JP2018168755A - Cooling system - Google Patents

Abstract

To provide a cooling device having a multiple flow control valve and securing reliability by using a simple configuration.SOLUTION: A cooling device includes: a multiple flow control valve 30 having a radiator port, a bypass port and a heater port to which a coolant discharged from a water pump 16 is introduced and that supply the coolant to a radiator flow passage 52, a bypass flow passage 54 and a heater flow passage 53, respectively; and control means 100 for controlling an opening of the multiple flow control valve. When an operating state of an engine 1 is determined to be in a predetermined cavitation generation region in which the possibility of generation of cavitation in a coolant flow passage is high, the control means transfers the radiator port to an opened state if the radiator port is in a closed state and transfers the heat port to an opened state if the radiator port is in the opened state and the heater port is in a closed state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cooling device having a multi-flow control valve that is provided in an engine coolant flow path and opens and closes a plurality of ports, and particularly to a device that ensures reliability by a simple configuration.

A water-cooled engine mounted on an automobile or the like passes cooling water discharged from a water pump driven by the output shaft of the engine through a water jacket (cooling water channel) formed in a portion such as a cylinder head that needs cooling. A cooling device is provided that circulates to the water pump via a radiator that is a heat exchanger that cools the cooling water by running air or the like after flowing.
Such a cooling device includes a bypass channel that bypasses the radiator channel for the purpose of preventing overcooling of the cooling water when it is cold, a heater channel that introduces cooling water as a heat source to the heater for heating, and the like. I have.

As a conventional technique related to an engine cooling device, for example, in Patent Document 1, an outlet of an oil cooler circulation channel and an outlet of a radiator bypass channel are connected, and cooling water is supplied downstream from the heater of the heater circulation channel. It is described that a three-way valve capable of simultaneously controlling the amount of cooling water in the oil cooler circulation passage and the radiator bypass passage is provided at the site to perform the oil temperature control while satisfying the heater requirement and reduce the work of the pump. Yes.
In Patent Document 2, when the flow control valve of the radiator is in a fully closed state and the engine rotational speed exceeds the reference rotational speed, the valve opening degree of the flow control valve is controlled from fully closed to slightly open, It describes that cavitation of the water pump is suppressed and durability is ensured.
In Patent Document 3, in the valve device that controls the distribution flow rate of the cooling liquid to the plurality of heat exchangers, when a predetermined pressure difference occurs, the water flow resistance of each heat exchange channel with the valve body as an intermediate position Is described, and the occurrence of cavitation of the water pump is described.
In Patent Document 4, when the engine speed is expected to reach a predetermined speed, at least one of a plurality of valves provided in the electronic control valve is opened even when the coolant temperature is low, and the coolant water is opened. It is described that the increase in the water pressure of the cooling system is avoided by suppressing the decrease in the engine warm-up efficiency by flowing the engine.

JP 2010-209818 A JP 2006-105104 A JP 2006-090226 A JP 2013-234605 A

In recent years, a multi-flow control valve (MCV) that includes ports connected to a radiator flow path, a bypass flow path, and a heater flow path, and controls the opening degree of each port according to a command from a control device (not shown) has been provided. It has been proposed to promote warm-up and optimize cooling water temperature control by controlling the opening of each port according to the operating state of the engine.
The cooling device having such a multi-flow control valve can arbitrarily switch the cooling water circuit, but depending on the opening, the pressure loss of the water circuit becomes high, so at the inlet of the water pump. There is concern about cavitation.
When cavitation occurs, it becomes difficult to ensure the function and reliability of the cooling device such as a decrease in the flow rate of the water circuit and erosion (damage) of the water pump propeller (impeller).
Furthermore, when the radiator flow path is blocked by the multi-flow control valve, it becomes impossible to adjust the pressure in the water circuit by the radiator cap, so that an excessive internal pressure is applied to the heater core that is a heat exchanger for heating the vehicle interior. This is a concern.
On the other hand, it is conceivable to set a new pressure regulating valve in the water circuit and manage the pressure in the water circuit, but there are problems such as an increase in the number of parts, a complicated structure, and an increase in cost and mass. It becomes.
In view of the above problems, an object of the present invention is to ensure reliability with a simple configuration in a cooling device having a multi-flow control valve.

The present invention solves the above-described problems by the following means.
According to a first aspect of the present invention, there is provided a water pump for discharging a coolant for cooling the engine, a radiator flow path for returning the coolant to the water pump via a radiator, and bypassing the radiator for the coolant. The bypass flow path for returning the water pump to the water pump, the heater flow path for returning the coolant to the water pump via a heater for heating the vehicle interior, and the coolant discharged from the water pump are introduced. A multi-flow control valve having a radiator port, a bypass flow channel, a radiator port for supplying the coolant to the heater flow channel, a bypass port, and a heater port, and the radiator port in the multi-flow control valve. , Opening degree of the bypass port and heater port A cooling device comprising a control means for controlling, when the control means determines that the operating state of the engine is a predetermined cavitation occurrence region where cavitation is likely to occur in the coolant, When the radiator port is closed, the radiator port is shifted to an open state, and when the radiator port is open and the heater port is closed, the heater port is shifted to an open state. This is a cooling device.
According to this, when the radiator port is in a closed state when the occurrence of cavitation is a concern, the coolant is introduced into the radiator by opening the radiator port, and the hydraulic pressure Can be reduced.
In particular, when the heater port is in the open state, the reliability of the heater can be ensured by reducing the internal pressure of the heater by opening the radiator port.
In addition, when there is a concern about the occurrence of cavitation when the radiator port is open and the heater port is closed, by opening the heater port, the flow rate flowing to the radiator is reduced to reduce the pressure loss generated in the radiator, and the cavitation Occurrence can be prevented.
All of these controls can be performed using the existing functions of the multi-flow control valve, so there is no need to add a new device and the reliability of the cooling system can be secured with a simple configuration. it can.

According to a second aspect of the present invention, the control means determines that the cavitation generation region is present when the temperature of the coolant and the output shaft rotational speed of the engine are equal to or higher than a predetermined temperature threshold and a speed threshold, respectively. And at least one of the temperature threshold value and the speed threshold value is changed according to a change in at least one opening state of the radiator port, the bypass port, and the heater port. It is a cooling device.
According to this, the temperature threshold and the speed threshold can be optimized according to the opening state of each port of the multiflow control valve, and an appropriate cavitation prevention effect can be obtained.

  As described above, according to the present invention, reliability can be ensured with a simple configuration in a cooling device having a multiflow control valve.

It is a figure which shows the structure of embodiment of the cooling device to which this invention is applied. It is a flow diagram of the multiflow control valve in the cooling device of an embodiment. It is a flowchart which shows the cavitation prevention control of the multiflow control valve in the cooling device of embodiment.

Hereinafter, embodiments of a cooling device to which the present invention is applied will be described.
The cooling device according to the embodiment is, for example, a water-cooling type cooling device that cools a portion that needs to be cooled in an engine mounted on an automobile such as a passenger car as a driving power source and its auxiliary equipment with cooling water (coolant). is there.
The cooling device also has a function of heating air for heating the vehicle interior by using cooling water as a heat source, and a function of cooling or heating the CVT fluid.
As the cooling water, long life coolant (LLC) containing water as a main component and added with additives for improving antifreeze and rust prevention properties is used.
Drawing 1 is a figure showing the composition of the cooling device of an embodiment.
In FIG. 1, the solid line arrows in the figure indicate the flow of cooling water, and the broken line arrows indicate the flow of electrical signals.

As an example, the engine 1 is a four-stroke horizontally opposed four-cylinder direct injection gasoline engine.
The engine 1 includes a cylinder block RH11, a cylinder block LH12, a cylinder head RH13, a cylinder head LH14, a throttle body 15, a water pump 16, and the like.

The cylinder block RH11 and the cylinder block LH12 are respectively arranged on the right side and the left side across a crankshaft (not shown) that is an output shaft of the engine 1.
The cylinder block RH11 and the cylinder block LH12 each have a half portion of a main bearing that rotatably supports a journal portion formed on the crankshaft.
In the cylinder block RH11, a first cylinder and a third cylinder are formed.
In the cylinder block LH12, cylinders of the second cylinder and the fourth cylinder are formed.
The cylinder block RH11 and the cylinder block LH12 are formed with a water jacket that is provided in a region on the combustion chamber side in the cylinder of each cylinder and is a water channel through which cooling water flows.

The cylinder head RH13 and the cylinder head LH14 are provided at the ends of the cylinder block RH11 and the cylinder block LH12 opposite to the crankshaft side, respectively.
The cylinder head RH13 and the cylinder head LH14 each have a combustion chamber, an intake / exhaust port, an intake / exhaust valve, a valve drive mechanism, a fuel injector, a spark plug, and the like.
The cylinder head RH13 and the cylinder head LH14 are formed with a water jacket that communicates with the water jackets of the cylinder block RH11 and the cylinder block LH12 and cools the combustion chamber and the like.
The cooling water after cooling the combustion chamber is returned into the cylinder block RH11 and the cylinder block LH12.

The throttle body 15 is a member that houses a throttle valve that adjusts the intake air amount of the engine 1.
The throttle valve is a butterfly valve provided in an intake device that introduces fresh air (combustion air) into the engine 1.
The throttle body 15 is configured to allow cooling water to flow for the purpose of preventing freezing and the like.

The water pump 16 pressurizes and discharges cooling water according to the rotation of the crankshaft of the engine 1.
The water pump 16 has a propeller (impeller) that interlocks with the crankshaft via a power transmission means such as a belt so that the discharge amount and the discharge pressure increase as the rotation speed (rotation speed) of the crankshaft increases. It has become.

  The cooling water passage of the engine 1 is further provided with a radiator 21, an EGR cooler 22, a CVT warmer 23, a heater 24, a multiflow control valve 30, and the like.

The radiator 21 is a heat exchanger provided in the front part of the vehicle body.
The radiator 21 is configured by providing a large number of fins formed of a thin plate such as an aluminum-based alloy at intervals between a plurality of tubes through which cooling water flows.
The radiator 21 cools the cooling water by exchanging heat with the airflow (traveling wind) flowing to the vehicle body during traveling.

The EGR cooler 22 is provided in an exhaust gas recirculation (EGR) device that extracts a part of exhaust gas (burned gas) from the exhaust device of the engine 1 and introduces it into the fresh air flowing through the intake device, and introduces it into the fresh air. The exhaust gas (EGR gas) is cooled.
The EGR cooler 22 is a heat exchanger that cools the EGR gas by heat conduction from the EGR gas to the cooling water.

The CVT warmer 23 heats the CVT fluid, which is a working fluid, using the cooling water of the engine 1 as a heat source in order to reduce the friction of a continuously variable transmission (CVT) that changes the output of the engine 1, and the viscosity of the CVT fluid is increased. It is to reduce.
The CVT warmer 23 is a heat exchanger that conducts heat from the cooling water to the CVT fluid.

  The heater 24 is a heat exchanger that heats air introduced into the vehicle interior by a blower fan (not shown) for heating the vehicle interior using cooling water as a heat source.

The multi-flow control valve (MCV) 30 is introduced with cooling water discharged from the main engine of the engine 1, and the cooling water is supplied to the radiator 21, the radiator flow path to the radiator 21, the heater flow path to the heater 24, and the radiator 21 and This is supplied to a bypass flow path that does not pass through the heater 24.
A part of the cooling water introduced into the multi-flow control valve 30 is always passed through the throttle body 15.
The function of the multiflow control valve 30 will be described in detail later.

Hereinafter, the structure of the flow path etc. which comprise the cooling water path of the engine 1 is demonstrated.
The cooling water discharged from the water pump 16 is first introduced into the flow path 41.
The channel 41 is branched into channels 42 to 45.
The flow path 42 introduces cooling water into the cylinder block LH12.
The flow path 43 introduces cooling water into the cylinder block RH11.
The flow path 44 introduces cooling water into the EGR cooler 22.
The channel 45 introduces cooling water into the CVT warmer 23.

The cooling water introduced into the cylinder block RH11 is introduced into the cylinder head RH13 via the flow path 46, and then returns to the cylinder block RH11 via the flow path 47.
The cooling water introduced into the cylinder block LH12 is introduced into the cylinder head LH14 via the flow path 48, and then returns to the cylinder block LH12 via the flow path 49.
The flow path 50 for discharging the cooling water from the cylinder block RH11 joins the flow path 51 for discharging the cooling water from the cylinder block LH12, and introduces the cooling water into the multi-flow control valve 30.

Channels 52 to 55 are connected to the multiflow control valve 30, respectively.
The flow path 52 is a radiator flow path for introducing cooling water from the multi-flow control valve 30 to the radiator 21.
The cooling water that has passed through the radiator 21 is returned to the inlet side of the water pump 16 via the flow path 56.

The flow path 53 is a heater flow path for introducing cooling water from the multiflow control valve 30 to the heater 24.
The cooling water that has passed through the heater 24 is returned to the inlet side of the water pump 16 via the flow path 57.

The flow path 54 is a bypass flow path that recirculates cooling water to the inlet side of the water pump 16 without passing through a heat exchanger such as the radiator 21 or the heater 24.
The cooling water discharged from the EGR cooler 22 and the CVT warmer 23 merges with the flow path 54 via the flow paths 58 and 59, respectively, and is returned to the water pump 16 via the flow path 54.

The channel 55 introduces cooling water into the throttle body 15.
The cooling water that has passed through the throttle body 15 merges with the flow path 57 via the flow path 60 and is returned to the water pump 16 via the flow path 57.

Next, the function of the above-described multiflow control valve 30 will be described in more detail.
The multi-flow control valve 30 is configured such that the opening of the radiator port to which the flow path 52 is connected, the bypass port to which the flow path 54 is connected, and the heater port to which the flow path 53 is connected is set to an electric actuator such as a stepping motor. It is possible to change by rotating a single input shaft driven by.
In addition, the port to which the flow path 55 for introducing the cooling water into the throttle body 15 is connected is normally open (water flow state).
The angular position of the input shaft of the multiflow control valve 30 will be described below as “MCV opening”.

The multi-flow control valve 30 is driven by the electric actuator so that its MCV opening substantially coincides with the target MCV opening indicated by the engine control unit 100.
The engine control unit (ECU) 100 is a control device that comprehensively controls the engine 1 and its accessories.
The engine control unit 100 includes information processing means such as a CPU, storage means such as RAM and ROM, an input / output interface, a bus connecting these, and the like.

A crank angle sensor 101 and a water temperature sensor 102 are connected to the engine control unit 100, and these output values can be acquired.
The crank angle sensor 101 is provided at one end of the crankshaft.
The crank angle sensor has a sensor plate attached to the crankshaft and formed with a plurality of teeth radially, and a magnet pickup provided to face the teeth of the sensor plate.
The crank angle sensor 101 outputs one pulse signal each time the teeth of the sensor plate pass near the sensor portion of the magnet pickup.
The engine control unit 100 calculates the rotational speed (the number of revolutions per minute) of the crankshaft based on the pulse signal output from the crank angle sensor 101.

The water temperature sensor 102 is a temperature sensor that detects the temperature of the cooling water of the engine 1.
The water temperature sensor 102 is configured using a thermistor whose resistance value changes in inverse proportion to the temperature.

FIG. 2 is a flow diagram of the multi-flow control valve in the cooling device of the embodiment.
In FIG. 2, the horizontal axis indicates the angular position (phase) of the input shaft of the multi-flow control valve 30, which is substantially equal to the angular position of the output shaft of the actuator.
Moreover, the vertical axis | shaft has each shown the opening degree of the radiator port, the bypass port, and the heater port.

As shown in FIG. 2, the MCV opening (the angular position of the input shaft of the multi-flow control valve 30) can take a value from −90 to 85 °, for example.
The radiator port is fully opened in the region where the MVC opening is −85 ° or less.
In the region of −85 ° to −50 °, the opening decreases in proportion to the increase in the MCV opening, and in the region of −50 ° to 30 °, it is fully closed.
In the region of 30 ° to 80 °, the opening increases in proportion to the increase in the MCV opening, and in the region of 80 ° or more, the opening is fully opened.

The bypass port is fully closed in the region where the MCV opening is −80 ° or less.
In the region from −80 ° to −50 °, the opening increases in proportion to the increase in the MCV opening, and is fully opened at −50 °.
In the region of −50 ° to −40 °, the valve is fully opened.
In the region from -40 ° to -5 °, the opening decreases in proportion to the increase in the MCV opening, and in the region from -5 ° to 10 °, it is fully closed.
In the range of 10 ° to 30 °, the opening increases in proportion to the increase in the MCV opening, and the opening is about 80% at 30 °.
In the region of 30 ° to 80 °, the opening decreases in proportion to the increase in the MCV opening, and in the region of 80 ° or more, it is fully closed.

The heater port is fully closed when the MCV opening is 10 ° or less.
In the region of 10 ° to 25 °, the opening increases in proportion to the increase in the MCV opening, and in the region of 25 ° or more, the opening is fully opened.

Next, control of the multiflow control valve 30 in the present embodiment will be described.
FIG. 3 is a flowchart illustrating cavitation prevention control of the multiflow control valve in the cooling device of the embodiment.
Hereinafter, the steps will be described step by step.

<Step S01: Condition Determination 1>
The ECU 100 determines whether or not the current operating state of the engine 1 satisfies the following conditions that may cause the occurrence of cavitation (whether or not it is a cavitation generation region).
MCV opening -90 ° to -80 ° (region Z1 in FIG. 2: radiator port open state, bypass port, heater port are substantially closed)
And cooling water temperature 110 degreeC or more and engine speed (NE) 5000 rpm or more It progresses to step S11, when satisfy | filling the said conditions, and when not satisfying, it progresses to step S02.

<Step S02: Condition Judgment 2>
The ECU 100 determines whether or not the current operating state of the engine 1 satisfies the following conditions that may cause the occurrence of cavitation (whether or not it is a cavitation generation region).
MCV opening -90 ° to -80 ° (region Z1 in FIG. 2: radiator port open state, bypass port, heater port are substantially closed)
And cooling water temperature 100 degreeC or more and engine speed (NE) 6000 rpm or more It progresses to step S12, when satisfy | filling the said conditions, and when not satisfying, it progresses to step S03.

<Step S03: Condition Judgment 3>
The ECU 100 determines whether or not the current operating state of the engine 1 satisfies the following conditions that may cause the occurrence of cavitation (whether or not it is a cavitation generation region).
MCV opening -50 ° to -40 ° (region Z2 in FIG. 2: both radiator port and heater port are substantially closed, bypass port is open)
And cooling water temperature 110 degreeC or more and engine speed (NE) 5000 rpm or more It progresses to step S13, when satisfy | filling the said conditions, and when not satisfying, it progresses to step S04.

<Step S04: Condition Determination 4>
The ECU 100 determines whether or not the current operating state of the engine 1 satisfies the following conditions that may cause the occurrence of cavitation (whether or not it is a cavitation generation region).
MCV opening -50 ° to -40 ° (region Z2 in FIG. 2: both radiator port and heater port are substantially closed, bypass port is open)
And cooling water temperature 100 degreeC or more and engine speed (NE) 6000 rpm or more It progresses to step S14 when the said conditions are satisfied, and when it is not satisfied, it progresses to step S05.

<Step S05: Condition Determination 5>
The ECU 100 determines whether or not the current operating state of the engine 1 satisfies the following conditions that may cause the occurrence of cavitation (whether or not it is a cavitation generation region).
MCV opening -5 ° to 30 ° (region Z3 in FIG. 2: radiator port closed state, heater port and bypass port closed state or open state)
And cooling water temperature 90 degreeC or more and engine speed (NE) 5000 rpm or more When it satisfies the said conditions, it progresses to step S15, and when not satisfying, it progresses to step S06.

<Step S06: MCV normal control>
The ECU 100 increases the opening degree of the radiator port according to an increase in the cooling water temperature, decreases the opening degree of the bypass port, and increases the opening degree of the heater port according to an increase in heating demand. Perform normal control.
Thereafter, the series of processing is terminated (returned).

<Step S11: Instructing MCV opening degree 80 °>
The engine control unit 100 sets the target opening of the multi-flow control valve 30 to 80 ° and fully opens both the radiator port and the heater port.
Thereafter, the series of processing is terminated (returned).

<Step S12: Specify 80 ° MCV opening>
The engine control unit 100 sets the target opening of the multi-flow control valve 30 to 80 ° and fully opens both the radiator port and the heater port.
Thereafter, the series of processing is terminated (returned).

<Step S13: Specify MCV opening -65 °>
The engine control unit 100 sets the target opening of the multi-flow control valve 30 to −65 °, and opens the radiator port from the fully closed state to the half open state.
Thereafter, the series of processing is terminated (returned).

<Step S14: Specify MCV opening -65 °>
The engine control unit 100 sets the target opening of the multi-flow control valve 30 to −65 °, and opens the radiator port from the fully closed state to the half open state.
Thereafter, the series of processing is terminated (returned).

<Step S15: Instructing MCV opening degree 80 °>
The engine control unit 100 sets the target opening of the multi-flow control valve 30 to 80 ° and fully opens both the radiator port and the heater port.
Thereafter, the series of processing is terminated (returned).

According to this embodiment described above, the following effects can be obtained.
(1) When the radiator port is in the closed state when the MCV opening is in the region Z1, Z2, and Z3 and the cavitation generation is concerned with high rotation and high cooling water temperature, the radiator port When the is opened, water can be passed to the radiator 21 and the hydraulic pressure can be reduced.
In particular, when the heater port is in the open state, the reliability of the heater 24 can be ensured by reducing the internal pressure of the heater 24 by opening the radiator port.
Further, when there is a concern about the occurrence of cavitation when the radiator port is in the open state and the heater port is in the closed state, by opening the heater port, the flow rate flowing through the radiator 21 is reduced, and the pressure loss generated in the radiator 21 is reduced. Occurrence of cavitation can be prevented.
Furthermore, any of these controls can be performed by using the existing function of the multiflow control valve 30, and it is not necessary to add a new device, and the reliability of the cooling device is ensured by a simple configuration. be able to.
(2) By varying the engine speed and cooling water temperature threshold values for intervening control for preventing cavitation according to the MCV opening, it is possible to optimize each threshold value and obtain an appropriate cavitation preventing effect.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) The configuration of the engine and the cooling device is not limited to the above-described embodiment, and can be changed as appropriate.
For example, the cylinder layout, the number of cylinders, the flow path configuration of the cooling water, and the like can be changed as appropriate.
Further, the present invention is not limited to a gasoline engine but can be applied to a diesel engine or other water-cooled internal combustion engine.
Furthermore, the cooling liquid is not limited to the cooling water, and may be other liquids.
(2) The flow path switching mode of the multi-flow control valve and the threshold setting such as the engine speed and the engine coolant temperature in the embodiment are merely examples, and can be changed as appropriate.

1 Engine 11 Cylinder block RH 12 Cylinder block LH
13 Cylinder head RH 14 Cylinder head LH
15 Throttle body 16 Water pump 21 Radiator 22 EGR cooler 23 CVT warmer 24 Heater 30 Multi-flow control valve (MCV)
41-60 flow path 100 engine control unit (ECU)
101 Crank angle sensor 102 Water temperature sensor

Claims (2)

A water pump that discharges coolant for cooling the engine;
A radiator flow path for returning the coolant to the water pump via a radiator;
A bypass passage for bypassing the coolant to the water pump and bypassing the radiator;
A heater flow path for returning the coolant to the water pump via a heater for heating the vehicle interior;
A multi-flow having a radiator port, a bypass port, and a heater port that introduces the coolant discharged from the water pump and supplies the coolant to the radiator flow path, the bypass flow path, and the heater flow path, respectively. A control valve,
A cooling device comprising: the radiator port in the multi-flow control valve; the bypass port; a control means for controlling the opening of the heater port;
When the radiator port is in a closed state when it is determined that the operating state of the engine is a predetermined cavitation generation region where cavitation is likely to occur in the coolant, A cooling device, wherein the port is shifted to an open state, and the heater port is shifted to an open state when the radiator port is open and the heater port is closed. The control means determines the cavitation generation region when the temperature of the coolant and the output shaft rotational speed of the engine are equal to or higher than a predetermined temperature threshold and a speed threshold, respectively, and the radiator port, the bypass 2. The cooling device according to claim 1, wherein at least one of the temperature threshold and the speed threshold is changed in accordance with a change in at least one opening state of the port and the heater port.

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