Engine lubrication system

Abstract

To provide a cooling device for an engine capable of improving fuel economy by reducing a load applied to an oil pump and capable of supplying sufficient oil to a piston regardless of an oil temperature.SOLUTION: A lubrication device includes a main jet and a sub jet for supplying oil to a piston of an engine. The lubrication device includes each sensor for detecting an injection amount and an engine speed as an engine load, a sensor for detecting an oil temperature as a temperature of the engine, and a control unit for controlling an oil supply amount to the piston on the basis of the engine load and the oil temperature. The control unit controls so that the oil is supplied only from the sub jet when the load is in a low load state in which the injection amount is equal to or lower than a threshold injection amount, and that the oil is supplied from both of the main jet and the sub jet when the load is in a high load state in which the injection amount is higher than the threshold injection amount. The control unit changes the threshold injection amount in accordance with the oil temperature.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The present invention relates to a lubrication system for an engine. [Background technology]

[0002] Some engines have pistons that reciprocate within cylinder bores and are equipped with a cooling device that cools the pistons whose top surfaces face the combustion chamber. Patent Document 1 discloses an engine cooling device that includes a variable oil jet that can inject oil toward the entrance of the piston's cooling cavity (cooling channel) and a fixed oil jet that can inject oil toward the back surface of the piston. The cooling device disclosed in Patent Document 1 is configured to inject oil only from the variable oil jet when the engine load is low, and to inject oil from both the variable oil jet and the fixed oil jet when the engine load is high. Patent Document 1 states that, as described above, by selecting whether or not to inject oil from the fixed oil jet depending on the engine load, it is possible to cool the pistons while reducing the load on the oil pump. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-131972 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the technology disclosed in Patent Document 1, when the oil temperature is low, the amount of oil supplied to the piston may be insufficient even when the engine load is low, and the piston may not be sufficiently cooled or lubricated. That is, when the oil temperature is low, the viscosity of the oil increases, and it is thought that the amount of oil supplied to the piston may be insufficient even when the engine load is low.

[0005] As described above, if the amount of oil supplied to the piston is insufficient due to low oil temperature, the piston cannot be sufficiently cooled and the space between the cylinder bore and the piston cannot be sufficiently lubricated, which leads to a decrease in engine reliability.

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide an engine cooling device that improves fuel efficiency by reducing the load on the oil pump and can supply sufficient oil to the pistons regardless of the oil temperature. [Means for solving the problem]

[0007] The lubrication device for an engine according to one aspect of the present invention includes a reciprocating lubricating member in a cylinder bore. Made of steel An apparatus for lubricating an engine having a piston. The lubrication apparatus includes an oil jet, an oil pump, an engine load sensor, an engine temperature sensor, and a control unit. The oil jet supplies oil to the piston. The oil pump supplies oil to the oil jet. The engine load sensor detects the load of the engine. The engine temperature sensor detects the temperature of the engine. The control unit controls the amount of oil supplied from the oil jet to the piston based on the load and temperature of the engine.

[0008] In the engine lubrication device of this embodiment, when the engine load is in a low load state where it is below a set threshold load, the control unit lowers the oil pressure from the oil pump to the oil jet compared to when the engine load is in a high load state where it is higher than the threshold load, and when the engine temperature is relatively low, the control unit lowers the threshold load compared to when the engine temperature is relatively high.

[0009] In the engine lubrication device according to the above aspect, the oil pressure from the oil pump to the oil jet is lower when the engine load is low compared to when the engine load is high, so the load on the oil pump can be reduced compared to when the oil pressure is kept constant regardless of the engine load. Therefore, the engine lubrication device according to the above aspect can improve fuel efficiency compared to when the oil pressure is kept constant regardless of the engine load.

[0010] In addition, in the engine lubrication device according to the above aspect, the threshold load, which is the standard for switching between high and low oil pressure to the oil jet, is lower when the engine temperature is relatively low than when it is relatively high, so that sufficient oil can be supplied to the piston even when the engine temperature is low and the oil viscosity is high. Therefore, the engine lubrication device according to the above aspect can ensure the reliability of the engine.

[0011] In the engine lubrication device according to the above aspect, the control unit may increase or decrease the threshold load within a range in which the engine temperature exceeds a first threshold temperature and is lower than a second threshold temperature that is higher than the first threshold temperature.

[0012] In the engine lubrication device according to the above aspect, the threshold load is increased or decreased within a range where the engine temperature exceeds the first threshold temperature and is lower than the second threshold temperature, making control easier than when the threshold load is increased or decreased across the entire engine temperature range.

[0013] An engine lubrication device according to another aspect of the present invention is a device for lubricating an engine having a piston that reciprocates within a cylinder bore. The lubrication device includes an oil jet, an oil pump, an engine load sensor, an engine temperature sensor, and a control unit. The oil jet supplies oil to the piston. The oil pump supplies oil to the oil jet. The engine load sensor detects the load of the engine. The engine temperature sensor detects the temperature of the engine. The control unit controls the amount of oil supplied from the oil jet to the piston based on the load and temperature of the engine. In the engine lubrication device of this embodiment, when the engine load is in a low load state where it is equal to or less than a set threshold load, the control unit lowers the oil pressure from the oil pump to the oil jet compared to when the engine load is in a high load state where it is higher than the threshold load, and when the engine temperature is relatively low, the control unit lowers the threshold load compared to when the engine temperature is relatively high, and increases or decreases the threshold load within a range where the engine temperature exceeds a first threshold temperature and is lower than a second threshold temperature that is higher than the first threshold temperature.

[0014] In the engine lubrication device according to the above aspect, the oil pressure from the oil pump to the oil jet is lower when the engine load is low compared to when the engine load is high, so the load on the oil pump can be reduced compared to when the oil pressure is kept constant regardless of the engine load. Therefore, the engine lubrication device according to the above aspect can improve fuel efficiency compared to when the oil pressure is kept constant regardless of the engine load. In addition, in the engine lubrication device according to the above aspect, the threshold load, which is the standard for switching between high and low oil pressure to the oil jet, is lower when the engine temperature is relatively low than when it is relatively high, so that sufficient oil can be supplied to the piston even when the engine temperature is low and the oil viscosity is high. Therefore, the engine lubrication device according to the above aspect can ensure the reliability of the engine. In addition, in the engine lubrication device according to the above aspect, the threshold load is increased or decreased within a range where the engine temperature exceeds the first threshold temperature and is lower than the second threshold temperature, making control easier than when the threshold load is increased or decreased across the entire engine temperature range.

[0017] In the engine lubrication device according to the above aspect, the control unit may maintain the threshold load at a predetermined value when the engine temperature is below the first threshold temperature and when the engine temperature is above the second threshold temperature.

[0018] In the engine lubrication device according to the above aspect, the threshold load remains unchanged when the engine temperature is below the first threshold temperature, so that the piston can be sufficiently cooled and lubricated even when the temperature is low and the oil viscosity is high. Furthermore, in the engine lubrication device according to the above aspect, the threshold load remains unchanged even when the engine temperature is above the second threshold temperature, so that the piston and its surroundings can be sufficiently cooled and lubricated even when the engine temperature is high. Therefore, the engine lubrication device according to the above aspect can reduce the load on the oil pump when the engine load is low, thereby improving fuel efficiency, while providing sufficient piston cooling and lubrication regardless of the engine temperature, which is advantageous in ensuring engine reliability.

[0019] In the engine lubrication device according to the above aspect, the control unit may specify the threshold load to increase or decrease in a linear function relationship with respect to the engine temperature in a range where the engine temperature exceeds a first threshold temperature and is lower than a second threshold temperature that is higher than the first threshold temperature.

[0020] In the engine lubrication device according to the above aspect, the threshold load is specified to increase or decrease in a linear function relationship with respect to the engine temperature when the engine temperature is between the first threshold temperature and the second threshold temperature, so that the load on the oil pump can be reduced and the piston and its surroundings can be cooled and lubricated with simple control. In the engine lubrication device according to the above aspect, the engine may further include a piston ring attached to the outer periphery of the piston and sliding against the inner wall surface of the cylinder bore, the oil jet having a first oil jet that supplies oil to the piston ring and a second oil jet that supplies oil to the back surface of the piston, and the control unit may supply oil from only the second oil jet when the engine load is in the low load state. The engine lubrication device according to the above aspect is equipped with a first oil jet and a second oil jet, and when the engine load is low, oil is supplied to the piston only from the second oil jet, so that the oil supplied to the back surface of the piston can cool the piston and also lubricate the piston pin and other components disposed on the back surface of the piston. When the engine load is low, the supply of oil from the first oil jet is stopped, reducing the load on the oil pump and improving fuel efficiency. In the engine lubrication device according to the above aspect, the control unit may supply oil from both the first oil jet and the second oil jet when the engine load is in the high load state. In the engine lubrication device according to the above aspect, when the engine load is high, oil is supplied from both the first oil jet and the second oil jet, so that the piston and its surroundings can be sufficiently cooled and lubricated even when the engine load is high. Therefore, the engine lubrication device according to the above aspect can sufficiently ensure engine reliability by providing sufficient cooling and lubrication even when the engine load is high.

[0021] In the engine lubrication device according to the above aspect, the oil pump may be a variable displacement oil pump, and the control unit may control the oil pressure discharged from the oil pump to the oil jet by controlling the oil pump.

[0022] In the engine lubrication device according to the above aspect, by adopting a variable displacement oil pump as the oil pump, the oil pressure to the oil jet can be controlled by controlling the discharge oil pressure from the variable displacement oil pump, thereby improving fuel efficiency when the engine load is low and ensuring high engine reliability by supplying sufficient oil to the piston and its surroundings even when the engine temperature is low.

[0023] In the engine lubrication device according to the above aspect, the control unit may use a hysteresis control method to set a target oil pressure of the oil supplied from the oil pump to the oil jet.

[0024] In the engine lubrication device according to the above aspect, a hysteresis control method is used to set the target oil pressure, so that a stable target oil pressure can be set even when the engine load fluctuates around a threshold value. [Effects of the Invention]

[0025] The engine lubrication device according to each of the above aspects improves fuel economy by reducing the load on the oil pump, and can supply sufficient oil to the piston regardless of whether the oil temperature is high or low. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a cross-sectional view showing a configuration of an engine to which a lubrication device according to an embodiment of the present invention is applied; [Figure 2] FIG. 2 is a side view showing the arrangement of the main jet and the sub-jets relative to the piston. [Figure 3] FIG. 10 is a bottom view showing the arrangement of the main jet and the sub-jets relative to the piston. [Figure 4] FIG. 2 is a bottom view showing the configuration of the piston. [Figure 5] FIG. 5 is a cross-sectional view showing a cross section along line VV in FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 4. [Figure 7] FIG. 2 is a cross-sectional view showing the positional relationship between a piston, a piston pin, and a connecting rod. [Figure 8] FIG. 2 is a hydraulic circuit diagram showing the configuration of a hydraulic circuit in the lubrication device. [Figure 9] FIG. 2 is a block diagram showing a control configuration of the lubrication device. [Figure 10] FIG. 2 is a diagram showing a first table stored in a table storage unit. [Figure 11] FIG. 10 is a diagram showing a second table stored in a table storage unit. [Figure 12] (a) is a characteristic diagram showing the relationship between engine speed and target oil pressure when the oil temperature is 20°C or less and the injection amount is 15 mm3 / str or less, and (b) is a characteristic diagram showing the relationship between injection amount and target oil pressure when the oil temperature is 20°C or less and the engine speed is 2000 rpm or less. [Figure 13] (a) is a characteristic diagram showing the relationship between engine speed and target oil pressure when the oil temperature is 50°C or higher and the injection amount is 45 mm3 / str or less, and (b) is a characteristic diagram showing the relationship between injection amount and target oil pressure when the oil temperature is 50°C or higher and the engine speed is 2000 rpm or less. [Figure 14] FIG. 4 is a characteristic diagram showing the relationship between the oil temperature calculated by the threshold injection amount calculation unit and the threshold injection amount. [Figure 15] 10 is a part of a flowchart showing an engine lubrication method executed by a control unit. [Figure 16] 11 is the remaining part of the flowchart showing the engine lubrication method executed by the control unit. [Figure 17] 10A and 10B are characteristic diagrams showing a method for setting a target oil pressure according to a modified example, in which FIG. 10A is a characteristic diagram showing the relationship between engine speed and target oil pressure when the oil temperature is 20°C or lower and the injection amount is 15 mm3 / str or lower, and FIG. 10B is a characteristic diagram showing the relationship between injection amount and target oil pressure when the oil temperature is 20°C or lower and the engine speed is 2000 rpm or lower. [Figure 18]10A and 10B are characteristic diagrams showing a method for setting a target oil pressure according to a modified example, in which (a) is a characteristic diagram showing the relationship between engine speed and target oil pressure when the oil temperature is 50°C or higher and the injection amount is 45 mm3 / str or less, and (b) is a characteristic diagram showing the relationship between injection amount and target oil pressure when the oil temperature is 50°C or higher and the engine speed is 2000 rpm or less. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described below is an example of the present invention, and the present invention is not limited to the following embodiment except for its essential configuration.

[0028] 1. Engine 1 Configuration The configuration of an engine 1 to which a lubrication device according to an embodiment of the present invention is applied will be described with reference to Fig. 1. Note that the engine 1 is a multi-cylinder engine, but Fig. 1 shows only one cylinder.

[0029] As shown in Fig. 1, the engine 1 includes a cylinder block 10, a cylinder head 11, and an oil pan 12. The cylinder block 10 is composed of an upper block 101 disposed on the upper side in the Z direction, and a lower block 102 disposed below the upper block 101. A cylinder liner 15 is fitted into the block inner peripheral surface 10b on the upper block 101 side. The cylinder liner 15 is fitted into the upper block 101 by press fitting or casting. It is In addition, the water jacket is not shown in FIG.

[0030] An inner peripheral surface 15a of the cylinder liner 15 corresponds to the inner peripheral surface of the cylinder bore.

[0031] The cylinder head 11 is provided above the upper block 101 of the cylinder block 10. The cylinder head 11 is provided with an intake port 11a that draws air into the combustion chamber 10a in the cylinder block 10, and an exhaust port 11b that discharges gas (exhaust gas) from the combustion chamber 10a after combustion. An openable / closable intake valve 19 is provided at the port end of the intake port 11a on the combustion chamber 10a side, and an openable / closable exhaust valve 20 is provided at the port end of the exhaust port 11b on the combustion chamber 10a side.

[0032] The oil pan 12 is provided below the lower block 102 in the Z direction of the cylinder block 10. The oil pan 12 stores oil that drips down from above.

[0033] The engine 1 further includes a piston 13, a plurality of piston rings 14, a piston pin 16, a connecting rod 17, and a crankshaft 18. The piston 13 includes a piston head portion 13a having a top surface facing the combustion chamber 10a, and a piston skirt portion 13b provided below the piston head portion 13a. In this embodiment, the piston 13 is made of steel, for example.

[0034] The piston skirt portion 13b is provided with a portion that pivotally supports a piston pin 16, and a connecting rod 17 is connected via the piston pin 16. The piston 13 reciprocates in the Z direction within a cylinder bore defined by an inner peripheral surface 15a of the cylinder liner 15 as the crankshaft 18 rotates.

[0035] Furthermore, inside the upper block 101 of the cylinder block 10, a main jet (first oil jet) 21 and a sub-jet (second oil jet) 22 are provided below in the Z direction the region into which the cylinder liner 15 is fitted. These oil jets 21, 22 belong to the lubrication device according to this embodiment.

[0036] 2. Arrangement of oil jets 21 and 22 The arrangement of the oil jets 21, 22 relative to the piston 13 will be described with reference to Figures 2 and 3. Note that in Figures 2 and 3, the piston 13, the piston ring 14, and the oil jets 21, 22 are illustrated in isolation.

[0037] 2, the oil jets 21 and 22 are disposed below the back surface 13c of the piston 13 in the Z direction. Both the main jet 21 and the sub-jet 22 are configured to inject oil upward in the Z direction toward where the piston 13 and piston ring 14 are located.

[0038] 3, the main jet 21 and the sub jet 22 are spaced apart from each other in the Y direction. The nozzles of the main jet 21 and the sub jet 22 are formed to extend radially inward of the piston head portion 13a of the piston 13. In this embodiment, the nozzle of the sub jet 22 is formed to extend radially inward of the piston head portion 13a further than the nozzle of the main jet 21.

[0039] 3. Configuration of the piston head portion 13a of the piston 13 The configuration of the piston head portion 13a will be described with reference to FIG.

[0040] As shown in FIG. 4, the piston head portion 13a has a recess 13d formed in an approximately radially central portion thereof so as to recess from a lower surface 13l of the piston head portion 13a (a surface opposite in the Z direction from the top surface facing the combustion chamber 10a in FIG. 1) toward the top surface side (the back side in FIG. 4).

[0041] A tunnel-shaped cooling cavity (cooling channel) 13e is formed inside the piston head portion 13a. The cooling cavity 13e is formed in a donut shape (annular) along the outer circumferential surface of the piston head portion 13a. The piston head portion 13a also has three holes 13f, 13g, and 13i that open from the lower surface 13l toward the cooling cavity 13e. Of these, holes 13f and 13g are located on opposite sides of the circumferential center of the cooling cavity 13e. Hole 13f is a hole that serves as an oil inlet (oil inlet) for the cooling cavity 13e, and hole 13g is a hole that serves as an oil outlet for the cooling cavity 13e.

[0042] Hole 13i is formed at the end of branch passage 13h that branches off from the vicinity of the position where hole 13g is formed in cooling cavity 13e toward the radial center. Hole 13i is also a hole that serves as an outlet for oil from cooling cavity 13e.

[0043] 4. Supply of oil to the piston 13 and piston ring 14 The supply of oil to the piston 13 and the piston ring 14 will be described with reference to Figures 4 to 7. The main jet 21 described with reference to Figure 1 is disposed so as to inject oil toward the hole 13f, as shown by arrow C1 in Figure 5. As shown by arrows B1 and B2 in Figure 4, the oil supplied from the hole 13f to the cooling cavity 13e flows toward the hole 13g while absorbing heat from the piston head 13a. Then, as shown by arrow C2 in Figure 5, the oil flows from the hole 13g outward (downward) of the piston 13.

[0044] 5, some of the oil injected from the main jet 21 passes through a window 13j provided at the boundary between the piston skirt 13b and the piston head 13a and is also supplied to the piston ring 14. This provides lubrication between the piston ring 14 and the inner circumferential surface 15a of the cylinder liner 15.

[0045] As shown by arrow B2 in FIG. 4 and arrow D1 in FIG. 6, a portion of the oil supplied to the cooling cavity 13e passes through the branch passage 13h and is discharged from the hole 13i toward the connecting rod 17 (arrow D2). The connecting rod 17 has an oil supply hole 17a through which the oil discharged from the hole 13i can enter. The oil supply hole 17a is formed to penetrate to the inner circumferential surface 17b. As shown by arrow D2, the oil discharged from the hole 13i passes through the oil supply hole 17a and is supplied between the outer circumferential surface 16a of the piston pin 16 and the inner circumferential surface 17b of the connecting rod 17. This provides lubrication between the outer circumferential surface 16a of the piston pin 16 and the inner circumferential surface 17b of the connecting rod 17.

[0046] As shown in Fig. 7, the sub-jet 22 is disposed so as to inject oil toward a recess 13d provided in the piston head portion 13a. As described with reference to Fig. 4, the recess 13d is formed in an area corresponding to the radial center of the top surface of the piston head portion 13a. Therefore, the oil supplied to the recess 13d absorbs heat from the piston head portion 13a. This also cools the piston head portion 13a.

[0047] 7, the oil supplied to recess 13d collides with the wall surface of recess 13d and flows downward toward piston pin 16 (arrow E1). This provides lubrication between outer peripheral surface 16a of piston pin 16 and inner peripheral surface 17b of connecting rod 17 and pin hole inner peripheral surface 13k of piston 13.

[0048] 5. Configuration of hydraulic circuit in lubrication device 2 The configuration of the hydraulic circuit in the lubrication device 2 according to this embodiment will be described with reference to FIG.

[0049] 8, the lubrication device 2 includes, in addition to the oil jets 21 and 22 described above, an oil pump 23, an oil supply passage 25, a hydraulic control valve 26, and a control unit 27. The oil pump 23 is, for example, a variable displacement oil pump that serves as an auxiliary device driven in conjunction with the rotation of the crankshaft 18 of the engine 1. The oil pump 23 has a drive shaft 231, a rotor 232, a vane 233, a cam ring 234, a spring 235, a ring member 236, and a housing 237.

[0050] Drive shaft 231 is driven to rotate in accordance with the rotation of crankshaft 18 of engine 1. Roller 232 is connected to drive shaft 231. Vane 233 is provided so as to be movable forward and backward in the radial direction from rotor 232. Cam ring 234 houses rotor 232 and vane 233, and is configured so as to be able to adjust the amount of eccentricity of rotor 232 from the center of rotation. Spring 235 elastically biases cam ring 234 in a direction that increases the amount of eccentricity of rotor 232 from the center of rotation. Ring member 236 is disposed inside rotor 232. Housing 237 houses rotor 232, vane 233, cam ring 234, spring 235, and ring member 236.

[0051] One end of the drive shaft 231 extends from the housing 237 and is connected to a driven sprocket. A timing chain is wound around the driven sprocket. As a result, the drive shaft 231 and the rotor 232 are rotated via the timing chain in conjunction with the rotation of the crankshaft 18.

[0052] When the rotor 232 rotates, the vanes 233 always slide on the inner circumferential surface of the cam ring 234. The oil pump 23 is provided with a plurality of pump chambers 239. Each pump chamber 239 is partitioned by the rotor 232, two circumferentially adjacent vanes 233, the cam ring 234, and the housing 237.

[0053] The housing 237 is provided with an intake port 240 and an exhaust port 241. The intake port 240 is an opening through which oil is drawn into the pump chamber 239. An oil strainer 242 is connected to the intake port 240. The oil strainer 242 is immersed in the oil pan 12. The oil stored in the oil pan 12 is drawn into the pump chamber 239 through the intake port 240 via the oil strainer 242.

[0054] The discharge port 241 is an opening through which oil is discharged from the pump chamber 239. The discharge port 241 is connected to the oil supply passage 25. The oil pressurized by the oil pump 23 is discharged from the discharge port 241 to the oil supply passage 25.

[0055] Cam ring 234 is supported by housing 237 so as to be swingable around fulcrum 238. Spring 235 biases cam ring 234 to one side around fulcrum 238. In this embodiment, spring 235 biases cam ring 234 clockwise.

[0056] A pressure chamber 243 is defined between cam ring 234 and housing 237. Oil is supplied to pressure chamber 243 from the outside. Specifically, oil is supplied to pressure chamber 243 from control oil supply passage 252 via hydraulic control valve 26. Cam ring 234 is urged toward the other side (counterclockwise side) around fulcrum 238 by the hydraulic pressure of pressure chamber 243.

[0057] Cam ring 234 oscillates according to the balance between the biasing force from spring 235 and the oil pressure in pressure chamber 243, and the amount of eccentricity of cam ring 234 with respect to the center of rotation of rotor 232 is determined. The capacity of oil pump 23 changes according to the amount of eccentricity of cam ring 234. In other words, the amount of oil discharged from oil pump 23 (discharge pressure) is adjusted based on the amount of eccentricity of cam ring 234.

[0058] The oil supply passage 25 has a main gallery 250, a communication passage 251, and a control oil supply passage 252. The main gallery 250 is formed in the cylinder block 10 of the engine 1 so as to extend in the cylinder row direction. The communication passage 251 is formed so as to connect the discharge port 241 of the oil pump 23 and the main gallery 250. The control oil supply passage 252 is formed so as to connect the main gallery 250 and the pressure chamber 243 of the oil pump 23.

[0059] An oil filter 32 and an oil cooler 33 are provided in the communication passage 251 in this order from the oil pump 23 side. Oil discharged from a discharge port 241 of the oil pump 23 is filtered by the oil filter 32, and the oil temperature is adjusted by the oil cooler 33 before being supplied to the main gallery 250.

[0060] Six main jets 21 and six sub-jets 22 are connected to the main gallery 250. The main jet 21 has a check valve inserted between the main gallery 250 and the nozzle. Thus, in the lubrication device 2, when the oil pressure in the main gallery 250 reaches a predetermined value or higher (for example, 230 kPa or higher), the check valve opens and oil is injected from the main jet 21. Oil supply units 30, 31, 35, and 37 are also connected to the main gallery 250.

[0061] The oil supply unit 30 is a section that supplies oil to the bearing metal of the crank bearing section that rotatably supports the journal section of the crankshaft 18. The oil supply unit 31 is a section that supplies oil to the bearing metal that is arranged on the crank pin to which the big end of the connecting rod 17 of each cylinder is rotatably connected. The oil supply unit 35 is a section that supplies oil to a hydraulic chain tensioner. The oil supply unit 37 is a section that supplies (injects) oil to the timing chain. Furthermore, the main gallery 250 is also connected to an oil pressure sensor 36 that detects the oil pressure of the main gallery 250. The oil pressure of the main gallery 250 detected by the oil pressure sensor 36 is input to the control unit 27.

[0062] An oil filter is inserted in the control oil supply passage 252 between the main gallery 250 and the hydraulic control valve 26. The oil flowing through the control oil supply passage 252 is filtered by the oil filter .

[0063] A control unit 27 is connected to the hydraulic control valve 26. The hydraulic pressure in the oil supply passage 25 is adjusted by the hydraulic adjustment valve 26, which is controlled by the control unit 27.

[0064] 6. Configuration related to control in lubrication device 2 The configuration relating to control in the lubrication device 2 will be described with reference to FIG.

[0065] 9, the control unit 27 is signal-connected to an accelerator opening sensor 40 that detects the opening of the accelerator, an engine speed sensor 41 that detects the rotation speed of the engine 1, and an oil temperature sensor 42 that detects the temperature of the oil. As a result, when the key is on, various signals related to the accelerator opening, engine speed, and oil temperature are input continuously or intermittently to the control unit 27.

[0066] The control unit 27 is connected to a signal of the hydraulic control valve 26. The control unit 27 outputs a signal to the hydraulic control valve 26 so as to set the hydraulic pressure in the oil supply passage 25 to a predetermined value. The control unit 27 has a control unit 271 and a table storage unit 272. The control unit 271 is configured with a microprocessor including an MPU / CPU, an ASIC, etc. The control unit 271 has a threshold injection amount calculation unit 271a that calculates a threshold injection amount (threshold load). The role played by the threshold injection amount calculation unit 271a will be described later.

[0067] The table storage unit 272 is composed of storage devices such as ROM, RAM, etc. The table storage unit 272 stores a first table that defines the relationship between the load of the engine 1 and the target oil pressure (the target oil pressure of the oil supplied from the oil pump 23 to the oil supply passage 25) when the oil temperature (the temperature of the engine 1) is in the range of -10°C to 20°C, and a second table that defines the relationship between the load of the engine 1 and the target oil pressure when the oil temperature is in the range of 50°C to 100°C. In this embodiment, an oil temperature of 20°C corresponds to the "first threshold temperature," and an oil temperature of 50°C corresponds to the "second threshold temperature."

[0068] 7. The first table and the second table stored in the table storage unit 272 The first table and the second table stored in the table storage unit 272 will be described with reference to FIGS.

[0069] 10, the target oil pressure (the set value of the oil pressure discharged from the oil pump 23) according to the engine load when the oil temperature (the temperature of the engine 1) is in the range of more than -10°C and less than 20°C is specified. As shown in FIG. 10, the first table specifies the target oil pressure (the set value of the oil pressure discharged from the oil pump 23) according to the engine load when the engine speed is 2000 rpm or less and the fuel injection amount is 15 mm 3 The range below / str is defined as a low load state, and the other range is defined as a high load state.

[0070] In the first table, when the engine load is low, the target oil pressure is set to 140 kPa. In this case, oil is not injected from the main jet 21, and oil is injected only from the sub-jet 22.

[0071] The engine load is high and the fuel injection amount is 15mm 3 When the engine speed is below 2000 rpm, the target oil pressure is set to 230 kPa. 3 / str > 45mm 3When the target oil pressure is set to 230 kPa, oil is injected from both the main jet 21 and the sub-jet 22.

[0072] Fuel injection volume: 45mm 3 When the oil pressure exceeds / str, the target oil pressure is set to 300 kPa regardless of the engine speed. In this case, oil is injected from both the main jet 21 and the sub-jet 22.

[0073] The second table shown in Fig. 11 defines the target oil pressure according to the engine load when the oil temperature (temperature of the engine 1) is in the range of 50°C or higher and lower than 100°C. As shown in Fig. 11, the second table defines the target oil pressure according to the engine load when the engine speed is 2000 rpm or lower and the fuel injection amount is 45 mm 3 The range below / str is defined as a low load state, and the other range is defined as a high load state.

[0074] In the second table, when the engine load is low, the target oil pressure is set to 140 kPa. In this case, as in the above, oil is not injected from the main jet 21, and oil is injected only from the sub-jet 22.

[0075] The engine load is high and the fuel injection amount is 45mm 3 When the engine speed is below 2000 rpm, the target oil pressure is set to 230 kPa. 3 When the target oil pressure exceeds / str, the target oil pressure is set to 300 kPa regardless of the engine speed. In this way, when the target oil pressure is set to 230 kPa or 300 kPa, oil is injected from both the main jet 21 and the sub-jet 22.

[0076] 8. Threshold Load The threshold load set as the boundary between the low load state and the high load state will be described with reference to FIGS.

[0077] In this embodiment, when defining the target oil pressure, whether the load on the engine 1 is in a low load state or a high load state is determined based on two parameters: the engine speed and the fuel injection amount.

[0078] As shown in FIG. 12(a), when the target oil pressure is determined by referring to the first table, the fuel injection amount is set to 15 mm 3 When the engine speed is less than 2000 rpm, the engine is judged to be in a low load state and the target oil pressure is set to 140 kPa. When the engine speed is more than 2000 rpm, the engine is judged to be in a high load state and the target oil pressure is set to 230 kPa. In other words, the fuel injection amount is set to 15 mm 3 If the load is equal to or less than / str, the threshold rotation speed is 2000 rpm, which is the boundary between the low load state and the high load state.

[0079] As shown in FIG. 12(b), when the target oil pressure is determined by referring to the first table, the engine speed is 2000 rpm or less and the fuel injection amount is 15 mm 3 When the load is below / str, the engine is judged to be in a low load state, and the target oil pressure is set to 140 kPa, and the fuel injection amount is set to 15 mm 3 If the engine speed exceeds / str, it is determined to be in a high load state, and the target oil pressure is set to 230 kPa or 300 kPa. In other words, if the engine speed is 2000 rpm or less, the 15 mm difference, which is the boundary between a low load state and a high load state, is set. 3 / str is the threshold injection amount.

[0080] As shown in FIG. 13(a), when the target oil pressure is determined by referring to the second table, the fuel injection amount is set to 45 mm 3 When the engine speed is less than 2000 rpm, the engine is judged to be in a low load state and the target oil pressure is set to 140 kPa. When the engine speed is more than 2000 rpm, the engine is judged to be in a high load state and the target oil pressure is set to 230 kPa. In other words, when the fuel injection amount is 45 mm 3If the load is equal to or less than / str, the threshold rotation speed is 2000 rpm, which is the boundary between the low load state and the high load state.

[0081] As shown in FIG. 13(b), when the target oil pressure is determined by referring to the second table, the engine speed is 2000 rpm or less and the fuel injection amount is 45 mm 3 When the load is below / str, the engine is judged to be in a low load state, and the target oil pressure is set to 140 kPa, and the fuel injection amount is set to 45 mm 3 If the engine speed exceeds / str, it is determined to be in a high load state and the target oil pressure is set to 300 kPa. In other words, if the engine speed is 2000 rpm or less, the 45 mm 3 / str is the threshold injection amount.

[0082] As shown in Figures 12(a) and 13(a), the threshold rotation speed is set to the same value of 2000 rpm in both the first and second tables, whereas as shown in Figures 12(b) and 13(b), different values ​​are used for the threshold injection amount in the first and second tables.

[0083] Furthermore, when the oil temperature is 20°C or lower, the target oil pressure is determined by referring to the first table, so the threshold load (threshold rotation speed, threshold injection amount) remains unchanged. Similarly, when the oil temperature is 50°C or higher, the target oil pressure is determined by referring to the second table, so the threshold load (threshold rotation speed, threshold injection amount) remains unchanged.

[0084] Next, a method for calculating the threshold load when the oil temperature is in the range of more than 20°C and less than 50°C will be described with reference to FIG. 14. Note that even when the oil temperature is in the range of more than 20°C and less than 50°C, the threshold rotation speed is set to 2000 rpm. In contrast, the threshold injection amount Q TH The threshold injection amount calculation unit 271a of the control unit 271 calculates this based on the oil temperature.

[0085] As shown in FIG. 14, in the range where the oil temperature is greater than 20° C. and less than 50° C. (the range indicated by F), the threshold injection amount calculation unit 271a calculates the threshold injection amount Q TH Specifically, the threshold injection amount calculation unit 271a calculates the threshold injection amount Q based on the following relational expression: TH Calculate. Q TH =Q TH1 +(T OIL -T TH1 )×(Q TH2 -Q TH1 ) / (T TH2 -T TH1 ) ·(Formula 1) In the above equation, T OIL indicates the oil temperature.

[0086] Also, Q TH1 is the first threshold injection amount 15 mm shown in Figure 12(b). 3 / str, Q TH2 is the second threshold injection amount 45 mm shown in Figure 13(b). 3 / str. Furthermore, T TH1 is the first threshold temperature 20°C, which is the upper limit temperature at which the first table is adopted, and T TH2 is the second threshold temperature of 50°C, which is the lower limit temperature at which the second table is adopted.

[0087] 9. Control method for oil supply executed by the control unit 271 The control method for oil supply executed by the control unit 271 will be described with reference to FIGS.

[0088] 15, the control section 271 in the control unit 27 reads various signals from the accelerator opening sensor 40, the engine rotation speed sensor 41, and the oil temperature sensor 42 (step S1). The control section 271 reads the various signals continuously or intermittently when the key is on.

[0089] The control unit 271 calculates the amount of fuel injected into the combustion chamber 10a from the information related to the accelerator opening degree that has been read (step S2). The calculation of the fuel injection amount by the control unit 271 is performed based on a map (not shown) that defines the relationship between the accelerator opening degree and the fuel injection amount, which is stored in advance in the control unit 271.

[0090] Next, the control unit 271 calculates the oil temperature T OIL is -10°C or more (step S3), and the oil temperature T OIL is 100°C or less (step S4). If the determination in either step S3 or step S4 is "NO", the control unit 271 returns control. If the determination in either step S3 or step S4 is "NO", a separate control relating to oil supply, the description of which will be omitted, can be performed.

[0091] If the determinations in both steps S3 and S4 are "YES," the control unit 271 next calculates the oil temperature T OIL It is determined whether the oil temperature T is 20°C or less (step S5). OIL corresponds to the "first threshold temperature."

[0092] In step S5, the control unit 271 OIL 10 from the table storage unit 272 (step S6). Then, the control unit 271 determines whether the engine load is in a low load state or a high load state based on the engine speed that has been read and the calculated fuel injection amount, and then sets the target oil pressure by referring to the first table (step S7).

[0093] The control unit 271 sends a control signal to the hydraulic control valve 26 so that the pressure (hydraulic pressure) of the oil discharged from the oil pump 23 becomes the target hydraulic pressure (step S8). When the engine load is in a low load state, the target hydraulic pressure is set to 140 kPa, so that oil is supplied only from the sub-jet 22. On the other hand, when the engine load is in a high load state, the target hydraulic pressure is set to 230 kPa or 300 kPa, so that oil is supplied from both the main jet 21 and the sub-jet 22.

[0094] In step S5, the control unit 271 OIL If it is determined that the oil temperature T OIL It is determined whether the oil temperature T is 50°C or higher (step S9). OIL corresponds to the "second threshold temperature."

[0095] In step S9, the control unit 271 OIL 11 from the table storage unit 272 (step S10). Then, the control unit 271 determines whether the engine load is in a low load state or a high load state based on the engine speed that has been read and the calculated fuel injection amount, and then sets the target oil pressure by referring to the second table (step S11).

[0096] The control unit 271 sends a control signal to the hydraulic control valve 26 so that the pressure (hydraulic pressure) of the oil discharged from the oil pump 23 becomes the target hydraulic pressure (step S8). When the engine load is in a low load state, the target hydraulic pressure is set to 140 kPa, so that oil is supplied only from the sub-jet 22. On the other hand, when the engine load is in a high load state, the target hydraulic pressure is set to 230 kPa or 300 kPa, so that oil is supplied from both the main jet 21 and the sub-jet 22.

[0097] In step S9, the control unit 271 OIL If it is determined that the oil temperature T is less than 50°C (step S9: NO), as shown in FIG. 16, the threshold injection amount calculation unit 271a OIL Based on the threshold injection amount Q TH (Step S12). TH The calculation is performed based on FIG. 14 and the above relational expression.

[0098] The control unit 271 determines whether the fuel injection amount QLMTAC calculated in step S2 is equal to or greater than the threshold injection amount Q calculated in step S12. TH In step S13, the control unit 271 determines whether the fuel injection amount QLMTAC is equal to or less than the threshold injection amount Q TH If it is determined that the engine speed NE is equal to or less than 2000 rpm (step S13: YES), it is determined whether the read engine speed NE is equal to or less than 2000 rpm (step S14). The determinations made by the control unit 271 in steps S13 and S14 correspond to determining whether the engine load is in a low load state or a high load state.

[0099] If the control unit 271 determines in step S14 that the engine speed NE is 2000 rpm or less (step S14: YES), it determines that the engine load is in a low load state and sets the target oil pressure to 140 kPa (step S15).Then, the control unit 271 sends a control signal to the oil pressure control valve 26 so that the pressure (oil pressure) of the oil discharged from the oil pump 23 becomes the target oil pressure of 140 kPa (step S8).

[0100] In step S13, the control unit 271 determines whether the fuel injection amount QLMTAC is equal to or greater than the threshold injection amount Q TH If it is determined that the fuel injection amount QLMTAC is greater than 45 mm 3 In step S16, the control unit 271 determines whether the fuel injection amount QLMTAC is 45 mm / str or less. 3If it is determined that the engine speed NE is equal to or lower than / str (step S16: YES), the control unit 271 sets the target oil pressure to 230 kPa (step S17). Also, if it is determined in step S14 that the engine speed NE is higher than 2000 rpm (step S14: NO), the control unit 271 sets the target oil pressure to 230 kPa (step S17). Then, the control unit 271 sends a control signal to the oil pressure control valve 26 so that the pressure (oil pressure) of the oil discharged from the oil pump 23 becomes the target oil pressure of 230 kPa (step S8).

[0101] In step S16, the control unit 271 determines whether the fuel injection amount QLMTAC is 45 mm 3 If it is determined that the pressure is greater than / str (step S16: NO), the control unit 271 sets the target oil pressure to 300 kPa (step S18). Then, the control unit 271 sends a control signal to the oil pressure control valve 26 so that the pressure (oil pressure) of the oil discharged from the oil pump 23 becomes the target oil pressure of 300 kPa (step S8).

[0102] Here, the oil temperature T OIL Even when the temperature is greater than 20°C and less than 50°C, if the engine load is low, the target oil pressure is set to 140 kPa, so oil is supplied only from the sub-jet 22; if the engine load is high, the target oil pressure is set to 230 kPa or 300 kPa, so oil is supplied from both the main jet 21 and the sub-jet 22.

[0103] 10.Effects In the lubrication device 2 of the engine 1 according to this embodiment, when the engine load is low, the target oil pressure from the oil pump 23 is lower than when the engine load is high, so the load on the oil pump 23 can be reduced compared to when the oil pressure is kept constant regardless of the engine load. Therefore, in the lubrication device 2 of the engine 1 according to this embodiment, fuel economy can be improved compared to when the oil pressure is kept constant regardless of the engine load.

[0104] In addition, in the lubrication device 2 according to this embodiment, a threshold load (threshold injection amount Q TH ) to the engine 1 temperature (oil temperature T OIL ) is low, it is lower than when it is high, so the oil temperature T OIL Even when the temperature is low and the viscosity of the oil is high, a sufficient amount of oil can be supplied to the piston 13. Therefore, the lubrication device 2 of the engine 1 according to this embodiment can ensure the reliability of the engine 1.

[0105] The lubrication device 2 of the engine 1 according to this embodiment is equipped with a main jet (first oil jet) 21 and a sub jet (second oil jet) 22, and when the engine load is in a low load state, oil is supplied to the piston 13 only from the sub jet 22, so that the oil supplied to the back surface 13c of the piston 13 can cool the piston 13 and also lubricate the piston pin 16 and other components arranged on the back surface 13c side of the piston 13. When the engine load is in a low load state, the supply of oil from the main jet 21 is stopped, so the load on the oil pump 23 is reduced and the fuel efficiency of the engine 1 can be improved.

[0106] In the lubrication device 2 of the engine 1 according to this embodiment, when the engine load is high, oil is supplied from both the main jet 21 and the sub-jet 22, so that the piston 13 and its surroundings (piston ring 14, piston pin 16, connecting rod 17) can be sufficiently cooled and lubricated even in a high-load state. Therefore, in the lubrication device 2 of the engine 1 according to this embodiment, the reliability of the engine 1 can be sufficiently ensured by sufficiently cooling and lubricating even in a high-load state.

[0107] In the lubrication device 2 of the engine 1 according to this embodiment, the oil temperature T OIL is greater than 20°C (first threshold temperature) and less than 50°C (second threshold temperature), the threshold injection amount (threshold load) Q TH The oil temperature T OILIn any temperature range, the threshold injection amount Q TH This makes it easier to control than when trying to increase or decrease the

[0108] In the lubrication device 2 of the engine 1 according to this embodiment, the oil temperature T OIL is in the range of 20℃ or less, the threshold injection amount Q TH 15mm 3 / str is unchanged, so the oil temperature T OIL Even when the oil temperature T OIL Even if the temperature is 50°C or higher, the threshold injection amount Q TH 45mm 3 / str is unchanged, so the oil temperature T OIL Even when the oil temperature T OIL This allows sufficient cooling and lubrication of the piston 13 regardless of the temperature, which is advantageous in ensuring the reliability of the engine 1.

[0109] In the lubrication device 2 of the engine 1 according to this embodiment, the oil temperature T OIL In the temperature range of more than 20°C and less than 50°C, the oil temperature T OIL Threshold injection amount Q TH is specified to increase or decrease in the relationship of a linear function, it is possible to reduce the load on the oil pump 23 and cool and lubricate the piston 13 and its surroundings with simple control.

[0110] In the lubrication device 2 of the engine 1 according to this embodiment, a variable displacement oil pump is used as the oil pump 23, and the oil pressure to the oil jets 21 and 22 can be controlled by controlling the discharge oil pressure from the variable displacement oil pump. This improves the fuel efficiency of the engine 1 when the engine load is low, and reduces the oil temperature TOIL Even when the temperature is low, sufficient oil is supplied to the piston 13 and its surroundings, thereby ensuring high reliability of the engine 1.

[0111] As described above, in the lubrication device 2 of the engine 1 according to this embodiment, the load on the oil pump 23 is reduced to improve fuel economy, and the oil temperature T OIL Therefore, sufficient oil can be supplied to the piston 13 regardless of the level of the pressure.

[0112] [Variations] A lubrication device for an engine according to a modified example will be described with reference to Figures 17 and 18. Figure 17(a) is a characteristic diagram corresponding to Figure 12(a) of the above embodiment, and Figure 17(b) is a characteristic diagram corresponding to Figure 12(b) of the above embodiment. Also, Figure 18(a) is a characteristic diagram corresponding to Figure 13(a) of the above embodiment, and Figure 18(b) is a characteristic diagram corresponding to Figure 13(b) of the above embodiment.

[0113] Except for the configuration described below, the lubrication device for the engine according to this modified example has the same configuration as the lubrication device 2 for the engine 1 according to the above embodiment.

[0114] As shown in FIG. 17(a), in the lubrication device for the engine according to this modification, the oil temperature T OIL is 20℃ or less and the injection amount QLMTAC is 15mm 3 When the engine speed NE is below / str and changes from below 2000 rpm to above 2000 rpm, the target oil pressure is changed from 140 kPa to 230 kPa. This is the same as in the above embodiment.

[0115] However, in the lubrication system for the engine according to this modification, the oil temperature T OIL is 20℃ or less and the injection amount QLMTAC is 15mm 3When the engine speed NE is below / str, the target oil pressure is not changed from 230 kPa to 140 kPa when the engine speed NE changes from above 2000 rpm to below 2000 rpm, but is changed from 230 kPa to 140 kPa when the engine speed NE changes from above 1950 rpm to below 1950 rpm. That is, in this modified example, as shown by H1 in Figure 17(a), the target oil pressure is set using a hysteresis control method that provides a 50 rpm difference between the engine speed NE (2000 rpm) when increasing the target oil pressure and the engine speed NE (1950 rpm) when decreasing it.

[0116] Similarly, as shown in FIG. 17(b), the oil temperature T OIL When the temperature is 20°C or less and the engine speed NE is 2000 rpm or less, the injection amount when increasing the target oil pressure as in H2 and H3 and the injection amount when decreasing it are 2 mm 3 The target oil pressure is set using a hysteresis control method that sets a difference between / str.

[0117] As shown in Figure 18(a) at H4, the oil temperature T OIL is 50°C or higher and the injection amount QLMTAC is 45mm 3 Even when the oil pressure is below / str, the target oil pressure is set using a hysteresis control method that sets a difference of 50 rpm between the engine speed NE (2000 rpm) when increasing the target oil pressure and the engine speed NE (1950 rpm) when decreasing it.

[0118] Similarly, as shown by H5 in Figure 18(b), the oil temperature T OIL When the temperature is 50°C or higher and the engine speed NE is 2000 rpm or lower, the injection amount when increasing the target oil pressure and the injection amount when decreasing it are 2 mm 3 The target oil pressure is set using a hysteresis control method that sets a difference between / str.

[0119] Although not shown in the figure, even when the oil temperature TOIL is in the range of more than 20°C and less than 50°C, a hysteresis control method is used to set the relationship between the engine speed NE or injection amount and the target oil pressure.

[0120] The lubrication device for an engine according to this modified example has the same configuration as the above embodiment except for the above-mentioned configuration, and therefore can achieve the same effects as the above embodiment.

[0121] In addition, in the engine lubrication device of this modified example, a hysteresis control method is adopted to set the relationship between the engine speed NE or injection amount QLMTAC and the target oil pressure, thereby providing a dead zone between when the target oil pressure is increased and when it is decreased, thereby making it possible to control at a stable target oil pressure even when the engine speed NE or injection amount QLMTAC fluctuates.

[0122] [Other variations] In the above embodiment and the above modified example, when the engine load is low, oil is supplied to the piston 13 only from the sub-jet 22, but in the present invention, oil may be supplied to the piston 13 only from the main jet 21.

[0123] In the above embodiment and modified example, a configuration is adopted in which both the main jet 21 and the sub jet 22 are connected to the main gallery 250, but in the present invention, it is also possible to provide separate galleries for connecting the main jet 21 and the sub jet 22. In this case, one valve is provided at the base end (upstream end in the oil flow direction) of the gallery to which the main jet 21 is connected, and the supply of oil from the main jet 21 can be controlled by opening and closing the valve.

[0124] In the above embodiment and modified example, a six-cylinder engine is used as the engine 1, but the present invention can also be used in engines with five or fewer cylinders or seven or more cylinders. In addition, the present invention can be applied to both gasoline engines and diesel engines.

[0125] In the above embodiment and the above modification, the oil temperature T OIL When the temperature is 20°C or lower and when the temperature is 50°C or higher, the threshold injection amount Q TH However, the present invention is OIL Even if the engine temperature (for example, oil temperature T OIL ) depending on the threshold load (e.g., threshold injection amount Q TH ) can also be changed.

[0126] In the above embodiment and the above modification, the oil temperature T OIL Even if the oil temperature T OIL Even when the temperature is 50°C or higher, the engine speed of 2000 rpm is set as the threshold speed. However, in the present invention, the engine temperature (for example, the oil temperature T OIL ) the threshold rotation speed can also be changed depending on the

[0127] In the above embodiment and modified example, a configuration is adopted in which a portion of the oil injected from the main jet 21 passes through the window portion 13j and is supplied to the piston ring 14, but this configuration is not essential in the present invention. That is, in the present invention, the entire amount of oil injected from the main jet 21 can also be supplied to the cooling cavity 13e.

[0128] In the above embodiment and modified example, when the oil pressure reaches 230 kPa or higher, the check valve of the main jet 21 opens and oil is injected from the nozzle of the main jet 21. However, in the present invention, the oil pressure at which the check valve opens is not limited to this.

[0129] In the above embodiment and the above modification, the oil temperature T OILis defined as "the temperature of engine 1," but the present invention is not limited to this, and it is also possible to directly detect the temperature of the coolant or the temperature of metal parts such as the cylinder block 10 or the cylinder head 11 and use this as "the temperature of the engine."

[0130] In the above embodiment and the above modified example, a variable displacement oil pump 23 that is driven in accordance with the rotation of the crankshaft 18 is used in the hydraulic circuit, but the present invention can also use an electric pump or the like.

[0131] In the above embodiment and the above modification, the oil temperature T OIL In the range of more than 20°C and less than 50°C, the oil temperature T OIL Although the relationship between the target hydraulic pressure and the target oil pressure is a linear function, in the present invention, it is also possible to make the relationship an exponential function or a multi-order function. [Explanation of symbols]

[0132] 1 engine 2 Lubrication device 13 Piston 21 Main jet (first oil jet) 22 Sub-jet (second oil jet) 23 Oil pump 25 Fuel Line 26 Hydraulic control valve 27 Control Unit 40 Accelerator opening sensor 41 Engine revolution sensor 42 Oil temperature sensor (engine temperature sensor) 271 Control Unit 271a Threshold injection amount calculation unit 272 Table storage section

Claims

1. A lubrication system for an engine, comprising: The engine includes a steel piston reciprocating within a cylinder bore; The lubrication device is an oil jet for supplying oil to the piston; an oil pump that supplies oil to the oil jet; an engine load sensor that detects a load on the engine; an engine temperature sensor for detecting the temperature of the engine; a control unit that controls the amount of oil supplied from the oil jet to the piston based on the load and temperature of the engine; Equipped with The control unit When the engine load is in a low load state where it is equal to or less than a set threshold load, the oil pressure from the oil pump to the oil jet is lowered compared to when the engine load is in a high load state where it is higher than the threshold load, When the temperature of the engine is relatively low, the threshold load is lowered compared to when the temperature of the engine is relatively high. Engine lubrication system.

2. In the engine lubrication device described in claim 1, The control unit increases or decreases the threshold load when the temperature of the engine exceeds a first threshold temperature and is lower than a second threshold temperature that is higher than the first threshold temperature. Engine lubrication system.

3. A lubrication device for an engine, comprising: The engine includes a piston that reciprocates within a cylinder bore, The lubrication device is an oil jet for supplying oil to the piston; an oil pump that supplies oil to the oil jet; an engine load sensor that detects a load on the engine; an engine temperature sensor for detecting the temperature of the engine; a control unit that controls the amount of oil supplied from the oil jet to the piston based on the load and temperature of the engine; Equipped with The control unit When the engine load is in a low load state where it is equal to or less than a set threshold load, the oil pressure from the oil pump to the oil jet is lowered compared to when the engine load is in a high load state where it is higher than the threshold load, When the temperature of the engine is relatively low, the threshold load is lower than when the temperature of the engine is relatively high; The threshold load is increased or decreased when the engine temperature exceeds a first threshold temperature and is lower than a second threshold temperature that is higher than the first threshold temperature. Engine lubrication system.

4. In the engine lubrication device according to claim 2 or claim 3, the control unit maintains the threshold load at a predetermined value when the engine temperature is equal to or lower than the first threshold temperature and when the engine temperature is equal to or higher than the second threshold temperature; Engine lubrication system.

5. In the engine lubrication device according to any one of claims 2 to 3, The control unit defines the threshold load to increase or decrease in a linear function relationship with the temperature of the engine in a range where the temperature of the engine exceeds a first threshold temperature and is lower than a second threshold temperature that is higher than the first threshold temperature. Engine lubrication system.

6. In the engine lubrication device according to any one of claims 1 to 5, The engine further includes a piston ring that is annularly mounted on an outer periphery of the piston and slides against an inner wall surface of the cylinder bore. The oil jet includes a first oil jet that supplies oil to the piston ring and a second oil jet that supplies oil to a back surface of the piston, The control unit supplies oil only from the second oil jet when the load of the engine is in the low load state. Engine lubrication system.

7. In the engine lubrication device described in claim 6, The control unit supplies oil from both the first oil jet and the second oil jet when the load of the engine is in the high load state. Engine lubrication system.

8. The engine lubrication device according to any one of claims 1 to 7, the oil pump is a variable displacement oil pump, The control unit controls the oil pump to control the oil pressure discharged from the oil pump to the oil jet. Engine lubrication system.

9. The engine lubrication device according to any one of claims 1 to 8, The control unit uses a hysteresis control method to set a target oil pressure of the oil supplied from the oil pump to the oil jet. Engine lubrication system.

Images