JP2012241610A - Cooling device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a piston beating sound in an internal combustion engine.SOLUTION: A cooling device of the internal combustion engine includes a cylinder head water jacket and a cylinder block water jacket in which cooling water pressure-fed by a water pump circulates, a control valve controlling a communicated condition between the cylinder head water jacket and the cylinder block water jacket, a piston beating sound detecting means detecting the occurrence of the piston beating sound emitted by a piston sliding in a cylinder formed in a cylinder block, and a control part opening the control valve and making the cylinder head water jacket and the cylinder block water jacket communicated when the occurrence of the piston beating sound is detected or estimated by the piston beating sound detecting means.

Description

  The present invention relates to a cooling device for an internal combustion engine.

  Conventionally, various proposals for the purpose of early warm-up of an internal combustion engine have been made. For example, a proposal to promote engine warm-up while suppressing local temperature rise around the cylinder and partial boiling of cooling water by controlling the flow of cooling water in the water jacket inside the engine body after a cold start. (See Patent Document 1).

JP 2006-214280 A

  By the way, the piston that slides in the cylinder may emit piston hitting sound if the temperature distribution in the sliding direction of the cylinder block is non-uniform. That is, in the cylinder block, the temperature on the side close to the cylinder head in which the combustion chamber is formed is likely to rise, and the liner may be partially expanded if the temperature distribution becomes uneven. As a result, the piston collides with the liner, and piston hitting noise is likely to occur. In particular, when cooling water circulation control is performed for the purpose of early warming up of the internal combustion engine, the temperature distribution of the cylinder block may become non-uniform, and piston hitting noise is likely to occur accordingly. The piston hitting sound may reach the ear of the user of the vehicle equipped with the internal combustion engine. The engine cooling device disclosed in Patent Document 1 also does not take special measures against piston hitting sound.

  Therefore, the cooling device for an internal combustion engine disclosed in this specification has an object of suppressing piston hitting sound in the internal combustion engine.

  In order to solve the above-described problems, a cooling device for an internal combustion engine disclosed in the present specification includes a cylinder head water jacket and a cylinder block water jacket through which cooling water pumped by a water pump circulates, the cylinder head water jacket, and the cylinder block. A control valve for controlling the communication state with the water jacket, piston striking sound detecting means for detecting the occurrence of piston striking sound generated by a piston sliding in a cylinder formed in the cylinder block, and the piston striking sound detecting means And a controller that opens the control valve to cause the cylinder head water jacket and the cylinder block water jacket to communicate with each other when the occurrence of a piston hitting sound is detected or predicted.

  In the internal combustion engine, the temperature of the cylinder head in which the combustion chamber is formed is likely to rise. For this reason, the temperature near the cylinder head of the cylinder block tends to rise. Therefore, the movement of the cooling water by natural convection is promoted by opening the control valve and communicating the cylinder head water jacket and the cylinder block water jacket. As a result, the cylinder head is cooled, the temperature distribution in the cylinder block is made uniform, and the occurrence of piston hitting noise is suppressed. Here, by using natural convection of the cooling water, it is possible to achieve both early warm-up of the internal combustion engine and suppression of piston hitting sound. That is, when abundant cooling water is circulated by the water pump, the temperature variation of the cylinder block is reduced and the piston hitting sound is suppressed. However, on the other hand, the warm-up effect is suppressed by circulating cooling water having a low temperature. By using natural convection of cooling water, both can be achieved.

  When the control unit determines that the volume of the piston hitting sound is large, the cylinder head water jacket and the cylinder block water jacket are communicated in a half-open state by the opening control of the control valve, and the water pump The discharged cooling water is supplied to the cylinder head water jacket.

  As described above, when abundant cooling water is circulated by the water pump, the warm-up effect may be suppressed. Therefore, when it is determined that the volume of the piston hitting sound is high, that is, when it is determined that only natural convection of the cooling water is not sufficient as a countermeasure against the piston hitting sound, for example, when the temperature difference between the cylinder blocks is large Makes the control valve half open. Thereby, maintenance of a warm-up effect and suppression of piston hitting sound can be made compatible. Here, the half-open state does not include the fully-open state of the control valve. The opening degree of the control valve is appropriately adjusted within a range that does not significantly impair the warm-up effect.

  The piston striking sound detection means can measure a temperature difference between an upper portion and a lower portion of a cylinder liner provided in the cylinder block.

  The piston hitting sound is generated by the sliding direction of the cylinder block (cylinder liner), that is, due to partial expansion caused by the temperature difference between the upper part and the lower part. Therefore, the temperature difference between the upper part and the lower part of the cylinder liner is measured, and detection or prediction of the occurrence of piston hitting sound is performed based on the measured temperature difference. The temperature may be measured by any method as long as the temperatures of the upper and lower portions of the cylinder liner can be grasped. For example, the temperature of the cylinder block having a correlation with the temperature of the cylinder liner may be measured, or a simulation may be performed in advance to grasp the temperature difference in light of the operation pattern of the internal combustion engine.

  The piston hitting sound detection means may be a knock sensor. Even if a knock sensor is used, it is possible to determine whether or not piston hitting sound is generated, and further, the degree of piston hitting sound.

  According to the cooling device for an internal combustion engine disclosed in the present specification, it is possible to suppress piston hitting sound in the internal combustion engine.

FIG. 1 is an explanatory diagram illustrating a schematic configuration of an internal combustion engine in which the cooling device according to the first embodiment is incorporated. FIG. 2 is an explanatory diagram showing a schematic configuration of a rotary valve which is an example of a control valve. FIG. 3 is a flowchart illustrating an example of control of the cooling device. FIG. 4 is a table showing an example of control of the cooling device. FIG. 5 is an explanatory diagram showing a state of the rotary valve in the complete water stop state. FIG. 6 is an explanatory view showing a state in which cooling water moves by natural convection between the cylinder head water jacket and the cylinder block water jacket. FIG. 7 is an explanatory diagram showing a state of the rotary valve when the cooling water naturally convects. FIG. 8 is an explanatory diagram showing how the cooling water moves by natural convection over a wide range of the internal combustion engine. FIG. 9 is an explanatory view showing the rotary valve in a half-open state. FIG. 10 is an explanatory diagram illustrating a schematic configuration of an internal combustion engine in which the cooling device according to the second embodiment is incorporated. FIG. 11 is a table showing an example of control of the cooling device. FIG. 12 is an explanatory diagram showing a state of the rotary valve when the cooling water naturally convects. FIG. 13 is a block diagram of the cooling device according to the third embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. However, in the drawings, the dimensions, ratios, and the like of each part may not be shown so as to completely match the actual ones. Further, details may be omitted depending on the drawings.

  First, a schematic configuration of an internal combustion engine 10 incorporating an internal combustion engine cooling device (hereinafter simply referred to as “cooling device”) 1 according to a first embodiment will be described with reference to FIG. The internal combustion engine 10 includes a cylinder head 11 and a cylinder block 12. A cylinder head water jacket 11 a is provided in the cylinder head 12. A cylinder block water jacket 12 a is provided in the cylinder block 12. A cylinder 13 is provided in the cylinder block 12. A cylinder liner 13a is provided in the cylinder 13, and a piston 14 is slidably accommodated therein.

  The internal combustion engine 10 includes a water pump 15. The water pump 15 is an electric type. Extending from the water pump 15 is a first introduction pipe 16 connected to the cylinder head water jacket 11a. From the first introduction pipe 16, a second introduction pipe 17 connected to the cylinder block water jacket 12a is branched.

  The cooling device 1 includes a rotary valve 20 as a control valve. FIG. 2 is an explanatory diagram showing a schematic configuration of the rotary valve 20. The rotary valve 20 includes a cylindrical rotating member 30 inside a cylindrical main body 20a. The rotating member 30 is provided with a plurality of grooves, for example, a groove 30a and a groove 30b. The main body 20a is provided with a plurality of ports A to H. The port A is connected to the cylinder head 11 (cylinder head water jacket 11a). The port B is connected to the cylinder block 12 (cylinder block water jacket 12a). Port C is connected to the radiator. Port D is connected to the radiator bypass. Port E is connected to a CVT (Continuously Variable Transmission) warmer. Port F is connected to the throttle body. Port G is connected to the heater core. Port H is connected to the heater core bypass path. The rotary valve 20 includes a drive unit 22 that rotates the rotating member 30. When the rotary member 30 is rotated by the drive unit 22 and the position of the groove coincides with the position of the port, the port is opened.

  The cooling device 1 includes an ECU (Electronic control unit) 21 as a control unit. The ECU 21 is electrically connected to the electric water pump 15 and the drive unit 22 of the rotary valve 20. The cooling device also includes a first temperature sensor 23 and a second temperature sensor 24 on the wall surface of the cylinder block 12. The first temperature sensor 23 is attached to the upper part of the cylinder block 12. The second temperature sensor 24 is attached to the lower part of the cylinder block 12. The 1st temperature sensor 23 acquires the temperature of the upper part of cylinder liner 13a by measuring the temperature of the cylinder block upper part. The second temperature sensor 24 obtains the temperature of the lower part of the cylinder liner 13a by measuring the temperature of the lower part of the cylinder block. The first temperature sensor 23 and the second temperature sensor 24 are electrically connected to the ECU 21. The ECU 21 calculates the temperature difference between the upper part and the lower part of the cylinder liner 13a based on the values acquired from the first temperature sensor 23 and the second temperature sensor 24. Thus, the function of the piston sound detection means can be obtained by the combination of the first temperature sensor 23, the second temperature sensor 24, and the ECU 21. That is, if the temperature difference between the upper and lower sides of the cylinder liner reaches a predetermined value, it can be determined that the piston hitting sound is generated. In addition, when the temperature difference between the upper and lower sides of the cylinder liner is close to a predetermined value, the occurrence of piston hitting sound can be predicted.

  An example of the operation of the cooling device 1 configured as described above will be described with reference to the flowchart shown in FIG. 3 and the table shown in FIG. The operation of the cooling device is performed by the ECU 21. First, in step S1, a temperature difference Δt is calculated. That is, the temperature difference Δt between the upper and lower sides of the cylinder liner is calculated from the measured value of the first temperature sensor 23 and the measured value of the second temperature sensor 24. In step S2, the occurrence state of the hitting sound is determined. The occurrence state of the hitting sound is performed by comparing the temperature difference Δt with a threshold value. Then, in step S3, a command is issued to the rotary valve 20 and the water pump 15 to perform cooling water flow control.

  First, the first threshold value t1 defines a range of the temperature difference Δt that is an allowable range of piston hitting sound. When Δt <t1, the warm-up of the internal combustion engine 10 is promoted as a complete water stop state. Specifically, the water pump 15 is stopped and all the ports A to H of the rotary valve 20 are closed. FIG. 5 shows the positional relationship between the port A and the groove 30a and the relationship between the port B and the groove 30b. The positions of the port A and the groove 30a do not coincide with each other, and the port A is closed. The positions of the port B and the groove 30b do not coincide with each other, and the port B is closed.

  Next, the second threshold value t2 defines a range of the temperature difference Δt in which the piston hitting sound has a low volume. When Δt <t2, a small natural convection is generated to take measures against piston hitting sound. Specifically, referring to FIG. 6, the cylinder head water jacket 11a and the cylinder block water jacket 12a are communicated to promote the movement of the cooling water by natural convection. At this time, referring to FIG. 7, the position of the port A of the rotary valve 20 and the position of the groove 30a coincide with each other, and the port B and the groove 30b coincide with each other, thereby bringing the port A and the port B into communication. The other ports are kept closed.

  Next, the third threshold value t3 defines the range of the temperature difference Δt in which the piston hitting sound has a medium volume. When Δt <t3, a large natural convection is generated to take measures against piston hitting sound. Specifically, referring to FIG. 4 and FIG. 8, in addition to opening the ports A and B, the ports E to H are also opened. This causes natural convection in a wider area. As a result, cooling water having a low temperature can be taken into natural convection, the cylinder head 11 can be efficiently cooled, and the temperature distribution in the cylinder block 12 (cylinder liner 13a) can be made uniform. Even in this state, the water pump 15 is turned off and the active coolant circulation is stopped, so that the warm-up effect is maintained and the fuel efficiency effect due to the early warm-up is also expected. Various combinations of ports that are opened can be changed.

  Next, a countermeasure when Δt ≧ t3 is described. When Δt ≧ t3, the piston hitting sound has a large volume. At this time, the cooling water is circulated by the water pump 15. Here, if the cooling water is circulated in a large amount, the warm-up effect is lowered. Therefore, the ports A and B are set in a half-open state. Referring to FIGS. 9A and 9B, the groove 30a has a positional relationship overlapping with a part of the opening A1 of the port A. Further, the groove 30b has a positional relationship overlapping with a part of the opening B1 of the port B. Further, the port H is selected as a path for supplying the cooling water pumped by the water pump 15, and the cooling water circulates in the heater core bypass path. As a result, the temperature distribution of the cylinder liner 13a can be made uniform, and excessive cooling can be avoided to maintain the warm-up promoting effect.

  Next, Example 2 will be described with reference to FIG. The cooling device 51 according to the second embodiment is incorporated in the internal combustion engine 10. The cooling device 51 includes a water pump 51. Unlike the first embodiment, the water pump 52 is a mechanical type. For this reason, the operating state cannot be arbitrarily controlled. The cooling device 51 includes a rotary valve 60 instead of the rotary valve 20 of the first embodiment. Similar to the rotary valve 20, the rotary valve 60 includes a rotating member provided with a plurality of grooves, and includes a drive unit 61 that drives the rotating member. The rotary valve 60 includes ports X to Z. The port X is connected to the cylinder head 11 (cylinder head water jacket 11a). The port Y is connected to the cylinder block 12 (cylinder block water jacket 12a). The port Z is connected to the water pump 52. In addition, about the structure which is common in Example 1, the same reference number is attached | subjected in drawing and the detailed description is abbreviate | omitted.

  The operation of the cooling device 51 will be described with reference to the table shown in FIG.

  First, the first threshold value ta defines the range of the temperature difference Δt that is an allowable range of piston hitting sound. When Δt <ta, the warm-up of the internal combustion engine 10 is promoted as a complete water stop state. Specifically, all the ports X, Y, and Z of the rotary valve 60 are closed. The water pump 52 is a mechanical type and cannot be stopped while the internal combustion engine is operating. However, when the port Z is closed, the pumping of the cooling water by the water pump 52 is stopped.

  Next, the second threshold value tb defines a range of the temperature difference Δt in which the piston hitting sound has a low volume. When Δt <tb, a small natural convection is generated to take measures against piston hitting sound. Specifically, the ports A and Y are opened. Thereby, as shown in FIG. 12, the cylinder head water jacket 11a and the cylinder block water jacket 12a are communicated, and the movement of the cooling water by natural convection is promoted.

  Next, a countermeasure when Δt ≧ tb is described. When Δt ≧ tb, the piston hitting sound has a large volume. At this time, the cooling water is circulated by the water pump 52. Here, if the cooling water is circulated in a large amount, the warm-up effect is lowered. Therefore, the ports X and Y are set in a half-open state. The port Z connected to the water pump 52 is fully opened. As a result, the temperature distribution of the cylinder liner 13a can be made uniform, and excessive cooling can be avoided to maintain the warm-up promoting effect.

  Next, Example 3 will be described with reference to FIG. The cooling device 100 according to the third embodiment includes a knock sensor 101 as a piston hitting sound detection unit. The degree of knocking detected by the knock sensor 101 is made to correspond to the piston hitting sound, and the valve opening control of the rotary valve 20 is performed according to the degree of knocking. Thereby, suppression of a piston hitting sound and warming-up promotion can be made compatible.

  The above embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to these, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

DESCRIPTION OF SYMBOLS 1, 51, 100 Cooling device 10 Internal combustion engine 11 Cylinder head 11a Cylinder block water jacket 12 Cylinder block 12a Cylinder block water jacket 13 Cylinder 13a Cylinder liner 14 Piston 15, 52 Water pump 16 1st introduction pipe 17 2nd introduction pipe 20, 60 Rotary valve 21 ECU
23 First temperature sensor 24 Second temperature sensor 101 Knock sensor A to H, X to Z Port

Claims (4)

A cylinder head water jacket and a cylinder block water jacket through which the cooling water pumped by the water pump circulates;
A control valve that controls communication between the cylinder head water jacket and the cylinder block water jacket;
Piston striking sound detecting means for detecting the occurrence of piston striking sound generated by a piston sliding in a cylinder formed in the cylinder block;
A control unit that opens the control valve to cause the cylinder head water jacket and the cylinder block water jacket to communicate with each other when the occurrence of piston hitting sound is detected or predicted by the piston hitting sound detection means; ,
A cooling device for an internal combustion engine. When the control unit determines that the volume of the piston hitting sound is high, the cylinder head water jacket and the cylinder block water jacket are communicated in a half-open state by opening control of the control valve,
The cooling device for an internal combustion engine according to claim 1, wherein cooling water discharged by the water pump is supplied to a cylinder head water jacket.   The cooling device for an internal combustion engine according to claim 1 or 2, wherein the piston sound detection means measures a temperature difference between an upper portion and a lower portion of a cylinder liner provided in the cylinder block.   The cooling device for an internal combustion engine according to claim 1 or 2, wherein the piston sound detection means is a knock sensor.

Images