JP4158025B2 - Variable flow rate water pump controller - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water pump for circulating cooling water of an engine, and more particularly to a control device for a variable flow rate water pump capable of adjusting the flow rate of cooling water.
[0002]
[Related background]
As is well known, the cooling performance of a water-cooled engine is greatly related to the flow rate of the cooling water circulated by the water pump, and the pump capacity is set in accordance with the operation region where the cooling performance is most required. Since the water pump is driven by the engine, it is generally a low rotation and high load range, such as when a vehicle is towing uphill. Is done. Therefore, it is desirable to set the pump capacity so that a sufficient flow rate of cooling water is ensured even in such an operation region.
[0003]
However, when the pump capacity is simply increased, another problem of cavitation in a high rotation range occurs. That is, FIG. 6 is a graph comparing the flow characteristics when the pump capacity is small and when the pump capacity is large, but when the pump capacity is large compared to the case where the pump capacity is small, larger cooling water at the same engine speed. Although the flow rate can be obtained, the water pressure before the impeller suddenly decreases (negative pressure increases) as the engine speed increases and reaches the saturated water vapor pressure in the high rotation range. It can be seen that cavitation is generated. As a result, the increase in pump capacity is limited, and as a result, a sufficient coolant flow rate in the low rotation and high load region cannot be realized.
[0004]
On the other hand, the above description has been made on a general water pump having the same engine rotation speed and a constant flow rate. However, a variable flow rate water pump capable of adjusting the cooling water flow rate has also been proposed (for example, see Patent Document 1). In Patent Document 1, the suction side and the discharge side of the water pump are communicated with each other by a reflux path provided with an on-off valve, and a part of the cooling water discharged from the water pump is returned to the reflux path according to the opening degree of the on-off valve. The technique of making it return to the discharge side via this, and reducing the pump efficiency by this and changing the flow volume of cooling water is disclosed.
[0005]
[Patent Document 1]
JP 2001-295647 A (FIGS. 1 and 6)
[0006]
[Problems to be solved by the invention]
The technique described in Patent Document 1 uses the variable flow rate function of the water pump for proper cooling of the engine. That is, the target water temperature is obtained from the engine load and the engine rotation speed, and the opening / closing valve opening (that is, the flow rate of the cooling water) is controlled so that the actual cooling water temperature becomes the target water temperature. When the rotational speed is low, the warm-up is promoted by decreasing the flow rate of the cooling water based on the high target water temperature.
[0007]
However, since the technique of Patent Document 1 does not consider cavitation at all, cavitation in the high rotation range is unavoidable as in the case of a general water pump with a constant flow rate, and the above problem can be solved. There wasn't.
An object of the present invention is to provide a variable flow rate type capable of reliably suppressing cavitation in a high rotation range after sufficiently securing a flow rate of cooling water in a low rotation high load range and realizing good cooling performance. It is providing the control apparatus of a water pump.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 comprises a water pump that is rotationally driven by the driving force of the engine, and a flow rate adjusting means that can adjust the flow rate of the cooling water discharged from the water pump. In a control device for a variable flow rate water pump that adjusts the flow rate of cooling water in accordance with an operating state, an engine rotation speed detection unit that detects an engine rotation speed, a water temperature detection unit that detects an engine cooling water temperature, and an engine rotation When the engine rotation speed detected by the speed detection means is in the vicinity of a preset cavitation generation rotation range, the flow rate of the cooling water that increases with the engine rotation speed is limited by the flow rate adjustment means and detected by the water temperature detection means. also a flow control means in accordance with the increase in the coolant temperature increases the limit amount of the cooling water flow rate to be It is.
[0009]
Therefore, since the water pump is rotationally driven by the engine, the flow rate of the cooling water increases with the engine speed, and in the high speed range, for example, the water pressure before the impeller reaches the saturated water vapor pressure to generate cavitation , The higher the cooling water temperature, the higher the saturated water vapor pressure and the easier it is to generate cavitation . At this time, assuming that the engine rotation speed is in the vicinity of a preset cavitation generation rotation region, for example, a region equal to or higher than a predetermined generation rotation speed, the flow rate control unit restricts the flow rate of the cooling water by the flow rate adjustment unit , and the cooling water temperature Since the limit amount of the cooling water flow rate by the flow rate control means is increased as the flow rate increases , the occurrence of cavitation is suppressed in advance. Therefore, it is no longer necessary to reduce the pump capacity (corresponding to the upper limit of the flow rate adjustment range) in order to suppress cavitation, and it is possible to achieve a good cooling performance by securing a sufficient cooling water flow rate even in a low rotation and high load range. Become.
[0012]
A second aspect of the present invention, in claim 1, comprising an engine load detecting means to detect the load of the engine, the flow control means, the cooling water flow rate with an increase in engine load detected by the engine load detecting means The amount of increase in the amount of restriction due to the cooling water temperature is set to be larger than the amount of decrease in the amount of restriction due to the engine load, or the restriction due to the cooling water temperature is given priority over the restriction due to the engine load. .
[0013]
Therefore, the higher the engine load, the higher the cooling performance required from the engine side. However, as the engine load increases, the limit of the cooling water flow rate by the flow rate control means decreases, resulting in an increase in the cooling water flow rate. on demand Te cooling performance Ru is realized. In addition, the amount of increase in the limit due to the cooling water temperature is set to be greater than the amount of decrease in the limit due to the engine load, or the limit due to the cooling water temperature is given priority over the limit due to the engine load, so cavitation is reliably suppressed. it can.
[0014]
The invention of claim 3 comprises the pressure detection means for detecting the pressure of the cooling water according to claim 1 or 2, wherein the flow rate control means is a limiting amount of the cooling water flow rate by the pressure of the cooling water detected by the pressure detection means. Is to correct.
Therefore, the pressure of the cooling water fluctuates between the vicinity of the atmospheric pressure at the time of cold start to the radiator set pressure after the completion of warming, and also fluctuates when the pipe resistance changes according to the opening and closing of the thermostat. The limit amount of the cooling water flow rate is corrected by the pressure of the cooling water.
According to a fourth aspect of the present invention, in any one of the first to third aspects, the flow rate adjusting means includes a return path that communicates the suction side and the discharge side of the water pump, and an opening / closing means that opens and closes the return path. The flow rate of the cooling water is adjusted by controlling the opening degree of the opening / closing means.
Therefore, the opening degree of the opening / closing means is controlled by the flow rate control means, a part of the cooling water discharged from the water pump is recirculated to the suction side, and the flow rate of the cooling water supplied to the engine side according to the recirculation amount Thus, the flow rate of the cooling water can be adjusted with a simple configuration in which the opening / closing means is provided in the reflux path.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
Hereinafter, a first embodiment in which the present invention is embodied in a control device for a variable flow rate water pump for an engine mounted on a vehicle will be described.
FIG. 1 is a view showing a cooling water path of an engine. A water pump 2 is provided at a rear portion of a cylinder block 1a of the engine 1, and a poppet type opening / closing valve 3a is provided at a front portion of a cylinder head 1b of the engine 1. A thermostat 3 is provided. The water pump 2 and the thermostat 3 communicate with each other via a cooling water passage (not shown) formed in the cylinder block 1a and the cylinder head 1b. The thermostat 3 is connected to the inlet side of a radiator 4 provided at the front of the vehicle, and the outlet side of the radiator 4 is connected to the water pump 2 via a water pipe 5.
[0016]
The cooling water discharged from the water pump 2 performs a cooling action in the cooling water passage of the engine 1, is then introduced into the radiator 4 through the thermostat 3, and is dissipated while flowing through the radiator 4. Then, it is again sucked into the water pump 2 and circulates through the above path.
The thermostat 3 is connected to the water pipe 5 via the bypass path 6, and when the cooling water temperature is lower than the set temperature, the on-off valve 3 a is closed and the cooling water is guided to the bypass path 6 to promote warming up of the engine 1. When the cooling water temperature becomes equal to or higher than the set temperature, the on-off valve 3a is opened and the cooling water is guided to the radiator 4 to cool the engine 1.
[0017]
Next, the details of the water pump 2 will be described. FIG. 2 is a sectional view showing the vicinity of the water pump of the engine 1, and a pump shaft 12 is rotatably supported in the casing 11 of the water pump 2. The front end side of the pump shaft 12 protrudes out of the casing 11 and a pulley 13 is fixed. The pulley 13 is connected to a crankshaft (not shown) of the engine via a belt 14 and is driven to rotate. A pump chamber 15 is formed in the casing 11, and a base end side of the pump shaft 12 protrudes into the pump chamber 15 and an impeller 16 is fixed.
[0018]
A suction port 15 a is formed in the pump chamber 15 corresponding to the rotation center of the impeller 16, and the pump chamber 15 communicates with the chamber chamber 17 through the suction port 15 a. One end of the water pipe 5 is connected to the chamber 17. A discharge port 15 b is formed in the pump chamber 15 on one side in the radial direction of the impeller 16, and the discharge port 15 b communicates with the cooling water passage of the engine 1.
[0019]
Accordingly, during operation of the engine, the impeller 16 is rotated together with the pump shaft 12 by the crankshaft, and the cooling water on the suction port 15a side of the pump chamber 15 is discharged to the discharge port 15b side by the impeller 16, whereby the water pump 2 is a so-called shaft. It functions as a flow pump and circulates the cooling water as described above. Here, since the water pump 2 is driven by the engine 1, the flow rate of the cooling water is changed in proportion to the engine rotational speed Ne. In this embodiment, the low rotational height at which the cooling performance is most required. A relatively large pump capacity is set so that a sufficient cooling water flow rate can be secured even in the load range.
[0020]
Further, the discharge port 15b of the pump chamber 15 and the chamber chamber 17 are connected by a reflux path 18 (flow rate adjusting means), and the reflux path 18 is provided with a butterfly type on-off valve 19 (open / close means, flow rate adjusting means). Yes. An actuator 20 is connected to the on-off valve 19, and is driven by the actuator 20 so that the on-off valve 19 is switched between two positions of fully closed and fully open. Since all the cooling water discharged from the water pump 2 is supplied to the engine 1 side when the on-off valve 19 is closed, all of the set pump capacity is used for circulation of the cooling water, while the on-off valve 19 When the valve is opened, a part of the cooling water discharged from the water pump 2 is recirculated to the chamber chamber 17 side through the recirculation path 18, so that the flow rate of the cooling water decreases as the pump efficiency decreases.
[0021]
Although the pump efficiency is reduced due to the reflux of the cooling water as described above, in this type of axial flow pump, the driving loss of the engine 1 is also reduced together with the reduction of the pump efficiency. It is effectively used to improve fuel efficiency without any problems.
On the other hand, an input / output device (not shown), a storage device (ROM, RAM, etc.) used for storage of a control program, a control map, etc., a central processing unit (CPU), a timer counter, etc. Control unit) 31 is installed. Various sensors such as a rotation speed sensor 32 (engine rotation speed detection means) for detecting the rotation speed Ne of the engine 1 and a water temperature sensor 33 (water temperature detection means) for detecting the cooling water temperature Tw are connected to the input side of the ECU 31 and output. Various devices such as the actuator 20 are connected to the side.
[0022]
The ECU 31 operates the engine 1 by controlling the fuel injection valve, the ignition igniter and the like based on detection information from the sensors, and drives the on-off valve 19 based on the cooling water temperature Tw during the operation of the engine 1. The flow rate of the cooling water by the water pump 2 is controlled. Therefore, the state of flow control by the ECU 31 will be described.
The ECU 31 executes the pump control routine shown in FIG. 3 at a predetermined control interval. First, the engine speed Ne and the cooling water temperature Tw are read in step S2, and the switching point is switched from the cooling water temperature Tw according to a map set in advance in step S4. Find Nec. The switching point Nec is for switching the open / close state of the on-off valve 19 according to the engine speed Ne, and map characteristics are set in view of the following points.
[0023]
FIG. 4 shows the flow characteristics of the water pump 2 of the present embodiment. As shown by the thick line, the on-off valve 19 is switched to the closed side in the region where the engine speed Ne is less than the switching point Nec, and the switching point Nec. In the above region, it is switched to the open side. As described above, the pump capacity is set to be relatively large so that a sufficient cooling water flow rate can be secured even in a low rotation region where the cooling water flow rate is difficult to obtain, and the cooling water flow rate increases with the engine rotational speed Ne. If the on-off valve 19 is closed and the engine shifts to a high rotation range, the water pressure before the impeller reaches the saturated water vapor pressure and cavitation occurs. For example, in the prior test, the on-off valve 19 is held closed to increase the engine rotational speed Ne to determine the cavitation generation rotational speed, and the switching point Nec is set as the generated rotational speed or a slightly lower rotational speed. (In FIG. 4, Nec = cavitation generation rotational speed).
[0024]
Further, since the saturated water vapor pressure is affected by the cooling water temperature Tw and becomes higher (approaching atmospheric pressure) and cavitation is likely to occur, the cooling water temperature Tw is, for example, based on the cooling water temperature Tw in the above test. The switching point Nec is set to the low rotation side as the value increases.
After setting the switching point Nec according to such a characteristic map, the ECU 31 proceeds to step S6. In step S6, it is determined whether or not the engine speed Ne is less than the switching point Nec. When the determination is YES (positive), the on-off valve 19 is closed by the actuator 20 in step S8, while the determination is NO (negative) ), After opening the on-off valve 19 in step S10, the routine is terminated.
[0025]
As a result of the above control of the on-off valve 19 by the ECU 31, the flow rate of the cooling water by the water pump 2 is adjusted as shown in FIG. That is, since the on-off valve 19 is closed when the engine rotational speed Ne is less than the switching point Nec, the entire pump capacity is used for the circulation of the cooling water, so that a sufficient flow rate of the cooling water can be obtained even in the low rotation and high load range. Is ensured to achieve good cooling performance, and overheating of the engine 1 can be reliably avoided. On the other hand, since the on-off valve 19 is opened in the region where the engine rotational speed Ne is equal to or higher than the switching point Nec, the pump efficiency is reduced due to the circulation of the cooling water, and the water pressure before the impeller becomes saturated steam as the engine rotational speed Ne increases. The situation of reaching the pressure is prevented, and cavitation in the high rotation range can be reliably suppressed.
[0026]
In addition, since the switching point Nec is set according to the cooling water temperature Tw, even if the saturated water vapor pressure fluctuates with a change in the water temperature, cavitation can be more reliably suppressed without being affected by the change. Therefore, the advantage that the reliability as a control apparatus can be improved further is also acquired.
On the other hand, as described above, the flow rate of the cooling water is adjusted by a simple configuration in which the on-off valve 19 is provided in the reflux path 18, and thus the above-described various advantages can be obtained at a very low manufacturing cost.
[0027]
[Second Embodiment]
Next, a second embodiment in which the present invention is embodied in another variable flow rate water pump control device will be described. The control device of the present embodiment continuously controls the opening degree θw without switching the on-off valve 19 between two positions of fully closed and fully opened as in the first embodiment, and The difference is that the target average effective pressure Pe is reflected in the control as engine load information in addition to the cooling water temperature Tw, and the other configurations are the same as those of the first embodiment. Therefore, common constituent parts are given the same member numbers, description thereof is omitted, and differences are mainly described.
[0028]
The ECU 31 executes the pump control routine shown in FIG. 5 at a predetermined control interval. First, in step S12, the engine speed Ne, the coolant temperature Tw, and the target average effective pressure Pe are read. For example, the target average effective pressure Pe is set to the throttle opening degree θth detected by the throttle sensor 41 (engine load detecting means) shown in FIG. 2 and the engine rotational speed Ne detected by the rotational speed sensor 32 (engine load detecting means). Based on the predetermined map. The engine load information can be variously changed without being limited to the target average effective pressure Pe, and may be replaced with, for example, volumetric efficiency Ev.
[0029]
In the subsequent step S14, the opening degree θw of the on-off valve 19 is obtained from the engine speed Ne, the cooling water temperature Tw, and the target average effective pressure Pe according to a preset map. The map characteristics are set in view of the following points.
First, with respect to the engine rotation speed Ne, since it is necessary to suppress cavitation in a high rotation range as described in the first embodiment, for example, the rotation speed of the on-off valve 19 is reduced to a rotation speed at which cavitation occurs or a slightly lower rotation speed. The opening degree θw is maintained at 0 (fully closed), and the opening degree θw is gradually increased in the rotation range beyond that.
[0030]
As for the cooling water temperature Tw, as described in the first embodiment, the saturated water vapor pressure increases as the temperature increases, so that the opening degree θw of the on-off valve 19 is set to increase as the cooling water temperature Tw increases. Further, the cavitation generation rotational speed (Nec) for maintaining the opening degree θw of the on-off valve 19 at 0 (fully closed) may be set to the lower rotation side as the cooling water temperature Tw is higher.
[0031]
On the other hand, with respect to the target average effective pressure Pe, the higher the engine load, the higher the cooling performance required from the engine side. Therefore, it is necessary to secure a larger amount of cooling water flow to avoid overheating. Therefore, as the target average effective pressure Pe is higher, the opening degree θw of the on-off valve 19 is set to the decreasing side. Further, the switching point Nec may be set to the higher rotation side as the engine load is higher.
[0032]
The correction amount (increase amount of the limit amount) to the increase side of the opening degree θw of the on-off valve 19 according to the cooling water temperature Tw is the decrease side of the opening degree θw of the on-off valve 19 by the engine load (target average effective pressure Pe). Although it may be set to be equal to the correction amount (reduction amount of the limit amount), the increase side of the opening degree θw of the on-off valve 19 according to the cooling water temperature Tw in order to reliably suppress the occurrence of cavitation The correction amount may be set to be larger than the correction amount to the decrease side of the opening degree θw of the on-off valve 19 due to the engine load.
[0033]
In order to preferentially set the opening degree θw of the on-off valve 19 according to the cooling water temperature Tw over the setting of the opening degree θw of the on-off valve 19 due to the engine load, a switching point Nec set according to the cooling water temperature Tw. May be set lower than the switching point Nec set according to the engine load.
After setting the opening degree θw of the on-off valve 19 according to such a characteristic map, the ECU 31 proceeds to step S16 to drive and control the on-off valve 19 by the actuator 20 based on the set opening degree θw, and then ends the routine. To do.
[0034]
As described above, since the opening degree of the on-off valve 19 is continuously controlled in the present embodiment, the flow rate of the cooling water is more precisely compared with that of the first embodiment in accordance with the engine specifications and the like. Can be controlled. For example, when a turbo engine and an NA engine are set for the same vehicle type, a turbo engine that requires higher cooling performance in a higher rotation range than the NA engine has a NA higher than the cavitation generation rotation speed. If the opening degree θw of the on-off valve 19 is reduced from the engine, overheating can be prevented by a sufficient cooling water flow rate, and as a result, cooling characteristics corresponding to both engine specifications are realized, such as the water pump 2 and the radiator 4 The cooling system can be shared.
[0035]
Moreover, since the opening degree θw of the on-off valve 19 is set not only based on the engine speed Ne and the cooling water temperature Tw but also on the target average effective pressure Pe as engine load information, it is required according to the load state of the engine 1. Even if the cooling performance changes, an appropriate cooling water flow rate can always be realized, thus reliably preventing overheating regardless of the operating state of the engine 1 and further improving the reliability as a control device. .
[0036]
This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in each of the embodiments described above, the control device for the variable flow rate water pump 2 provided in the vehicle engine is embodied. However, the type and use of the engine are not limited to this, for example, a power generation engine or the like. You may actualize as a control apparatus with respect to a water pump.
[0037]
Further, in each of the above embodiments, the reflux path 18 and the on-off valve 19 are integrally provided in the casing 11 of the water pump 2, but the configuration of the water pump 2 is not limited to this. The on-off valve 19 may be provided on the engine 1 side as a separate body from the casing 11, and the type of the on-off valve 19 is not limited to the butterfly type, and may be a poppet type, for example.
[0038]
Further, in each of the above embodiments, the flow rate of the cooling water is adjusted by returning a part of the cooling water to the suction side of the water pump 2 through the reflux path 18 according to the opening degree θw of the on-off valve 19. The principle of adjustment is not limited to this.
For example, even if the cooling water is recirculated in the same manner, as described in Japanese Utility Model Publication No. 2-17145, the discharge side and the suction side of the water pump are adjacent to each other, and the on-off valve is positioned therebetween. A layout may be used. Further, as described in Japanese Patent Publication No. 5-11359 and Japanese Patent Publication No. 5-20598, the cover covering the impeller is slid in the axial direction to change the effective length of the impeller. You may comprise so that discharge amount, ie, a cooling water flow rate, may be adjusted. Furthermore, as described in JP-A-10-122177, each blade constituting the impeller is moved by engagement between the guide groove and the pin, thereby changing the outer diameter of the impeller to adjust the discharge amount, or As described in JP-A-7-208393, each blade may be bent from an intermediate portion, thereby changing the outer diameter of the impeller to adjust the discharge amount.
[0039]
On the other hand, in the first embodiment, the switching point Nec is changed according to the cooling water temperature Tw. However, the cooling water temperature Tw is not necessarily considered, and a single switching point Nec may be applied. Further, a different switching point Nec may be set in the increasing direction and decreasing direction of the engine speed Ne, and a hysteresis may be provided between the switching of the on-off valve 19 to the open side and the switching to the closed side. With this configuration, it is possible to prevent unnecessary switching of the on-off valve 19 when the engine speed Ne frequently fluctuates in the vicinity of the switching point Nec.
[0040]
In each of the above embodiments, the opening / closing valve 19 is controlled to open / close based on the engine speed Ne, the cooling water temperature Tw, and the target average effective pressure Pe. However, other factors may be taken into account, for example, cavitation is likely to occur. Since the cooling water pressure affects the cooling water pressure, the cooling water pressure may be taken into consideration. Specifically, the cooling water pressure fluctuates between the vicinity of the atmospheric pressure at the time of cold start and the radiator set pressure after completion of warm-up, and the cooling water flow path is changed to the radiator 4 according to the opening and closing of the thermostat 3 shown in FIG. This also varies when the pipe resistance is changed by switching between the bypass side and the bypass path 6 side. Therefore, it may be correct the switching point Nec and opening θw based on the opening and closing conditions of the measured value and the thermostat 3 the cooling water pressure (cooling detection means). In addition, since the rise process of the cooling water pressure during warm-up and the opening / closing status of the thermostat 3 can both be estimated from the cooling water temperature Tw, a map characteristic relating to the cooling water temperature Tw is set by a test taking these factors into account, and based on the set map Thus, the switching point Nec and the opening degree θw may be obtained.
[0041]
【The invention's effect】
As described above, according to the control device for the variable flow rate water pump of the first aspect of the present invention, the flow rate of the cooling water in the low rotation and high load region is sufficiently ensured to achieve a good cooling performance, and thus the engine In addition, the cavitation in the high rotation range can be reliably suppressed without being affected by the cooling water temperature .
[0043]
According to the control device for the variable flow rate water pump of the second aspect of the invention, in addition to the first aspect , overheat can be prevented more reliably without being affected by the engine load , and cavitation in the high rotation range can be further improved. It can be surely suppressed.
According to the control device for the variable flow rate water pump of the invention of claim 3, in addition to claim 1, cavitation in the high rotation region can be more reliably suppressed without being affected by the pressure of the cooling water. .
According to the control device for the variable flow rate water pump of the invention of claim 4 , in addition to claims 1 to 3 , the flow rate of the cooling water can be adjusted with a simple configuration, and the manufacturing cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a view showing a cooling water channel of an engine of an embodiment.
FIG. 2 is a sectional view showing the vicinity of a water pump of an engine.
FIG. 3 is a flowchart showing a pump control routine executed by the ECU of the first embodiment.
FIG. 4 is a view showing a flow rate characteristic of the water pump according to the first embodiment.
FIG. 5 is a flowchart showing a pump control routine executed by the ECU of the second embodiment.
FIG. 6 is a diagram comparing the flow rate characteristics when the conventional pump capacity is small and large.
[Explanation of symbols]
1 Engine 2 Water pump 18 Return path (flow rate adjusting means)
19 On-off valve (flow rate adjusting means, opening / closing means)
31 ECU (flow rate control means)
32 Rotational speed sensor (engine rotational speed detection means, engine load detection means)
33 Water temperature sensor (water temperature detection means)
41 Throttle sensor (engine load detection means)

Claims (4)

A water pump that is rotationally driven by the driving force of the engine, and a flow rate adjusting means that can adjust the flow rate of the cooling water discharged from the water pump, and the flow rate of the cooling water is adjusted according to the operating state of the engine In the control device for the variable flow rate water pump,
Engine rotation speed detection means for detecting the rotation speed of the engine;
Water temperature detecting means for detecting the cooling water temperature of the engine;
When in the generation speed region near the cavitation engine rotational speed is set in advance that is detected by the engine rotational speed detection means, the flow rate of the cooling water increases with the engine rotational speed as well as limited by the flow rate adjusting means, A control device for a variable flow rate water pump, comprising: flow rate control means for increasing a limit amount of the cooling water flow rate as the cooling water temperature detected by the water temperature detection means increases . An engine load detecting means to detect the load of the upper SL engine,
It said flow control means with an increase in engine load detected by the above SL engine load detecting means together with reducing the limit amount of the cooling water flow rate, limited by the engine load increase limit amount by the cooling water temperature 2. The control device for a variable flow rate water pump according to claim 1, wherein the control unit is set to be larger than the amount of decrease, or the restriction by the cooling water temperature is performed with priority over the restriction by the engine load. Pressure detecting means for detecting the pressure of the cooling water,
3. The variable flow rate water pump control device according to claim 1, wherein the flow rate control unit corrects the limit amount of the cooling water flow rate based on the cooling water pressure detected by the pressure detection unit. The flow rate adjusting means includes a reflux path communicating the suction side and the discharge side of the water pump and an opening / closing means for opening and closing the reflux path, and the flow rate control means controls the opening degree of the opening / closing means. control device for a variable flow rate water pump according to any one of claims 1 to 3, characterized in that adjusting the flow rate of the cooling water by.

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