degree of the thermostat 4 is small, it can suppress that the flow volume of cooling water falls, for example.

  As described above, the control device for the variable flow rate water pump according to the first embodiment includes the thermostat valve opening degree calculation means for obtaining the valve opening degree of the thermostat based on the coolant temperature of the thermostat, and the valve of the thermostat. And a variable flow rate water pump control means for controlling the variable flow rate water pump based on the opening degree. By doing in this way, the control apparatus of the variable flow rate water pump which concerns on 1st Embodiment can control the flow volume of cooling water in consideration of the influence on the flow volume of cooling water by the valve opening degree of a thermostat. .

[Second Embodiment]
FIG. 5 is a diagram showing a schematic configuration of a cooling system 100a to which a control device for a variable flow rate water pump according to a second embodiment of the present invention is applied. In FIG. 5, as in FIG. 1, the solid line arrows indicate the flow of the cooling water, and the broken line arrows indicate the input / output of signals. A solid line indicated by a bold line indicates a passage (cooling water passage) through which the cooling water flows.

  Similarly to the cooling system 100 according to the first embodiment, the cooling system 100a according to the second embodiment cools the engine 1 using the cooling water and performs heat exchange between the cooling water and the exhaust gas. This is a system that collects exhaust heat and performs the warming up of the engine 1 and the heat source of the heater.

  As shown in FIG. 5, in the cooling system 100 a according to the second embodiment, unlike the cooling system 100 according to the first embodiment, the water temperature sensor 6 is attached to the cooling water outlet of the engine 1. That is, the thermostat 4 is attached to the cooling water inlet side of the engine 1, while the water temperature sensor 6 is attached to the cooling water outlet side of the engine 1. In this case, the coolant temperature measured by the coolant temperature sensor 6 may be different from the coolant temperature in the thermostat 4. This is because in the engine 1, the cooling water releases or absorbs heat by warming up or cooling the cylinder, and the water temperature changes.

  Therefore, in the control device for the variable flow rate water pump according to the second embodiment, the ECU 50 determines the coolant temperature measured by the water temperature sensor 6 in order to obtain the valve opening of the thermostat 4, that is, the coolant of the engine 1. Based on the water temperature on the outlet side of the engine 1, the water temperature on the inlet side of the cooling water of the engine 1, that is, the water temperature of the cooling water in the thermostat 4 is obtained. The details will be described below.

  First, the ECU 50 obtains the cooling loss Qw of the engine 1 using the following equation (1) based on the engine displacement V, the engine speed Ne, and the engine output Le.

ここで、定数ｘ、ｙ、ａ、ｂ、ｃ、ｄは、エンジン１の特性によって予め決まる値である。なお、エンジン１の冷却損失を求める方法としては、式（１）を用いる方法に限られない。代わりに、例えば、エンジン回転数Ｎｅとエンジン出力Ｌｅとの関係を示すマップを用いて、エンジン１の冷却損失Ｑｗを求めるとしてもよい。

Here, the constants x, y, a, b, c, and d are values determined in advance by the characteristics of the engine 1. In addition, as a method of calculating | requiring the cooling loss of the engine 1, it is not restricted to the method of using Formula (1). Instead, for example, the cooling loss Qw of the engine 1 may be obtained using a map showing the relationship between the engine speed Ne and the engine output Le.

  Next, the ECU 50 obtains the temperature difference ΔT at the cooling water inlet / outlet of the engine 1 using the following equation (2) based on the cooling loss Qw of the engine 1 and the flow rate Vw of the cooling water. Since the coolant flow rate Vw is a value determined by the output of the flow variable WP5, the ECU 50 determines the coolant flow rate Vw based on, for example, the control signal S5 supplied to the flow variable WP5.

ここで、冷却水比熱Ｃｐ、冷却水密度ρは、冷却水の性質によって予め決まる値である。

Here, the cooling water specific heat Cp and the cooling water density ρ are predetermined values depending on the properties of the cooling water.

  Then, the ECU 50 can obtain the water temperature Tin on the cooling water inlet side of the engine 1 using the following equation (3) based on the water temperature Tout on the cooling water outlet side of the engine 1.

ＥＣＵ５０は、このようにして求められたエンジン１の冷却水の入口側の水温Ｔｉｎを、サーモスタット４における冷却水の水温として、図２に示したグラフより、サーモスタットの弁開度を求めることができる。この後、ＥＣＵ５０は、第１実施形態で述べたのと同様の方法を用いることにより、サーモスタット４の弁開度による冷却水の流量への影響を考慮した冷却水の流量の制御を行うことができる。具体的には、ＥＣＵ５０は、求められたサーモスタット４の弁開度を基に、図３に示したグラフを用いて、冷却水の圧力損失を求め、当該冷却水の圧力損失を基に、図４に示したグラフを用いて、要求流量を満たす流動可変ＷＰ５の負荷を求め、当該負荷で流動可変ＷＰ５の制御を行う。

The ECU 50 can determine the valve opening degree of the thermostat from the graph shown in FIG. 2 using the water temperature Tin on the inlet side of the cooling water of the engine 1 thus determined as the water temperature of the cooling water in the thermostat 4. . Thereafter, the ECU 50 can control the flow rate of the cooling water in consideration of the influence of the valve opening of the thermostat 4 on the flow rate of the cooling water by using the same method as described in the first embodiment. it can. Specifically, the ECU 50 determines the pressure loss of the cooling water using the graph shown in FIG. 3 based on the obtained valve opening of the thermostat 4, and based on the pressure loss of the cooling water, 4 is used to determine the load of the flow variable WP 5 that satisfies the required flow rate, and the flow variable WP 5 is controlled with the load.

  As described above, in the control device for the variable flow rate water pump according to the second embodiment, the thermostat is attached to the cooling water inlet side of the engine and the water temperature sensor is attached to the cooling water outlet side of the engine. Also, based on the cooling water temperature at the cooling water outlet side of the engine, the cooling water flow rate, and the cooling loss of the engine, the water temperature at the cooling water inlet side of the engine, that is, the cooling water temperature at the thermostat is calculated. Can be sought. Therefore, the control device for the variable flow rate water pump according to the second embodiment obtains the opening degree of the thermostat based on the coolant temperature in the thermostat, similarly to the control device for the variable flow rate water pump according to the first embodiment. The flow rate variable water pump can be controlled based on the obtained opening degree of the thermostat. That is, the control device for the variable flow rate water pump according to the second embodiment can adjust the flow rate of the cooling water so as to satisfy the required flow rate, similarly to the control device for the variable flow rate water pump according to the first embodiment.

  Next, a control method of the flow variable WP 5 according to the second embodiment will be described using the flowchart of FIG. FIG. 6 is a flowchart showing a control process of the flow variable WP 5 according to the second embodiment.

  In step S101, the water temperature sensor 6 measures the water temperature on the outlet side of the cooling water of the engine 1 and supplies the ECU 50 with a detection signal S6 corresponding to the measured water temperature. The ECU 50 obtains the water temperature Tout on the outlet side of the cooling water of the engine 1 based on the detection signal S6.

  In steps S <b> 102 to S <b> 104, the ECU 50 obtains a water temperature Tin on the inlet side of the cooling water of the engine 1. That is, as described above, first, the ECU 50 obtains the cooling loss Qw of the engine 1 using the equation (1) based on the engine displacement V, the engine speed Ne, and the engine output Le ( Step S102). Next, the ECU 50 obtains the temperature difference ΔT at the inlet / outlet of the cooling water of the engine 1 using the equation (2) based on the cooling loss Qw of the engine 1 and the flow rate Vw of the cooling water (step S103). Then, the ECU 50 uses the equation (3) based on the water temperature Tout on the cooling water outlet side of the engine 1 and the temperature difference ΔT on the cooling water inlet / outlet of the engine 1 to calculate the water temperature on the cooling water inlet side of the engine 1. Tin is obtained (step S104).

  That is, through the process from step S101 to step S104, the ECU 50 causes the cooling water of the engine 1 to be cooled based on the water temperature Tout on the outlet side of the cooling water of the engine 1, the cooling loss Qw of the engine 1, and the flow rate Vw of the cooling water. The water temperature Tin on the inlet side can be obtained. Thus, even when the water temperature sensor 6 is attached to the cooling water outlet side of the engine 1 and the thermostat 4 is attached to the cooling water inlet side of the engine 1, the ECU 50 causes the water temperature of the cooling water in the thermostat 4 to be Can be requested.

  Steps S105 to S107 described below are the same as the control process of the flow variable WP5 according to the first embodiment.

  In step S105, the ECU 50 creates a table showing the relationship between the coolant temperature in the thermostat 4 and the valve opening of the thermostat 4 shown in the graph of FIG. 2 based on the obtained coolant temperature in the thermostat 4. Using this, the valve opening of the thermostat 4 is obtained. Thereby, ECU50 can obtain | require the valve opening degree of the thermostat 4 corresponding to the coolant temperature.

  In step S106, the ECU 50 uses the table showing the relationship between the valve opening of the thermostat 4 and the pressure loss of the cooling water shown in the graph of FIG. 3 based on the obtained valve opening of the thermostat 4. Obtain the cooling water pressure loss. As a result, the ECU 50 can determine the pressure loss of the cooling water due to the opening and closing of the valve of the thermostat 4.

  In step S107, the ECU 50 shows the relationship between the required flow rate and the load (or the rotational speed) of the flow variable WP 5 corresponding to each of the plurality of cooling water pressure losses shown in the graphs 41 to 43 of FIG. From this, a table corresponding to the calculated pressure loss of the cooling water is determined. And ECU50 calculates | requires the load (or rotation speed) of flow variable WP5 corresponding to a request | required flow volume using the determined table, and controls flow variable WP5 with the said load (or rotation speed). Thereby, ECU50 can adjust the flow volume of a cooling water so that a required flow volume may be satisfy | filled according to the pressure loss of the cooling water by opening and closing of the valve | bulb of the thermostat 4. FIG.

[Third Embodiment]
Next, a control device for a variable flow rate water pump according to a third embodiment will be described. As described in the above embodiments, the valve opening of the thermostat 4 changes according to the coolant temperature in the thermostat 4. However, the valve opening of the thermostat 4 does not change immediately in response to a change in the temperature of the cooling water, but a certain response time (approximately 20 minutes) to reach an opening corresponding to the water temperature after the change of the cooling water. Seconds).

  The graph shown in FIG. 7 is a graph showing how the valve opening of the thermostat 4 changes with time when the coolant temperature changes. Specifically, the graph shown in FIG. 7 is a graph showing how the valve opening of the thermostat 4 increases with time when the coolant temperature rises. As can be seen from the graph shown in FIG. 7, the valve opening of the thermostat 4 is a function of a first-order lag system with respect to the passage of time, and after a sufficient amount of time has elapsed, that is, after the response time has elapsed. , Become a certain size.

  Therefore, in the control device for the variable flow rate water pump according to the third embodiment, the ECU 50 determines the valve opening degree of the thermostat 4 based on the coolant temperature in the thermostat 4 (in the flowchart of FIG. 6, In step S105), the response time of the valve opening of the thermostat 4 is also taken into consideration. Specifically, the ECU 50 obtains the valve opening of the thermostat 4 as a function of time using the relationship of the graph shown in FIG. The value of the function of the valve opening of the thermostat 4 is a function that becomes the value of the valve opening of the thermostat 4 obtained using the graph of FIG. 2 at the time when the response time has elapsed.

  The ECU 50 determines the valve opening degree of the thermostat 4 corresponding to the time when the predetermined time has passed, based on the function of the valve opening degree of the thermostat 4 every time the predetermined time has elapsed since the coolant temperature has changed. Based on the obtained valve opening of the thermostat 4, the pressure loss of the cooling water is obtained, and the load of the flow variable WP 5 corresponding to the required flow rate is obtained.

  As described above, the control device for the variable flow rate water pump according to the third embodiment determines the valve opening of the thermostat based on the response time of the valve opening of the thermostat with respect to the change in the coolant temperature in the thermostat. Ask. Thereby, the control apparatus of the flow variable water pump which concerns on 3rd Embodiment can adjust the flow volume of cooling water so that a required flow volume may be satisfy | filled according to the opening degree at the time of the opening and closing of the valve of a thermostat.

  In the above-described example, the example in which the valve opening of the thermostat 4 is obtained based on the response time of the valve opening of the thermostat 4 with respect to the change in the coolant temperature is shown. Not limited to this. In addition to this, the response time of the flow variable WP5 and the response time of the temperature difference ΔT of the cooling water inlet / outlet of the engine 1 when the flow rate of the cooling water changes may be taken into consideration.

  As an example of taking into account the response time of the flow variable WP5, for example, the ECU 50 can determine the control timing of the flow variable WP5 based on the response time of the flow variable WP5 (about 0.5 seconds). . Thereby, the ECU 50 can adjust the flow rate of the cooling water so as to satisfy the required flow rate more accurately. Further, as an example of taking into account the response time of the temperature difference ΔT at the cooling water inlet / outlet of the engine 1, for example, the ECU 50 determines the temperature difference ΔT of the cooling water inlet / outlet of the engine 1 when the flow rate of the cooling water changes. Based on the response time (about 2 seconds), the water temperature Tin on the inlet side of the cooling water of the engine 1 can be obtained as a function of time. Thereby, ECU50 can calculate | require the opening degree at the time of the transition which the valve of the thermostat 4 opens and closes more correctly.

[Fourth Embodiment]
Next, a control device for a variable flow rate water pump according to a fourth embodiment of the present invention will be described. In each of the embodiments described above, the ECU 50 determines the pressure loss of the cooling water based on the valve opening of the thermostat 4, but the method of determining the pressure loss of the cooling water is not limited to this. Instead of based on the valve opening of the thermostat 4, the ECU 50 determines, for example, the relationship between the load commanded to the flow variable WP5 and the power consumption of the flow variable WP5 based on the operating state of the flow variable WP5. Using a map or the like based on one of the relationship between the load to be instructed and the rotational speed of the variable flow WP5 and the relationship between the rotational speed instructed to the variable flow WP5 and the power consumption of the variable flow WP5 The pressure loss of the cooling water can also be obtained. The ECU 50 obtains the load of the flow variable WP5 corresponding to the required flow rate, for example, using the graph shown in FIG. 5 based on the pressure loss of the cooling water thus obtained, and the flow variable WP5 based on the load. Even if this is controlled, the flow rate of the cooling water can be adjusted so as to satisfy the required flow rate.

  The pressure loss of the cooling water based on the operating state of the flow variable WP 5 is not obtained based on the valve opening of the thermostat 4. Therefore, in the control device for the variable flow rate water pump according to the fourth embodiment, the ECU 50 is based on the pressure loss of the cooling water based on the operation state of the variable flow WP5 and the water temperature of the cooling water in the thermostat 4. The operation of the thermostat 4 will be confirmed. Therefore, the ECU 50 also functions as a thermostat operation confirmation unit in the present invention. In the following example, it is assumed that the water temperature sensor 6 is attached in the vicinity of the thermostat 4 for explanation.

  A method for confirming the operation of the thermostat 4 will be specifically described. The ECU 50 estimates the valve opening of the thermostat 4 from the graph shown in FIG. 2 on the basis of the coolant temperature in the thermostat 4 measured by the water temperature sensor 6, and based on the estimated valve opening of the thermostat 4. Then, the pressure loss of the cooling water is obtained from the graph shown in FIG. Thus, the pressure loss of the cooling water based on the estimated valve opening of the thermostat 4 is obtained. Then, the ECU 50 compares the pressure loss of the cooling water based on the operating state of the variable flow WP5 with the pressure loss of the cooling water based on the estimated valve opening of the thermostat 4. For example, although the pressure loss of the cooling water based on the estimated valve opening of the thermostat 4 is a pressure loss that is considered that the valve opening of the thermostat 4 is sufficiently open. When the pressure loss of the cooling water based on the operation state of the variable flow WP5 is the pressure loss when the valve opening of the thermostat 4 is closed, the ECU 50 causes the thermostat 4 to malfunction. Thus, it can be determined that the valve does not open even when the temperature of the cooling water is high. In this way, the ECU 50 can confirm whether or not the thermostat 4 is operating normally, and can improve the accuracy of the diagnosis of the thermostat 4.

  Further, the ECU 50 can confirm the operation of the water temperature sensor 6 based on the pressure loss of the cooling water based on the operation state of the flow variable WP 5 and the water temperature of the cooling water in the thermostat 4. Therefore, the ECU 50 also functions as a water temperature sensor operation confirmation unit. Below, the method to confirm operation | movement of the water temperature sensor 6 is described concretely.

  The ECU 50 obtains the valve opening of the thermostat 4 from the graph shown in FIG. 3 based on the pressure loss of the cooling water based on the operation state of the variable flow WP5, and based on the obtained valve opening of the thermostat 4. Next, the coolant temperature in the thermostat 4 is obtained from the graph shown in FIG. The ECU 50 compares the temperature of the cooling water based on the pressure loss of the cooling water with the temperature of the cooling water measured by the water temperature sensor 6 to determine whether the water temperature sensor 6 is operating normally. Can be determined. For example, according to the temperature of the cooling water based on the pressure loss of the cooling water, the temperature of the cooling water measured by the water temperature sensor 6 is the same even though the water temperature is sufficiently high to open the thermostat 4. When it is low, the ECU 50 can determine that the water temperature sensor 6 has failed. In this way, the ECU 50 can confirm whether or not the water temperature sensor 6 is operating normally, and can improve the accuracy of the diagnosis of the water temperature sensor 6.

[Fifth Embodiment]
Next, a control device for a variable flow rate water pump according to a fifth embodiment of the present invention will be described. Since the cooling water generally has a chemical substance such as ethylene glycol, the viscosity increases as the water temperature decreases, and the viscosity decreases as the water temperature increases.

  The cooling water specific heat Cp described in the second embodiment varies depending on the proportion of the chemical substance such as ethylene glycol in the cooling water, the so-called LLC concentration. Specifically, when the LLC concentration increases, the cooling water specific heat Cp decreases, and when the LLC concentration decreases, the cooling water specific heat Cp increases. Therefore, in the control device for the variable flow rate water pump according to the fifth embodiment, the ECU 50 includes the pressure loss of the cooling water based on the operation state of the variable flow WP5, the cooling water temperature measured by the water temperature sensor 6, and Based on the above, the LLC concentration is determined using a map or the like. The ECU 50 changes the cooling water specific heat Cp based on the obtained LLC concentration. By doing in this way, ECU50 can improve the precision of the cooling water specific heat Cp, and can improve the calculation precision of the cooling loss Qw of the engine 1. FIG.

It is a figure which shows schematic structure of the cooling system which concerns on 1st Embodiment. It is a graph which shows the relationship between the water temperature of a cooling water, and the valve opening degree of a thermostat. It is a graph which shows the valve opening degree of a thermostat, and the relationship between the pressure loss of cooling water. It is a graph which shows the relationship between a request | requirement flow volume and the load (or rotation speed) of flow variable WP. It is a figure which shows schematic structure of the cooling system which concerns on 2nd Embodiment. It is a flowchart which shows the control processing of the flow variable WP which concerns on 2nd Embodiment. It is a graph which shows the mode of the change of the valve opening degree of the thermostat 4 with respect to time.

Explanation of symbols

1 engine (internal combustion engine)
2 Exhaust heat recovery device 3 Radiator 4 Thermostat 5 Flow variable WP
6 Water temperature sensor 7 Cooling water passage 50 ECU
100, 100a Cooling system

Claims (6)

A control device for a flow rate variable water pump that circulates cooling water in an engine through a thermostat,
Thermostat valve opening calculation means for determining the valve opening of the thermostat based on the temperature of the cooling water in the thermostat;
A variable flow rate water pump control device comprising: a variable flow rate water pump control means for controlling the variable flow rate water pump based on a valve opening of the thermostat.   When the thermostat is provided on an inlet side of the cooling water of the engine, the thermostat valve opening degree calculation means is configured such that the cooling water temperature on the cooling water outlet side of the engine, and the cooling water 2. The control device for a variable flow rate water pump according to claim 1, wherein a temperature of the cooling water in the thermostat is obtained based on a flow rate and a cooling loss of the engine.   3. The control device for a variable flow rate water pump according to claim 1, wherein the thermostat valve opening degree calculation means obtains the valve opening degree of the thermostat based on a response time of the valve opening degree of the thermostat. . Pressure loss calculating means for determining a pressure loss of the cooling water based on an operating state of the flow rate variable water pump;
The thermostat operation confirmation means for confirming the operation of the thermostat based on the pressure loss of the cooling water and the water temperature of the cooling water in the thermostat. The control device of the variable flow rate water pump according to one item. A water temperature sensor for measuring the temperature of the cooling water;
Pressure loss calculating means for determining a pressure loss of the cooling water based on an operating state of the flow rate variable water pump;
The water temperature sensor operation confirmation means for confirming the operation of the water temperature sensor based on the pressure loss of the cooling water and the water temperature of the cooling water measured by the water temperature sensor. The control apparatus of the flow variable water pump as described in any one of 1-4. Pressure loss calculating means for determining a pressure loss of the cooling water based on an operating state of the flow rate variable water pump;
The cooling water specific heat calculating means for calculating a specific heat of the cooling water based on a pressure loss of the cooling water and a water temperature of the cooling water is provided. The control apparatus of the flow variable water pump as described in an item | term.

Images