Engine equipment

Abstract

To further properly cool a piston or suppress a temperature rise.SOLUTION: An engine device estimates a piston top surface temperature of a top surface of a piston of an engine, an uppermost ring groove bottom temperature of a bottom portion of the uppermost ring groove closest to the top surface of ring grooves of the piston, a lowermost ring groove bottom temperature of a bottom portion of the lowermost ring groove farthest from the top surface of the ring grooves of the piston, and a pin hole top portion temperature of a pin hole top portion formed on a back side of the top surface of the piston on the basis of a rotation speed of the engine, a load of the engine, and a temperature of coolant of the engine. The engine device executes predetermined control performing the cooling of the piston or suppressing a temperature rise by using any one of the piston top surface temperature, the uppermost ring groove bottom temperature, the lowermost ring groove bottom temperature, and the pin hole top potion temperature.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an engine device. [Background technology]

[0002] Conventionally, as this type of engine device, one that performs an oil jet that injects oil toward the back surface of the piston has been proposed (see, for example, Patent Document 1). In this engine device, when the engine cooling water temperature rises to a predetermined temperature while the oil jet is stopped, the oil jet is started to cool the piston. Also, when the engine lubricating oil temperature drops to a predetermined temperature while the oil jet is running, a delay time is determined based on the amount of change in engine speed and the amount of change in intake air filling rate during a predetermined period, and the oil jet is stopped after the delay time has elapsed. This makes the timing of switching the oil jet more appropriate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-71999 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above engine device, the oil jet starts when the engine cooling water temperature rises to a certain temperature that takes into consideration the safety of the temperature resistance of each part of the piston, so there are cases where the oil jet is performed even when the temperature of each part of the piston does not require cooling. In addition, in addition to the oil jet, the cooling of the piston and the suppression of the temperature rise can also be achieved by increasing the fuel injection amount and limiting the load on the engine.

[0005] A main object of the engine apparatus of the present invention is to more appropriately cool the piston or suppress a temperature rise. [Means for solving the problem]

[0006] In order to achieve the above-mentioned main object, the engine device of the present invention employs the following means.

[0007] The engine device of the present invention comprises: An engine device including an engine and a control device that controls the engine, The control device estimates a piston top surface temperature of a top surface of a piston of the engine, a top ring groove bottom temperature of a bottom of a top ring groove that is closest to the top surface of the ring grooves of the piston, a bottom ring groove bottom temperature of a bottom of a bottom ring groove that is farthest from the top surface of the ring grooves of the piston, and a pin hole top temperature of a pin hole top formed on a back side of the top surface of the piston, based on the engine speed, the engine load, and the temperature of cooling water of the engine, and executes a predetermined control for cooling the piston or suppressing a temperature rise by using any of the piston top surface temperature, the top ring groove bottom temperature, the bottom ring groove bottom temperature, and the pin hole top temperature. It is characterized by:

[0008] In the engine device of the present invention, the piston top surface temperature of the top surface of the piston of the engine, the top ring groove bottom temperature of the bottom of the top ring groove closest to the piston top surface of the piston ring groove, the bottom ring groove bottom temperature of the bottom of the bottom ring groove furthest from the piston top surface of the piston ring groove, and the pin hole top temperature of the pin hole top formed on the back side of the top surface of the piston are estimated based on the engine speed, the engine load, and the temperature of the engine cooling water. Then, a predetermined control is executed to cool the piston or suppress the temperature rise using any of the estimated piston top surface temperature, top ring groove bottom temperature, bottom ring groove bottom temperature, and pin hole top temperature. In this way, the piston top surface temperature, top ring groove bottom temperature, bottom ring groove bottom temperature, and pin hole top temperature are estimated, and the piston is cooled or the temperature rise is suppressed using any of the estimated piston top surface temperature, top ring groove bottom temperature, bottom ring groove bottom temperature, and pin hole top temperature, so that the piston can be cooled or the temperature rise can be suppressed more appropriately. The specified control includes a control for cooling the piston or suppressing a temperature rise by using an oil jet to inject hydraulic oil onto the piston, a control for cooling the piston or suppressing a temperature rise by increasing the amount of fuel injection, and a control for cooling the piston or suppressing a temperature rise by imposing a limit on the engine load.

[0009] In the engine device of the present invention, the control device may execute, as the predetermined control, control for turning on and off an oil jet that injects hydraulic oil into the piston when any one of the following conditions is satisfied: the piston top surface temperature is equal to or higher than a first threshold, the top ring groove bottom temperature is equal to or higher than a second threshold, the bottom ring groove bottom temperature is equal to or higher than a third threshold, or the pin hole top temperature is equal to or higher than a fourth threshold. In this way, the oil jet that injects hydraulic oil into the piston can be more appropriately turned on and off.

[0010] In the engine device of the present invention, the control device may estimate the piston top surface temperature, the top ring groove bottom temperature, the bottom ring groove bottom temperature, and the pin hole top temperature in the order of the largest degree of temperature rise over time, namely, the piston top surface temperature, the top ring groove bottom temperature, the bottom ring groove bottom temperature, and the pin hole top temperature, in the order of the largest degree of temperature rise over time, and estimate the piston top surface temperature, the top ring groove bottom temperature, the bottom ring groove bottom temperature, and the pin hole top temperature in the order of the largest degree of temperature drop over time, namely, the piston top surface temperature, the top ring groove bottom temperature, the bottom ring groove bottom temperature, and the pin hole top temperature, in the order of the largest degree of temperature rise or drop over time, based on consideration of the transfer of heat and cold due to explosive combustion. In this way, the piston top surface temperature, the top ring groove bottom temperature, the bottom ring groove bottom temperature, and the pin hole top temperature can be more accurately estimated. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram showing an outline of the configuration of an engine device 10. FIG. [Diagram 2] 4 is an explanatory diagram showing an example of input / output signals of an electronic control unit 70. FIG. [Diagram 3] 13 is a flowchart showing an example of an oil jet process executed by an electronic control unit 70. [Figure 4] 2 is a diagram showing an outline of the configuration of a piston 33. FIG. [Diagram 5] FIG. 11 is an explanatory diagram showing an example of the temperature change rate over time in the temperature rise of each of the piston top surface temperature Ttop, the top ring groove bottom temperature Tlngup, the bottom ring groove bottom temperature Tlngdw, and the pin hole top temperature Tpin. [Figure 6] FIG. 11 is an explanatory diagram showing an example of the time change in temperature change rate in the temperature drop of each of the piston top surface temperature Ttop, the top ring groove bottom temperature Tlngup, the bottom ring groove bottom temperature Tlngdw, and the pin hole top temperature Tpin. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Next, embodiments for carrying out the present invention will be described using examples.

Example

[0013] FIG. 1 is a configuration diagram showing an outline of the configuration of an engine device 10 as an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing an example of input / output signals of an electronic control unit 70. The engine device 10 of the embodiment is mounted on a general vehicle that runs using the power from the engine 12 or various hybrid vehicles that include a motor in addition to the engine 12. As shown in FIGS. 1 and 2, the engine device 10 includes an engine 12, a supercharger 40, a fuel supply device 16, and an electronic control unit 70.

[0014] The engine 12 is configured as an internal combustion engine that outputs power using fuel such as gasoline or light oil supplied from a fuel tank 11. The engine 12 has a port injection valve 28 that injects fuel into an intake port, an in-cylinder injection valve 29 that injects fuel into a combustion chamber 31, and a spark plug 32. The in-cylinder injection valve 29 is disposed substantially at the center of the top of the combustion chamber 31 and injects fuel in a spray form. The spark plug 32 is disposed in the vicinity of the in-cylinder injection valve 29 so as to be able to ignite the fuel sprayed in a spray form from the in-cylinder injection valve 29.

[0015] The engine 12 can be operated in any one of a port injection mode, an in-cylinder injection mode, and a common injection mode by having the port injection valve 28 and the in-cylinder injection valve 29. In the embodiment, the ratio of the fuel injection amount by the port injection valve 28 to the total fuel injection amount is defined as a port injection ratio Rp (0 ≦ Rp ≦ 1). The port injection mode is the case where the port injection ratio Rp has a value of 1, the in-cylinder injection mode is the case where the port injection ratio Rp has a value of 0, and in the common injection mode, the port injection ratio Rp is greater than 0 and less than 1 (0 < Rp < 1).

[0016] In the port injection mode, air purified by the air cleaner 22 is drawn into the intake pipe 23 and passes through the intercooler 25, the throttle valve 26, and the surge tank 27 in that order, and fuel is injected from the port injection valve 28 downstream of the surge tank 27 of the intake pipe 23 to mix the air and fuel. This mixture is drawn into the combustion chamber 31 through the intake valve 30, and is explosively combusted by an electric spark from the spark plug 32. The reciprocating motion of the piston 33, which is pushed down by the energy of the explosive combustion, is converted into the rotational motion of the crankshaft 14. In the in-cylinder injection mode, air is drawn into the combustion chamber 31 in the same manner as in the port injection mode, and fuel is injected from the in-cylinder injection valve 29 once or in multiple times during the intake stroke, compression stroke, or expansion stroke, and is explosively combusted by an electric spark from the spark plug 32 to obtain the rotational motion of the crankshaft 14. In particular, when fuel is injected during the expansion stroke, fuel injection from the in-cylinder injection valve 29 during the expansion stroke is synchronized with ignition from the spark plug 32 so that the spray-like fuel injected from the in-cylinder injection valve 29 can be ignited. In the shared injection mode, fuel is injected from the port injection valve 28 when air is drawn into the combustion chamber 31, and fuel is injected from the in-cylinder injection valve 29 once or multiple times during the intake stroke, compression stroke, or expansion stroke, and is exploded and burned by an electric spark from the spark plug 32 to generate rotational motion for the crankshaft 14.

[0017] Exhaust discharged from the combustion chamber 31 to the exhaust pipe 35 via the exhaust valve 34 is discharged into the outside air via a purification device 37 having a catalyst (three-way catalyst) that purifies harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). A starter (not shown) that cranks the engine 12 and an alternator 48 that generates electricity using the power of the engine 12 are attached to the crankshaft 14. The alternator 48 supplies the generated electricity to a power line that supplies power from a battery (not shown) to a fan motor 38d, a water pump 38e, and the like of the engine cooling system 38.

[0018] The fuel supply device 16 includes a fuel tank 11, a feed pump 11p, a low-pressure supply pipe 17, a high-pressure pump 18, and a high-pressure supply pipe 19. Fuel from the fuel tank 11 is pumped by the feed pump 11p and supplied to the port injection valve 28 via the low-pressure supply pipe 17. The feed pump 11p is configured as an electric pump that operates by receiving power from a battery (not shown), and is disposed in the fuel tank 11. Although not shown, the low-pressure supply pipe 17 is also provided with a check valve that allows fuel to flow in the direction from the feed pump 11p side to the port injection valve 28 side and regulates fuel flow in the opposite direction. In addition, the fuel from the low-pressure supply pipe 17 is pumped by the high-pressure pump 18 and supplied to the in-cylinder injection valve 29 via the high-pressure supply pipe 19. The high-pressure pump 18 is configured as a pump driven by power from the engine 12 (in the embodiment, the rotation of the intake camshaft that opens and closes the intake valve 30). The high-pressure pump 18 has an electromagnetic valve 18a connected to its intake port which opens and closes when pressurizing the fuel, a check valve 18b connected to its discharge port which regulates the backflow of fuel and maintains the fuel pressure in the high-pressure supply pipe 19, and a plunger 18c which operates by the rotation (rotation of the intake camshaft) of the engine 12. When the electromagnetic valve 18a is opened while the engine 12 is running, the high-pressure pump 18 sucks in fuel from the low-pressure supply pipe 17, and when the electromagnetic valve 18a is closed, the fuel compressed by the plunger 18c is intermittently sent to the high-pressure supply pipe 19 via the check valve 18b, thereby pressurizing the fuel to be supplied to the high-pressure supply pipe 19. Note that when the high-pressure pump 18 is driven, the fuel pressure in the low-pressure supply pipe 17 and the fuel pressure (fuel pressure) in the high-pressure supply pipe 19 pulsate in response to the rotation of the engine 12 (rotation of the intake camshaft).

[0019] The engine 12 is provided with an engine cooling system 38 that cools the engine 12 with a heat exchange medium (cooling water, etc.). The engine cooling system 38 includes a circulation flow path 38a that circulates the heat exchange medium between a water jacket (not shown) of the engine 12 and a radiator 38b. A fan 38c driven by a fan motor 38d is attached to the radiator 38b, and the internal heat exchange medium (water, etc.) is cooled by outside air. A water pump 38e that circulates the heat exchange medium is attached to the circulation flow path 38a.

[0020] The supercharger 40 is configured as a turbocharger, and includes a compressor 41, a turbine 42, a rotating shaft 43, a wastegate valve 44, and a blow-off valve 45. The compressor 41 is disposed upstream of the intercooler 25 in the intake pipe 23. The turbine 42 is disposed upstream of the purification device 37 in the exhaust pipe 35. The rotating shaft 43 connects the compressor 41 and the turbine 42. The wastegate valve 44 is provided in a bypass pipe 36 that connects the upstream side and downstream side of the turbine 42 in the exhaust pipe 35, and is controlled by an electronic control unit 70. The blow-off valve 45 is provided in a bypass pipe 24 that connects the upstream side and downstream side of the compressor 41 in the intake pipe 23, and is controlled by the electronic control unit 70.

[0021] In this turbocharger 40, the opening degree of the wastegate valve 44 is adjusted to adjust the distribution ratio between the amount of exhaust gas flowing through the bypass pipe 36 and the amount of exhaust gas flowing through the turbine 42, thereby adjusting the rotational driving force of the turbine 42, adjusting the amount of air compressed by the compressor 41, and adjusting the supercharging pressure (intake pressure) of the engine 12. In detail, the distribution ratio is adjusted so that the smaller the opening degree of the wastegate valve 44, the smaller the amount of exhaust gas flowing through the bypass pipe 36 and the larger the amount of exhaust gas flowing through the turbine 42. When the wastegate valve 44 is fully open, the engine 12 can operate in the same manner as a naturally aspirated engine without the turbocharger 40.

[0022] In addition, in the turbocharger 40, when the pressure downstream of the compressor 41 in the intake pipe 23 is somewhat higher than the pressure upstream of the intake pipe 23, the blow-off valve 45 is opened to release the excess pressure downstream of the compressor 41. Note that, instead of a valve controlled by the electronic control unit 70, the blow-off valve 45 may be configured as a check valve that opens when the pressure downstream of the compressor 41 in the intake pipe 23 becomes somewhat higher than the pressure upstream of the intake pipe 23.

[0023] Oil (hydraulic oil) stored in an oil pan 50 disposed below the engine 12 and the transmission (not shown) is supplied to the engine 12 and the transmission by an oil pump 52. The oil pump 52 is a mechanical pump driven by the rotational drive of the crankshaft 14, and pumps the oil stored in the oil pan 50 to an oil pipe 54. An oil branch pipe 55 is connected to the oil pipe 54, and an oil injection nozzle 56 that injects oil onto the back side of the piston 33 is attached to the oil branch pipe 54. An electromagnetic valve 57 is attached to the oil branch pipe 54 just before the oil injection nozzle 56 (on the side of the branch with the oil pipe 54).

[0024] The electronic control unit 70 is configured as a microprocessor with a CPU at its core, and in addition to the CPU, is equipped with a ROM for storing processing programs, a RAM for temporarily storing data, a non-volatile flash memory for storing and holding data, an input / output port, and a communication port. Signals from various sensors are input to the electronic control unit 70 via the input ports.

[0025] Examples of signals input to the electronic control unit 70 include a tank internal pressure Ptnk from an internal pressure sensor 11a that detects the pressure inside the fuel tank 11, a crank angle θcr from a crank position sensor 14a that detects the rotational position of the crankshaft 14 of the engine 12, a coolant temperature Tw from a water temperature sensor 38f that detects the temperature of the coolant for the engine 12, and a throttle opening TH from a throttle position sensor 26a that detects the opening of the throttle valve 26. Another example of signals input to the electronic control unit 70 is a cam position θca from a cam position sensor (not shown) that detects the rotational positions of an intake camshaft that opens and closes the intake valve 30 and an exhaust camshaft that opens and closes the exhaust valve 34. Other examples include the intake air amount Qa from the air flow meter 23a attached upstream of the compressor 41 of the intake pipe 23, the intake air temperature Tin from the intake air temperature sensor 23t attached upstream of the compressor 41 of the intake pipe 23, the intake pressure (pre-compressor pressure) Pin from the intake pressure sensor 23b attached upstream of the compressor 41 of the intake pipe 23, and the boost pressure Pc from the boost pressure sensor 23c attached between the compressor 41 of the intake pipe 23 and the intercooler 25. Other examples include the surge pressure (post-throttle pressure) Ps from the surge pressure sensor 27a attached to the surge tank 27, and the surge temperature Ts from the temperature sensor 27b attached to the surge tank 27. Other examples include the low-pressure fuel pressure Pfp from the fuel pressure sensor 28a that detects the pressure of the fuel supplied to the port injection valve 28, and the high-pressure fuel pressure Pfd from the fuel pressure sensor 29a that detects the pressure of the fuel supplied to the in-cylinder injection valve 29. Examples of the air-fuel ratio include a front air-fuel ratio AF1 from a front air-fuel ratio sensor 35a attached upstream of the purification device 37 of the exhaust pipe 35, and a rear air-fuel ratio AF2 from a rear air-fuel ratio sensor 35b attached downstream of the purification device 37 of the exhaust pipe 35. Another example is the oil temperature Poil from an oil temperature sensor 51 attached to the oil pan 50.

[0026] Various control signals are output from the electronic control unit 70 via the output port. Examples of signals output from the electronic control unit 70 include a control signal to the alternator 15, a control signal to the throttle valve 26, a control signal to the port injection valve 28, a control signal to the in-cylinder injection valve 29, and a control signal to the spark plug 32. Examples of the signals output from the electronic control unit 70 include a drive signal to the fan motor 38d and the water pump 38e of the engine cooling device 38, and a drive signal to the fan motor 39d and the circulation pump 39e of the intercooler cooling device 39. Examples of the signals include a control signal to the wastegate valve 44, a control signal to the blow-off valve 45, and a control signal to the solenoid valve 18a.

[0027] The electronic control unit 70 calculates the rotation speed Ne and the load factor KL (the ratio of the volume of air actually taken in one cycle to the stroke volume per cycle of the engine 12) of the engine 12. The rotation speed Ne is calculated based on the crank angle θcr from the crank position sensor 14a. The load factor KL is calculated based on the amount of intake air Qa from the air flow meter 23a and the rotation speed Ne.

[0028] In the engine system 10 of this embodiment configured as described above, the electronic control unit 70 performs intake air amount control that controls the opening of the throttle valve 26, fuel injection control that controls the amount of fuel injected from the in-cylinder injection valve 28, ignition control that controls the ignition timing of the spark plug 31, supercharging control that controls the opening of the wastegate valve 44, and fuel pressure control in the high-pressure supply pipe 19 by opening and closing the solenoid valve 18a, based on the required load rate KL* of the engine 12.

[0029] Next, an operation of the engine device 10 of the embodiment will be described, in particular, an operation when performing an oil jet to inject oil onto the back side of the piston 33. Fig. 3 is a flowchart showing an example of an oil jet process executed by the electronic control unit 70 of the embodiment. This oil jet process is repeatedly executed at predetermined time intervals.

[0030] When the oil jet processing is executed, the electronic control unit 70 first executes a process of inputting data required for the processing, such as the rotation speed Ne of the engine 12, the load factor KL of the engine 12, and the cooling water temperature Tw of the engine 12 from the water temperature sensor 38f (step S100).

[0031] Next, based on the rotation speed Ne of the engine 12, the load factor KL of the engine 12, and the cooling water temperature Tw of the engine 12, the following are estimated for each part shown in the schematic configuration of the piston 33 in FIG. 4: the temperature (piston top temperature) Ttop of the top surface 33a of the piston 33, the top ring groove bottom temperature Tlngup which is the temperature of the bottom (top ring groove bottom) 33b of the ring groove of the piston 33 that is closest to the top surface 33a, the bottom ring groove bottom temperature Tlngdw which is the temperature of the bottom (bottom ring groove bottom) 33c of the ring groove of the piston 33 that is farthest from the top surface 33a, and the pin hole top temperature Tpin which is the temperature of the top (pin hole top) 33d of the pin hole of the piston 33 (step S110).

[0032] In the embodiment, the piston top surface temperature Ttop is set by determining the relationship between the engine speed Ne, the load factor KL of the engine 12, the cooling water temperature Tw of the engine 12, and the piston top surface temperature Ttop in advance by experiment or the like and storing the relationship as a piston top surface temperature setting map, and when the engine speed Ne, the load factor KL, and the cooling water temperature Tw of the engine 12 are given, the corresponding piston top surface temperature Ttop is derived from the map. In the embodiment, the top ring groove bottom temperature Tlngup is set by determining the relationship between the engine speed Ne, the load factor KL of the engine 12, the cooling water temperature Tw of the engine 12, and the top ring groove bottom temperature Tlngup in advance by experiment or the like and storing the relationship as a top ring groove temperature setting map, and when the engine speed Ne, the load factor KL, and the cooling water temperature Tw of the engine 12 are given, the corresponding top ring groove bottom temperature Tlngup is derived from the map. In the embodiment, the relationship between the engine 12 rotation speed Ne, the engine 12 load factor KL, the engine 12 cooling water temperature Tw, and the lowest ring groove bottom temperature Tlngdw is obtained in advance by experiment or the like and stored as a lowest ring groove temperature setting map, and when the engine 12 rotation speed Ne, the engine 12 load factor KL, and the engine 12 cooling water temperature Tw are given, the lowest ring groove bottom temperature Tlngdw is set by deriving the corresponding lowest ring groove bottom temperature Tlngdw from the map. In the embodiment, the pin hole top temperature Tpin is obtained in advance by experiment or the like and stored as a pin hole top temperature setting map, and when the engine 12 rotation speed Ne, the engine 12 load factor KL, the engine 12 cooling water temperature Tw, and the pin hole top temperature Tpin are given, the corresponding pin hole top temperature Tpin is set by deriving the corresponding pin hole top temperature Tpin from the map.

[0033] In the embodiment, the order of the degree of change over time of temperature rise and drop of each of the piston top surface temperature Ttop, the top ring groove bottom temperature Tlngup, the bottom ring groove bottom temperature Tlngdw, and the pin hole top temperature Tpin is set to be piston top surface temperature Ttop, top ring groove bottom temperature Tlngup, bottom ring groove bottom temperature Tlngdw, and pin hole top temperature Tpin. Fig. 5 shows an example of the change over time of the temperature change rate in each of the temperature rise of the piston top surface temperature Ttop, the top ring groove bottom temperature Tlngup, the bottom ring groove bottom temperature Tlngdw, and the pin hole top temperature Tpin, and Fig. 6 shows an example of the change over time of the temperature change rate in each of the temperature drop of the piston top surface temperature Ttop, the top ring groove bottom temperature Tlngup, the bottom ring groove bottom temperature Tlngdw, and the pin hole top temperature Tpin. In the figure, curves A1 and A2 show the change in temperature rate of change of piston top temperature Ttop, curves B1 and B2 show the change in temperature rate of change of top ring groove bottom temperature Tlngup, curves C1 and C2 show the change in temperature rate of change of bottom ring groove bottom temperature Tlngdw, and curves D1 and D2 show the change in temperature rate of change of pin hole top temperature Tpin.

[0034] Next, it is determined whether the piston top surface temperature Ttop is equal to or higher than a threshold value Tref1, whether the top ring groove bottom temperature Tlngup is equal to or higher than a threshold value Tref2, whether the bottom ring groove bottom temperature Tlngdw is equal to or higher than a threshold value Tref3, and whether the pin hole top temperature Tpin is equal to or higher than a threshold value Tref4 (steps S120 to S150). The threshold value Tref1 is set to a temperature slightly lower than the maximum allowable temperature for the top surface 33a of the piston 33 (e.g., 270°C or 280°C), and the threshold value Tref2 is set to a temperature slightly lower than the maximum allowable temperature for the top ring groove bottom 33b of the piston 33 (e.g., 220°C or 230°C). The threshold value Tref3 is set to a temperature (e.g., 130°C or 140°C) slightly lower than the maximum allowable temperature for the bottom ring groove bottom 33c of the piston 33, and the threshold value Tref4 is set to a temperature (e.g., 190°C or 200°C) slightly lower than the maximum allowable temperature for the pin hole top 33d of the piston 33.

[0035] In steps S120 to S150, when it is determined that the piston top surface temperature Ttop is equal to or higher than the threshold value Tref1, the top ring groove bottom temperature Tlngup is equal to or higher than the threshold value Tref2, the bottom ring groove bottom temperature Tlngdw is equal to or higher than the threshold value Tref3, or the pin hole top temperature Tpin is equal to or higher than the threshold value Tref4, the oil jet that injects oil from the oil injection nozzle 56 onto the back side of the piston 33 to cool the piston 33 is turned on (step S170), and this process ends. The oil jet is turned on by opening the electromagnetic valve 57 of the oil branch pipe 55 to which the oil injection nozzle 56 is attached. As a result, each part of the piston 33 is cooled.

[0036] On the other hand, when it is determined in steps S120 to S150 that the piston top surface temperature Ttop is less than the threshold value Tref1, the top ring groove bottom temperature Tlngup is less than the threshold value Tref2, the bottom ring groove bottom temperature Tlngdw is less than the threshold value, and the pin hole top temperature Tpin is less than the threshold value Tref4, the process waits for a predetermined time to elapse after this condition is met (step S160), turns off the oil jet (step S180), and ends this process. The oil jet is turned off by closing the electromagnetic valve 57 of the oil branch pipe 55, specifically. This makes it possible to suppress excessive oil jet.

[0037] In the engine device 10 described above, the piston top surface temperature Ttop, the top ring groove bottom temperature Tlngup, the bottom ring groove bottom temperature Tlngdw, and the pin hole top temperature Tpin are estimated based on the rotation speed Ne, the load factor KL, and the coolant temperature Tw of the engine 12. Then, when any of the following is true: the piston top surface temperature Ttop is equal to or higher than the threshold value Tref1, the top ring groove bottom temperature Tlngup is equal to or higher than the threshold value Tref2, the bottom ring groove bottom temperature Tlngdw is equal to or higher than the threshold value Tref3, or the pin hole top temperature Tpin is equal to or higher than the threshold value Tref4, the oil jet that injects oil from the oil injection nozzle 56 onto the back side of the piston 33 to cool the piston 33 is turned on. This makes it possible to suppress unnecessary oil jets, and to more appropriately cool the piston 33. Moreover, the oil jet is turned off when a predetermined time has elapsed since the piston top temperature Ttop is less than the threshold value Tref1, the top ring groove bottom temperature Tlngup is less than the threshold value Tref2, the bottom ring groove bottom temperature Tlngdw is less than the threshold value Tref3, and the pin hole top temperature Tpin is less than the threshold value Tref4. This makes it possible to prevent excessive oil jetting and suppress the generation of particulate matter such as fuel dilution and soot.

[0038] In the engine device 10 of the embodiment, the piston top surface temperature Ttop, the top ring groove bottom temperature Tlngup, the bottom ring groove bottom temperature Tlngdw, and the pin hole top temperature Tpin are estimated based on the rotation speed Ne, the load factor KL, and the coolant temperature Tw of the engine 12. However, the piston top surface temperature Ttop, the top ring groove bottom temperature Tlngup, the bottom ring groove bottom temperature Tlngdw, and the pin hole top temperature Tpin may be estimated based on the rotation speed Ne and the load factor KL of the engine 12 using the oil temperature Toil instead of the coolant temperature Tw. Also, the piston top surface temperature Ttop, the top ring groove bottom temperature Tlngup, the bottom ring groove bottom temperature Tlngdw, and the pin hole top temperature Tpin may be estimated based on other elements (e.g., the oil temperature Toil) in addition to the rotation speed Ne, the load factor KL, and the coolant temperature Tw of the engine 12.

[0039] In the engine device 10 of the embodiment, the piston top surface temperature Ttop, the top ring groove bottom temperature Tlngup, the bottom ring groove bottom temperature Tlngdw, and the pin hole top temperature Tpin are estimated based on the rotation speed Ne, the load factor KL, and the coolant temperature Tw of the engine 12, and the oil jet is turned on when these temperatures reach or exceed the corresponding thresholds. However, in addition to this process, the temperature of another part of the piston 33 may be estimated based on the rotation speed Ne, the load factor KL, and the coolant temperature Tw of the engine 12, and the oil jet may also be turned on when the temperature of that part reaches or exceeds the threshold.

[0040] In the engine device 10 of the embodiment, an oil pump 52 that functions by the rotation of the crankshaft 14 and an electromagnetic valve 57 are provided in an oil branch pipe 55 to which an oil injection nozzle 56 is connected, and the oil jet is turned on and off by opening and closing the electromagnetic valve 57 based on the estimated piston top surface temperature Ttop, the top ring groove bottom temperature Tlngup, the bottom ring groove bottom temperature Tlngdw, and the pin hole top temperature Tpin. However, a variable hydraulic system that does not have the electromagnetic valve 57 and uses a variable oil pump instead of the oil pump 52 may be used, and the oil jet may be turned on and off by increasing or decreasing the hydraulic pressure with the variable oil pump based on the estimated piston top surface temperature Ttop, the top ring groove bottom temperature Tlngup, the bottom ring groove bottom temperature Tlngdw, and the pin hole top temperature Tpin.

[0041] In the engine device 10 of the embodiment, the oil jet is turned on and off based on the estimated piston top surface temperature Ttop, the top ring groove bottom temperature Tlngup, the bottom ring groove bottom temperature Tlngdw, and the pin hole top temperature Tpin. However, other controls may be performed based on the estimated piston top surface temperature Ttop, the top ring groove bottom temperature Tlngup, the bottom ring groove bottom temperature Tlngdw, and the pin hole top temperature Tpin. For example, when any of the following is true: the piston top surface temperature Ttop is equal to or higher than the threshold value Tref1, the top ring groove bottom temperature Tlngup is equal to or higher than the threshold value Tref2, the bottom ring groove bottom temperature Tlngdw is equal to or higher than the threshold value Tref3, or the pin hole top temperature Tpin is equal to or higher than the threshold value Tref4, a fuel increase control may be performed to increase the fuel injection amount in order to cool the piston 33 or suppress a temperature rise, or a load limit control may be performed to limit the load on the engine 12 in order to cool the piston 33 or suppress a temperature rise.

[0042] In the engine device 10 of the embodiment, the engine 12 used has an in-cylinder injection valve 29 arranged approximately in the center of the top of the combustion chamber 31, but it is also possible to use an engine in which the in-cylinder injection valve 29 is arranged on the side wall (side) of the combustion chamber 31.

[0043] In the engine device 10 of the embodiment, the engine 12 has a port injection valve 28 and an in-cylinder injection valve 29, but it may also be an engine having only a port injection valve 28 or an engine having only an in-cylinder injection valve 29.

[0044] Although the engine device 10 of the embodiment is provided with the engine 12 having the turbocharger 40, it may be provided with an engine that does not have the turbocharger 40.

[0045] In the engine system 10 of the embodiment, the supercharger 40 is configured as a turbocharger in which a compressor 41 disposed in the intake pipe 23 and a turbine 42 disposed in the exhaust pipe 35 are connected via a rotating shaft 43. However, instead of this, the supercharger may be configured as a supercharger in which a compressor driven by the engine 12 or a motor is disposed in the intake pipe 23.

[0046] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be described below. In the embodiment, the engine 12 corresponds to the "engine" and the electronic control unit 70 corresponds to the "control device."

[0047] The correspondence between the main elements of the Examples and the main elements of the invention described in the Summary of the Problem column does not limit the elements of the invention described in the Summary of the Problem column, since the Examples are examples for specifically explaining the mode for implementing the invention described in the Summary of the Problem column. In other words, the interpretation of the invention described in the Summary of the Problem column should be based on the description in that column, and the Examples are merely a specific example of the invention described in the Summary of the Problem column.

[0048] Although the form for carrying out the present invention has been described above using examples, the present invention is not limited to these examples in any way, and it goes without saying that the present invention can be carried out in various forms without departing from the scope of the gist of the present invention. [Industrial Applicability]

[0049] The present invention can be used in the engine device manufacturing industry and the like. [Explanation of symbols]

[0050] 10 engine device, 11 fuel tank, 11a internal pressure sensor, 11p feed pump, 12 engine, 14 crankshaft, 14a crank position sensor, 16 fuel supply device, 17 low pressure supply pipe, 18 high pressure pump, 18a solenoid valve, 18b check valve, 18c plunger, 19 high pressure supply pipe, 22 air cleaner, 23 intake pipe, 23a air flow meter, 23b intake pressure sensor, 23c boost pressure sensor, 24 bypass pipe, 25 intercooler, 26 throttle valve, 26a throttle position sensor, 27 surge tank, 27a surge pressure sensor, 27b temperature sensor, 28 in-cylinder injection valve, 28a fuel pressure sensor, 29 intake valve, 30 combustion chamber, 31 spark plug, 33 piston, 33a piston top surface, 33b top ring groove bottom, 33c bottom ring groove bottom, 33d pin hole top, 34 exhaust valve, 35 exhaust pipe, 35a front air-fuel ratio sensor, 35b rear air-fuel ratio sensor, 36 bypass pipe, 37 purification device, 38 engine cooling system, 38a circulation flow path, 38b radiator, 38c fan, 38d fan motor, 38e water pump, 38f temperature sensor, 40 turbocharger, 41 compressor, 42 turbine, 43 rotating shaft, 44 wastegate valve, 45 blow-off valve, 50 oil pan, 52 oil pump, 54 oil pipe, 55 oil branch pipe, 56 oil injection nozzle, 57 solenoid valve, 70 electronic control unit.

Claims

1. An engine device including an engine and a control device that controls the engine, the control device estimates a piston top surface temperature of the top surface of a piston of the engine, a top ring groove bottom temperature of a bottom of a top ring groove that is closest to the top surface of the ring grooves of the piston, a bottom ring groove bottom temperature of a bottom of a bottom ring groove that is farthest from the top surface of the ring grooves of the piston, and a pin hole top temperature of a pin hole top formed on a back side of the top surface of the piston, based on the engine speed, the engine load, and the temperature of cooling water of the engine, and executes a predetermined control for cooling the piston or suppressing a temperature rise using the piston top surface temperature, the top ring groove bottom temperature, the bottom ring groove bottom temperature, and the pin hole top temperature. An engine device characterized by:

2. 2. The engine device according to claim 1, The control device performs control to turn on an oil jet that injects hydraulic oil into the piston as the predetermined control when any one of the conditions of the piston top surface temperature being equal to or higher than a first threshold value, the top ring groove bottom temperature being equal to or higher than a second threshold value, the bottom ring groove bottom temperature being equal to or higher than a third threshold value, and the pin hole top temperature being equal to or higher than a fourth threshold value is satisfied, and performs control to turn off an oil jet that injects hydraulic oil into the piston as the predetermined control when all of the conditions of the piston top surface temperature being equal to or higher than the first threshold value, the top ring groove bottom temperature being equal to or higher than a second threshold value, the bottom ring groove bottom temperature being equal to or higher than a third threshold value, and the pin hole top temperature being equal to or higher than a fourth threshold value are not satisfied. Engine equipment.

3. 3. The engine device according to claim 1 or 2, The control device includes: During a temperature rise, the piston top surface temperature, the top ring groove bottom temperature, the bottom ring groove bottom temperature, and the pin hole top temperature are estimated in the order of the largest degree of change over time of the temperature rise, that is, the piston top surface temperature, the top ring groove bottom temperature, the bottom ring groove bottom temperature, and the pin hole top temperature; During a temperature drop, the piston top surface temperature, the top ring groove bottom temperature, the bottom ring groove bottom temperature, and the pin hole top temperature are estimated in the order of the smallest degree of change over time in temperature drop, that is, the piston top surface temperature, the top ring groove bottom temperature, the bottom ring groove bottom temperature, and the pin hole top temperature. Engine equipment.

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