Abstract:
A cooler apparatus includes: a coolant passageway; a water pump that circulates coolant in the coolant passageway; a thermostat that includes a heater that heats a temperature sensitive portion; and a controller. The controller is configured to drive the water pump and cause electric current to flow through the heater at a first energization amount when an operation in which the coolant is injected into the coolant passageway is started. The controller is also configured to stop electric current to flow through the heater if the water pump races when the electric current flows through the heater at the first energization amount.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a cooler apparatus and a control method for the cooler apparatus. 
     2. Description of Related Art 
     There have been known cooler apparatuses equipped with a coolant passageway, and a water pump and a thermostat that are provided on the coolant passageway (see, e.g., Japanese Patent Application Publication No. 2009-185744 (JP 2009-185744 A)). This thermostat has a heater that heats a temperature sensitive portion, and is capable of forcing its valve to open, irrespective of the temperature of the coolant. 
     A cooler apparatus of Japanese Patent Application Publication No. 2009-185744 (JP 2009-185744 A) is constructed so that when a coolant injection start signal is input, electric current is caused to flow through the heater of the thermostat so that the thermostat is forced to open its valve so as to drain air from the coolant passageway. 
     However, as for the related-art cooler apparatus disclosed in Japanese Patent Application Publication No. 2009-185744 (JP 2009-185744 A), there is possibility that if a worker&#39;s operation of injecting coolant is interrupted, energization of the heater may be continued with the thermostat not supplied with coolant. In such a case, it is conceivable that the thermostat will be excessively heated and therefore the thermostat will fail. 
     SUMMARY OF THE INVENTION 
     The invention provides a cooler apparatus that restrains a thermostat from failing, and a control method for the cooler apparatus. 
     A cooler apparatus in a first aspect of the invention includes: a coolant passageway; a water pump that circulates coolant in the coolant passageway; a thermostat that includes a heater that heats a temperature sensitive portion; and a controller configured to drive the water pump and cause electric current to flow through the heater at a first energization amount when an operation in which the coolant is injected into the coolant passageway is started, the controller being configured to stop the electric current to flow through the heater if the water pump races when the electric current flows through the heater at the first energization amount. 
     Due to the foregoing aspect, in the case where the operation in which the coolant is injected into the coolant passage by a worker is interrupted and therefore the thermostat is not supplied with the coolant, electric current is stopped from flowing through the heater, so that excessive heating of the thermostat can be restrained. Therefore, the thermostat can be restrained from failing. 
     In the foregoing aspect, the controller may output a warning indicating that the coolant in the coolant passageway is insufficient in amount, if the water pump races when the electric current flows through the heater at the first energization amount. 
     Due to the foregoing construction, insufficiency of the coolant in amount can be notified to workers. 
     In the foregoing aspect, the controller may cause the electric current to flow through the heater at a second energization amount that is greater than the first energization amount, if the water pump is not racing when electric current flows through the heater at the first energization amount. 
     Due to the foregoing construction, air can be drained from the coolant passageway if a worker&#39;s operation of injecting the coolant into the coolant passageway is appropriately performed. 
     According to the cooler apparatus in the aspect of the invention, the thermostat can be restrained from failing. In the foregoing aspect, the controller may be configured to stop the electric current to flow through the heater in a case that the water pump races after elapse of a predetermined time from a time when electric current starts to flow through the heater at the first energization amount. In the forgoing aspect, the cooler apparatus may further include a radiator provided on the coolant passageway, and may be constructed so that the predetermined time is a time that is required in order for the coolant passageway to be filled with the coolant when the coolant is injected into the passageway via a filling port of the radiator while water pump is being driven. In the foregoing aspect, the cooler apparatus may further include a maintenance-purpose tool configured to input a signal to the controller, the signal indicating that the operation in which the coolant is injected into the coolant passageway has started, and may be constructed so that when the signal is input to the controller from the maintenance-purpose tool, the controller determines that the operation in which the coolant is injected into the coolant passageway has started. In the foregoing aspect, the cooler apparatus may further include a sensor configured to detect rotation speed of the water pump, and may be constructed so that the controller determines that the water pump is racing, if the rotation speed detected by the sensor is higher than a target rotation speed of the water pump. 
     Furthermore, a second aspect of the invention is a control method for a cooler apparatus that includes a coolant passageway, a water pump configured to circulate coolant in the coolant passageway, and a thermostat having a heater that heats a temperature sensitive portion. The control method includes: driving the water pump and causing electric current to flow through the heater at a first energization amount when an operation in which the coolant is injected into the coolant passageway is started; and stopping the electric current to flow through the heater if the water pump races when the electric current flows through the heater at the first energization amount. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein: 
         FIG. 1  is a circuit diagram showing a cooler apparatus according to an embodiment of the invention; 
         FIG. 2  is a block diagram showing an electrical construction of the cooler apparatus shown in  FIG. 1 ; 
         FIG. 3  is a diagram for describing a coolant circulating action performed during a cold state by a cooler apparatus according to an embodiment of the invention; 
         FIG. 4  is a diagram for describing a coolant circulating action performed during a completely warmed-up state by a cooler apparatus according to an embodiment of the invention; and 
         FIG. 5  is a flowchart for describing an action performed by a cooler apparatus according to an embodiment of the invention at the time of an operation of injecting coolant. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Embodiments of the invention will be described hereinafter with reference to the drawings. 
     Firstly, with reference to  FIGS. 1 and 2 , a construction of a cooler apparatus  100  according to an embodiment of the invention will be described. 
     As shown in  FIG. 1 , the cooler apparatus  100  includes a coolant passageway  1 , an electric water pump  2  that circulates coolant in the coolant passageway  1 , a radiator  3  that cools the coolant that circulates in the coolant passageway  1 , and a thermostat  4  and a heater core  5  that are disposed on a path of the coolant passageway  1 . This cooler apparatus  100  is constructed so as to cool an engine (internal combustion engine)  150  by the coolant that circulates in the coolant passageway  1 . 
     The engine  150  is a gasoline engine or a diesel engine mounted in a vehicle. The engine  150  includes a cylinder head  151  and a cylinder block  152 . Within the cylinder head  151  there is formed a head-side water jacket (intra-head coolant passageway)  151   a  for cooling the cylinder head  151 . Within the block  152  there is formed a block-side water jacket (intra-block coolant passageway)  152   a  for cooling the cylinder block  152 . Incidentally, in the engine  150  according to the embodiment, the head-side water jacket  151   a  and the block-side water jacket  152   a  communicate with each other. 
     The coolant passageway  1  includes a passageway  11  that connects the electric water pump  2  and the engine  150 , a passageway  12  that connects the engine  150  and the radiator  3 , a passageway  13  that connects the radiator  3  and the thermostat  4 , and a passageway  14  that connects the thermostat  4  and the electric water pump  2 . The coolant passageway  1  further includes a passageway  15  that connects the engine  150  and the heater core  5 , and a passageway  16  that connects the heater core  5  and the thermostat  4 . 
     Concretely, the passageway  11  connects a discharge port of the electric water pump  2  and an inlet opening of the engine  150  (the block-side water jacket  152   a ). The passageway  12  connects an outlet opening of the engine  150  (the head-side water jacket  151   a ) and an upper tank  32  of the radiator  3 . The passageway  13  connects a lower tank  31  of the radiator  3  and one of two inlet openings of the thermostat  4 . The passageway  14  connects an outlet opening of the thermostat  4  and a suction port of the electric water pump  2 . The passageway  15  connects the outlet opening of the engine  150  (the head-side water jacket  151   a ) and an inlet opening of the heater core  5 . The passageway  16  connects an outlet opening of the heater core  5  and the other one of the two inlet openings of the thermostat  4 . 
     The electric water pump  2  has a function of producing streams for circulating the coolant. The electric water pump  2  has an electric motor (not shown) that is driven by electric power from a battery (not shown). By controlling the rotation speed of the electric motor, the discharge flow rate (ejection pressure) can be variably set. Incidentally, the electric water pump  2  is controlled by an ECU  6  (see  FIG. 2 ) so that the discharge flow rate is controlled according to the state of operation of the engine  150  and the like. 
     The radiator  3  is, for example, of a down-flow type, and includes the lower tank  31 , the upper tank  32 , and a radiator core  33  disposed between the lower tank  31  and the upper tank  32 . The radiator  3  is constructed so as to release heat from the coolant to the outside through heat exchange between the coolant and the outside air when the coolant recovered in the upper tank  32  flows down toward the lower tank through an interior of the radiator core  33 . 
     Furthermore, a radiator cap  34  is detachably attached to the upper tank  32  of the radiator  3 . The radiator cap  34  has a function of keeping the internal pressure of the coolant passageway  1  at or above the atmospheric pressure and thus heightening the boiling point of the coolant so that the efficiency of heat exchange in the radiator core  33  is increased. Incidentally, the radiator cap  34  is removed from the upper tank  32  when the coolant is injected into the coolant passageway  1  (when the coolant is replaced). On this occasion, a filling port (not shown) of the radiator  3  is made open, so that the coolant passageway  1  communicates with the atmosphere. 
     The thermostat  4  is a valve device that is actuated by, for example, expansion and contraction of a thermo wax (a temperature sensitive portion). This thermostat  4  has a heater  41  (see  FIG. 2 ) that is embedded within the thermo wax. The temperature of the wax can be controlled by the heat produced by energization of the heater  41 . That is, as for the thermostat  4 , the valve opening temperature (the valve of the coolant at which the thermostat  4  opens) can be controlled by controlling the current that is passed through the heater  41 . Incidentally, the current passed through the heater  41  is controlled by the ECU  6 . 
     The thermostat  4  is constructed so that when the temperature of the coolant is low, the valve is closed to shut off the passageway between the lower tank  31  of the radiator  3  and the electric water pump  2 . Furthermore, the thermostat  4  is constructed so that when the coolant temperature is high, the valve is opened to provide communication between the lower tank  31  of the radiator  3  and the electric water pump  2 . 
     The heater core  5  is provided for the purpose of heating a cabin of the vehicle by utilizing heat of the coolant, and is disposed so as to face a blower duct of an air-conditioner. That is, when the cabin is heated (when the heater is on), air-conditioned wind flowing in the blower duct passes by the heater core  5 , and is thereby turned into warm wind before it is supplied into the cabin. On other occasions (e.g., at the time of cooling the cabin) (i.e., when the heater is off), the air-conditioned wind bypasses the heater core  5 . 
     Furthermore, the cooler apparatus  100  includes the ECU  6  that controls the cooler apparatus  100 , as shown in  FIG. 2 . This ECU  6  includes a CPU  61 , a ROM  62 , a RAM  63 , a backup RAM  64 , and an input/output interface  65 . 
     The CPU  61  has a function of executing computation processes on the basis of various control programs and maps that are stored in the ROM  62 . The ROM  62  stores various control programs, maps that are referred to at the time of execution of the control programs, etc. The RAM  63  is a memory for temporarily storing results of computation performed by the CPU  61 , detection results provided by various sensors, etc. The backup RAM  64  is a non-volatile memory for storing data or the like that need to be stored when the engine  150  is stopped. 
     The input/output interface  65  is connected to a water temperature sensor  71  that detects the temperature of the coolant, a water pump rotation speed sensor  72  that detects the rotation speed of the electric water pump  2 , etc. Detection results provided by the various sensors are input to the input/output interface  65 . The water temperature sensor  71  is disposed near the outlet opening of the engine  150  (the head-side water jacket  151   a ). The water pump rotation speed sensor  72  is disposed near a rotating shaft of the electric water pump  2 . 
     Furthermore, the heater  41  of the thermostat  4 , the electric water pump  2 , etc. are also connected to the input/output interface  65 . The ECU  6  is constructed so as to control the valve opening temperature of the thermostat  4  by controlling the energization amount (duty ratio) of the heater  41 . Furthermore, the ECU  6  is constructed so as to, control the electric water pump  2  according to the state of operation of the engine  150 , and the like. 
     Still further, a meter device  160  that displays various kinds of information is connected to the input/output interface  65 . Furthermore, a maintenance-purpose tool  170  for reading out information regarding failures of the vehicle, etc., is detachably connected to the input/output interface  65 . The maintenance-purpose tool  170  is constructed so as to output to the ECU  6  a signal indicating that an operation in which the coolant is injected into the coolant passageway  1  has started. 
     It is recommended that the coolant in the coolant passageway be periodically replaced. After replacement of the coolant in the coolant passageway  1 , it is necessary to drain air from the coolant passageway  1 . Therefore, after an action of circulating the coolant in the coolant passageway  1  at an ordinary time is described, an action performed at the time of the operation in which the coolant is injected into the coolant passageway  1  will be described in detail. Incidentally, the discharging of the coolant from the coolant passageway  1  is carried out by a worker removing a drain bolt (not shown) provided on a lower portion of the radiator and also removing the radiator cap  34 . At this time, a drain bolt (not shown) provided on the cylinder block  152  of the engine  150  may also be removed. Furthermore, injection of the coolant into the coolant passageway  1  is carried out via the filling port that is opened by removing the radiator cap  34 . 
     Coolant Circulating Action 
     Next, with reference to  FIGS. 3 and 4 , a coolant circulating action in the cooler apparatus  100  according to an embodiment of the invention will be described. 
     [ACTION DURING COLD STATE (DURING WARM-UP)] Firstly, immediately after the engine  150  is started, the temperature of the coolant is low, so that the thermostat  4  is in the closed valve state, as shown in  FIG. 3 . 
     Then, as the electric water pump  2  is driven, the coolant is caused to flow through the electric water pump  2 , the passageway  11 , the block-side water jacket  152   a , the head-side water jacket  151   a , the passageway  15 , the heater core  5 , the passageway  16 , the thermostat  4 , the passageway  14  and the electric water pump  2  in this order. 
     Therefore, since the circulating coolant bypasses the radiator  3 , the coolant is not cooled by the radiator  3 , so that the warm-up of the engine  150  is completed accordingly earlier. 
     [ACTION DURING COMPLETELY WARMED-UP STATE (AFTER WARM-UP IS COMPLETED)] Then, as the temperature of the coolant increases, the thermostat  4  opens its valve as shown in  FIG. 4 . 
     Since the electric water pump  2  is driven, the coolant is caused flow through the electric water pump  2 , the passageway  11 , the block-side water jacket  152   a , the head-side water jacket  151   a , the passageway  12 , the radiator  3 , the passageway  13 , the thermostat  4 , the passageway  14  and the electric water pump  2  in this order, in addition to the aforementioned path. That is, the coolant having flown out of the head-side water jacket  151   a  branches toward the radiator  3 , and the coolant having passed through the radiator  3  merges, at the thermostat  4 , with the coolant from the heater core  5 . 
     Therefore, part of the coolant flows through the radiator  3 , so that heat of the coolant is released to the external air. 
     Action Performed at the Time of Operation of Injecting Coolant 
     Next, the action performed at the time of the operation of injecting the coolant in the cooler apparatus  100   b  will be described with reference to  FIG. 5 . Incidentally, the steps described below are executed by the ECU  6  (see  FIG. 2 ). 
     Firstly, in step S 1  in  FIG. 5 , it is determined whether the operation in which the coolant is injected into the coolant passageway  1  (see  FIG. 1 ) has started. Incidentally, whether the operation in which the coolant is injected into the coolant passageway  1  has started is determined on the basis of, for example, a signal input from the maintenance-purpose tool  170  (see  FIG. 2 ). Concretely, if a signal indicating that the operation in which the coolant is injected has started is input from the maintenance-purpose tool  170 , it is determined that the operation in which the coolant is injected into the coolant passageway  1  has started. Then, if it is determined that the operation in which the coolant is injected has started, the process proceeds to step S 2 . On the other hand, if it is determined that the operation in which the coolant is injected has not started, step S 1  is repeated. 
     Next, in step S 2 , the electric water pump  2  (see  FIG. 2 ) is driven. Incidentally, the driving of the electric water pump  2  is performed, irrespective of the state of operation of the engine  150 . 
     Then, in step S 3 , it is determined whether the electric water pump  2  is racing. Incidentally, in this determination, it is determined that the electric water pump  2  is racing, for example, in the case where an actual rotation speed of the electric water pump  2  detected by the water pump rotation speed sensor  72  (see  FIG. 2 ) is higher than a target rotation speed of the electric water pump  2  output from the ECU  6 . Then, if it is determined that the electric water pump  2  is racing, it is considered that the coolant present in the coolant passageway  1  is insufficient in amount. Then, the process proceeds to step S 4 . On the other hand, if it is determined that the electric water pump  2  is not racing, it is considered that the coolant passageway  1  is filled with the coolant, and then the process proceeds to step S 9 . 
     Next, in step S 4 , the heater  41  (see  FIG. 2 ) of the thermostat  4  is energized at a first energization amount. Due to this, the thermostat  4  is forced to open, irrespective of the temperature of the coolant and the like. Incidentally, at this time, the thermostat  4  is opened to a first degree of opening. Furthermore, the first energization amount is a pre-set value that is smaller than a second energization amount mentioned below, and the first degree of opening is such a degree of opening that, for example, in the case where the coolant is being injected into the radiator  3 , the injected coolant can be supplied to the electric water pump  2 . 
     Next, in step S 5 , it is determined whether a predetermined time has elapsed. Incidentally, the predetermined time is a pre-set time, for example, a time that is required in order to fill the coolant passageway  1  with the coolant in the case where the coolant is injected via the filling port of the radiator  3  while the electric water pump  2  is being driven. Then, if it is determined that the predetermined time has not elapsed, step  5  is repeated. That is, the ECU  6  waits until the predetermined time elapses. Then, when it is determined that the predetermined time has elapsed, the process proceeds to step S 6 . 
     Next, in step S 6 , it is determined whether the electric water pump  2  is racing. This determination is performed in the same manner as in step S 3 . Then, if it is determined that the electric water pump  2  is racing, it is considered that the coolant present in the coolant passageway  1  is insufficient in amount. Then, the process proceeds to step S 7 . On the other hand, if it is determined that the electric water pump  2  is not racing, it is considered that the coolant passageway  1  is filled with the coolant, and the process proceeds to step S 9 . 
     Next, in step S 7 , the energization of the heater  41  of the thermostat  4  is stopped, and the driving of the electric water pump  2  is stopped. Then, in step S 8 , the meter device  160  (see  FIG. 2 ) is caused to display a warning indicating that the coolant in the coolant passageway  1  is insufficient in amount. After that, the action performed at the time of the operation in which the coolant is injected is ended. 
     Firstly, if the electric water pump  2  is not racing (No in step S 3  or NO in step S 6 ), the heater  41  of the thermostat  4  is energized at a second energization amount in step S 9 . Therefore, the thermostat  4  is forced to open its valve, irrespective of the temperature of the coolant and the like. Incidentally, at this time, the thermostat  4  is opened to a second degree of opening. The second energization amount is a pre-set value that is greater than the first energization amount, and the second degree of opening is a degree of opening at which the thermostat  4  is completely open (fully open). 
     Then, in step S 10 , a control of draining air from the coolant passageway  1  during a state in which the thermostat  4  is open at the second degree of opening is executed. Incidentally, this air-draining control is performed by, for example, increasing or decreasing the discharge flow rate of the electric water pump  2 . Concretely, the air-draining control is performed as follows. That is, air residing at locations where flow is relatively easy is caused to flow by driving the electric water pump  2  at a first discharge flow rate, and then air residing at locations where flow is less easy is caused to flow by driving the electric water pump  2  at a second discharge flow rate that is greater than the first discharge flow rate. After that, the action performed at the time of the operation in which the coolant is injected is ended. 
     Effects 
     In this embodiment, the heater  41  is energized at the first energization amount and, if the electric water pump  2  is racing after the predetermined time has elapsed, the energization of the heater  41  is stopped. Therefore, in the case where the coolant is not being supplied to the thermostat  4  due to interruption of the worker&#39;s operation of injecting the coolant, the energization of the heater  41  is stopped, so that excessive heating of the thermostat  4  can be restrained. Therefore, the thermostat  4  can be restrained from failing. 
     Furthermore, in the embodiment, if the heater  41  is energized at the first energization amount and then the electric water pump  2  is racing after the predetermined time elapses, the warning indicating that the coolant in the coolant passageway  1  is insufficient in amount is displayed on the meter device  160 , so that the insufficiency of the coolant in amount in the coolant passageway can be notified to a worker. 
     Furthermore, in the embodiment, if the heater  41  is energized at the first energization amount and then the electric water pump  2  is not racing after the predetermined time elapses, the control of draining air from the coolant passageway  1  by energizing the heater  41  at the second energization amount is performed. Therefore, in the case where the operation in which the coolant is injected by the worker is appropriately performed, air in the coolant passageway  1  can be drained. 
     Furthermore, in the embodiment, before the heater  41  is energized at the first energization amount, it is determined whether the electric water pump  2  is racing. If the electric water pump  2  is not racing, the control of draining air by energizing the heater  41  at the second energization amount. Therefore, in the case where the coolant passageway  1  is filled with the coolant, the control of draining air can be carried out early. 
     Other Embodiments 
     The embodiments disclosed herein are illustrative in all respects, and do not serve as a basis for limitative interpretation. Therefore, the technical scope of the invention is not to be interpreted only by the forgoing embodiments, but is defined on the basis of what is described in the claims for patent. Furthermore, the technical scope of the invention includes all modifications and alterations within the meaning and scope equivalent to the claims. 
     For example, in the foregoing embodiment, the cooler apparatus  100  equipped with the heater core  5  is shown. However, the invention is not limited to this construction. The invention may also be applied to cooler apparatuses equipped with other heat exchangers, such as EGR coolers and the like. 
     Furthermore, in the embodiment, the cooler apparatus  100  is provided with only one thermostat  4 . However, this is not restrictive. The cooler apparatus may also be provided with a plurality of thermostats. 
     Furthermore, in the embodiment, before the heater  41  is energized at the first energization amount, it is determined whether the electric water pump  2  is racing. However, this is not restrictive. It is permissible not to determine whether the electric water pump is racing before the heater is energized at the first energization amount. That is, the process of step S 3  shown in  FIG. 5  may be omitted. 
     Furthermore, although in the embodiment, the first energization amount and the second energization amount are pre-set values, this is not restrictive. The first energization amount and the second energization amount may be changed according to the temperature of the coolant. 
     Furthermore, although in the embodiment, it is determined whether the coolant-injecting operation has been performed on the basis of the signal input from the maintenance-purpose tool  170 , this is not restrictive. Whether the cooling-injecting operation has been performed may be determined on the basis of a signal input from an operating portion (not shown) of the vehicle. 
     Further, although in the embodiment, the meter device  160  is caused to display the warning indicating that the coolant in the coolant passageway  1  is insufficient in amount, this is not restrictive. The maintenance-purpose tool may be caused to display the warning indicating that the coolant in the coolant passageway is insufficient in amount. 
     The invention is applicable to a cooler apparatus for an engine and, more particularly, can be effectively used in a cooler apparatus that performs a control of draining air by forcing the thermostat to open its valve.