JP7167499B2 - vehicle - Google Patents

Description

The present invention relates to vehicles.

Vehicles such as automobiles are known to have a cooling system having a thermostat, a radiator, and the like for cooling a power source such as an engine.
In such a cooling system, a thermostat is generally used to control whether or not the cooling water flows through the radiator in order to adjust the temperature of the cooling water that cools the power source. , the temperature control may not be successful.
Therefore, there is known a configuration in which failure diagnosis means is provided to perform failure diagnosis of the thermostat using the temperature of cooling water flowing in the cooling system (see, for example, Patent Documents 1 and 2).

On the other hand, in order to adjust the temperature of cooling water flowing in the radiator, there is known a configuration in which an openable and closable grille shutter is provided on the front side of the vehicle and the opening and closing state is controlled (see, for example, Patent Documents 1 to 3, etc.). ).
By the way, especially in a vehicle equipped with an engine, a configuration is known in which control processing called fuel cut is performed to improve fuel efficiency by stopping fuel supply when the engine is stopped. During such a fuel cut, the temperature of the cooling water tends to drop gradually, but if the cooling water flows to the radiator side due to a thermostat failure, the cooling water temperature will drop too much. There is a risk that it will occur.

JP 2017-171138 A JP 2015-129460 A JP 2017-137814 A

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thermostat failure diagnosis means capable of high detection accuracy even when a grille shutter is also used.

A vehicle according to claim 1 of the present invention includes a radiator for cooling cooling water of an engine mounted on the vehicle, and a grille shutter disposed in front of the radiator for opening and closing a grill disposed on the vehicle. a thermostat that switches the flow path of the cooling water between a flow path that passes through the radiator and a flow path that does not pass through the radiator; temperature detection means for detecting the actual temperature of the cooling water; a failure determination means for determining a failure of the thermostat based on the change in the actual temperature, and performing a fuel cut to stop the fuel supply to the engine while the vehicle is running, The failure determination means keeps the grille shutter closed during the fuel cut, and performs failure determination of the thermostat during the continuation of the fuel cut so that the actual temperature exceeds the valve opening temperature of the thermostat. The failure determination is performed when the fuel cut is performed in this state .

A vehicle according to claim 2 of the present invention is the vehicle according to claim 1, wherein the failure determination means detects the cooling water when the pre-set estimated temperature of the cooling water becomes equal to or lower than a predetermined value. The failure determination is performed based on the actual temperature of water and the estimated temperature.

A vehicle according to claim 3 of the present invention is the vehicle according to claim 1 or 2, wherein the failure determination means determines whether the thermostat is turned on within a predetermined time after the estimated temperature becomes equal to or lower than a predetermined value. The failure determination is a primary failure determination, and the thermostat failure determination performed when the fuel cut is completed and the estimated temperature reaches or exceeds a predetermined value is a secondary failure determination.

A vehicle according to claim 4 of the present invention is the vehicle according to claim 3, wherein the grille shutter is opened when the fuel cut is completed.

A vehicle according to claim 5 of the present invention is the vehicle according to claim 3 or 4, wherein the failure determination means determines that the difference between the actual temperature and the estimated temperature of the cooling water in the primary failure determination is The secondary failure determination is omitted when the value is equal to or greater than a predetermined value.

According to the present invention, it is possible to provide thermostat failure diagnosis means with high detection accuracy even when a grille shutter is also used.

It is a figure showing an example of a part of composition of vehicles as an embodiment of the present invention. 2 is a diagram showing an example of a functional configuration of a control unit shown in FIG. 1; FIG. It is a figure which shows an example of the temperature control of the cooling water using a thermostat. It is a figure which shows an example of the temperature control and grill shutter control in this embodiment. FIG. 4 is a flow chart showing an example of operation of a control unit;

Hereinafter, as an embodiment of the present invention, a vehicle 100 equipped with a fault diagnosis means 30 for a thermostat 20 will be described.
In the present embodiment, detailed descriptions of the functions and operations of the internal combustion engine, steering, and other parts of the vehicle that are not directly related to the present invention will be omitted as appropriate. Also, in this embodiment, a case where a water-cooled engine is used as a drive source will be described in particular, but the configuration is not limited to such a configuration, and a configuration in which a thermostat is used to control the temperature of water or other coolants may be used. .

As shown in FIG. 1, the vehicle 100 includes an engine 11 as a drive source, a flow path 12 through which cooling water Q for cooling the engine 11 flows, and cooling the cooling water Q by allowing the cooling water Q to pass through. and a radiator 13 .
The vehicle 100 also includes a grille shutter 21 for opening and closing the grill in front of the radiator 13 , and a flow path 12 a for the cooling water Q passing through the radiator 13 and a flow path 12 b not passing through the radiator 13 . and a switching thermostat 20 . The grille shutter 21 is opened and closed to adjust the running wind supplied to the radiator, thereby contributing to temperature control of the radiator.
The vehicle 100 also includes a vehicle speed sensor 80, an automatic transmission 15 for transmitting power from the engine 11 to the tires 14, a pump 16 as a circulator for circulating the cooling water Q in the flow path 12, and an ECU 90 that is a control unit that controls each part of the vehicle 100 .

The ECU 90 has a function as a control section for controlling the vehicle 100, and is a microcomputer centering on a CPU.
The ECU 90 includes, as shown in FIG. and a failure determination means 30 for performing determination.
Further, the function of the ECU 90 is not limited to such a configuration, and may control the rotation of the engine 11 and the fan attached to the radiator 13, for example.

The thermostat 20 is provided at the junction of the flow paths 12a and 12b, and functions as flow path switching means for switching between the flow paths 12a and 12b.
Specifically, the thermostat 20 opens the flow passage 12a side so that the cooling water Q flows to the radiator 13 on the condition that the actual temperature or the estimated water temperature of the cooling water Q reaches a predetermined thermostat valve opening temperature T1. Control to flow in.
The estimated water temperature here is the water temperature estimated from the amount of heat generated by the engine and the amount of heat released from the engine. The failure determination means 30 determines whether the actual water temperature reaches a predetermined value at the time t0 when the estimated water temperature reaches a predetermined value, for example, the thermostat valve opening temperature T1, or at a time after a predetermined time Δt from the time t0. Temporary failure determination is performed by referring to That is, if the deviation between the estimated water temperature and the actual water temperature is large, it is determined to be faulty, and if the deviation between the estimated water temperature and the actual water temperature is small, it is determined to be normal. Note that the actual temperature of the cooling water is detected based on the temperature detection means, specifically the temperature sensor.
Especially in this embodiment, the trigger for failure determination is "when the estimated water temperature reaches the thermostat valve opening temperature T1". This is synonymous with checking whether the actual water temperature at the time has reached a predetermined value, but the configuration is not limited to this.
Note that the thermostat valve opening temperature T1 may be any designed temperature, but may be 77° C., for example.

The radiator 13 is a heat exchanger that exchanges the heat of the cooling water Q with the outside air via the surface of the radiator 13 as the cooling water Q flows inside.
In this embodiment, when the grille shutter 21 is in the open state, the flow rate of air hitting the surface of the radiator 13 increases, thereby improving the cooling performance.
On the other hand, when the grille shutter 21 is closed, the flow rate of air hitting the surface of the radiator 13 is reduced, so the cooling performance is reduced compared to when it is open.

In a normal state, the grille shutter 21 opens and closes according to the vehicle speed, adjusts the temperature of the cooling water Q, and reduces the air resistance of the vehicle 100 to contribute to the improvement of fuel efficiency.
Specifically, in the closed state, the aerodynamic characteristics of vehicle 100 are improved, and in the open state, the air resistance of vehicle 100 increases while the cooling performance of radiator 13 improves.

In this embodiment, the drive control unit 91 stops the supply of fuel to the engine 11 when the rotation of the engine 11 is not required during normal running, that is, when the accelerator is not depressed. make a cut.
During such a fuel cut, the rotation of the engine 11 is stopped, so the temperature of the cooling water Q gradually decreases as shown in FIG.
For example, when the vehicle 100 is running, the fuel cut is started when the foot is removed from the accelerator on a downhill or the like, and can be terminated at an arbitrary time by a driver's operation such as stepping on the accelerator of the vehicle 100. can. Under what trigger condition the fuel cut is performed may be appropriately changed depending on the design, but in general, it is determined by the number of revolutions of the engine 11 and whether or not the accelerator is operated.

It is more desirable that the grille shutter 21 is closed during such fuel cut. This is because if the temperature of the cooling water Q drops excessively, the time until the accelerator is depressed and the engine 11 warms up again becomes longer.
Therefore, in the present embodiment, the grille shutter control unit 92 forcibly closes the grille shutter 21 during the fuel cut, thereby suppressing the temperature drop of the cooling water Q and improving the aerodynamic characteristics. to control.

Now, in a normal state where all devices are operating normally, the ECU 90 controls the opening and closing of the grill shutter 21 and the thermostat 20 based on the estimated water temperature or the actual water temperature as shown in FIG. there is The temperature of the cooling water Q is controlled by opening and closing the grill shutter 21 and the thermostat 20 .

In such a case, a method of determining a failure by the failure determining means 30 when the vehicle 100 is in the fuel cut state will be described with reference to FIGS. 4 and 5. FIG.

Now, when the vehicle 100 shifts to fuel cut, it is considered that the engine 11 is always running and the temperature of the cooling water Q is maintained at a predetermined value or higher.
Therefore, in FIG. 4, for the sake of simplicity of explanation, the vehicle 100 is running, and both the estimated water temperature and the actual water temperature of the cooling water Q start from a running state, and the temperature of the cooling water Q decreases. (Section A in FIG. 4), the section from when the estimated water temperature of cooling water Q falls below a predetermined value to when the accelerator is depressed and the fuel cut ends (section B in FIG. 4), the estimated water temperature of cooling water Q A driving state of the vehicle 100 that transitions between the sections A to D, that is, the section (C section) until the temperature rises and reaches the predetermined value again (section C) and the section that returns to normal driving (D section). However, it is not limited to such operation.

In the initial state, the vehicle 100 is in a running state, and the thermostat 20 is in an open state because the actual water temperature of the cooling water Q is sufficiently high. Since the engine 11 is stopped during the fuel cut, the actual water temperature of the cooling water Q gradually decreases (see section A in FIG. 4 in particular).
When the ECU 90 detects that the estimated water temperature has fallen below the thermostat valve opening temperature T1 (step S101), it instructs the thermostat 20 to close (step S102).

Substantially simultaneously with the instruction to close the thermostat 20 in step S102, the grille shutter 21 is forcibly closed (step S103). This is because when the thermostat 20 is closed, it is not necessary to open and close the grille shutter 21, and the closed state of the grille shutter 21 improves the aerodynamic characteristics of the vehicle 100. FIG.

Now, when the thermostat 20 is operating normally, it is considered that the water temperature estimated value and the actual water temperature change as indicated by the dashed line as normal after the valve closing instruction is issued in step S102.
However, if the thermostat 20 is stuck open, the coolant Q flows into the radiator 13, which should not flow. The deviation ΔT from the water temperature gradually widens (especially see section B in FIG. 5).
Therefore, at the primary failure determination time t1 after a predetermined time Δt after the estimated water temperature of the cooling water Q becomes equal to or lower than the thermostat valve opening temperature T1, the failure determination means 30 determines the primary failure as a provisional failure determination. Failure determination is performed (step S104).
In step S104 at the primary failure determination time t1, if the difference ΔT between the actual water temperature and the estimated water temperature is equal to or greater than a predetermined value, it is determined that the thermostat 20 is stuck open. The deviation ΔT, which is such a predetermined value, can take various designed values depending on the amount of cooling water Q, the amount of heat generated from the engine 11, and the like. Here, a method of diagnosing the failure of the thermostat 20 in consideration of the deviation ΔT between the actual water temperature and the estimated water temperature has been described. You may carry out an abnormality diagnosis of the thermostat. Specifically, the behavior of the actual water temperature when the thermostat is normal is stored, and when the behavior of the temperature change greatly deviates from the normal behavior, it is determined that the thermostat has a failure.
In step S104, if the difference ΔT between the actual water temperature and the estimated water temperature is smaller than a predetermined value, the failure determining means 30 determines that the thermostat 20 is operating normally, and processes and controls the normal state. is continued (step S201).

In the primary failure determination in step S104, as is clear from FIG. 4, the failure is determined with the grille shutter 21 kept closed at a time before the primary failure determination time t1.
That is, the failure determination means 30 of the present embodiment closes the grille shutter 21 during the fuel cut, and when the estimated water temperature of the cooling water Q is equal to or lower than the thermostat valve opening temperature T1, which is a predetermined value, during the continuation of the fuel cut. If so, the thermostat 20 is determined to be faulty.
With such a configuration, it is possible to provide the failure diagnosis means 30 for the thermostat 20 with high detection accuracy even when the grille shutter 21 is used together with the radiator 13 .

In step S104, when the failure determining means 30 determines that the thermostat 20 is out of order, that is, when the branch of step S104 is No, the process proceeds to step S105 to confirm the failure determination.
Specifically, when the accelerator is stepped on and the rotation of the engine 11 increases (step S105), the grille shutter control section 91 causes the grille shutter 21 to open (step S106).
When the rotation speed of the engine 11 increases and the water temperature estimated value of the cooling water Q again exceeds the thermostat valve opening temperature T1, the failure determination means 30 performs secondary failure determination (step S107). The time t2 at which the secondary failure determination is performed is defined as the secondary failure determination time, and the shutter valve opening time t3 at which the grille shutter 21 is shifted to the open state is a predetermined time Δt′ before the secondary failure determination time t2. is the time of

Thus, by opening the grille shutter 21 in step S106, the secondary failure is determined at the secondary failure determination time t2 in step S107 using the water temperature estimated value including the case where the grille shutter 21 is open. It can be performed.
That is, the failure determination means 30 of the present embodiment reverses the open/closed state of the grille shutter 21 for the primary failure determination and the secondary failure determination, and performs the failure determination twice. can be done.

In step S107, when the difference ΔT between the actual water temperature of the cooling water Q and the water temperature estimated value is smaller than a predetermined value, the failure determination means 30 determines that the thermostat 20 is operating normally, and performs normal state processing. - Control is continued (step S201).
In step S107, when the deviation .DELTA.T between the actual water temperature of the cooling water Q and the estimated water temperature is equal to or greater than a predetermined value, the failure determining means 30 determines that the thermostat 20 is out of order (step S108).
When the failure determination is confirmed in step S108, the ECU 90 may notify the driver that the thermostat 20 is in a failure state by turning on a display or the like (step S109).
The result of such failure determination may be notified to the driver by a display (not shown) or the like mounted on the vehicle 100, or the failure notification may be communicated via a network or the like.
When the failure determination process ends, the ECU 90 returns the control of the grille shutter 21 to the normal control state (see section D in FIG. 4) and terminates the failure determination process.

In the present embodiment, the time required from the primary failure determination time t1 to the secondary failure determination time t2 is determined based on the condition that the water temperature estimated value reaches a predetermined value. It may be determined by the deviation ΔT between the estimated water temperature at t1 and the actual water temperature. Note that the reference value of the predetermined time Δt may be set to any value according to the configuration of the thermostat 20 and the radiator 13 .
Here, when the difference between the water temperature estimated value and the actual water temperature at the primary failure determination time t1 is large, it can be said that the water temperature cannot be correctly estimated at the primary failure determination time t1, so the possibility of failure is higher. , in other words, it is considered that the temperature control is not going well.
Therefore, when the deviation .DELTA.T is large, it is considered that the diagnostic accuracy of the primary failure determination is high. Therefore, as shown in FIG. 6, the secondary failure determination may be omitted. With such a configuration, the time required for the grille shutter 21 to return to normal control is shortened, so the aerodynamic characteristics of the vehicle 100 are improved, contributing to an improvement in fuel efficiency and the like.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and unless otherwise limited in the foregoing description, the present invention is set forth in the appended claims. Various modifications and changes are possible within the scope of the spirit.
For example, in the present embodiment, only the case of a vehicle having an engine has been described, but it may also be used in a hybrid vehicle or the like that uses a motor and an engine as drive sources.

The effects described in the embodiments of the present invention are merely enumerations of the most suitable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

DESCRIPTION OF SYMBOLS 11... Engine, 12... Flow path, 12a... Flow path which passes through a radiator, 12b... Flow path which does not pass through a radiator, 20... Thermostat, 21... Grille shutter, 30... Failure determination means, 100... Vehicle

Claims (9)

a radiator for cooling cooling water for an engine mounted on a vehicle;
a grill shutter disposed in front of the radiator for opening and closing a grill disposed on the vehicle;
a thermostat that switches the flow path of the cooling water between a flow path that passes through the radiator and a flow path that does not pass through the radiator;
temperature detection means for detecting the actual temperature of the cooling water;
failure determination means for performing failure determination of the thermostat based on the change in the actual temperature detected by the temperature detection means;
A vehicle that performs a fuel cut to stop fuel supply to the engine while the vehicle is running,
The failure determination means is
while holding the grille shutter closed during the fuel cut, and determining a failure of the thermostat while the fuel cut continues ;
A vehicle , wherein the failure determination is performed when the fuel cut is performed in a state where the actual temperature is equal to or higher than a valve opening temperature of the thermostat . A vehicle according to claim 1,
The failure determination means performs the failure determination based on the actual temperature of the cooling water and the estimated temperature when the preset estimated temperature of the cooling water becomes equal to or lower than the valve opening temperature of the thermostat. A vehicle characterized by: A vehicle according to claim 2 ,
The failure determination means regards a failure determination of the thermostat performed within a predetermined time period after the estimated temperature becomes equal to or lower than a predetermined value as a primary failure determination, and the estimated temperature becomes equal to or higher than the predetermined value after the fuel cut is completed. A vehicle characterized in that the failure determination of the thermostat that is performed when a second failure is determined is a secondary failure determination. A vehicle according to claim 3,
A vehicle, wherein the grille shutter is opened when the fuel cut is completed. A vehicle according to claim 3 or 4,
The vehicle, wherein the failure determination means omits the secondary failure determination when a difference between the actual temperature of the cooling water and the estimated temperature is equal to or greater than a predetermined value in the primary failure determination. a radiator for cooling cooling water for an engine mounted on a vehicle;
a grill shutter disposed in front of the radiator for opening and closing a grill disposed on the vehicle;
a thermostat that switches the flow path of the cooling water between a flow path that passes through the radiator and a flow path that does not pass through the radiator;
temperature detection means for detecting the actual temperature of the cooling water;
failure determination means for performing failure determination of the thermostat based on the change in the actual temperature detected by the temperature detection means;
A vehicle that performs a fuel cut to stop fuel supply to the engine while the vehicle is running,
The failure determination means is
while holding the grille shutter closed during the fuel cut, and determining a failure of the thermostat while the fuel cut continues;
A vehicle according to claim 1, wherein the failure determination is performed based on the actual temperature of the cooling water and the estimated temperature when the preset estimated temperature of the cooling water becomes equal to or lower than a predetermined value. A vehicle according to claim 6,
The failure determination means regards a failure determination of the thermostat performed within a predetermined time period after the estimated temperature becomes equal to or lower than a predetermined value as a primary failure determination, and the estimated temperature becomes equal to or higher than the predetermined value after the fuel cut is completed. A vehicle characterized in that the failure determination of the thermostat that is performed when a second failure is determined is a secondary failure determination. A vehicle according to claim 7,
A vehicle, wherein the grille shutter is opened when the fuel cut is completed. A vehicle according to claim 7 or 8,
The vehicle, wherein the failure determination means omits the secondary failure determination when a difference between the actual temperature of the cooling water and the estimated temperature is equal to or greater than a predetermined value in the primary failure determination.

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