JP2011074891A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain unnecessary increase of fuel consumption of an internal combustion engine while appropriately restraining excessive temperature rise of a piston of the internal combustion engine. <P>SOLUTION: A pressure stage of oil discharged from an engine driven oil pump and injected and supplied to the piston of the internal combustion engine is switched between a lower pressure stage and a high pressure stage. If an engine rotation speed NE is equal to or higher than a predetermined value NEth or a fuel injection quantity Q is equal to or larger than a predetermined value Qth, the pressure stage of the oil is set to the high pressure stage. As for an electronic control device, three temperature areas (T1≤THW<T2, T2≤THW<T3, T3≤THW<T5) are arranged about a cooling water temperature THW detected by a water temperature sensor and the predetermined values NEth, Qth are set for the respective plurality of temperature areas. When distribution of the cooling water in a cooling water passage is permitted, the predetermined values NEth, Qth set for the temperature areas including the cooling water temperature THW are arranged to be larger compared to the case when the distribution is inhibited. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention makes the flow rate of the cooling water in the cooling water passage of the internal combustion engine variable based on the engine operating state, and is injected and supplied to the piston of the internal combustion engine when the engine state quantity is equal to or greater than a predetermined threshold value. The present invention relates to a control device for an internal combustion engine that increases oil pressure.

  Conventionally, in an internal combustion engine control device, the pressure of oil supplied to each part of the internal combustion engine is set to a high pressure when the engine rotational speed exceeds a predetermined threshold or the fuel injection amount exceeds a predetermined threshold. Yes. In addition, there is a technique that suppresses an excessive temperature rise of the piston by injecting and supplying more oil per unit time to the piston of the internal combustion engine with a high oil pressure. Here, as the temperature of the piston is higher, the temperature of the cooling water flowing through the cooling water passage of the internal combustion engine is higher, and in a situation where the temperature of the piston is higher, it is necessary to cool the piston early, It is conceivable to provide a water temperature sensor that detects the temperature of the cooling water in the cooling water passage, and to set the predetermined threshold value smaller than when the temperature of the cooling water detected by the water temperature sensor is high. Note that such a water temperature sensor is usually provided on the downstream side of the cylinder block and the cylinder head constituting the internal combustion engine body in the cooling water passage.

  Further, in the control device for the internal combustion engine, the flow rate of the cooling water in the cooling water passage is variable based on the engine operating state. An example of such a control device for an internal combustion engine is disclosed in Patent Document 1. In a conventional internal combustion engine control device including the technique described in Patent Document 1, the flow control of the cooling water in the cooling water passage is switched based on the engine operating state through the drive control of the water pump. . Specifically, when the temperature of the cooling water is included within a predetermined temperature range, the warm-up of the internal combustion engine is promoted by prohibiting the circulation of the cooling water in the cooling water passage. Further, when the flow of the cooling water is prohibited, when the internal combustion engine shifts to a high load operation or a high rotation operation, the cooling water is circulated in the cooling water passage to suppress an excessive temperature rise of the internal combustion engine. Like to do.

JP 2008-169750 A

  Incidentally, as described above, the water temperature sensor is provided at a position spaced apart from the vicinity of the piston in the cooling water passage of the internal combustion engine. Further, when the cooling water is circulating in the cooling water passage, a lot of heat is transferred to the cooling water when passing through the position near the piston and the inside of the cylinder head. For these reasons, the temperature of the cooling water at the position where the water temperature sensor is disposed is higher than the temperature of the cooling water near the piston. On the other hand, when the circulation of the cooling water in the cooling water passage is prohibited through the drive control of the water pump, a large amount of heat is transmitted from the piston to the cooling water remaining in the vicinity of the piston. The temperature of the cooling water at the installation position is lower than the temperature of the cooling water near the piston. Therefore, in the configuration in which the predetermined threshold value for setting the pressure of the oil supplied to the piston to be high according to the temperature of the cooling water detected by the water temperature sensor is set, for example, the cooling water in the cooling water passage When the flow of water is prohibited, that is, assuming that the temperature of the cooling water at the position near the piston is the highest with respect to the temperature of the cooling water detected by the water temperature sensor, the cooling water detected by the water temperature sensor It is considered preferable to regulate the relationship between the temperature and the predetermined threshold value in order to reliably suppress an excessive temperature rise of the piston. However, in this case, when the circulation of the cooling water in the cooling water passage is allowed, the following problem occurs. That is, when the temperature of the cooling water at the position where the water temperature sensor is disposed rises, and the predetermined threshold value is set small accordingly, and the engine speed becomes equal to or higher than the predetermined threshold value, as described above, the oil pressure However, at this time, the temperature of the piston of the internal combustion engine is so high that cooling with oil is required. There will be a situation where no As a result, there may be a problem that the fuel consumption of the internal combustion engine unnecessarily increases by the amount of high oil pressure to inject and supply more oil to the piston per unit time.

  These problems are not limited to switching between permitting and prohibiting the flow of cooling water in the cooling water passage, and are generally common if the flow rate of the cooling water is variable based on the engine operating state. Can occur.

  The present invention has been made in view of such circumstances, and its object is to suppress an unnecessary increase in fuel consumption of the internal combustion engine while accurately suppressing an excessive temperature rise of the piston of the internal combustion engine. An object of the present invention is to provide a control device for an internal combustion engine.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
(1) The invention according to claim 1 is a cooling water temperature detecting means provided in a position separated from a position in the vicinity of the piston in the cooling water passage of the internal combustion engine for detecting the temperature of the cooling water at the separated position, and the cooling Cooling water flow rate variable means for changing the flow rate of the cooling water in the water passage based on the engine operating state, and the pressure of oil supplied to the piston of the internal combustion engine when the engine state amount exceeds a predetermined threshold value Threshold setting means which is applied to an internal combustion engine having an oil pressure variable means for increasing, and sets the predetermined threshold value smaller than when the temperature of the cooling water detected by the cooling water temperature detecting means is high compared to when it is low In the control apparatus for an internal combustion engine, the threshold value setting means may be configured such that the cooling water temperature is lower than when the flow rate of the cooling water in the cooling water passage is small. And as its gist to increase the predetermined threshold value set for the temperature of the cooling water detected by the detecting means.

  The cooling water temperature detecting means is provided in a position separated from the position near the piston in the cooling water passage of the internal combustion engine and detects the temperature of the cooling water at the separated position, and is thus detected by the cooling water temperature detecting means. Even if the temperature of the cooling water is the same, the temperature of the cooling water in the vicinity of the piston is lower when the flow rate of the cooling water in the cooling water passage is large than when the flow rate is low.

  According to the above configuration, when the flow rate of the cooling water in the cooling water passage is large, compared to when the flow rate is low, that is, the temperature of the cooling water at the position near the piston based on the cooling water temperature detected by the cooling water temperature detecting means. When the temperature is relatively low, the predetermined threshold set with respect to the temperature of the cooling water detected by the cooling water temperature detecting means is made larger than when it is high. As described above, when setting the predetermined threshold, not only the temperature of the cooling water detected by the cooling water temperature detecting means but also the temperature of the cooling water and the flow rate of the cooling water in the cooling water passage are grasped. In consideration of the temperature of the cooling water at the position near the piston, the predetermined threshold value can be set according to the temperature of the cooling water at the actual position near the piston. As a result, the oil pressure can be suitably maintained in a low state in a wider engine state quantity region. Accordingly, it is possible to suppress an unnecessary increase in the fuel consumption of the internal combustion engine while accurately suppressing an excessive temperature rise of the piston of the internal combustion engine.

  (2) The invention according to claim 2 is the control apparatus for an internal combustion engine according to claim 1, wherein the cooling water flow rate varying means switches between permitting and prohibiting the flow of the cooling water in the cooling water passage. And the threshold value setting means is more sensitive to the temperature of the cooling water detected by the cooling water temperature detecting means than when it is prohibited when the flow of the cooling water in the cooling water passage is allowed. The gist of the invention is to increase the predetermined threshold value set in this manner.

  The cooling water temperature detecting means is provided in a position separated from the position near the piston in the cooling water passage of the internal combustion engine and detects the temperature of the cooling water at the separated position, and is thus detected by the cooling water temperature detecting means. Even when the temperature of the cooling water is the same, the temperature of the cooling water in the vicinity of the piston is lower when the cooling water is flowing in the cooling water passage than when the cooling water is not flowing.

  According to the above configuration, the vicinity of the piston is based on the temperature of the cooling water detected by the cooling water temperature detection means as compared with the time when the circulation of the cooling water in the cooling water passage is permitted, compared to when it is prohibited. When the temperature of the cooling water at the position is relatively low, the predetermined threshold set with respect to the temperature of the cooling water detected by the cooling water temperature detecting means is made larger than when the temperature is high. Accordingly, it is possible to suppress an unnecessary increase in the fuel consumption of the internal combustion engine while accurately suppressing an excessive temperature rise of the piston of the internal combustion engine.

  (3) In the configuration in which a plurality of temperature regions are provided for the temperature of the cooling water detected by the cooling water temperature detecting means, and the predetermined threshold is set for each of the plurality of temperature regions, When the cooling water flow rate in the cooling water passage is small, the predetermined threshold value set for the temperature range including the temperature of the cooling water detected by the cooling water temperature detecting means is small. It can be embodied with an aspect of making it larger than that. Even in this case, it is possible to achieve the effect according to the effect of the invention described in claim 1 and the effect of the invention described in claim 2.

  (4) In the configuration including the engine rotational speed as the engine state quantity, the oil pressure varying means includes the piston of the internal combustion engine when the engine rotational speed becomes a predetermined value or more. The embodiment can be embodied in such a manner that the pressure of the oil supplied to the fuel is increased.

  (5) In the configuration including the engine load as the engine state quantity, the oil pressure varying means is configured so that the engine load is greater than a predetermined value with respect to the piston of the internal combustion engine. Thus, the embodiment can be embodied with a mode of increasing the pressure of the oil supplied by injection. Here, when the present invention is applied to a control device for a diesel engine, for example, a fuel injection amount can be adopted as the engine load. In addition, when the present invention is applied to a control device for a gasoline engine, for example, an intake air amount can be adopted as an engine load.

  (6) According to the invention as described in any one of claims 1 to 5, according to the invention as set forth in claim 6, the oil pressure variable means is discharged from an engine-driven oil pump and is connected to the internal combustion engine. A pressure stage switching mechanism that switches a pressure stage of oil supplied to an engine piston between a low pressure stage and a high pressure stage, and when the engine state quantity is equal to or greater than the predetermined threshold value, the oil pressure stage is changed to a high pressure stage. On the other hand, when the engine state quantity is less than the predetermined threshold value, the oil pressure stage can be embodied as a low pressure stage. The above-described problem of the present invention also occurs in the same manner even in the case of including a pressure stage switching mechanism that switches the oil pressure stage between a low pressure stage and a high pressure stage. In this regard, if the inventions according to claims 1 to 5 are applied to the invention according to claim 6, the fuel of the internal combustion engine can be suppressed while suppressing an excessive temperature rise of the piston of the internal combustion engine. An unnecessary increase in consumption can be suppressed.

The schematic block diagram which shows schematic structure of the cooling water circulation system of an internal combustion engine about one Embodiment of the control apparatus of the internal combustion engine which concerns on this invention. The schematic block diagram which shows schematic structure of the oil supply system of the internal combustion engine in the embodiment. (A) Sectional drawing which shows sectional structure of relief valve when switching valve is opened, (b) Sectional drawing which shows sectional structure of relief valve when switching valve is closed. The map which prescribed | regulated the relationship between the engine rotational speed and fuel injection quantity in predetermined cooling water temperature, and the oil pressure stage about the switching control of the oil pressure stage in the embodiment. The graph which shows an example of the relationship between the engine speed NE and the oil pressure P in predetermined fuel-injection amount about the switching control of the oil pressure stage in the embodiment. The flowchart which shows the process sequence about the drive control of the water pump in the embodiment. The flowchart which shows the process sequence about the switching control of the pressure stage of the oil in the embodiment. (A)-(c) The map which prescribed | regulated the predetermined value NEth of the engine speed NE and the predetermined value Qth of the fuel injection quantity in each temperature area | region of cooling water temperature about the switching control of the pressure stage of the oil in the embodiment.

Hereinafter, an embodiment in which a control device for an internal combustion engine according to the present invention is embodied as a control device for an in-vehicle diesel engine (hereinafter, internal combustion engine) 1 will be described with reference to FIGS.
FIG. 1 shows a schematic configuration of a cooling water circulation system for an internal combustion engine 1 to which a control device according to this embodiment is applied.

  As shown in FIG. 1, the internal combustion engine 1 includes an internal combustion engine body 2 including a cylinder block 3 and a cylinder head 4. A cylinder bore 31 is formed inside the cylinder block 3, and a piston 32 that is drivingly connected to the engine output shaft is provided in the cylinder bore 31 so as to be capable of reciprocating.

  Further, the internal combustion engine 1 is provided with a cooling water passage 5 as a flow path through which the cooling water circulates. The cooling water passage 5 has a block-side water jacket 53 formed so as to surround the cylinder bore 31 in the cylinder block 3 and a head-side water jacket 54 formed in the cylinder head 4. The block side water jacket 53 and the head side water jacket 54 are connected in series.

  In the cooling water passage 5, a main cooling water passage 51 is connected between the downstream end portion of the head side water jacket 54 and the upstream end portion of the block side water jacket 53. A radiator 56 for cooling the cooling water is provided in the middle of the main cooling water passage 51. The main cooling water passage 51 is connected to a sub cooling water passage 52 that connects the upstream portion and the downstream portion of the main cooling water passage 51 with respect to the radiator 56 and bypasses the radiator 56. In addition, a thermostat 57 that switches communication and blocking between the sub-cooling water passage 52 and the main cooling water passage 51 is provided at a connection portion between the main cooling water passage 51 and the downstream end of the sub-cooling water passage 52. .

  An engine-driven water pump 55 that sucks and discharges cooling water is provided between the thermostat 57 and the cylinder block 3 in the cooling water passage 5. Further, a clutch 58 is provided between the input shaft of the water pump 55 and the engine output shaft for switching between transmission and shutoff of the engine output to the input shaft of the water pump 55. When the engine output is transmitted to the input shaft of the water pump 55 through the clutch 58, the water pump 55 is driven, and as shown by the arrows in the figure, the block-side water jacket 53 and the head-side water jacket. Cooling water flows in the order of 54.

  The vehicle is equipped with an electronic control unit 9 that executes various controls of the internal combustion engine 1 including the operation control of the clutch 58, that is, the drive control of the water pump 55. The electronic control unit 9 includes a CPU that executes various arithmetic processes related to various controls such as start control and fuel injection control of the internal combustion engine 1, a ROM that stores programs and data necessary for various controls, and a calculation result of the CPU is temporarily stored. RAM, an input / output port for inputting / outputting signals to / from the outside, and the like.

  A temperature of cooling water (hereinafter referred to as “cooling water temperature”) THW at the connection position between the head side water jacket 54 and the main cooling water passage 51 is detected at the input port of the electronic control unit 9 outside the cylinder head 4. A water temperature sensor 81, an ignition switch for the internal combustion engine 1, a rotational speed sensor for detecting the engine rotational speed NE, which is the rotational speed of the engine output shaft, an intake pressure sensor for detecting the pressure of the intake air used for combustion of the internal combustion engine 1, etc. The various sensors are connected.

  In the present embodiment, when the internal combustion engine 1 is warmed up through the electronic control unit 9, the flow control of the cooling water in the cooling water passage 5 is switched based on the engine operating state through the drive control of the water pump 55. ing. Specifically, when the cooling water temperature THW detected by the water temperature sensor 81 is included in a predetermined temperature range (T0 ≦ THW ≦ T4), the driving of the water pump 55 is stopped and the cooling water in the cooling water passage 5 is stopped. By prohibiting the circulation, warm-up of the internal combustion engine 1 is promoted. In the present embodiment, “5 ° C.” is adopted as the temperature T0. Further, “80 ° C.” is adopted as the temperature T4. Further, when the flow of the cooling water is prohibited as described above, when the operation is shifted to the high load operation or the high rotation operation, the water pump 55 is driven to allow the flow of the cooling water, thereby allowing the internal combustion An excessive temperature rise of the engine 1 is suppressed. The water pump 55 and the clutch 58 in the present embodiment correspond to the cooling water flow rate varying means according to the present invention.

FIG. 2 shows a schematic configuration of the oil supply system of the internal combustion engine 1 in the present embodiment.
As shown in the figure, the internal combustion engine 1 is provided with a main supply passage 61 for supplying the oil stored in the oil pan 63 to each part of the internal combustion engine 1. An engine-driven oil pump 64 that sucks and discharges oil is provided in the middle of the main supply passage 61. When engine output is transmitted to the input shaft of the oil pump 64, the oil pump 64 is driven and oil is supplied to each part of the internal combustion engine through the main supply passage 61. Specifically, a sub supply passage 65 for branching from the main supply passage 61 to supply oil to the lubricated portion of the internal combustion engine 1 is provided on the downstream side of the oil pump 64 in the main supply passage 61. Yes. Further, an oil jet mechanism 66 for supplying and supplying oil for cooling the piston 32 to the piston 32 of the internal combustion engine 1 is connected to the downstream end portion of the main supply passage 61 via a check valve 67. Yes. The check valve 67 is closed when the pressure of oil acting on the valve body of the check valve 67 from the main supply passage 61 side is less than a predetermined pressure, while the pressure of the oil becomes equal to or higher than the predetermined pressure. The valve is opened, and whether to inject and supply oil to the piston 32 through the oil jet mechanism 66 is switched.

  The main supply passage 61 is provided with a relief passage 62 that connects the downstream portion and the upstream portion of the oil pump 64 in the main supply passage 61. A relief valve 71 is provided in the middle of the relief passage 62. The relief valve 71 is closed when the oil pressure upstream of the relief valve 71 in the relief passage 62 is less than a predetermined valve opening pressure, while the oil pressure becomes equal to or higher than the predetermined valve opening pressure. The valve is opened, and whether to relieve oil through the relief passage 62 is switched.

Hereinafter, the configuration of the relief valve 71 will be described.
The relief valve 71 is housed in a cylindrical housing 72 having a bottom on one side, and a housing chamber 73 that is an internal space of the housing 72, and is displaced with respect to the axial direction of the housing 72 (hereinafter, “axial direction A”). A cylindrical valve body 75 is provided. A movable member 74 that is displaceable along the axial direction A is provided between the inner peripheral surface of the housing 72 and the outer peripheral surface of the valve body 75 in the accommodation chamber 73. The movable member 74 has a bottomed cylindrical shape on one side, and its outer diameter is slightly smaller than the inner diameter of the housing 72, and its inner diameter is slightly larger than the outer diameter of the valve body 75. A fixing member 76 that covers the opening is provided at the end 72 </ b> B of the housing 72. The fixing member 76 includes a cylindrical large-diameter portion 76A and a cylindrical small-diameter portion 76B that is provided integrally and coaxially with the large-diameter portion 76A and has a smaller outer diameter than the large-diameter portion 76A. is doing. The large diameter portion 76 </ b> A has an upper end surface in contact with the lower end surface of the end portion 72 </ b> B of the housing 72, and the small diameter portion 76 </ b> B has a side surface in contact with the inner surface of the end portion 74 </ b> B of the movable member 74. A spring 77 is provided between the upper surface of the small diameter portion 76B of the fixed member 76 and the lower surface of the valve body 75 to urge the valve body 75 toward the bottom 74A side (upper side in the drawing) of the movable member 74. .

  The length of the movable member 74 in the axial direction A is shorter than that of the housing chamber 73, the lower surface of the end portion 74B of the movable member 74, the inner surface of the end portion 72B of the housing 72, and the upper surface of the large diameter portion 76A. The outer circumferential surface of the small diameter portion 76B of the fixing member 76 forms an annular gap 73F.

  In the center of the bottom portion 72A of the housing 72 and the bottom portion 74A of the movable member 74, an inlet side through hole 72C and an inlet side communication hole 74C having the same diameter as the inlet side through hole 72C are formed. 72C and communication hole 74C form part of the relief passage 62. In the side portion of the housing 72, an outlet side through hole 72D penetrating the same side portion is formed. In addition, an outlet-side communication hole 74 </ b> D that penetrates the same side portion and is shorter in the axial direction A than the outlet-side through hole 72 </ b> D of the housing 72 is formed in the side portion of the movable member 74. Here, in the accommodation chamber 73, in the state where the movable member 74 is located closest to the upper side in the drawing, the upper end surface in the drawing in the outlet side communication hole 74D and the upper end surface in the outlet side through hole 72D coincide. Further, in the accommodation chamber 73, in a state where the movable member 74 is located closest to the lower side in the drawing, the lower end surface in the drawing at the outlet side communication hole 74D and the lower end surface at the outlet side through hole 72D coincide. As described above, by changing the position of the movable member 74 in the storage chamber 73, the opening position of the outlet portion 73 </ b> D of the storage chamber 73 is changed in the axial direction A.

  An introduction through-hole 72 </ b> E that connects the gap 73 </ b> F and the outside of the housing 72 is formed in the end 72 </ b> B of the housing 72. An introduction passage 78 is connected between the introduction through hole 72 </ b> E and the upstream portion of the relief valve 71 in the relief passage 62. An electromagnetic solenoid type switching valve 79 that is energized and controlled by the electronic control unit 9 is provided in the introduction passage 78. When the solenoid of the switching valve 79 is energized through the electronic control unit 9, the switching valve 79 is opened, and oil on the upstream side of the relief valve 71 in the relief passage 62 passes through the introduction passage 78 into the gap 73F. Will be introduced. When the energization of the switching valve 79 to the solenoid is stopped, the switching valve 79 is closed and oil is not introduced into the gap 73F. Note that a discharge passage (not shown) is connected to the gap 73F. When oil is not introduced into the gap 73F, the oil present in the gap 73F is discharged to the outside through the discharge passage.

Next, the operation mode of the relief valve 71 will be described with reference to FIG.
FIG. 3A shows a cross-sectional structure of the relief valve 71 when the switching valve 79 is opened. FIG. 3B shows a sectional structure of the relief valve 71 when the switching valve 79 is closed.

  As shown in FIG. 3A, when the switching valve 79 is opened, a part of the oil discharged from the oil pump 64 is introduced into the gap 73F through the relief passage 62 and the introduction passage 78. . As a result, the movable member 74 is pushed upward by the oil pressure in the gap 73 </ b> F, so that the movable member 74 is held in a state in which the bottom 74 </ b> A is in contact with the bottom 72 </ b> A of the housing 72. In such a state, the engine output increases and the pressure of the oil discharged from the oil pump 64 rises, and the pressure of the oil acting on the valve body 75 through the relief passage 62 rises. When displaced to the position shown in FIG. 3A, the inlet 73C and outlet 73D of the storage chamber 73 are in communication. As a result, part of the oil in the main supply passage 61 is relieved to the upstream side of the oil pump 64 through the relief passage 62, so that the pressure stage of the oil supplied to each part of the internal combustion engine 1 is changed to the low pressure stage. Is done.

  As shown in FIG. 3B, when the switching valve 79 is closed, no oil is introduced into the gap 73F. As a result, the force that pushes up the movable member 74 upward in the drawing is reduced, so that the movable member 74 is held in a state where its end 74B is in contact with the large diameter portion 76A of the fixed member 76. In such a state, the engine output increases and the pressure of the oil discharged from the oil pump 64 rises, and the pressure of the oil acting on the valve body 75 through the relief passage 62 rises. If it moves to the position shown in FIG.3 (b), the entrance part 73C and exit part 73D of the storage chamber 73 will be in a communication state. As a result, a part of the oil in the main supply passage 61 is relieved to the upstream side of the oil pump 64 through the relief passage 62, so that the pressure stage of the oil supplied to each part of the internal combustion engine is a high pressure stage. The

  In the present embodiment, oil pressure stage switching control is performed through the electronic control unit 9 based on the engine speed NE and the fuel injection amount Q. Specifically, when the engine speed NE is equal to or higher than a predetermined value NEth, the pressure stage of the oil is switched from the low pressure stage to the high pressure stage through the energization control of the switching valve 79. Further, when the fuel injection amount Qth is equal to or greater than the predetermined value Qth, the oil pressure stage is switched from the low pressure stage to the high pressure stage through the energization control of the switching valve 79.

FIG. 4 shows an example of a map defining the relationship between the engine rotational speed NE and the fuel injection amount Q and the oil pressure stage (low pressure stage, high pressure stage) at a predetermined coolant temperature THW.
As shown in the figure, in the region where the engine rotational speed NE is lower than the predetermined value NEth and the fuel injection amount Q is lower than the predetermined value Qth, the oil pressure stage is a low pressure stage, and the engine rotational speed NE is In the region where the predetermined value NEth or more or the fuel injection amount Q is the predetermined value Qth or more, the oil pressure stage is a high pressure stage. Here, the predetermined value NEth and the predetermined value Qth correspond to the predetermined threshold value according to the present invention.

  FIG. 5 shows the relationship between the engine speed NE at a predetermined fuel injection amount Q (where Q <Qth) and the pressure P of oil that is regulated by the relief valve 71 and supplied to each part of the internal combustion engine 1. An example of a graph is shown.

Since the driving force of the oil pump 64 increases as the engine output increases, the oil pressure P increases as the engine rotational speed NE increases as shown in FIG.
Here, when the switching valve 79 is opened, that is, when the oil pressure stage is a low pressure stage, when the engine speed NE reaches a predetermined value NE0, the relief valve 71 is opened and the main supply passage is opened. 61 oil is relieved (point A in the figure). As a result, in the region where the engine rotational speed NE is greater than or equal to the predetermined value NE0, the amount of increase in the oil pressure P relative to the amount of increase in the engine rotational speed NE is smaller than in the region less than the predetermined value NE0.

  On the other hand, when the engine speed NE further increases and reaches the predetermined value NEth illustrated in FIG. 4 (point C in the figure), the switching valve 79 is closed, that is, the oil pressure stage is set to the high pressure stage. As shown in FIG. 3B, since the movable member 74 is lowered and the valve opening pressure of the relief valve 71 is increased, the relief valve 71 is closed again. As a result, oil relief through the relief passage 62 and the relief valve 71 is not performed, so that the oil pressure P increases rapidly. When the relief valve 71 is opened again, the oil in the main supply passage 61 is relieved. As a result, the oil pressure P increases as the engine rotational speed NE increases. However, the oil pressure corresponding to the engine rotational speed NE is higher than when the oil pressure stage is a low pressure stage. The pressure P is high.

  Thus, by switching the oil pressure stage to the high pressure stage, the oil pressure becomes high, the check valve 67 is opened, and high pressure oil is injected and supplied to the piston 32 through the oil jet mechanism 66. The Further, as the pressure of the oil supplied and supplied to the piston 32 becomes higher in this way, more oil is supplied and supplied to the piston 32 per unit time, and the cooling effect of the piston 32 increases. Will be. In this way, an excessive temperature rise of the piston 32 is suppressed. The oil supply system in the present embodiment corresponds to the oil pressure variable means according to the present invention, and the relief passage 62, the relief valve 71, the introduction passage 78, and the switching valve 79 in the present embodiment are pressure stages according to the present invention. It corresponds to a switching mechanism.

  Here, as the temperature of the piston 32 is higher, the temperature of the cooling water flowing through the cooling water passage 5 of the internal combustion engine 1 is higher, and in a situation where the temperature of the piston 32 is higher, the piston 32 needs to be cooled earlier. Therefore, when the coolant temperature THW detected by the coolant temperature sensor 81 is high, the predetermined values NEth and Qth are set smaller than when the coolant temperature THW is low. Specifically, three temperature regions (first temperature region (T1 ≦ THW <T2), second temperature region (T2 ≦ THW <T3), third temperature) about the coolant temperature THW detected by the water temperature sensor 81 A temperature region (T3 ≦ THW <T5) is provided, and the predetermined values NEth and Qth are set for each of these three temperature regions. Incidentally, in the present embodiment, the relationship between the temperatures is “T0 <T1 <T2 <T3 <T4 <T5”.

  Incidentally, as described above, the water temperature sensor 81 is provided at a position spaced apart from the vicinity of the piston 32 in the cooling water passage 5 of the internal combustion engine 1. Further, when the cooling water is circulating in the cooling water passage 5, a large amount of heat is transmitted to the cooling water when passing through the position near the piston 32 in the block side water jacket 53 and the head side water jacket 54. For these reasons, the cooling water temperature THW at the position where the water temperature sensor 81 is disposed is higher than the cooling water temperature THW near the piston 32. On the other hand, when the circulation of the cooling water in the cooling water passage 5 is prohibited through the drive control of the water pump 55 described above, a large amount of heat is transmitted from the piston 32 to the cooling water remaining in the vicinity of the piston 32. Therefore, the cooling water temperature THW at the position where the water temperature sensor 81 is disposed is lower than the temperature of the cooling water near the piston 32. Therefore, it is assumed that when the coolant flow in the coolant passage 5 is prohibited, that is, the coolant temperature in the vicinity of the piston 32 is the highest with respect to the coolant temperature THW detected by the coolant temperature sensor 81. Therefore, it is considered preferable to prescribe the relationship between the cooling water temperature THW detected by the water temperature sensor 81 and the predetermined values NEth and Qth in order to reliably suppress an excessive temperature rise of the piston 32. However, in this case, when the circulation of the cooling water in the cooling water passage 5 is allowed, the following problem occurs. That is, when the cooling water temperature THW at the position where the water temperature sensor 81 is disposed rises, the predetermined values NEth and Qth are set small, and the engine speed NE and the fuel injection amount Q become equal to or higher than the predetermined values NEth and Qth. As described above, the oil pressure stage is set to the high pressure stage, and the oil is injected and supplied to the piston 32. However, at this time, in reality, a situation occurs in which the temperature of the piston 32 is not so high as to require cooling with oil. As a result, the driving load of the oil pump 64 is increased by the amount that the oil pressure stage is set to the high pressure stage to inject and supply oil to the piston 32, and the fuel consumption of the internal combustion engine 1 is unnecessarily increased. Problems may arise.

  Therefore, in the present embodiment, even if the coolant temperature THW detected by the coolant temperature sensor 81 is the same, the piston is less than when it is prohibited when the coolant flow in the coolant passage 5 is permitted. The predetermined values NEth and Qth are set through the electronic control unit 9 in consideration that the temperature of the cooling water near the position 32 is low. That is, when the predetermined values NEth and Qth set for the temperature range including the coolant temperature THW detected by the coolant temperature sensor 81 are prohibited when the coolant flow in the coolant passage 5 is allowed. By making it larger than the above, an excessive increase in the temperature of the piston 32 is accurately suppressed, and an unnecessary increase in the fuel consumption of the internal combustion engine 1 is suppressed. The electronic control device 9 of this embodiment corresponds to a threshold setting unit.

  Next, with reference to the flowchart of FIG. 6, the processing procedure for the drive control of the water pump 55 described above will be described. Note that a series of processes shown in the figure is repeatedly executed at predetermined intervals while the internal combustion engine 1 is warmed up through the electronic control unit 9.

  As shown in the figure, in this series of processes, first, as the process of step S101, the engine speed NE, the fuel injection amount Q, and the coolant temperature THW at that time are read. Next, as a process of step S102, it is determined whether or not the engine speed NE is equal to or less than a predetermined value NEhigh. That is, it is determined whether the internal combustion engine 1 is in a low rotation state or a medium rotation state. If the engine speed NE is greater than the predetermined value NEhigh (step S102: “NO”), the process proceeds to step S106. In step S106, the internal combustion engine 1 is in a high rotation state, and in order to cool the internal combustion engine 1, the water pump 55 is driven and this series of processes is temporarily terminated.

  On the other hand, when the engine speed NE is equal to or lower than the predetermined value NEhigh in step S102 (step S102: “YES”), the process proceeds to step S103. In step S103, it is determined whether or not the fuel injection amount Q is equal to or less than a predetermined value Qhigh. That is, it is determined whether the internal combustion engine 1 is in a low load state or a medium load state. Here, when the fuel injection amount Q is larger than the predetermined value Qhigh (step S103: “NO”), the process proceeds to step S106. In step S106, the internal combustion engine 1 is in a high load state, and in order to cool the internal combustion engine 1, the water pump 55 is driven and this series of processes is temporarily terminated.

  On the other hand, when the fuel injection amount Q is equal to or less than the predetermined value Qhigh in step S103 (step S103: “YES”), the process proceeds to step S104. In step S104, it is determined whether or not the coolant temperature THW is included in a predetermined temperature range (T0 ≦ THW ≦ T4). Here, for example, it is determined whether or not the internal combustion engine 1 is in a low temperature state and whether or not the warm-up of the internal combustion engine 1 has been completed. As a result, when the coolant temperature THW is not included in the predetermined temperature range (step S104: “NO”), the process proceeds to step S106. In step S106, when the coolant temperature THW is higher than the upper limit value (T4) of the predetermined temperature range, the water pump 55 is driven to cool the internal combustion engine 1. Further, when the cooling water temperature THW is lower than the lower limit value (T0) of the predetermined temperature range, the water pump 55 is set in the driving state so as to circulate the cooling water to each part of the internal combustion engine 1 and suppress the freezing thereof. Is done.

  On the other hand, when the coolant temperature THW is included in the predetermined temperature range in step S104 (step S104: “YES”), the process proceeds to step S105. In step S105, in order to promote warm-up of the internal combustion engine 1, the water pump 55 is stopped and this series of processes is temporarily terminated.

  Next, with reference to the flowchart of FIG. 7, the processing procedure for the above-described oil pressure stage switching control will be described. Note that a series of processes shown in the figure is repeatedly executed at predetermined intervals while the internal combustion engine 1 is warmed up through the electronic control unit 9.

  As shown in the figure, in this series of processes, first, as the process of step S201, the coolant temperature THW at that time is read. Next, as a process of step S202, it is determined whether or not the water pump 55 is stopped, that is, whether or not the circulation of the cooling water in the cooling water passage 5 is prohibited. Here, when the water pump 55 is stopped (step S202: “YES”), next, referring to the map for stopping the water pump, the oil pressure stage switching control is executed (step S203). ), This series of processes is temporarily terminated.

  On the other hand, when the water pump 55 is not stopped in step S202 (step S202: “NO”), that is, the water pump 55 is driven and the circulation of the cooling water in the cooling water passage 5 is allowed. Next, referring to the map for driving the water pump, the switching control of the oil pressure stage is executed (step S204), and this series of processing is once ended.

  FIG. 8 shows a map that defines a predetermined value NEth of the engine rotational speed NE and a predetermined value Qth of the fuel injection amount that are used for switching control of the oil pressure stage for each temperature region of the coolant temperature THW. 8A is a map applied when the coolant temperature THW is in the first temperature region (T1 ≦ THW <T2), and FIG. 8B is a map where the coolant temperature THW is the first temperature range. FIG. 8C is a map applied when the temperature is in the second temperature region (T2 ≦ THW <T3) higher than the temperature region, and FIG. 8C shows the third temperature in which the cooling water temperature THW is higher than the second temperature region. It is a map applied when it exists in a temperature area | region (T3 <= THW <T5). In each figure, the water pump driving map is shown by a solid line, and the water pump stopping map is shown by a broken line.

  As shown by the solid line in the figure, when the water pump 55 is driven and the cooling water is flowing in the cooling water passage 5, the first temperature region, the second temperature region, and the third temperature. The predetermined value NEth of the engine speed NE and the predetermined value Qth of the fuel injection amount Q are made smaller in the order of the regions, that is, the higher the temperature region (NE1> NE2> NE3, Q1> Q2> Q3). Similarly, when the water pump 55 is stopped and the cooling water does not flow in the cooling water passage 5, similarly, in the order of the first temperature region, the second temperature region, and the third temperature region, that is, The higher the temperature range, the smaller the predetermined value NEth of the engine rotational speed NE and the predetermined value Qth of the fuel injection amount Q (NE11> NE12> NE13, Q11> Q12> Q13). However, the predetermined value NEth (NE1, NE2, NE3) of the engine rotation speed NE when cooling water is circulating in the cooling water passage 5 is the engine rotation speed when cooling water is not flowing in the cooling water passage 5. The values are larger than the predetermined value NEth (NE11, NE12, NE13) (NE1> NE11, NE2> NE12, NE3> NE13). Further, the predetermined value Qth (Q1, Q2, Q3) of the fuel injection amount Q when the cooling water is flowing in the cooling water passage 5 is the fuel injection amount when the cooling water is not flowing in the cooling water passage 5. It is larger than the predetermined value Qth (Q11, Q12, Q13) of Q (Q1> Q11, Q2> Q12, Q3> Q13).

According to the control apparatus for an internal combustion engine according to the present embodiment described above, the following effects can be obtained.
(1) The internal combustion engine 1 is provided at a position separated from the position near the piston 32 in the cooling water passage 5 and detects the cooling water temperature THW at the separated position, and the flow of the cooling water in the cooling water passage 5 A water pump 55 and a clutch 58 for switching between allowance and prohibition are provided. In addition, a relief passage 62, a relief valve 71, an introduction passage 78, which switches a pressure stage of oil discharged from an engine-driven oil pump 64 and injected and supplied to the piston 32 of the internal combustion engine 1 between a low pressure stage and a high pressure stage; A switching valve 79 is provided, and the oil pressure stage is set to the high pressure stage when the engine speed NE is equal to or higher than the predetermined value NEth or when the fuel injection amount Q is equal to or higher than the predetermined value Qth. In addition, the electronic control unit 9 provides three temperature regions (T1 ≦ THW <T2, T2 ≦ THW <T3, T3 ≦ THW <T5) for the coolant temperature THW detected by the water temperature sensor 81, and these three temperatures. The predetermined values NEth and Qth are set for each region. When the predetermined values NEth and Qth set for the temperature range including the coolant temperature THW detected by the coolant temperature sensor 81 are prohibited when the coolant flow in the coolant passage 5 is permitted. It was supposed to be larger than

  Since the water temperature sensor 81 is provided at a position separated from the position near the piston 32 in the cooling water passage 5 and detects the cooling water temperature THW at the separated position, the cooling water temperature THW detected by the water temperature sensor 81 is the same. Even so, the temperature of the cooling water in the vicinity of the piston 32 is lower when the cooling water is flowing in the cooling water passage 5 than when the cooling water is not flowing.

  As a result, the cooling water in the vicinity of the piston 32 is compared with the case where the cooling water flow in the cooling water passage 5 is permitted, that is, when it is prohibited, that is, based on the cooling water temperature THW detected by the water temperature sensor 81. When the temperature is relatively low, the predetermined values NEth and Qth set for the coolant temperature THW detected by the coolant temperature sensor 81 are made larger than when the temperature is relatively high. As described above, when setting the predetermined values NEth and Qth, not only the cooling water temperature THW detected by the water temperature sensor 81 but also the cooling water temperature THW and the circulation mode of the cooling water in the cooling water passage 5 are grasped. In consideration of the temperature of the cooling water in the vicinity of the piston 32, the predetermined values NEth and Qth can be set in accordance with the actual temperature of the cooling water in the vicinity of the piston 32. As a result, the oil pressure can be suitably maintained in a low state in a wider engine rotation speed region and fuel injection region. Therefore, an unnecessary increase in the fuel consumption of the internal combustion engine 1 can be suppressed while accurately suppressing an excessive temperature rise of the piston 32 of the internal combustion engine 1.

Note that the control device for an internal combustion engine according to the present invention is not limited to the configuration exemplified in the above embodiment, and can be implemented as, for example, the following forms appropriately modified.
In the above-described embodiment, the engine-driven water pump 55 and the clutch 58 are exemplified. However, the cooling water flow rate varying means according to the present invention is not limited to this, and for example, an electric water pump Can also be adopted.

  In the above-described embodiment, the relief passage 62, the relief valve 71, the introduction passage 78, and the switching valve 79 are exemplified. However, the pressure stage switching mechanism according to the present invention is not limited thereto, and is an engine drive type. As long as the pressure stage of the oil discharged from the oil pump 64 and supplied to the piston 32 is switched between the low pressure stage and the high pressure stage, this may be changed to any configuration.

  In the above-described embodiment, the engine drive type oil pump 64 is exemplified. However, the configuration of the oil pump is not limited to this, and an electric oil pump may be adopted.

  In the above embodiment, in the oil supply system, the check valve 67 is provided between the main supply passage 61 and the oil jet mechanism 66, but by omitting such a check valve 67, the main supply passage 61 and Oil may be always supplied to the piston 32 through the oil jet mechanism 66. In this case, the higher the oil pressure, that is, the greater the amount of oil that is injected and supplied per unit time, the greater the cooling effect of the piston 32 by the oil.

  In the above embodiment, both the engine rotational speed NE and the fuel injection amount Q are employed as the engine state quantity used for switching the oil pressure stage. Alternatively, only the fuel injection amount Q can be used.

  In the above embodiment, the fuel injection amount Q is adopted as the engine load, but intake air pressure or the like can be adopted instead. In the case of a gasoline engine, for example, an intake air amount can be adopted as the engine load.

  In the above embodiment, the water temperature sensor 81 is provided outside the cylinder head 4, but the cooling water temperature detecting means according to the present invention is not limited to this. If it is provided at a position separated from the position near the piston in the cooling water passage of the internal combustion engine and detects the temperature of the cooling water at the separated position, it is provided downstream from the position exemplified in the above embodiment. You may do it.

  In the above embodiment, three temperature regions are provided for the cooling water temperature THW detected by the water temperature sensor 81, and the predetermined values NEth and Qth are set for each of these three temperature regions. Two temperature regions or four or more temperature regions may be used. Even in this case, the predetermined threshold value set for the temperature of the cooling water detected by the cooling water temperature detecting means is increased as compared with the case where the flow rate of the cooling water in the cooling water passage is large. do it.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Internal combustion engine main body, 3 ... Cylinder block, 31 ... Cylinder bore, 32 ... Piston, 4 ... Cylinder head, 5 ... Cooling water passage, 51 ... Main cooling water passage, 52 ... Sub cooling water passage, 53 ... Water jacket, 54 ... Water jacket, 55 ... Water pump, 56 ... Radiator, 57 ... Thermostat, 58 ... Clutch, 61 ... Main supply passage, 62 ... Relief passage, 63 ... Oil pan, 64 ... Oil pump, 65 ... Deputy Supply passage, 66 ... Oil jet mechanism, 67 ... Check valve, 71 ... Relief valve, 72 ... Housing, 72A ... Bottom, 72B ... End, 72C ... Inlet side through hole, 72D ... Outlet side through hole, 72E ... For introduction Through-hole, 73 ... accommodating chamber, 73C ... inlet part, 73D ... outlet part, 73E ... introducing part, 73F ... gap, 74 ... movable member, 74A ... bottom , 74B ... end, 74C ... inlet side communication hole, 74D ... outlet side communication hole, 75 ... valve body, 76 ... fixing member, 76A ... large diameter part, 76B ... small diameter part, 77 ... spring, 78 ... introduction passage, 79 ... a switching valve, 81 ... a water temperature sensor, 9 ... an electronic control unit.

Claims (6)

A coolant temperature detecting means provided at a position spaced from the vicinity of the piston in the coolant passage of the internal combustion engine and detecting the temperature of the coolant at the spaced position;
A cooling water flow rate varying means for varying the flow rate of the cooling water in the cooling water passage based on the engine operating state;
Applied to an internal combustion engine comprising oil pressure variable means for increasing the pressure of oil supplied to the piston of the internal combustion engine when the engine state quantity is equal to or greater than a predetermined threshold,
In the control apparatus for an internal combustion engine comprising threshold setting means for setting the predetermined threshold to be smaller than when the temperature of the cooling water detected by the cooling water temperature detection means is high,
The threshold value setting means sets the predetermined threshold value set with respect to the temperature of the cooling water detected by the cooling water temperature detection means, as compared to when the flow rate of the cooling water in the cooling water passage is small. A control device for an internal combustion engine characterized by being enlarged. The control apparatus for an internal combustion engine according to claim 1,
The cooling water flow rate variable means switches between permitting and prohibiting the circulation of the cooling water in the cooling water passage,
The threshold value setting means is set with respect to the temperature of the cooling water detected by the cooling water temperature detecting means, compared to when the flow of the cooling water in the cooling water passage is permitted and prohibited. The control apparatus for an internal combustion engine, wherein the predetermined threshold value is increased. The control apparatus for an internal combustion engine according to claim 1 or 2,
The threshold value setting means sets the predetermined threshold value for each of a plurality of temperature regions provided for the temperature of the cooling water detected by the cooling water temperature detection means, and is detected by the cooling water temperature detection means. The predetermined threshold value set for one temperature region of the plurality of temperature regions including the temperature of the cooling water is smaller than when the flow rate of the cooling water in the cooling water passage is small. A control device for an internal combustion engine characterized by being enlarged. The control apparatus for an internal combustion engine according to any one of claims 1 to 3,
The engine state quantity includes the engine rotation speed,
The control device for an internal combustion engine, wherein the oil pressure varying means increases the pressure of oil injected and supplied to a piston of the internal combustion engine when the engine rotational speed becomes a predetermined value or more. The control apparatus for an internal combustion engine according to any one of claims 1 to 4,
The engine state quantity includes the engine load,
The control device for an internal combustion engine, wherein the oil pressure varying means increases the pressure of oil injected and supplied to a piston of the internal combustion engine when the engine load becomes a predetermined value or more. In the control device for an internal combustion engine according to any one of claims 1 to 5,
The oil pressure variable means includes a pressure stage switching mechanism that switches a pressure stage of oil discharged from an engine-driven oil pump and supplied to a piston of an internal combustion engine between a low pressure stage and a high pressure stage. An internal combustion engine characterized in that when the state quantity is equal to or greater than the predetermined threshold value, the oil pressure stage is a high pressure stage, and when the engine state quantity is less than the predetermined threshold value, the oil pressure stage is a low pressure stage. Control device.

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