JP2004293430A - Engine cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine cooling device capable of suppressing increase in size of a motor-driven water pump, securing maximum required cooling water flow rate in an operation range at low vehicle speed and heavy load, and preventing wasted output loss even if engine rotation speed is increased during light load operation. <P>SOLUTION: The engine controlling device is equipped with a mechanical water pump 8 provided to a cooling water circulation path coupled to a crank shaft 11 of an engine through the medium of a clutch, a motor-driven water pump 13 provided to the cooling water circulation path so as to form a serial state with the mechanical water pump 8, and a controller 46 for selectively driving and controlling the mechanical water pump 8 and the motor-driven water pump 13 in accordance with an accelerator opening θa of an engine 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an engine cooling device, and more particularly to an engine cooling device in which a mechanical variable water pump driven by an engine crankshaft and an electric water pump are arranged in a cooling water circulation path of an engine.
[0002]
[Prior art]
In the engine, a cooling water circulation path is provided in the engine body, and the cooling water in the cooling water circulation path is circulated to the radiator side by driving a water pump to cool the engine.
By the way, the maximum value of the required cooling water flow rate of the engine is a value corresponding to the cooling capacity required at the time of low vehicle speed and high load operation in which the heat radiation capacity of the radiator is poor. As described above, the engine requires a large flow rate of cooling water during high-load operation, and does not require a large flow rate of cooling water during low-load operation even if the engine speed increases.
[0003]
However, if the water pump is a direct-acting type driven by receiving engine rotation via a belt-type or chain-type rotation transmission system, the pulley rotation speed (engine rotation speed) is approximately proportional to the pump discharge amount. For this reason, the discharge amount in the high-speed rotation range is too large, and the pump drive loss is likely to increase.In order to suppress this unnecessary pump rotation and prevent over-rotation, a fluid coupling between the water pump and the engine crankshaft must be provided. Some have been deployed. In this case, as shown in FIGS. 7A and 7B, the pump impeller rotation speed converges to a predetermined value as the pulley rotation speed (engine rotation speed) increases. The discharge amount of the pump can be suppressed.
However, the useless work of the water pump that is always connected to the crankshaft is not largely eliminated by using the fluid coupling or changing the characteristics of the water pump itself.
[0004]
Therefore, the engine rotation from the belt-type rotation transmission system is connected to the pump shaft of the water pump via a clutch, and this clutch is disconnected and the clutch is slipped to prevent the engine from rotating excessively. Pumps are considered. Japanese Patent Application Laid-Open No. H10-159874 (Patent Document 1) discloses that an engine rotation from a belt-type rotation transmission system is connected to a pump shaft of a water pump via a fluid coupling, and a transmission torque characteristic of the fluid coupling is electronically controlled. In this case, the increase / decrease control is performed, thereby changing the engine rotation transmission amount in multiple steps, thereby improving the cooling performance at a high temperature and reducing the noise at a cold time.
[0005]
On the other hand, recently, the use of an electric water pump that can easily secure the flow rate according to the load has been studied.However, in order to secure the required cooling water flow rate of the engine using only the electric water pump, the size of the electric water pump must be increased. Invites problems such as cost increase and mountability. Considering this point, the use of a conventional direct-acting water pump in such a manner as to be assisted by an electric water pump is being studied. In this case, for example, as shown in FIG. 8, the pump discharge amount q1 proportional to the engine speed is secured by the water pump, and the pump discharge amount q2 (assist amount) of the electric water pump is added to the pump discharge amount q1. It is conceivable to secure the required cooling water flow rate Q0.
[0006]
[Patent Document 1]
JP 10-159874 A
[Problems to be solved by the invention]
The water pump with a fluid coupling described in Patent Document 1 described above can increase or decrease the discharge amount in accordance with the temperature of the cooling water, but is directly driven by the crankshaft of the engine. You cannot do it.
On the other hand, in the case of the type in which the direct-acting water pump described with reference to FIG. 8 is assisted by the discharge amount of the electric water pump, the discharge amount q1 of the water pump in the high rotation range can be relatively suppressed. The assist amount q2 of the electric water pump in the region becomes relatively large, and the electric water pump is likely to be increased in size.
[0008]
As described above, an engine cooling device that uses a direct-acting water pump and an electric water pump is desired to be able to suppress an increase in the size of the electric water pump. It is desired that the maximum required cooling water flow rate can be ensured in the region, and that even during low load operation, even if the engine speed increases, the increase in the cooling water flow rate can be suppressed to prevent useless output loss.
[0009]
The present invention is based on the above-mentioned problem, and in an engine cooling device of a type using a direct-acting water pump and an electric water pump, in addition to suppressing the size of the electric water pump from increasing, the engine cooling device in a low vehicle speed and high load operation range. It is an object of the present invention to provide an engine cooling device capable of securing a maximum required cooling water flow rate and preventing useless output loss even when the engine speed increases during low load operation.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a mechanical water pump provided in a cooling water circulation path and connected to a crankshaft of an engine via a clutch, and an electric water pump provided in the cooling water circulation path A pump and the clutch and the electric water pump according to load information of the engine to drive the electric water pump when the engine is under a low load and to drive the electric water pump and the mechanical water pump when the engine is at a high load. And control means for controlling the driving of the device.
As described above, since the control means selectively uses the operation range of the electric water pump and the mechanical water pump having the clutch according to the load information, it is possible to eliminate unnecessary driving of the mechanical water pump, and It is also possible to suppress an increase in the size of the pump.
That is, since the control means cuts off the clutch at low load and drives only the electric water pump, it is possible to prevent unnecessary output loss of the mechanical water pump at low load and control the drive of the clutch at high load. As a result, it is not necessary to increase the size of the electric water pump.
[0011]
According to a second aspect of the present invention, in the engine cooling device according to the first aspect, the control means controls the clutch so as to increase the discharge amount of the mechanical variable water pump as the load increases according to the load information of the engine. It is characterized by.
In this case, as the load increases, the slip amount of the clutch is suppressed to increase the flow rate of the cooling water, so that the cooling performance during the high load operation can be sufficiently ensured. It is possible to suppress the drive of the mechanical variable water pump during the load operation and to eliminate useless work.
Since the control means increases the slip amount of the clutch as the rotation speed increases, the drive of the mechanical variable water pump is suppressed as the rotation speed increases, the cooling water discharge flow rate is reduced, and unnecessary work of the engine is eliminated. Can be.
[0012]
According to a third aspect of the present invention, in the engine cooling device according to the first aspect, the control means suppresses an increase in the discharge amount of the mechanical variable water pump with respect to an increase in the number of revolutions of the engine when the engine has a low load. The driving of the clutch is controlled according to the information on the number of revolutions of the engine.
The control means increases the slip amount of the clutch as the engine speed increases, thereby suppressing the drive of the mechanical variable water pump and efficiently eliminating wasteful work of the engine when the engine rotates at a high speed.
[0013]
According to a fourth aspect of the present invention, in the engine cooling device according to the first aspect, the control means drives the mechanical variable water pump when the low load of the engine exceeds a predetermined value, and the predetermined value is set to the engine value. It is characterized in that the characteristic is set to decrease as the number of rotations increases.
In this case, the higher the rotation speed, the earlier the mechanical variable water pump is operated, so that the rotation of the engine can be used efficiently, and the lower the rotation speed, the relatively wider the operating range of the electric water pump alone. Output loss can be suppressed efficiently.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
1 and 2 show an engine cooling device as one embodiment of the present invention. The engine cooling device A is provided in a water-cooled engine 1 mounted on an automobile (not shown). The engine 1 has a water jacket 3 formed inside the main body 2, a radiator 4 disposed near the outside of the engine main body 2, and the radiator 4 is connected by a cooling circulation path. The cooling circulation path includes a main circulation path C1 through which the cooling water flows during a steady operation and a warm air circulation path C2 through which the cooling water flows during warm-up. Both the circulation paths can be switched by the thermostat 14. The main circuit C1 is branched and connected in parallel to the heater circuit C3. The heater circulation path C3 is formed so as to circulate and supply the cooling water when the heater 5 is driven.
[0015]
The engine body 2 has an inlet 6 and an outlet 7 for cooling water formed on a front wall f1 on the front end side, which is one end side (lower side in the drawing) of the engine longitudinal direction X (vertical direction in the drawing). Is formed. The water jacket 3 allows cooling water discharged by a mechanical water pump 8 to be described later to flow through an inlet 6, flows the cooling water in a substantially U-shape along the outer circumference of a plurality of cylinders arranged in series, and allows the cooling water to flow from an outlet 7. Formed to drain.
A mechanical water pump 8, an outflow port 7, and a protruding pipe 9 are integrally attached to a front wall f1 of the engine body 2, and a crankshaft 11 is provided so as to protrude therefrom. , A thermostat 14 and a fan 15, a dynamo (not shown) and the like are attached and provided.
[0016]
One end of an outflow pipe 16 is connected to the protruding pipe 9 of the outflow port 7, the other end is connected to the inlet of the radiator 4, and an electric water pump 13 and first and second branch portions a and b are provided on the way. Is established. One end of an inflow pipe 17 is connected to the outlet of the radiator 4, the other end is connected to a mechanical water pump 8, and a branch portion c and a thermostat 14 are provided on the way. Here, a flow path that is continuous with the outflow pipe 16 provided with the electric water pump 13, the radiator 4, the inflow pipe 17, and the mechanical water pump 8 forms a main circulation path C1.
[0017]
The radiator 4 is supported by a vehicle body front wall (not shown), and receives a cooling wind wc traveling from the front to the rear. The fan 15 is supported on a vehicle body front wall side (not shown) via a bracket 18 and is driven by a controller via a fan driving circuit (not shown). At this time, the radiator 4 allows the cooling air wcf passing from the front to the rear to pass therethrough. It is formed as follows.
[0018]
As shown in FIG. 2, the thermostat 14 has first and second inlets 21 and 22 and an outlet 19, and a cooling water-responsive switching valve 23 intermittently opening each of these openings. Here, the switching valve 23 is disposed in the second inflow chamber 25 of the second inlet 22 and retreats the core 26 when the water temperature is equal to or lower than a preset warm air water temperature Twh (for example, 80 ° C.). It includes a protruding temperature-sensitive actuator 24 and a pair of valve bodies 231 and 232 integrally supported by the core 26. Here, the pair of valve bodies 231 and 232 integrated with the core portion open the second inflow chamber 25 and the outlet 19 below the warm-air water temperature Twh to communicate with the warm-air circulation path C2, and exceed the warm-water temperature Twh. Then, the warm air circulation path C2 is closed, the first inflow chamber 27 of the first inlet 21 is opened to the outlet 19 (see the two-dot chain line), and the switching operation is performed so as to connect the main circulation path C1 and the heater circulation path C3.
One end of a bypass pipe 28 is connected to the second branch b of the outflow pipe 16, and the other end is connected to the second inlet 22 of the thermostat 14, and the second branch b of the outflow pipe 16, the bypass pipe 28, and the thermostat 14 And a flow path that continues to form a warm air circulation path C2.
[0019]
One end of a heater pipe 29 is connected to a first branch portion a of the outflow pipe 16, and the other end is connected to a branch portion c of the inflow pipe 17, and a heater 5 disposed in the vehicle compartment (not shown) is provided in the middle thereof. Connected. The heater pipe 29 and the heater 5 form a heater circulation path C3.
Here, a mechanical water pump 8 and an electric water pump 13 are formed in series in the main circulation path C1, the warm air circulation path C2, and the heater circulation path C3, and these forward circulation paths C1 are driven by driving at least one of the pumps. , C2 and C3 can be supplied with cooling water.
[0020]
The mechanical water pump 8 receives a rotational force of the crankshaft 11 protruding from the front wall f1 of the engine body 2 via a belt-type rotation transmission system 31 and is driven. As shown in FIGS. 3 and 1, the mechanical water pump 8 has front and rear rotating shafts 34, 35 pivotally attached to a pump casing 32 integrally attached to a front wall f <b> 1 via an electromagnetic clutch 33, and a rear rotating shaft. A pump impeller 36 and a pump pulley 37 are integrally mounted on a rear end of the front rotation shaft 35 and a front end of the front rotation shaft 34, respectively.
An endless belt 39 is wound around the pump pulley 37 and the crank pulley 38 on the crankshaft 11 side, so that the rotation of the crankshaft 11 is transmitted to the front rotation shaft 34.
[0021]
The electromagnetic clutch 33 includes a fixed clutch plate 41 integrated with the rear rotation shaft 35, a movable clutch plate 42 that is spline-fitted to the front rotation shaft 34, a spring 43 that presses the movable clutch plate 42 toward the fixed clutch plate 41, An exciting coil 44 for applying an electromagnetic force to pull the movable clutch plate 42 back. The excitation coil 44 is connected to a controller 46 via a first drive circuit 45.
[0022]
When the electromagnetic clutch 33 is de-energized (turned off), the mechanical water pump 8 operates with the clutch completely connected by the elastic force of the spring 43 and operates the pump to discharge the cooling water of the inflow pipe 17 from the inflow port 6. Further, the mechanical water pump 8 is formed so as to reduce the slip amount in accordance with the increase in the excitation output (duty output) to lower the clutch engagement state, and to stop the pump operation at a duty of 100%.
The electric water pump 13 of the outflow pipe 16 is supported on one side wall of the engine body 2 via the bracket 12 protruding from the side wall, and drives the impeller 47 in its casing by a motor 48. The controller 46 is connected to the motor 48 via a second drive circuit 49.
[0023]
In some cases, in addition to the electric water pump 13 of the outflow pipe 16, a second electric water pump 13 ′ (shown by a two-dot chain line) is provided between the thermostat 14 of the inflow pipe 17 and the mechanical water pump 8. It may be arranged, attached to the side wall of the engine body 2 via the bracket 12, and drive-controlled in the same manner as the first electric water pump 13.
[0024]
In this case, the second electric water pump 13 ′, the mechanical water pump 8, and the first electric water pump 13 are connected in series in this order with the water jacket 3 of the engine 1 interposed therebetween, and the circulation characteristics of the cooling water are stabilized. In particular, the size of the first and second electric water pumps 13 can be reduced, the maximum discharge amount of each water pump can be relatively reduced, and cavitation at the time of high rotation of the pumps can be prevented.
[0025]
The controller 46 detects the cooling water temperature Tw of the water jacket 3 of the engine 1 with the water temperature sensor 51, and further calculates the engine speed Ne detected by the engine rotation sensor 52 and the accelerator opening sensor 53 and the accelerator opening θa as a load. Import and rewrite to the latest value. Further, the controller 46, based on the operation information and the low-load pump map m1 and the high-load pump map m2 in FIGS. 4A and 4B, according to the pump drive routine in FIG. The electromagnetic clutch 33 and the motor 48 of the electric water pump 13 are selectively driven to control the circulation of cooling water to the main circuit C1, the warm air circuit C2, and the heater circuit C3.
[0026]
Hereinafter, the driving of the engine cooling device A will be described along the pump driving routine of FIG.
The controller 46 takes in the water temperature Tw, the engine speed Ne, and the accelerator opening θa in step s1. If the current water temperature is lower than the warm-up water temperature value Twh (for example, 80 ° C.) in step s2, it is determined that the warm-up is to be promoted. This is regarded as an operation range in which the thermostat 14 is closed. In step s3, the electromagnetic clutch 33 is turned on (clutch is disconnected), and the motor 48 of the electric water pump 13 is driven along the low-load pump map m1. The process of stopping the fan 15 is performed, the control of this time is ended, and the process returns.
[0027]
After completion of warm-up in which the current water temperature exceeds the warm-up water temperature value Twh (for example, 80 ° C.) in step s2, the process proceeds to step s5, where it is determined whether or not the accelerator opening θa, which is the current load information, exceeds the low load determination value θaL. If it is lower, the process proceeds to step s6, and if it is higher, the process proceeds to step s7. As shown in FIG. 6, the low load determination value θaL has a characteristic that it decreases as the engine speed Ne increases.
[0028]
In steps s6 and s8, it is determined that the accelerator operation amount θa is lower than the low load determination value θaL in the low load operation range. In this case, the electromagnetic clutch 33 is disengaged (turned on) and the mechanical water pump 8 is deactivated. Then, based on the low load pump map m1, the flow value qLm (control signal of the electric motor corresponding to the current engine speed) corresponding to the current engine speed is read, and the control signal is output to the motor 48 via the second drive circuit. As a result, the electric water pump 13 is driven to secure the target flow value qLm. Here, the low-load pump map m1 is set in advance to a flow rate value qLm that does not change much with a change in the engine speed.
[0029]
That is, in this low load operation range, only the electric water pump 13 is driven, and the discharge amount of the electric water pump 13 does not increase excessively even if the engine speed Ne reaches a high rotation range, and the flow rate value qLm does not excessively increase. Power consumption can be suppressed, and of course, there is no drive loss of the mechanical water pump 8 in this low load operation range.
[0030]
Thereafter, the process proceeds to step s9. When reaching step s9, it is determined whether or not the water temperature Tw exceeds a high water temperature range Twk (> Twh) which is higher than the warm-air water temperature value Twh. Proceeding to step s11, drive processing of the fan 15 is completed, and control is returned to this time.
[0031]
If it is determined in step s5 that the current accelerator opening θa exceeds the low load determination value θaL, the process proceeds to step s7. Here, an engine rotation-equivalent flow rate value qHk of the mechanical water pump 8 is obtained from the high-load pump map m2, and an excitation output (duty output) that can maintain a connection state equivalent to the flow rate value qHk is transmitted to the first drive circuit 45. And outputs the same to the electromagnetic clutch 33 to drive the same.
[0032]
Here, the flow rate value qHk is set in accordance with not only the engine speed Ne but also the accelerator opening degree θa, and the flow rate value qHk is set to increase as the accelerator opening degree θa increases. In addition, as the load becomes higher, the clutch slip is suppressed and the discharge flow rate increases.
Further, in step s12, a flow rate value qHm (control signal of the electric motor corresponding to the current value) corresponding to the current engine speed is read based on the high load pump map m2, and the control signal is transmitted to the motor 48 via the second drive circuit 49. By outputting, the electric water pump 13 is driven so as to secure the target flow value qHm.
[0033]
Thereafter, in steps s9, s10 and s11, it is determined whether or not the water temperature Tw exceeds a high water temperature range Twh (> Twk) higher than the warm-air water temperature value Twh. Is driven, and this control is terminated, and the routine returns.
That is, in this high load operation range, the mechanical water pump 8 and the electric water pump 13 are driven in the entire engine rotation range based on the high load pump map m2.
[0034]
In this case, the mechanical water pump 8 can be driven in the controllable region e1 (substantially trapezoidal region) of the electromagnetic clutch 33, and is prevented from over-rotating in a high rotation region, and is controlled in a high-load operation region. Excessive increase in drive loss of the pump 8 can be reliably prevented. Moreover, here, in order to secure the target flow rate Qo, a target flow rate qHm of the range in which the electric water pump 13 can assist the flow rate value qHk of the mechanical water pump 8 is set. The second drive circuit 49 is driven to drive the motor. As a result, the electric water pump 13 is driven to secure the target flow rate value qHm, so that the target flow rate Qo can be secured and unnecessary power consumption can be suppressed.
[0035]
In addition, since the mechanical water pump 8 and the electric water pump 13 are arranged in series in the main circuit C1, the maximum discharge amount of each water pump can be relatively reduced, and the occurrence of cavitation at the time of high pump rotation can be prevented. .
[0036]
【The invention's effect】
As described above, in the present invention, since the control means selectively uses the operation range of the electric water pump and the mechanical water pump having the clutch according to the load information, it is possible to eliminate unnecessary driving of the mechanical water pump. In addition, the size of the electric water pump can be suppressed.
[0037]
According to the second aspect of the present invention, as the load increases, the slip amount of the clutch is suppressed to increase the cooling water discharge flow rate, and the cooling performance during the high load operation can be sufficiently ensured. The drive of the variable water pump can be suppressed, and unnecessary work can be eliminated.
[0038]
According to the third aspect of the present invention, it is possible to efficiently eliminate wasteful work of the engine at the time of high engine rotation.
[0039]
According to the invention of claim 4, it is possible to set the operating range of the mechanical water pump in which the rotation of the engine can be used efficiently.
[Brief description of the drawings]
FIG. 1 is a schematic plan view of an engine to which an engine cooling device as one embodiment of the present invention is applied.
FIG. 2 is a schematic sectional configuration diagram of a thermostat used by the engine cooling device of FIG.
FIG. 3 is a sectional view of a mechanical water pump used by the engine cooling device of FIG. 1;
4A and 4B are control maps used by the engine cooling device of FIG. 1, wherein FIG. 4A is a low-load pump map and FIG. 4B is a high-load pump map.
FIG. 5 is a flowchart of a pump driving routine used by a controller of the engine cooling device of FIG. 1;
FIG. 6 is a characteristic diagram of the low load determination value θaL with respect to the engine speed Ne.
7A and 7B are characteristic diagrams of a water pump of a conventional engine cooling device, in which FIG. 7A is a pulley rotation speed-flow rate characteristic diagram, and FIG. 7B is a pulley rotation speed-impeller speed characteristic diagram.
FIG. 8 is an engine speed-flow rate characteristic diagram of a conventional engine cooling device.
[Explanation of symbols]
1 Engine 11 Crankshaft 8, 8a Mechanical Water Pump 13 Electric Water Pump 33 Electromagnetic Clutch (Clutch)
46 controller (control means)
m1 Pump map for low load m2 Pump map for high load θa Accelerator opening (load)
A, A1 Engine cooling device C1 Main circulation path (cooling water circulation path)
C2 Warm air circulation path (cooling water circulation path)
Ne Engine speed Twh Warm air temperature

Claims (4)

A mechanical water pump provided in the cooling water circulation path and connected to a crankshaft of the engine via a clutch,
An electric water pump provided in the cooling water circulation path,
When the load of the engine is low, the electric water pump is driven.When the load is high, the electric water pump and the mechanical water pump are driven. Control means for controlling;
An engine cooling device comprising: The engine cooling device according to claim 1,
The engine cooling device, wherein the control means controls the clutch so as to increase the discharge amount of the mechanical variable water pump as the load increases according to the load information of the engine. The engine cooling device according to claim 1,
The control means drives the clutch according to the engine speed information so that an increase in the discharge amount of the mechanical variable water pump is suppressed with respect to an increase in the engine speed at a low load of the engine. An engine cooling device characterized by controlling. The engine cooling device according to claim 1,
When the low load of the engine exceeds a predetermined value, the control means drives the mechanical variable water pump in response to an increase in the rotation speed of the engine at the time, and the predetermined value is the rotation speed of the engine. An engine cooling device characterized in that the characteristics are set to decrease with increasing.

Images