JP2012026372A - Cooling apparatus for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent too high slapping sound of a piston while warm-up promotion processing is being performed in a cooling apparatus for an internal combustion engine.SOLUTION: The internal combustion engine 10 includes a circulation waterway 20 through which cooling water circulates and a water temperature sensor 92 which detects the temperature of the cooling water, and executes warm-up promotion processing that controls the ejection rate of a pump 30 when a detection temperature θ is an upper limit water temperature θc or less. A control device 91 monitors a temperature of an upper end portion of a cylinder 12 as a cylinder temperature θc, monitors a temperature of a piston 15 as a piston temperature θp and predicts a level Ge of a slapping sound of a piston slapping sound based on the cylinder temperature θc and piston temperature θp. When the control device determines that the level Ge of the slapping sound is a determination value Gc or more, it discontinues the warm-up promotion processing and starts to operate the pump 30.

Description

  The present invention relates to a cooling device for an internal combustion engine that is intended to promote warm-up by temporarily limiting the discharge amount of a pump when the engine is cold.

  2. Description of the Related Art Conventionally, in an internal combustion engine cooling device, an engine drive type pump in which a rotating shaft is connected to an engine output shaft via a belt or the like is widely adopted as a pump for discharging cooling water. In such an engine-driven pump, there is a restriction that the discharge amount is uniquely determined based on the rotation speed of the engine output shaft because of its structure. For this reason, even when the internal combustion engine is in a low temperature state, for example, when the warm-up has not yet been completed, the cooling water forcedly discharged from the pump is circulated in the circulation channel, and this is the fuel efficiency. This is an obstacle to improvement.

  Therefore, as described in Patent Document 1, such an electric rotary type pump is adopted, and the cooling water is discharged without depending on the rotational speed of the engine output shaft, such as temporarily limiting the circulation of the cooling water. A cooling device capable of changing the amount has also been proposed. Further, not only such an electric rotary pump but also an engine-driven pump as described above, a configuration is provided in which a clutch is provided between the rotary shaft and the engine output shaft and the connection / disconnection state of the clutch is switched. If employed, the operation of the pump can be stopped without depending on the engine speed, and the circulation of the cooling water can be temporarily stopped.

  As described in Patent Document 1, in the cooling device employing such a discharge amount variable pump, for example, when the engine is cold, the engine is started until a predetermined period elapses, that is, Until the temperature of the cooling water rises to some extent, the amount of cooling water discharged from the pump can be reduced to restrict or prohibit the circulation of the cooling water (hereinafter referred to as “warm-up promotion process”). As a result, the cooling capacity of the cooling device can be temporarily reduced, and fuel consumption can be improved by promoting warm-up and reducing heat loss.

JP 2006-342680 A

By the way, this inventor acquired the knowledge that the following events which cannot be seen when not performing this during a warming-up promotion process may occur.
That is, during operation, the internal combustion engine is generated at the upper part of the engine combustion chamber, that is, at a portion located on the cylinder head side (+ z axis direction in FIG. 5A) in the cylinder as shown in FIG. The amount of heat is the largest and the temperature tends to rise. If the cooling device always circulates the cooling water through the circulating water channel even when the engine is cold, a relatively large amount of heat is generated in the cooling water from the most heat generated part. Since this is transmitted, there is no excessive temperature deviation in the vertical direction (z-axis direction) of the cylinder.

  (A) However, as described above, when the pump discharge amount is reduced and the circulation of the cooling water is limited, the heat exchange amount between the upper portion of the cylinder where the temperature rises most and the cooling water becomes small. For this reason, as shown in FIG. 5 (b), the upper part of the cylinder is thermally expanded more than other parts, and local thermal deformation occurs.

  (B) In particular, regarding a cylinder (intermediate cylinder) sandwiched between two cylinders, as shown in FIG. 5 (c), each adjacent cylinder expands due to thermal expansion. The external force f in the cylinder arrangement direction (x-axis direction) is applied. As a result, in the intermediate cylinder, the occurrence of the local thermal deformation as described above becomes more remarkable as compared with the cylinders (end cylinders) positioned at both ends in the cylinder arrangement direction. As a result, as shown in FIG. 5 (c), local thermal deformation, that is, deformation that becomes an elliptical shape as a whole increases in diameter occurs at the upper portion of the cylinder.

  (C) On the other hand, the piston shown in FIG. 5 (a) has a heat exchange amount with cooling water that is less than that of the cylinder in the first place, and therefore has a temperature different from that of the cylinder. For this reason, the amount of diameter expansion accompanying the thermal expansion of the piston when the above-described local thermal deformation of the cylinder is occurring varies from time to time. As a result, the clearance between the piston and the cylinder also varies depending on the temperature state.

  When the cooling capacity of the cooling device is temporarily reduced due to the above items (a) to (c), the clearance between the cylinders and the pistons, in particular, the direction orthogonal to the cylinder arrangement direction The clearance in the y-axis direction in FIG. 5 may be extremely large. When the clearance in the direction orthogonal to the cylinder arrangement direction increases as described above, as shown in FIG. 6, when the piston changes its movement direction (z-axis direction in FIG. 6) in the vicinity of the top dead center. Oscillating motion with the piston pin generated as a rotation center (the oscillation direction is indicated by “R”), that is, the amount of oscillation in the so-called swinging motion of the piston increases. As a result, it became clear that the impact force when the piston collides with the inner wall surface of the cylinder is increased, and piston hitting sound (piston slap) of a level that cannot be generated when circulating cooling water is generated. .

  Incidentally, the cooling device for an internal combustion engine described in Patent Document 1 is merely one in which the temperature of the cylinder is estimated and the warm-up promotion processing is terminated in order to suppress the excessive temperature rise, as described above. Not only does excessive piston hitting occur during the warm-up promotion process, but it does not suggest how to deal with the piston hitting noise that occurs even when the temperature of the cylinder does not rise excessively. .

  The present invention has been made on the basis of the inventor's knowledge as described above, and an object of the present invention is that excessive piston hitting noise is generated during the warm-up promotion process in the cooling device for the internal combustion engine. It is to suppress.

In the following, means for achieving the above object and its effects are described.
According to the first aspect of the present invention, the circulating water passage through which the cooling water of the internal combustion engine circulates, the detecting means for detecting the temperature of the cooling water in the circulating water passage, and the detected water temperature detected at or below the predetermined temperature Control means for controlling a driving state of a pump provided in the circulation water channel so that the circulation of the cooling water is restricted so as to execute the warm-up promotion process, and the detection means executes the warm-up promotion process Cylinder temperature monitoring means for monitoring the temperature of the upper part of the cylinder and the temperature of the piston in a cooling device for an internal combustion engine that detects the temperature of the cooling water that varies in correlation with the cooling water staying around the cylinder A piston temperature monitoring means for determining, and a determination means for determining whether or not a piston hitting sound of a predetermined level or higher is generated based on a cylinder temperature and a piston temperature at the time of executing the warm-up promotion process. Wherein the control means is summarized in that to interrupt the warm-up facilitating processing when a predetermined level or more pistons hitting sound is made a determination that in the situation generated by the determining means.

  As described above, during the warm-up promotion process, local thermal deformation in which the upper portion of the cylinder has an elliptical shape is generated, thereby increasing the clearance between the cylinder and the piston. As the clearance increases, the level of piston hitting sound generated during the warm-up promotion process increases. Here, the size of the clearance largely depends on the temperature of the cylinder, particularly the upper portion thereof, but differs depending not only on the same temperature but also on the piston temperature. That is, even when the temperature of the upper part of the cylinder is relatively low, there is a concern that a piston hitting sound having a magnitude that cannot be ignored is generated depending on the temperature state of the piston.

  In consideration of this point, in the above configuration, during the warm-up promotion process, the temperature at the upper part of the cylinder is monitored, and the temperature of the piston is also monitored. Based on the monitored temperature, the temperature exceeds a predetermined level. It is determined whether or not piston hitting sound is generated. For this reason, the size of the clearance between the cylinder and the piston, in other words, the occurrence state of the piston hitting sound can be determined with high reliability. When the piston hitting sound exceeds the predetermined level, the warming-up promotion process is interrupted and the restriction on the circulation of the cooling water is released, so that the cooling capacity of the cooling device, particularly the upper part of the cylinder The cooling capacity in the surroundings can be increased. As a result, local thermal deformation at the upper part of the cylinder is mitigated, and generation of piston hitting sound can be suitably suppressed. The piston temperature and the cylinder temperature may be monitored by directly detecting them, or may be monitored by estimating them based on the engine operating state including the detected water temperature.

  Further, when determining whether or not a piston hitting sound of a predetermined level or more is generated, it can be directly determined based on the cylinder temperature and the piston temperature at the time of the warm-up promotion processing. According to the invention described in 2, the piston hitting sound level is predicted based on the cylinder temperature and the piston temperature monitored during the warm-up promotion process, and the predicted level is compared with a predetermined determination value. In addition, it is possible to adopt a configuration in which it is determined that piston hitting sound of a predetermined level or higher is generated when a comparison result is obtained that the predicted level exceeds a predetermined determination value. .

  According to a third aspect of the present invention, in the cooling apparatus for an internal combustion engine according to the first or second aspect, in the determination, the determination means is monitored as the monitored piston temperature is lower. The gist is that the higher the cylinder temperature, the higher the level of piston hitting sound that is generated during the execution of the warm-up acceleration processing.

  During the warm-up promotion process, the clearance between the cylinder and the cylinder tends to increase as the piston temperature is lower, that is, as the amount of expansion due to the temperature increase of the piston is smaller. As the level increases, the level of piston hitting sound also increases. Also, the higher the cylinder temperature, that is, the greater the local thermal deformation of the cylinder, the greater the clearance between the cylinder and the piston hitting sound level increases as the clearance increases. Become. According to the above configuration, by taking these points into consideration, it is possible to appropriately determine the level of piston hitting sound generated during the execution of the warm-up promotion process, and piston hitting sound of a predetermined level or higher is generated. It is possible to determine whether or not there is high accuracy.

  According to a fourth aspect of the present invention, in the internal combustion engine cooling apparatus according to any one of the first to third aspects, the control means is in a situation where a piston hitting sound of a predetermined level or more is generated by the determination means. After the determination is made and the warming-up promotion processing is interrupted, the determination means determines that there is no situation where piston hitting sound of a predetermined level or higher is generated. The gist is to continue the interruption of the warm-up promotion process until the time has elapsed.

  When the warming-up promotion process is interrupted when the piston hitting sound exceeds the specified level, the flow rate of the cooling water in the circulation channel increases, so the local thermal deformation of the cylinder is alleviated and the piston hitting sound level Will fall. Then, when the warm-up promotion processing is immediately restarted when the piston hitting sound is less than the predetermined level, the local thermal deformation of the cylinder increases again. The level of piston hitting sound will also increase. As a result, the piston hitting noise fluctuates in a manner that rises and falls with a predetermined level as a boundary, and as a result, the phenomenon that the warm-up promotion processing is frequently interrupted and executed repeatedly, in other words, the pump discharge amount is short. There is a concern that a phenomenon that pulsates between them, that is, a hunting phenomenon occurs. In this regard, according to the above configuration, the occurrence of such a hunting phenomenon can be suitably suppressed.

  In addition, the predetermined period may be a period set in advance, but when the invention according to claim 4 is applied to the structure according to claim 2, for example, the following structure may be adopted. it can. That is, when it is determined that there is no situation in which piston hitting sound of a predetermined level or higher occurs after the warm-up promotion processing is interrupted, the predicted level of piston hitting sound is lower than the predetermined level by a predetermined value or more from that time. You may make it set the period until it falls to a level as said predetermined period.

  Further, as a pump that can be employed in this cooling device, for example, an electric rotary pump can be cited, and the rotational force of the engine output shaft is transmitted to the rotary shaft of the pump as in the invention described in claim 5. A pump including a switching mechanism that switches between a possible state and a non-transmittable state may be employed. In this case, the switching mechanism is driven so that the pump drive state is stopped when the warm-up promotion process is executed, while the pump drive state is controlled to the operating state when the warm-up promotion process is interrupted. .

  In addition, when the invention according to claim 5 is applied to the configuration according to claim 4, the occurrence of the hunting phenomenon as described above is suitably suppressed, so that the switching operation by the switching mechanism is frequently performed. By repeating the above, it can be avoided that the service life of the mechanism is shortened or that the operation sound accompanying the switching operation is continuously generated.

  According to a fifth aspect of the present invention, in the internal combustion engine cooling apparatus according to any one of the first to fourth aspects, the pump has a state in which the rotational force of the engine output shaft can be transmitted to the rotational shaft of the pump. A switching mechanism that switches to a state incapable of transmission, and the control means drives the switching mechanism to stop the driving state of the pump during execution of the warm-up promotion process, while interrupting the warm-up promotion process Sometimes the gist is to control the driving state of the pump to the operating state.

  According to a sixth aspect of the present invention, in the internal combustion engine cooling apparatus according to any one of the first to fifth aspects, the cylinder temperature monitoring means is configured to detect the detected water temperature and the amount of combustion heat generated per time. Including a storage means for previously identifying and storing a function for returning the cylinder temperature at the time of warming-up promotion processing as a return value, and estimating the cylinder temperature based on the stored function To do.

  According to a seventh aspect of the present invention, in the internal combustion engine cooling apparatus according to the sixth aspect, the function is the amount of combustion heat generated by the change rate of the detected water temperature and cylinder temperature difference per unit time. The gist is that the relationship becomes higher as the value of is higher.

  According to an eighth aspect of the present invention, in the cooling apparatus for an internal combustion engine according to the sixth or seventh aspect, the function has a rate of change in the degree of deviation of the detected detected water temperature and cylinder temperature. The gist is that it has a relationship that becomes higher as the value is smaller.

  According to a ninth aspect of the present invention, in the cooling apparatus for an internal combustion engine according to the sixth aspect, the function stored in the storage means sequentially estimates the cylinder temperature θc (i) with a predetermined estimation period. , A detected water temperature θ (i) detected at a predetermined estimated timing t (i), a combustion heat quantity Q (i) per hour at the estimated timing t (i), and a cylinder temperature θc ( i) and the deviation degree Δθc (i) (= θb (i) −θ (i)) of the detected water temperature θ (i) and the deviation degree Δθc (i−1) at the previous estimated timing t (i−1). The following equations (1) and (2) used

にて定義されることを要旨とする。

The gist is defined as

  The present inventor has determined that the cylinder temperature during the warm-up promotion process is based on the detected water temperature, that is, the temperature of the cooling water that changes in temperature in correlation with the cooling water staying around the cylinder and the amount of combustion heat generated per hour. It was confirmed by experiment that it can be obtained approximately. Therefore, as described in claims 6 to 9, a function that includes the detected water temperature and the amount of combustion heat generated per hour as arguments and returns the cylinder temperature during the warm-up promotion process as a return value is identified in advance. By storing this, the cylinder temperature can be estimated based on the same function.

  Further, the present inventor has found that the rate of change of the degree of deviation between the detected water temperature and the cylinder temperature increases as the amount of combustion heat generated per hour increases, and the degree of deviation varies at the time of engine cold start. It was also confirmed that the higher the value, the higher the value. Therefore, the cylinder temperature at the time of the warm-up promotion process can be estimated more appropriately by adopting the configuration according to claims 7 to 9.

  A tenth aspect of the present invention is the internal combustion engine cooling apparatus according to any one of the first to ninth aspects, wherein the piston temperature monitoring means is configured to detect the detected water temperature and the amount of combustion heat generated per time. Including a storage means for previously identifying and storing a function for returning the piston temperature at the time of warming-up promotion processing as a return value, and estimating the piston temperature based on the stored function To do.

  According to an eleventh aspect of the present invention, in the cooling apparatus for an internal combustion engine according to the tenth aspect, the function is an amount of combustion heat generated by a change rate of the detected water temperature and the difference between the piston temperature per unit time. The gist is that the relationship becomes higher as the value of is higher.

  According to a twelfth aspect of the present invention, in the cooling device for an internal combustion engine according to the tenth or eleventh aspect, the function has a rate of change in the degree of deviation between the detected water temperature and the detected piston temperature. The gist is that it has a relationship that becomes higher as the value is smaller.

  According to a thirteenth aspect of the present invention, in the internal combustion engine cooling apparatus according to the tenth aspect, the function stored in the storage means sequentially estimates the piston temperature θp (i) with a predetermined estimation period. , Detected water temperature θ (i) detected at a predetermined estimated timing t (i), combustion heat quantity Q (i) per time at the estimated timing t (i), piston temperature θp (at the estimated timing t (i) i) and the deviation degree Δθp (i) (= θb (i) −θ (i)) of the detected water temperature θ (i) and the deviation degree Δθp (i−1) at the previous estimated timing t (i−1). The following formula (3) and formula (4) used

にて定義されることを要旨とする。

The gist is defined as

  The inventor has determined that the piston temperature during the warm-up promotion process is based on the detected water temperature, that is, the temperature of the cooling water that changes in correlation with the cooling water staying around the cylinder and the amount of combustion heat generated per hour. It was confirmed by experiment that it can be obtained approximately. Therefore, as in the inventions of claims 10 to 13, a function that includes the detected water temperature and the amount of combustion heat generated per hour as arguments and returns the piston temperature during the warm-up acceleration processing as a return value is identified in advance. By storing this, the piston temperature can be estimated based on the same function.

  Furthermore, the present inventor has found that the rate of change in the degree of deviation between the detected water temperature and the piston temperature increases as the amount of combustion heat generated per hour increases, and the degree of deviation varies during engine cold start. It was also confirmed that the higher the value, the higher the value. Therefore, the piston temperature at the time of warming-up promotion processing can be estimated more appropriately by adopting the configuration according to claims 11 to 13.

The schematic block diagram which shows the cooling device of the internal combustion engine concerning embodiment of this invention. The flowchart which shows the process sequence about a warming-up promotion process and a hit sound suppression process. An arithmetic map showing the relationship between the piston temperature and cylinder temperature and the sound level. (A) Intake air amount, (b) Cooling water temperature, (c) Piston temperature and cylinder temperature (d) Sound level, (e) Pump operating state during execution of warm-up promotion processing and sound suppression processing The timing chart which shows transition of. (A) The perspective view which shows the perspective structure of a cylinder and a piston, (b) The side view which shows the deformation | transformation aspect in the radial direction of a cylinder, (c) The front view which shows the deformation | transformation aspect in the radial direction of a cylinder. The schematic diagram which shows the swing motion which generate | occur | produces in a piston.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
First, the configuration of the cooling device for the internal combustion engine 10 will be described with reference to FIG. As shown in FIG. 1, the internal combustion engine 10 has four cylinders 12 (one of which is shown in FIG. 1) formed in the cylinder block 11. Inside the cylinders 12, engine combustion chambers 14 are defined by the inner peripheral surface, the top surface of the piston 15, and the lower surface of the cylinder head 13. In the cylinder block 11 and the cylinder head 13, a water jacket 21 through which cooling water circulates is formed around the cylinder 12.

  In addition to the water jacket 21, the circulating water passage 20 of the cooling device includes a radiator passage 24 that returns the cooling water flowing out from the water jacket 21 to the thermostat 27 via the radiator 22, and the radiator 22 is branched from the radiator passage 24. The detour passage 25 is connected to the thermostat 27 in a detouring manner, and the detour passage 25 returns the cooling water flowing out from the water jacket 21 to the thermostat 27. The cooling water thus returned to the thermostat 27 through the circulation water channel 20 is again discharged into the water jacket 21 by the pump 30.

  Thus, the cooling water discharged from the pump 30 circulates through the circulation water path 20 to cool the internal combustion engine 10 including the cylinder block 11 and the cylinder head 13. The thermostat 27 opens when the temperature of the cooling water rises due to the heat of the internal combustion engine 10 and becomes equal to or higher than a predetermined valve opening temperature. When the thermostat 27 is thus opened, the cooling water circulates in the radiator passage 24 and the radiator 22 radiates the cooling water.

  A pulley 32 is attached to a rotation shaft (not shown) of the pump 30 via an electromagnetic clutch 31. A belt 33 is suspended between the pulley 32 and pulleys (both not shown) attached to the engine output shaft. Therefore, when the clutch 31 is in the engaged state, the rotational force of the engine output shaft is transmitted to the rotational shaft of the pump 30, and the pump 30 is operated. On the other hand, when the clutch 31 is in the disengaged state, such power transmission is interrupted, so that the operation of the pump 30 is stopped. Thus, the pump 30 can be operated / stopped by switching the engagement / release state of the clutch 31 during engine operation. Such switching of the engagement / disengagement state of the clutch 31 is executed by the control device 91.

  Further, the internal combustion engine 10 is provided with various sensors for executing such control. For example, a water temperature sensor 92 is provided at the most upstream position of the detour passage 25 communicating with the water jacket 21 in the cylinder head 13. The water temperature sensor 92 detects the temperature of the cooling water in the bypass passage 25 (hereinafter, the detected water temperature θ). In the cooling device, the detected water temperature θ is used as an alternative value for the temperature of the cooling water staying around the cylinder 12, that is, in the water jacket 21. The detected water temperature θ detected by the water temperature sensor 92 is not limited to the case where the pump 30 is operated and the cooling water is circulated through the circulating water channel 20, and the operation of the pump 30 is stopped and the cooling water is circulated in the circulating water channel 20. Even if it is not, it has a correlation with the temperature of the cooling water staying in the water jacket 21.

  Further, an air flow meter 93 for detecting the intake air amount GA is provided in the intake passage (not shown). The control device 91 captures the detection values of these various sensors, and switches the engagement / disengagement state of the clutch 31 based on the captured detection values, in other words, controls the driving state of the pump 30 and the internal combustion engine. Various controls such as fuel injection control 10 are executed in an integrated manner. The control device 91 includes a memory 91a for storing such various control programs and calculation maps.

  The control device 91 monitors the detected water temperature θ from when the engine is started. When the detected water temperature θ is lower than a predetermined temperature (hereinafter, upper limit water temperature θg), the operation of the pump 30 is stopped and the bypass passage 25 or the radiator is stopped. Cooling water circulation in the circulation water channel 20 such as the passage 24 is stopped (warming-up promotion processing). By performing such warm-up promotion processing, the cooling capacity by the cooling water is reduced, so that warm-up of the internal combustion engine 10 is promoted.

  By the way, during execution of such warm-up promotion processing, local thermal deformation occurs in which the upper end portion of the cylinder 12 has an elliptical shape, and this occurs when cooling water is circulated. As described above, piston hitting sound at an unacceptable level may occur. Therefore, in the cooling device according to the present embodiment, the hammering sound suppressing process for suppressing the occurrence of the piston hammering sound is executed through the control device 91 together with the warming-up promotion process described above.

  Hereinafter, with reference to the flowchart shown in FIG. 2, an example of the execution procedure of the hitting sound suppression process and the warm-up promotion process will be described. 2 is repeatedly executed by the control device 91 with a predetermined control cycle.

  In this series of processing, first, it is determined whether or not the detected water temperature θ detected by the water temperature sensor 92 is lower than the upper limit water temperature θg (step S100). This upper limit water temperature θg is based on a comparison with the detected water temperature θ that the internal combustion engine 10 is not sufficiently warmed up and it is not necessary to circulate the cooling water to cool the internal combustion engine 10. This is a value for determination. That is, when the detected water temperature θ is lower than the upper limit water temperature θg, it is not necessary to cool the internal combustion engine 10 by circulating the cooling water, so the warm-up promoting process is executed. By executing such a warm-up promotion process, the cooling capacity of the cooling device is reduced, so that the warm-up of the internal combustion engine 10 is promoted. The upper limit water temperature θg is set to a temperature lower than the valve opening temperature of the thermostat 27. For this reason, when the detected water temperature θ is lower than the upper limit water temperature θg, the thermostat 27 is maintained in the valve closed state.

  When it is determined that the detected water temperature θ is equal to or higher than the upper limit water temperature θg (step S100: NO), that is, when it is determined that the warm-up of the internal combustion engine 10 is almost complete, it is not necessary to execute the warm-up promotion process. Therefore, the pump 30 shifts to normal operation (step S170). That is, the clutch 31 of the pump 30 is shifted to the engaged state, and the pump 30 is operated by the rotational force of the engine output shaft.

  On the other hand, when it is determined that the detected water temperature θ is lower than the upper limit water temperature θg (step S100: YES), the warm-up promotion process is basically executed. That is, the operation of the pump 30 is stopped and the circulation of the cooling water in the circulation water channel 20 is stopped. When it is determined that there is a possibility that the level of the piston hitting sound may not be ignored during the warm-up promotion process, the warm-up promotion process is temporarily interrupted and the pump 30 is turned off. The hit sound suppression process for setting the driving state is executed. Hereinafter, such a hitting sound suppression process will be described in detail.

  As described above, when it is determined that the detected water temperature θ is lower than the upper limit water temperature θg (step S100: YES), the warm-up promotion process is being executed based on the detected water temperature θ and the intake air amount GA. The temperature of the upper part of the cylinder 12 (hereinafter referred to as “cylinder temperature θc”) and the temperature of the piston 15 (hereinafter referred to as “piston temperature θp”) are estimated (step S110). Here, the intake air amount GA is used as a correlation value of the amount of combustion heat generated per hour in the engine combustion chamber 14.

  First, a method for estimating the piston temperature θp will be described with reference to the following equations (1) and (2). It should be noted that the functions expressed by the equations (1) and (2) are stored in advance in the memory 91a of the control device 91 as an interrupt program for estimating the piston temperature θp.

上式（１）に示されるように、ここでは、検出水温θに対して、今回の制御周期（推定周期）で更新されたピストン温度θｐと検出水温θとの乖離度Δθｐ（ｉ）を加算することで、ピストン温度θｐを推定するようにしている。従って、この乖離度Δθｐ（ｉ）が大きく、検出水温θが高いときほど、ピストン温度θｐは高いと推定されることとなる。

As shown in the above equation (1), here, the difference Δθp (i) between the piston temperature θp updated in the current control cycle (estimated cycle) and the detected water temperature θ is added to the detected water temperature θ. By doing so, the piston temperature θp is estimated. Accordingly, the piston temperature θp is estimated to be higher as the deviation degree Δθp (i) is larger and the detected water temperature θ is higher.

  Further, as shown in the above equation (2), the divergence degree Δθp (i) is calculated based on the intake air amount GA detected in the current control cycle and the divergence degree Δθp (i set in the previous control cycle. -1), more precisely, as an integrated value of the difference between the value obtained by correcting the intake air amount GA with the appropriate values α and γ and the value obtained by correcting the deviation degree Δθp (i-1) with the compatible value β. I am trying to calculate. As apparent from the equation (2), as the amount of heat generated in the engine combustion chamber 14 per unit time is larger, the amount of change in the deviation degree Δθp (i) per unit time, in other words, the deviation degree Δθp (i ) Is estimated to increase. Similarly, when the divergence degree Δθp (i−1) set in the previous control cycle is small, it is similarly estimated that the change rate of the divergence degree Δθp (i) is large.

  Here, the adaptive values α, β, γ are values that are appropriately set based on various characteristics of the internal combustion engine 10 and its cooling device. That is, in estimating the piston temperature θp based on the relationship between the intake air amount GA and the detected water temperature θ, the difference between the above-described divergence degree Δθp (i) and its actual value is the smallest within the range in which they change. In this case, the matching values α, β, and γ are preset as “α11”, “β11”, and “γ11” through experiments and the like, and are stored in the memory 91a.

  Similarly, the cylinder temperature θc is estimated based on the following formulas (3) and (4) according to the above formulas (1) and (2). It should be noted that the functions shown by these formulas (3) and (4) are similar to the functions shown by the previous formulas (1) and (2), respectively, as control programs as interrupt programs for estimating the cylinder temperature θc. 91 is stored in advance in the memory 91a.

即ち、上式（３）に示されるように、前回の制御周期にて設定されたシリンダ温度θｃと検出水温θとの乖離度Δθｃ（ｉ−１）を検出水温θに加算することでシリンダ温度θｃを推定する。また、上式（４）に示されるように、この乖離度Δθｃ（ｉ）は、前回の制御周期にて設定された乖離度Δθｃ（ｉ−１）と、今回の制御周期にて検出された吸入空気量ＧＡとの差分、正確には吸入空気量ＧＡを適合値α，γにて補正した値と乖離度Δθｐ（ｉ−１）を適合値βにて補正した値との差分の積算値として算出する。

That is, as shown in the above formula (3), the cylinder temperature is obtained by adding the deviation degree Δθc (i−1) between the cylinder temperature θc and the detected water temperature θ set in the previous control cycle to the detected water temperature θ. Estimate θc. Further, as shown in the above equation (4), this divergence degree Δθc (i) is detected in the current control period with the divergence degree Δθc (i−1) set in the previous control period. The integrated value of the difference between the intake air amount GA, more precisely, the value obtained by correcting the intake air amount GA with the appropriate values α and γ and the value obtained by correcting the deviation degree Δθp (i−1) with the compatible value β. Calculate as

  At this time, the above-mentioned corresponding values α, β, and γ are set as “α21”, “β21”, and “γ21” through experiments and the like, and stored in the memory 91a. The values (α21, β21, γ21) of the adaptive values α, β, γ are different from the values (α11, β11, γ11) of the adaptive values α, β, γ described above, and the intake air amount GA When the cylinder temperature θc is estimated based on the relationship with the detected water temperature θ, the difference between the above-described divergence degree Δθc (i) and its actual value is selected to be the smallest within the range in which they change. Value.

  By the way, the transitions of the piston temperature θp and the cylinder temperature θc when the pump 30 is operated and the hammering sound suppression process is executed are different from those transitions during the warm-up promotion process. For this reason, during execution of the hitting sound suppression process, the respective adaptation values α, β, γ used when estimating the piston temperature θp are different from the above-described values (α11, β11, γ11) (α12, β12, γ12) is set in advance through tests and the like. Similarly, during execution of the hitting sound suppression process, the respective adaptation values α, β, γ used when estimating the cylinder temperature θc are different from the above-described values (α21, β21, γ21) (α22, β22, γ22) is set in advance through tests and the like. In the above estimation method, the initial values of the piston temperature θp (i) and the cylinder temperature θc (i) are set equal to the detected water temperature θ at the time of starting the engine, and the deviation degrees Δθp (i) and Δθc (i) are set. The initial value is set to “0”.

  Next, based on the cylinder temperature θc and the piston temperature θp estimated in this way, a piston hitting sound level (hereinafter referred to as “sounding sound level Ge”) is predicted (step S120). The striking sound level Ge is the magnitude of the striking sound generated by the impact force that collides with the inner wall surface of the cylinder 12 when the piston 15 changes its movement direction in the vicinity of the top dead center as described above. Reference and predict. The calculation map shown in FIG. 3 is a map showing the relationship between the piston temperature θp, the cylinder temperature θc, and the striking sound level Ge, and is stored in the memory 91a of the control device 91.

  As shown in FIG. 3, the lower the piston temperature θp and the higher the cylinder temperature θc, the higher the striking sound level Ge is predicted. That is, when the piston temperature θp is low, the diameter expansion amount of the piston 15 is small, and when the cylinder temperature θc is high, the cylinder 12 is thermally deformed and the diameter expansion amount at the upper part of the cylinder 12 is large. For this reason, it can be predicted that the lower the piston temperature θp and the higher the cylinder temperature θc, the greater the clearance between the cylinder 12 and the piston 15 and the greater the sounding level Ge.

  Next, it is determined whether or not the hitting sound level Ge is less than the determination value Gc (step S130). The determination value Gc is a value for determining whether or not a piston hitting sound that cannot be ignored is generated based on the comparison with the hitting sound level Ge described above.

  Here, when it is determined that the hitting sound level Ge is equal to or higher than the determination value Gc (step S130: NO), the warm-up promotion process is interrupted (step S160). That is, the control device 91 starts the operation of the pump 30 with the clutch 31 engaged. As a result, the cooling water circulates in the circulation water channel 20 and the cooling water staying around the cylinder 12 flows, so that the cooling capacity of the cylinder 12 by the cooling water increases. . As a result, the cylinder temperature θc is lowered, the local thermal deformation of the cylinder 12 is alleviated, and the clearance level Ge gradually decreases as the clearance gradually decreases.

  On the other hand, when it is determined that the sound level Ge is less than the determination value Gc (step S130: YES), in other words, when the sound level Ge is lower than the determination value Gc from a state where the sound level Ge is equal to or higher than the determination value Gc. For example, it is determined whether or not a predetermined period Tc has elapsed since the hitting level Ge has dropped below the determination value Gc from the state where the warm-up promotion process is interrupted (step S140). Here, when it is determined that the predetermined period Tc has not elapsed since the sound hitting level Ge is less than the determination value Gc (step S140: NO), the warm-up promotion process is continuously interrupted and the pump 30 is operated. (Step S160). That is, when the pump 30 is once in an operating state through the execution of the hammering suppression process, even when it is determined that the hammering sound level Ge has decreased and becomes less than the determination value Gc, the state is maintained for a predetermined period Tc. I keep it until it passes. This is due to the following reason.

  That is, when the operation of the pump 30 is started and the cooling water circulates in the circulation channel 20, the local thermal deformation of the cylinder 12 is gradually eased, and the sound level Ge is also reduced. . However, even if it is determined that the striking sound level Ge is less than the determination value Gc, the local thermal deformation of the cylinder 12 may not be sufficiently mitigated. For this reason, when the circulation of the cooling water is immediately stopped based on the determination that the sound level Ge is less than the determination value Gc, the sound level Ge becomes the determination value Gc or more again in a short period of time. There is a high possibility that the pump 30 will need to be put into operation again. That is, there is concern about the occurrence of a hunting phenomenon in which execution / interruption of warm-up promotion processing, in other words, stop / operation of the pump 30 is frequently repeated within a short period of time. In the determination process of step S140, in order to avoid the occurrence of such a hunting phenomenon, when the pump 30 is once in an operating state, even if the hammering sound level Ge becomes less than the determination value Gc, the state is maintained for a predetermined period Tc. I keep it until it passes.

  On the other hand, when it is determined that the predetermined period Tc has elapsed since the sound level Ge is less than the determination value Gc (step S140: YES), the operation of the pump 30 is stopped and the warm-up promotion process is restarted (step S140). S150).

  Next, (a) intake air amount GA, (b) detected water temperature θ, (c) piston temperature θp (solid line) and cylinder temperature θc ( An example of each transition of the operating state of the pump 30 will be described with reference to FIG. In FIG. 4, transitions of the piston temperature θp, the cylinder temperature θc, and the sound level Ge after the pump 30 has shifted to the normal operation are indicated by broken lines. The transitions of the piston temperature θp, the cylinder temperature θc, and the striking sound level Ge will be described with reference to FIG. 3 described above.

  As shown in FIG. 4, when the operation of the internal combustion engine 10 is started (timing t0) and the intake air amount GA is maintained at a certain level, the heat generated in the engine combustion chamber 14 causes the cylinder 12 to move around. The temperature of the staying cooling water rises, and the detected water temperature θ detected by the water temperature sensor 92 gradually rises in a manner correlated with this. Here, while the detected water temperature θ is lower than the upper limit water temperature θg, the pump 30 is maintained in a stopped state. That is, the warm-up promotion process is executed (timing t0 to t1).

  During the execution of the warm-up promotion process, the temperature increase amount of the cylinder temperature θc is larger than that in the case where the warm-up promotion process is not executed. Along with this, the sound level Ge also gradually increases (timing t0 to t1). That is, as shown in FIG. 3, as the cylinder temperature θc rises, the sound hitting level Ge rises and reaches the determination value Gc. As described above, when the sound level Ge reaches the determination value Gc, the operation of the pump 30 is started. That is, the warm-up promotion process is temporarily interrupted and the hammering sound suppression process is started (timing t1).

  When the hitting suppression process is started in this manner, as shown in FIG. 4, the detected water temperature θ once decreases as the cooling water circulates in the circulating water channel 20, but then gradually increases. . On the other hand, each of the piston temperature θp and the cylinder temperature θc once increases (timing t1 to t2) and then decreases. At this time, since the amount of heat exchange between the cylinder 12 and the cooling water is larger than that of the piston 15, the amount of decrease in the cylinder temperature θc is larger than that of the piston temperature θp. When the intake air amount GA decreases, the piston temperature θp and the cylinder temperature θc further decrease (timing t2 to t3).

  With each transition of the cylinder temperature θc and the piston temperature θp, the striking sound level Ge once increases, but quickly decreases (timing t1 to t3). That is, as shown in FIG. 3, the sound hitting level Ge first reaches the determination value Gc (timing t1), and then exceeds the determination value Gc (timing t1 to t2). After that, it again approaches the determination value Gc (timing t2 to t3).

  Then, as shown in FIG. 4, when the sound hit level Ge reaches the determination value Gc (timing t3), the sound hit suppression process is continuously executed for a period until the predetermined period Tc elapses thereafter. . That is, the warm-up promotion process is continued. During this period, the striking sound level Ge further decreases as the cylinder temperature θc decreases (timing t3 to t4). That is, as shown in FIG. 3, the sound level Ge decreases and departs from the determination value Gc (timing t3 to t4).

  Then, as shown in FIG. 4, when the predetermined period Tc has passed (timing t4), the operation of the pump 30 is stopped and the warm-up promotion process is restarted (timing t4 to t5). When the piston temperature θp and the cylinder temperature θc rise with the execution of the warm-up promotion process, the sound level Ge reaches the determination value Gc again. As described above, when the sound level Ge reaches the determination value Gc, the warm-up promotion process is interrupted, the pump 30 enters the operating state, and the sound suppression process is started (timing t5).

  When the hammering sound suppression process is started in this manner, as described above, the detected water temperature θ once decreases and then gradually increases. On the other hand, each of the piston temperature θp and the cylinder temperature θc once increases (timing t5 to t6) and then decreases. At this time, for the reason described above, the amount of decrease in the cylinder temperature θc is larger than the piston temperature θp (from timing t6).

  Further, as the cylinder temperature θc and the piston temperature θp change as described above, the striking sound level Ge once rises and then decreases (timing t5 to 7) as in the period from the previous timing t1 to t3. That is, as shown in FIG. 3, the hitting sound level Ge first reaches the determination value Gc (timing t5), and then exceeds the determination value Gc (timing t5 to t6). After that, it again approaches the determination value Gc (timing t6 to t7).

  Then, as shown in FIG. 4, when the sound hitting level Ge reaches the determination value Gc (timing t7) and then a predetermined period Tc elapses (timing t8), the warm-up promotion process is started again (timing t8). ~).

  Then, since the warm-up promotion process is started in the state where the intake air amount GA is increased in this way, the detected water temperature θ is greatly increased (timing t8 to t9). And when this detected water temperature (theta) reaches upper limit water temperature (theta) g, the pump 30 transfers to normal driving | operation (timing t9-). As described above, after the pump 30 shifts to the normal operation, the cylinder temperature θc is greatly reduced, so that the sound level Ge is also greatly reduced. Thus, although the warm-up promotion process is basically executed, when the hitting sound level Ge becomes equal to or higher than the determination value Gc, the warm-up promotion process is temporarily interrupted and the hitting suppression process is executed. It becomes like this.

As described above, according to the present embodiment, the following operational effects can be achieved.
(1) In the present embodiment, the cylinder temperature θc and the piston temperature θp are monitored together, and the striking sound level Ge is predicted based on both of the monitored temperatures θc and θp. For this reason, even when the clearance between the cylinder 12 and the piston 15 is increased due to an increase in the cylinder temperature θc during execution of the warm-up promotion process or when the cylinder temperature θc is relatively low, the piston temperature θp Even when the clearance is increased due to the low value, the sound level Ge that increases with the clearance can be predicted with high reliability. Then, when the sound level Ge is predicted in this way and is in a situation where it is equal to or higher than the determination value Gc, the warm-up promotion process is interrupted and the sound suppression process is executed. The cooling capacity of the apparatus, particularly the cooling capacity around the upper part of the cylinder 12 can be increased. As a result, local thermal deformation at the top of the cylinder 12 can be quickly alleviated, and excessive piston hitting can be suitably suppressed.

  (2) During the execution of the warm-up promotion process, the lower the piston temperature θp, that is, the smaller the amount of expansion associated with the temperature rise of the piston 15 and the higher the cylinder temperature θc, that is, the temperature rise of the cylinder 12. As the local thermal deformation associated with is larger, it is predicted that the hitting level Ge is higher, so that the hitting level Ge can be appropriately predicted. That is, it is possible to determine with high accuracy whether or not piston hitting sound of a predetermined level or higher is generated.

  (3) When it is determined that the sound level Ge is less than the determination value Gc after the warm-up promotion process is interrupted, the warm-up promotion process is interrupted until a predetermined period Tc elapses from that time. The state is maintained. As a result, the striking sound level Ge fluctuates in a manner that rises and falls with the determination value Gc as a boundary, and due to this, the operation / stop of the pump 30, in other words, the execution / interruption of the warm-up promotion process is performed within a short period of time. The occurrence of a frequently repeated hunting phenomenon can be suppressed, and it can be suitably avoided that the effectiveness of the warm-up promotion process is reduced due to repeated circulation and stop of the cooling water. Become.

  (4) Furthermore, since the occurrence of such a hunting phenomenon can be suppressed, the service life of the clutch 31 is shortened due to frequent operation and stoppage of the pump 30, and the operating noise is apparent. It can also be avoided, and as a result, the durability of the cooling device can be improved and the noise can be reduced.

  In addition, the embodiment of the present invention is not limited to the embodiment exemplified in the above embodiment, and can be implemented by changing it as shown below, for example. Further, the following modifications are not applied only to the above-described embodiment, but can be implemented in a mode in which different modifications are appropriately combined.

  In the above embodiment, the piston temperature θp and the cylinder temperature θc are estimated based on the detected water temperature θ and the intake air amount GA, respectively, so that these temperatures are monitored. However, these temperatures θp and θb are, for example, thermocouples or the like. It is also possible to monitor by directly detecting using.

  In addition, the intake air amount GA is applied in addition to the detected water temperature θ as a parameter for estimating the piston temperature θp and the cylinder temperature θc as described above, but the correlation is made with the combustion heat amount generated in the engine combustion chamber 14. The piston temperature θp and the cylinder temperature θc may be estimated based on other parameters such as the fuel injection amount.

  -In each embodiment including the modification mentioned above, the striking sound level Ge was estimated based on piston temperature (theta) p and cylinder temperature (theta) c by referring the calculation map shown by FIG. Regardless of such map calculation, a function that returns the sound level Ge as a return value with the piston temperature θp and the cylinder temperature θc as arguments is stored in the memory 91a as a program, and the sound level Ge is predicted based on this function. You can also

  Further, in each of the above examples, as shown in FIG. 3, the case where the hitting level Ge is predicted to be higher as the piston temperature θp is lower and as the cylinder temperature θc is higher is illustrated. However, although there are correlations between the piston temperature θp and the cylinder temperature θc and the sound level Ge, the number and shape of the cylinders 12, the shape of the pistons 15, the manner of transmission of combustion heat generated in the engine combustion chamber 14, and so on. Depending on the correlation, the above-mentioned general tendency does not exist, and there is a case where the striking sound level Ge changes complicatedly depending on the situation of the piston temperature θp and the cylinder temperature θc. Even in such a case, the relationship between the piston temperature θp and the cylinder temperature θc and the striking sound level Ge is obtained in advance through experiments or the like, and this is stored in the memory 91a as a calculation map or function, and the stored calculation map The sound hitting level Ge can be predicted with reference to the above.

  -In each embodiment including the modification mentioned above, as shown in Formula (1)-Formula (4), it is at the time of warming-up acceleration processing based on the function which uses detected water temperature (theta) and intake air amount GA as an argument. The piston temperature θp and the cylinder temperature θc were estimated. However, the intake air amount GA is an alternative value for the amount of combustion heat generated per hour in the engine combustion chamber 14, and this change in the amount of combustion heat can be detected as a change in the detected water temperature θ. For example, since it can be assumed that the amount of combustion heat is larger as the rising speed of the detected water temperature θ is higher, the piston temperature θp and the cylinder temperature θc can be estimated based on the detected water temperature θ and the rising speed.

  In addition, in the functions shown in the equations (1) to (4), the intake air amount GA is applied as an alternative value of the combustion heat amount generated per hour in the engine combustion chamber 14, but this correlates with the combustion heat amount. It can also be changed to other parameters such as the fuel injection amount. Of course, in this case, the appropriate values α, β, γ are reset to appropriate values through experiments or the like.

  -In each embodiment including the modification mentioned above, even if the hitting level Ge becomes lower than the judgment value Gc after the hitting level Ge becomes equal to or higher than the judgment value Gc and the warm-up promotion processing is interrupted, Until the predetermined period Tc elapses, the warm-up promotion process is continued. In this case, the predetermined period Tc may be set in the following manner. That is, when the sound hitting level Ge falls below the determination value Gc, a period from that time until the sound hitting level Ge decreases to a level smaller than the determination value Gc by a predetermined value or more may be set as the predetermined period Tc. .

  In addition, after the hitting sound level Ge becomes equal to or higher than the determination value Gc and the warm-up promotion process is interrupted, when the hitting sound level Ge becomes lower than the determination value Gc, the warm-up promotion process is immediately restarted. You may do it. According to such a configuration, it is possible to ensure a long execution period of the warm-up promotion process, and a deterioration in fuel consumption due to a delay in warm-up and an increase in heat loss due to frequent interruption of the warm-up promotion process. Can be suppressed.

  In each embodiment including the above-described modifications, the sounding level Ge is predicted based on the piston temperature θp and the cylinder temperature θc, and the warming-up promotion process is performed when the sounding level Ge is equal to or higher than the determination level Gc. Was interrupted. Instead of this, a prediction calculation map that directly determines whether the warm-up promotion processing is permitted or interrupted by using the piston temperature θp and the cylinder temperature θc as parameters is omitted. It is possible to determine whether to execute the warm-up promotion processing or to interrupt it by referring to the same map obtained by such a method. For example, the line indicating the determination value Gc in the calculation map of FIG. 3 described above is set as a reference line, and the area located on the left side of the reference line in the map of FIG. An area located on the right side of the line including “” is defined as an “interruption area”. When the values on the map corresponding to the piston temperature θp and the cylinder temperature θc are “permitted areas”, it is determined that there is no situation in which piston hitting sound of a predetermined level or higher can be generated, and warm-up is promoted. While the process is executed, if the value on the map is “permitted area”, it is determined that there is a situation in which piston hitting sound of a predetermined level or more can be generated, and the warm-up promotion process is interrupted. A structure can also be adopted.

  -In each embodiment including the modification mentioned above, although the process which stops the driving | operation of the pump 30 and prohibits the circulation of the cooling water in the circulation water channel 20 was illustrated as a warming-up promotion process, Although the pump 30 is driven, the discharge amount is limited to a predetermined amount or less, for example, the minimum amount of cooling water that does not cause local boiling of the cooling water around the cylinder 12 is circulated through the circulation channel 20. Also included. Even in such a case, since the cooling capacity by the cooling water is extremely low, the cylinder 12 is thermally deformed, and there is a concern about the occurrence of piston hitting noise to some extent. Further, in this case, when the warm-up promotion process is prohibited, the cylinder 12 is cooled with a sufficiently high cooling capacity from the minimum amount that does not cause local boiling of the cooling water as described above, and the thermal deformation is promptly performed. The discharge amount of the pump 30 is increased to an amount that can be eliminated.

  In each of the embodiments including the above-described modifications, power transmission from the engine output shaft to the rotation shaft of the pump 30 is connected / disconnected by the clutch 31, but the rotational force of the engine output shaft is transmitted to the rotation shaft of the pump. If it is possible to switch between a possible state and a non-transmittable state, for example, the pulley 32 attached to the rotary shaft of the pump is pressed / separated with respect to the belt that travels as the engine output shaft rotates. You may make it perform this with other switching mechanisms, such as connecting / disconnecting power transmission. Furthermore, not only such an engine drive type pump but also an electric rotation type pump can be adopted, for example.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Cylinder block, 12 ... Cylinder, 13 ... Cylinder head, 14 ... Engine combustion chamber, 15 ... Piston, 20 ... Circulating water channel, 21 ... Water jacket, 22 ... Radiator, 24 ... Radiator passage, 25 ... Detour passage, 27 ... thermostat, 30 ... pump, 31 ... clutch (switching mechanism), 32 ... pulley, 33 ... belt, 91 ... control device (control means, detection means, determination means, cylinder temperature monitoring means, piston temperature monitoring means) ), 91a... Memory (storage means), 92... Water temperature sensor (cylinder temperature monitoring means, piston temperature monitoring means), 93... Air flow meter (cylinder temperature monitoring means, piston temperature monitoring means).

Claims (13)

A cooling water passage through which the cooling water of the internal combustion engine circulates, a detection means for detecting the temperature of the cooling water in the circulation water passage, and cooling to execute warm-up promotion processing when the detected water temperature is below a predetermined temperature. Control means for controlling the drive state of a pump provided in the circulation water path so that water circulation is restricted, and the detection means is cooling water that stays around the cylinder during the execution of the warm-up promotion process. In the cooling device for an internal combustion engine that detects the temperature of the cooling water that correlates with the temperature,
Cylinder temperature monitoring means for monitoring the temperature of the upper part of the cylinder;
Piston temperature monitoring means for monitoring the temperature of the piston;
Determination means for determining whether or not a piston hitting sound of a predetermined level or more is generated based on a cylinder temperature and a piston temperature at the time of executing the warm-up promotion process,
The cooling device for an internal combustion engine, wherein the control means interrupts the warm-up promotion process when the determination means determines that a piston hitting sound of a predetermined level or more is generated. The determination means predicts a piston hitting sound level based on a cylinder temperature and a piston temperature monitored during execution of the warm-up promotion processing, and the predicted piston hitting sound level is equal to or higher than the predetermined level. The cooling device for an internal combustion engine according to claim 1, wherein it is determined that a piston hitting sound of a predetermined level or more is generated. In the determination, when the monitored piston temperature is lower and when the monitored cylinder temperature is higher, the level of the piston hitting sound generated during execution of the warm-up promotion process is larger. The cooling device for an internal combustion engine according to claim 1 or 2. The control means determines that the piston hitting sound of a predetermined level or higher is generated by the determining means and interrupts the warm-up promotion processing, and then the piston hitting sound of a predetermined level or higher is generated by the determining means. The internal combustion engine according to any one of claims 1 to 3, wherein when it is determined that the situation is not present, the warm-up promotion process is continued until a predetermined period has elapsed since the determination was made. Cooling system. The pump includes a switching mechanism that switches between a state in which the rotational force of the engine output shaft can be transmitted to the rotational shaft of the pump and a state in which the rotational force cannot be transmitted to the pump.
The control means drives the switching mechanism to stop the driving state of the pump when the warming-up promotion process is executed, and controls the driving state of the pump to an operating state when the warming-up promotion process is interrupted. The cooling device for an internal combustion engine according to any one of claims 1 to 4. The cylinder temperature monitoring means pre-identifies and stores a function that includes the detected water temperature detected and the amount of combustion heat generated per hour as arguments and returns the cylinder temperature during warm-up acceleration processing as a return value. The cooling device for an internal combustion engine according to any one of claims 1 to 5, further comprising: means for estimating a cylinder temperature based on the stored function. The cooling function for an internal combustion engine according to claim 6, wherein the function has a relationship in which the rate of change of the detected water temperature and cylinder temperature detected increases as the amount of combustion heat generated per hour increases. apparatus. The cooling function for an internal combustion engine according to claim 6 or 7, wherein the function has a relation that the rate of change of the detected deviation between the detected water temperature and the cylinder temperature increases as the deviation becomes smaller. apparatus. The function stored in the storage means sequentially estimates the cylinder temperature θc (i) with a predetermined estimation period, and the detected water temperature θ (i) detected at a predetermined estimation timing t (i). Combustion heat quantity Q (i) per time at timing t (i), degree of deviation Δθc (i) (= θb (i) between cylinder temperature θc (i) and detected water temperature θ (i) at the estimated timing t (i) −θ (i)) and the following equations (1) and (2) using the degree of deviation Δθc (i−1) at the previous estimated timing t (i−1).

The cooling apparatus for an internal combustion engine according to claim 6, defined by: The piston temperature monitoring means pre-identifies and stores a function that returns the detected temperature of the detected water and the amount of combustion heat generated per hour as arguments and returns the piston temperature during the warm-up acceleration process as a return value. The cooling device for an internal combustion engine according to any one of claims 1 to 9, further comprising: means for estimating a piston temperature based on the stored function. The cooling function for an internal combustion engine according to claim 10, wherein the function has a relationship in which the rate of change between the detected water temperature and the detected piston temperature increases as the amount of combustion heat generated per hour increases. apparatus. The cooling function for an internal combustion engine according to claim 10 or 11, wherein the function has a relationship in which the change rate of the detected deviation between the detected water temperature and the piston temperature increases as the deviation is small. apparatus. The function stored in the storage means sequentially estimates the piston temperature θp (i) with a predetermined estimation period, and the detected water temperature θ (i) detected at the predetermined estimation timing t (i). Combustion heat quantity Q (i) per time at timing t (i), degree of deviation Δθp (i) (= θb (i) between piston temperature θp (i) and detected water temperature θ (i) at the same estimated timing t (i) −θ (i)) and the following formulas (3) and (4) using the degree of deviation Δθp (i−1) at the previous estimated timing t (i−1).

The cooling device for an internal combustion engine according to claim 10, defined by:

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