JP7170963B2 - engine cooling system - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine cooling system, and more particularly to an engine cooling system having a sensor attached to a cooling water pipe arranged laterally near an exhaust manifold.

Conventionally, a cooling system consisting of a radiator that exchanges heat with the cooling water of the engine, a bypass passage that bypasses the radiator, a thermostat that opens and closes the bypass passage, and an electric pump is provided. bypasses the radiator to warm up the engine early. When the thermostat is abnormally opened, such as when it is fully opened or half-opened, the engine is overcooled, resulting in deterioration of fuel consumption, emissions, and the like.
Therefore, failure diagnosis of the bypass function (OBD: On Board Diagnosis) is performed due to malfunction of the thermostat.

The diagnosis device of Patent Document 1 includes a thermostat that adjusts opening/closing of a bypass flow path, a water temperature sensor that detects the temperature of cooling water near the outlet of the cylinder head, and a diagnosis unit that diagnoses the state of the thermostat based on the temperature of the cooling water. The diagnostic unit executes heat radiation amount reduction control for reducing the heat radiation amount of the cooling water, and when the increase amount of the cooling water temperature becomes equal to or more than the increase threshold based on the execution of the heat radiation amount reduction control, the thermostat Diagnosing anomalies.

Normally, the open operating temperature of the thermostat is set as high as possible in consideration of fuel consumption and the like.
However, the wax-type thermostat has low responsiveness, so there is a concern that the temperature of the engine may rise transiently when the load suddenly increases even during a cold start.
Therefore, in addition to a thermostat that opens and closes the bypass passage, there is also a cooling system in which a flow rate adjustment means (electric switching valve) that can forcibly switch between the bypass passage and the water supply passage to the radiator is provided in the cooling water passage. is doing.

JP 2017-053269 A

Even when the bypass passage is provided with a flow rate adjusting means such as an on/off valve, it is necessary to perform a failure diagnosis regarding an operational abnormality and notify the user when the bypass function is abnormal, as described above.
The failure diagnosis of the flow rate adjusting means can be performed by measuring the temperature, flow rate or water pressure of cooling water flowing through the flow rate adjusting means when an operation command is input, thereby diagnosing the operating state.
However, due to the structure of the engine, there is a possibility that failure diagnosis of the flow rate adjusting means cannot be performed with high accuracy.

Due to layout requirements, when the bypass passage is arranged in the vicinity of the side of the exhaust manifold that collects the exhaust gas of the engine, the temperature, flow rate, water pressure, etc. of the cooling water flowing through the flow rate adjusting means are measured. A measurement sensor is also arranged near the exhaust manifold.
In general, a measurement sensor includes many synthetic resin parts such as a support member covering a control board, a coupler, a connector, etc., and the heat resistance limit of the synthetic resin part is approximately 120 to 130.degree.
On the other hand, the ambient temperature in the vicinity of the exhaust manifold is 200° C. or higher, and the parts arranged around the exhaust manifold are exposed to thermal radiation emitted from the exhaust manifold.
Therefore, since it is difficult to guarantee the operation of the flow rate adjusting means due to the heat damage of the sensor used for failure diagnosis, it may be difficult to perform highly accurate failure diagnosis.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an engine cooling device or the like capable of performing highly accurate fault diagnosis.

The engine cooling device according to claim 1 comprises an exhaust manifold for collecting exhaust gas of the engine, a cooling water pipe arranged from the upper side to the lower side near the side of the exhaust manifold, and the cooling water pipe. An engine equipped with a sensor for detecting the state of cooling water, a flow rate adjusting means capable of adjusting the amount of cooling water flowing through the cooling water pipe, and a mounting bracket for fixing the flow rate adjusting means to the engine. In the cooling device, the sensor is arranged above the cooling water pipe and the flow rate adjusting means is arranged below the sensor, and the mounting bracket is positioned between the exhaust manifold and the flow rate adjusting means. A heat shield member is provided between the exhaust manifold and the sensor at a position in the vertical direction corresponding to the space between the sensor and the mounting bracket .

In this engine cooling device, since the sensor is arranged above the cooling water pipe and the flow rate adjusting means is arranged below the sensor, the flow state of the cooling water linked to the operation of the flow rate adjusting means can be detected. can be detected.
Since the mounting bracket is disposed between the exhaust manifold and the flow rate adjusting means, the mounting bracket can be arranged to face the exhaust manifold while holding the flow rate adjusting means. Since a heat shielding member is provided between the exhaust manifold and the sensor at a vertical position corresponding to the space between the sensor and the mounting bracket, the heat shielding member blocks direct heat radiation from the exhaust manifold to the sensor. The heat radiation beyond the heat shield member can be guided through the mounting bracket to areas other than the sensor without being blocked.
As a result, heat damage to the sensor due to heat radiation from the exhaust manifold can be prevented.

The invention of claim 2 is the invention of claim 1, wherein the cooling water pipe is formed so as to extend from the cylinder head of the engine to one side in the front-rear direction and then curve downward, It is characterized in that heat radiation passing between the mounting brackets is directed toward the inside of the curved portion of the cooling water pipe.
According to this configuration, heat radiation can be diffused using the inside of the curved portion of the cooling water pipe.

The invention of claim 3 is characterized in that, in the invention of claim 1, the sensor is mounted in the vicinity of an upper side of a connecting portion that connects the cooling water pipe to the cylinder head .
According to this configuration, the cooling water piping is used to block heat radiation passing between the heat shield member and the mounting bracket while detecting the flow state of the cooling water interlocked with the operation of the flow rate adjusting means.

The invention of claim 4 is the invention of claim 2, wherein the cylinder head of the engine is provided with a rib portion protruding to one side in the front-rear direction, and the heat shield member is configured to shield heat radiation; and a fixing portion for fixing the main body portion to the cylinder head, and an overlapping portion that overlaps with the end portion of the main body portion to approach the cylinder head and is spaced apart from the rib portion. is characterized by
According to this configuration, the thermal radiation leaking from the gap between the heat shield member and the rib portion can be suppressed while the heat shield member and the rib portion are separated from each other.

The invention of claim 5 is characterized in that, in the invention of any one of claims 1 to 4, the sensor is a water pressure sensor.
According to this configuration, heat damage to the water pressure sensor can be prevented.

According to the engine cooling device of the present invention, highly accurate cooling water control can be performed by preventing heat damage to the sensor caused by heat radiation from the exhaust manifold.

1 is a conceptual configuration diagram of an engine cooling device according to Embodiment 1. FIG. It is a rear view of a bypass passage periphery part. It is a side view of a bypass passage periphery part. It is the figure which looked at a cylinder block, a cylinder head, and a bypass passage periphery part from the diagonally downward direction . 5 is an enlarged view of a main portion of FIG. 4; FIG. It is an overall view of the mounting bracket. It is an overall view of a heat shield member. It is a perspective view of a heat-shielding member.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail based on the drawings.
The following description exemplifies the application of the present invention to the in-line four-cylinder reciprocating engine 1, and does not limit the present invention, its applications, or its uses.

Embodiment 1 of the present invention will be described below with reference to FIGS. 1 to 8. FIG.
The engine 1 is an engine provided with a water pressure sensor 9 near an exhaust manifold 11 for use in fault diagnosis of the cooling system. First, the cooling system of the engine 1, which is a premise, will be described.
As shown in FIG. 1, the cooling system of the engine 1 includes a first circulation route R1 through which cooling water of the engine 1 flows during normal operation, a warm-up route R2 through which cooling water of the engine 1 flows during warm-up operation, and a normal operation. It has three main components, namely, an ATF (Automatic Transmission Fluid) 7 of the automatic transmission and a second circulation route R3 through which the cooling water of the oil cooler 8 flows.

The first circulation route R1 will be explained.
The first circulation route R1 includes a water supply passage L1, a radiator 4, and a water return passage L2.
A water jacket (not shown) of the cylinder head 2 of the engine 1 communicates with the radiator 4 in the water supply passage L1, and a switching valve 5 (flow rate adjusting means) is provided in the middle.
The switching valve 5 is an on/off valve that can electrically switch the flow direction of cooling water between the water supply passage L1 and a bypass passage B described later based on the temperature of the flowing cooling water. For example, when the cooling water is 90° C. or higher, it is turned off to communicate the water supply passage L1 and block the bypass passage B, and when the cooling water is below 90° C., it is turned on to communicate the bypass passage B and supply water. It blocks the passage L1.
Note that the switching valve 5 is turned off as a steady state. Also, as an exceptional operation when cold, even if the cooling water is less than 90° C., the off operation is performed in the transient operating state.

The water return passage L2 communicates the radiator 4 with an electric pump 6 connected to a water jacket (not shown) of the cylinder block 3 of the engine 1 .
A first thermostat S1 is provided between the radiator 4 and the electric pump 6 in the water return passage L2. For example, the first thermostat S1 fluidly communicates with the water return passage L2 when the cooling water is 90°C or higher, and closes the water return passage L2 when the cooling water is below 90°C.
During normal operation, the cooling water that flows from the water jacket of the cylinder block 3 to the water jacket of the cylinder head 2 flows from the cylinder head 2 to the water supply passage L1, passes through the switching valve 5, and reaches the radiator 4. The cooling water that has exchanged heat with the running air flows through the water return passage L2 and reaches the electric pump 6, and then is pressure-fed toward the water jacket of the cylinder block 3.

Next, the warm-up route R2 will be explained.
As shown in FIG. 1, the warm-up route R2 includes a bypass passage B that communicates the middle portion (the switching valve 5) of the water supply passage L1 and the middle portion (the electric pump 6) of the water return passage L2. This bypass passage B is connected between the first thermostat S1 and the electric pump 6 of the water return passage L2.
During warm-up operation such as cold start, the cooling water flowing from the cylinder head 2 is guided to the bypass passage B through the switching valve 5 . After bypassing the radiator 4 , the cooling water flows through the water return passage L<b>2 and reaches the electric pump 6 , and then is pressure-fed toward the water jacket of the cylinder block 3 .

Next, the second circulation route R3 will be explained.
The second circulation path R3 includes an ATF passage L3 that communicates the water jacket of the cylinder head 2 and the electric pump 6 with each other. A second thermostat S2, an ATF 7, and an oil cooler 8 are provided in the middle of the ATF passage L3.
For example, the second thermostat S2 fluidly communicates with the ATF passage L3 when the cooling water is 60°C or higher, and closes the ATF passage L3 when the cooling water is below 60°C.
During normal operation, the cooling water flowing from the cylinder head 2 to the ATF passage L3 reaches the oil cooler 8 after passing through the ATF 7 . The cooling water heat-exchanged by the ATF 7 and the oil cooler 8 reaches the electric pump 6 and is pressure-fed toward the water jacket of the cylinder block 3 .

In the engine 1, failure diagnosis (OBD: On Board Diagnosis) of the bypass function caused by an operation abnormality of the switching valve 5 is performed.
A temperature sensor (not shown) that detects the temperature of cooling water in the vicinity of each connecting portion of the water supply passage L1 and the water return passage L2 in the cylinder head 2, a load sensor (not shown) that detects the load of the engine 1, and a switching valve. A water pressure sensor 9 for detecting the cooling water pressure on the upstream side of 5 is provided.
The measured values detected by each sensor are input to an ECU (Electronic Control Unit), and an OFF operation command signal is output to the switching valve 5 when an OFF operation condition for the switching valve 5 is satisfied.
In addition, the ECU compares the pressure of the cooling water flowing in the bypass passage B with a determination threshold value in parallel with the switching valve 5 OFF operation, and if the cooling water pressure is higher than the determination threshold value, the switching valve 5 malfunctions. is reported.

Next, the peripheral structure of the bypass passage B will be described.
As shown in FIGS. 2 to 5, a switching valve 5, an electric pump 6, an exhaust manifold 11, a rubber pipe 12, a bypass passage B, and the like are arranged at the rear of the engine 1. FIG.
The electric pump 6 is arranged at the rear left end of the cylinder block 3 so that the rotating shaft extends back and forth . In the following description, the direction of arrow F is forward, the direction of arrow L is left, the direction of arrow R is right, and the direction of arrow U is upward.

The switching valve 5 is formed in a substantially cylindrical shape, and the axial extension line thereof is disposed so as to slope upward to the right .
As shown in FIG. 2, the switching valve 5 has an inflow portion 5a at its rear end, a first outflow portion 5b at its front end, a second outflow portion 5c at its lower rear end, and an intermediate portion. and a pair of upper and lower flange portions 5d. The first outflow portion 5b communicates with the radiator 4 through the water supply passage L1, and the second outflow portion 5c communicates with the introduction portion of the electric pump 6 through the bypass passage B. As shown in FIG.

As shown in FIGS. 2 to 5, the switching valve 5 is fastened and fixed to the electric pump 6 via a mounting bracket 13 made of sheet metal. The mounting bracket 13 is arranged vertically below the water pressure sensor 9 . As shown in FIG. 6, the mounting bracket 13 includes a mounting surface portion 13a to which the switching valve 5 is mounted, a fixing portion 13b for fixing the mounting surface portion 13a to the engine 1, a reinforcing bead portion 13c, and the like. .

The mounting surface portion 13a has an inclined flat plate structure so as to cover the entire front portion of the switching valve 5, and shifts leftward toward the bottom so as to intersect the left-right direction.
The mounting surface portion 13a is provided with a pair of upper and lower bolt holes corresponding to the pair of flange portions 5d of the switching valve 5, respectively, and the switching valve 5 is fastened via a pair of bolts.
The fixing portion 13b extends from the right end portion of the mounting surface portion 13a and has a pair of bolt holes. The fixed portion 13b is fastened to a pair of boss portions formed on the front edge of the electric pump 6 via a pair of bolts.
The bead portion 13c is formed to extend forward in a substantially J-shape from the central position of the rear portion of the fixing portion 13b to the intermediate position of the mounting surface portion 13a.
As a result, the mounting bracket 13 is interposed between the switching valve 5 and the exhaust manifold 11 to block heat radiation from the exhaust manifold 11 toward the switching valve 5 .

As shown in FIGS. 2 to 4, the exhaust manifold 11 is connected to four exhaust openings formed in the left wall of the cylinder head 2, and collects exhaust gas from each exhaust opening.
Exhaust gas discharged from each exhaust opening is once collected in a collection portion corresponding to the rear side exhaust opening, and the collected exhaust gas is guided vertically downward.
The exhaust manifold 11 is formed by welding together three parts made by pressing a metal plate material. Specifically, it is composed of an upper half portion 11a, a substantially L-shaped lower half portion 11b, and a substantially I-shaped rear lower half portion 11c.

As shown in FIG. 2, the pipe 12 constitutes a part of the water supply passage L1, extends leftward near the rear side of the exhaust manifold 11, and has a curved portion that curves from the top to the bottom. Configure. The pipe 12 communicates a connecting portion 14 made of synthetic resin, which is connected to the rear left end portion of the cylinder head 2 and protrudes leftward , and the inflow portion 5 a of the switching valve 5 .
Incidentally, the pipe 12 and the connecting portion 14 correspond to the cooling water pipe of the present invention.

A connector to which a water pressure sensor 9 for measuring the pressure of cooling water can be attached is integrally formed on the upper outer periphery of the connecting portion 14 . The water pressure sensor 9 is positioned above the pipe 12 and the connecting portion 14 when attached to the connector of the connecting portion 14 .
As shown in FIGS. 2 to 5, a heat shield member 15 is arranged between the water pressure sensor 9 and the exhaust manifold 11 to block thermal radiation emitted from the exhaust manifold 11. As shown in FIGS.

The heat shield member 15 is formed by pressing a metal plate.
The heat shield member 15 is arranged between the water pressure sensor 9 and the exhaust manifold 11 at a vertical position between the water pressure sensor 9 and the mounting bracket 13 .
Also, the heat shield member 15 is arranged between the water pressure sensor 9 and the exhaust manifold 11 in the left-right direction.

This blocks direct heat radiation emitted from the exhaust manifold 11 toward the water pressure sensor 9 . In addition, since the mounting surface portion 13a of the mounting bracket 13 shifts to the left as it goes down, heat radiation that has passed below the heat shield member 15 is reflected to the left of the water pressure sensor 9 (see the dashed arrow in FIG. 5), or It passes through the inside of the curved portion of the pipe 12 and is reflected to the right of the water pressure sensor 9 (see the dotted line arrow in FIG. 5).
Heat radiation passing between the heat shield member 15 and the mounting bracket 13 and reflected vertically upward by the mounting bracket 13 is blocked by the piping 12 and diffused to the left or right of the water pressure sensor 9. there is

As shown in FIGS. 7 and 8, the heat shield member 15 includes a body portion 15a for shielding heat radiation, a fixing portion 15b for fixing the body portion 15a to the cylinder head 2, and a front end portion of the body portion 15a. and a folded portion 15d formed at the lower end of the main body portion 15a.

The main body portion 15a is formed in a substantially trapezoidal shape, and is bent along a bending line extending in the front-rear direction of the middle portion in the vertical direction.
The fixing portion 15b is formed by bending the lower front end portion of the main body portion 15a to the right. The fixed portion 15b is fastened and fixed to a boss portion 2a projecting rearward from the rear wall portion of the cylinder head 2 via a bolt.

As shown in FIGS. 7 and 8, the overlapping portion 15c is formed by bending the upper front end portion of the body portion 15a into a crank shape. The overlapping portion 15c is arranged so as to overlap in the left-right direction while being separated from the reinforcing rib portion 2b that protrudes rearward from the rear wall portion of the cylinder head 2 and extends vertically. As a result, while preventing contact noise between the heat shield member 15 and the rib portion 2b, heat radiation passing through the gap between the heat shield member 15 and the rib portion 2b is suppressed (see the dashed arrow in FIG. 8). .
The folded portion 15d is formed so as to bend the lower end portion of the main body portion 15a to the right.
As a result, the heat radiation passing below the heat shield member 15 is guided toward the mounting bracket 13 (see the dotted line arrow in FIG. 8).

Next, the operation and effect of the engine cooling device will be described.
According to this engine 1 cooling device, since the water pressure sensor 9 is arranged above the connecting portion 14 connected to the pipe 12 and the switching valve 5 is arranged below the water pressure sensor 9, the switching valve 5 is operated. It is possible to detect the flow state of the cooling water interlocked with.
Since the mounting bracket 13 is arranged between the exhaust manifold 11 and the switching valve 5 , the mounting bracket 13 can be arranged to face the exhaust manifold 11 while holding the switching valve 5 . Since the heat shielding member 15 is provided between the exhaust manifold 11 and the water pressure sensor 9 and between the water pressure sensor 9 and the mounting bracket 13, direct heat radiation proceeding from the exhaust manifold 11 to the water pressure sensor 9 is blocked by the heat shielding member. 15 can be blocked, and the heat radiation beyond the heat shield member 15 without being blocked can be guided to an area other than the water pressure sensor 9 via the mounting bracket 13 .
As a result, heat damage to the water pressure sensor 9 caused by heat radiation from the exhaust manifold 11 can be prevented.

The pipe 12 is formed so as to extend rearward from the cylinder head 2 of the engine 1 and then curve downward. Since it is formed so as to point inward, heat radiation can be diffused using the inside of the curved portion of the pipe 12 .

Since the water pressure sensor 9 is attached to the upper outer periphery of the connecting portion 14 (pipe 12), the coolant passes between the heat shield member 15 and the mounting bracket 13 while detecting the flow state of the cooling water interlocked with the operation of the switching valve 5. A pipe 12 is used to block the heat radiation.

A cylinder head 2 of an engine 1 is provided with a rib portion 2b protruding rearward, and a heat shield member 15 is provided with a body portion 15a for shielding heat radiation, and the body portion 15a is connected to the body portion 15a and fixed to the cylinder head 2. and the overlapping portion 15c that overlaps with the rib portion 2b while approaching the cylinder head 2 from the front end portion of the body portion 15a and separating from the rib portion 2b. It is possible to suppress thermal radiation leaking from the gap between the heat shield member 15 and the rib portion 2b while separating them.

Since the sensor is the water pressure sensor 9, heat damage to the water pressure sensor 9 can be prevented, and fault diagnosis of the cooling system can be performed with high accuracy.

Next, a modified example in which the above embodiment is partially changed will be described.
1) In the above embodiment, an example of a water pressure sensor capable of measuring the pressure of cooling water has been described. It may be applied to a temperature sensor that detects temperature or a flow rate sensor that detects the flow rate of cooling water.
Also, although an example of the sensor arranged near the right side of the exhaust manifold has been described, the arrangement position is not limited, and the sensor may be arranged on the left side, the upper side, or the lower side.

2) In the above-described embodiment, the mounting bracket and the heat shield member have been described as dedicated parts, but other functions may be provided. Alternatively, the mounting bracket and the heat shield may be constructed as a single component. In this case, heat radiation passing between the mounting bracket and the heat shield member can be eliminated.

3) In the above embodiment, an example in which the switching valve is configured as an on/off valve has been described, but a flow rate adjusting valve that can linearly adjust the flow rate may be used.

4) In addition, without departing from the spirit of the present invention, a person skilled in the art can implement the above-described embodiment in a form in which various modifications are added or in a form in which each embodiment is combined. Any modifications are also included.

1 Engine 2 Cylinder head 2b Rib portion 5 Switching valve 9 Water pressure sensor 11 Exhaust manifold 12 Piping 13 Mounting bracket 14 Connecting portion 15 Heat shielding member 15a Body portion 15b Fixed portion 15c Overlapping portion

Claims (5)

An exhaust manifold that gathers the exhaust gas of the engine, a cooling water pipe arranged from the upper side to the lower side in the vicinity of the side of the exhaust manifold, and attached to the cooling water pipe to detect the state of the cooling water. A cooling device for an engine comprising: a sensor for cooling water, a flow rate adjusting means capable of adjusting the amount of cooling water flowing through the cooling water pipe, and a mounting bracket for fixing the flow rate adjusting means to the engine,
The sensor is arranged above the cooling water pipe and the flow rate adjusting means is arranged below the sensor,
the mounting bracket is disposed between the exhaust manifold and the flow control means;
An engine cooling device , wherein a heat insulating member is provided between the exhaust manifold and the sensor at a vertical position corresponding to the space between the sensor and the mounting bracket . the cooling water pipe is formed so as to extend from the cylinder head of the engine to one side in the front-rear direction and then curve downward;
2. The engine cooling system according to claim 1, wherein the heat radiation passing between the heat shield member and the mounting bracket is directed toward the inside of the curved portion of the cooling water pipe. 3. An engine cooling system according to claim 1, wherein said sensor is mounted near an upper side of a connecting portion connecting said cooling water pipe to said cylinder head . The cylinder head of the engine is provided with a rib protruding to one side in the front-rear direction,
The heat shield member includes a main body portion for shielding heat radiation, a fixing portion connected to the main body portion and for fixing the main body portion to the cylinder head, and an end portion of the main body portion that approaches the cylinder head. 3. The engine cooling device according to claim 2, further comprising an overlapping portion that overlaps with the rib portion while being separated from the rib portion. The engine cooling system according to any one of claims 1 to 4, wherein the sensor is a water pressure sensor.

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