Control device

Abstract

To provide a control device that suppresses a temperature drop of oil.SOLUTION: A control device controls a hydraulic circuit in which oil is introduced to a discharge part for discharging the oil toward the piston of an engine, and has a pump that pressure-feeds the oil, a first flow passage for letting the pressure-fed oil flow, a first heat exchanger that is disposed in the first flow passage and reduces the temperature of the oil through heat exchange with the oil flowing in the first flow passage, a second flow passage for letting the pressure-fed oil flow, and a switching part that switches flowing of the pressure-fed oil to either of the first flow passage and the second flow passage.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a control device. [Background technology]

[0002] Conventionally, a technique for discharging oil onto a piston in an engine to cool the piston or lubricate the piston's sliding has been put into practical use. Here, for example, if oil is supplied when the piston temperature is low, there is a risk of increased cooling loss and reduced work.

[0003] As a technique for suppressing cooling loss, for example, Patent Document 1 discloses a control device for an internal combustion engine that appropriately controls the injection and stopping of an oil jet according to the operating state of the internal combustion engine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-055562 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the control device of Patent Document 1 has a risk of causing a drop in the temperature of the oil in the hydraulic circuit when the oil jet is stopped. In particular, in a hydraulic circuit provided with a heat exchanger for cooling the oil discharged to the piston, even if the oil jet is stopped, the oil is cooled by the heat exchanger, so there is a risk of the oil temperature dropping significantly. When the oil temperature drops, the viscosity of the oil increases, which increases the drive loss of a pump that transports the oil in the hydraulic circuit, for example.

[0006] An object of the present disclosure is to provide a control device that suppresses a decrease in oil temperature. [Means for solving the problem]

[0007] The control device according to the present disclosure is a control device that controls a hydraulic circuit that guides oil to a discharge section that discharges the oil toward a piston of an engine, and has a pump that pressurizes the oil, a first flow path for flowing the pressurized oil, a first heat exchange section that is disposed in the first flow path and lowers the temperature of the oil by heat exchange with the oil flowing through the first flow path, a second flow path for flowing the pressurized oil, and a switching section that switches the flow of the pressurized oil to either the first flow path or the second flow path. Effect of the Invention

[0008] According to the present disclosure, it is possible to suppress a decrease in oil temperature. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a configuration of an engine system including a control device according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram illustrating a configuration of the control device in the first embodiment. [Diagram 3] FIG. 3 is a flowchart showing the operation of the first embodiment. [Figure 4] FIG. 4 is a diagram showing the configuration of the control device in the second embodiment. [Diagram 5] FIG. 5 is a diagram showing a heat exchange portion disposed in a recirculation passage in the second embodiment. [Figure 6] FIG. 6 is a diagram showing a heat exchange section disposed in a recirculation passage in a modified example of the second embodiment. [Figure 7] FIG. 7 is a diagram showing a heat exchange portion disposed in a recirculation passage in another modified example of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0011] (Embodiment 1) 1 shows a configuration of an engine system including a control device according to a first embodiment of the present disclosure. The engine system includes an engine 1 and a control device 2. The engine system may be mounted on a vehicle such as a commercial vehicle (e.g., a truck).

[0012] The engine 1 burns fuel to generate driving force for running a vehicle, and is, for example, a so-called four-stroke engine that repeats four strokes: an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. The engine 1 has a piston 3 that reciprocates within a cylinder, and this piston 3 forms a combustion chamber in which a mixture of fuel and air is burned. Examples of the engine 1 include a diesel engine and a gasoline engine.

[0013] The control device 2 has a discharge portion 4 and a hydraulic circuit 5 .

[0014] The discharge part 4 is formed with a discharge port 4a, and discharges oil (for example, lubricating oil) from the discharge port 4a toward the piston 3 of the engine 1. For example, the discharge part 4 may be composed of an oil jet that sprays oil.

[0015] The hydraulic circuit 5 guides the oil to the discharge portion 4 and is formed so that the oil circulates.

[0016] Next, the configuration of the control device 2 will be described in detail. As shown in Fig. 2, the control device 2 has a heat exchanger 6, a filter 7, and a control unit 8 in addition to a discharge unit 4 and a hydraulic circuit 5. The hydraulic circuit 5 has a pump 9, a pressure regulating valve 10, a switching unit 11, a flow rate regulating valve 12, an oil pan 13, and an oil passage 14.

[0017] The oil passage 14 guides the oil L to each part of the control device 2, and is formed to sequentially connect the pump 9, the pressure adjusting valve 10, the switching unit 11, the heat exchange unit 6, the filter 7, the flow rate adjusting valve 12, and the discharge unit 4. Here, the oil passage 14 is formed so that the oil does not pass through the heat exchange unit 6, and the oil passage 14b that connects the switching unit 11 and the filter 7 extends in parallel with the oil passage 14a that leads from the switching unit 11 to the filter 7 via the heat exchange unit 6. That is, the oil passage 14 is formed so as to branch into the oil passage 14a and the oil passage 14b. In addition, the oil passage 14 has an oil passage 14c that connects the filter 7 and the engine sliding unit 15 and guides the oil L that has passed through the filter 7 to the engine sliding unit 15. The engine sliding unit 15 operates by the lubrication action of the oil L in the engine system, and may include, for example, a gear train, a crankshaft, a camshaft, a transmission, etc. The oil passage 14a constitutes the first flow path of the present disclosure. Moreover, the oil passage 14b constitutes a second flow passage of the present disclosure.

[0018] The heat exchange unit 6 is disposed in the hydraulic circuit 5, and exchanges heat between the refrigerant flowing therein and the oil L flowing through the oil passage 14a to cool the oil L. The temperature of the refrigerant may be set according to the temperature of the oil L, and may be set based on the temperature of the oil L that increases as a result of being supplied to the piston 3. For example, the cooling water of the engine 1 may be used as the refrigerant.

[0019] The filter 7 is formed to remove impurities such as iron powder contained in the oil L.

[0020] The pump 9 draws up the oil L from the oil pan 13 and pumps out the oil. For example, the pump 9 may be a mechanical pump driven by the rotation of the engine 1. Alternatively, the pump 9 may be a variable displacement pump.

[0021] The pressure regulating valve 10 adjusts the pressure in the oil passage 14 and is configured, for example, to open when the pressure in the oil passage 14 reaches or exceeds a predetermined value to return the oil L to the oil pan 13. The pressure regulating valve 10 may be configured, for example, as a relief valve.

[0022] The switching unit 11 switches the connection of the oil passage 14, through which the oil L flows, between the oil passage 14a and the oil passage 14b. That is, the switching unit 11 switches between the oil passage 14a, through which the oil L can exchange heat with the heat exchange unit 6, and the oil passage 14b, which is not provided with the heat exchange unit 6. The switching unit 11 may be composed of, for example, a directional control valve that controls the flow direction of the oil L.

[0023] The flow rate adjustment valve 12 adjusts the flow rate of the oil L supplied to the discharge portion 4 .

[0024] The oil pan 13 stores oil L and may be disposed, for example, below the cylinder block of the engine 1 to store oil L discharged from the discharge portion 4, oil L that has circulated through the engine sliding parts 15, etc.

[0025] The control unit 8 is electrically connected to the switching unit 11, and switches the switching unit 11 based on the presence or absence of supply of oil L from the discharge unit 4 to the piston 3. Specifically, when oil L is supplied from the discharge unit 4 to the piston 3, the control unit 8 switches the switching unit 11 so that the oil L flows through the oil passage 14a that passes through the heat exchange unit 6. On the other hand, when the supply of oil L from the discharge unit 4 to the piston 3 is stopped, the control unit 8 switches the heat exchange unit 6 so that the oil L flows through the oil passage 14b through which the oil L does not pass through the heat exchange unit 6.

[0026] Furthermore, the control unit 8 is electrically connected to the pump 9 and controls the operation of the pump 9. For example, the control unit 8 may control the pressure regulating valve 10 and the pump 9 so that the oil L flows at a hydraulic pressure according to the operating range (high load, medium load, low load, etc.) of the engine 1.

[0027] Moreover, the control unit 8 is electrically connected to the flow rate adjustment valve 12 to control the supply amount of the oil L to the discharge unit 4, that is, the discharge amount of the oil L from the discharge unit 4. Here, when the oil L is supplied from the discharge unit 4 to the piston 3, the control unit 8 controls the flow rate adjustment valve 12 so that a predetermined amount of the oil L set based on the temperature of the piston 3 is supplied to the discharge unit 4. On the other hand, when the oil L is not supplied from the discharge unit 4 to the piston 3, the control unit 8 may stop the supply of the oil L to the discharge unit 4, or may limit the supply amount of the oil L to the discharge unit 4 so that the oil L does not reach the piston 3. In addition, the control unit 8 may stop the drive of the discharge unit 4, or may control the discharge unit 4 to discharge the oil L at a discharge amount that does not reach the piston 3. At this time, the control unit 8 may obtain piston temperature information indicating the temperature of the piston 3 from the control unit of the engine 1, and may determine whether or not to supply the oil L from the discharge unit 4 to the piston 3 based on the piston temperature information. For example, the control unit 8 may obtain an operating range (such as high load) in which the engine 1 is driven as piston temperature information, and determine whether or not to supply the oil L from the discharge unit 4 to the piston 3 based on the operating range.

[0028] The functions of the control unit 8 can also be realized by a computer program. For example, a reading device of a computer reads a program for realizing the functions of the control unit 8 from a recording medium on which the program is recorded, and stores the program in a storage device. Then, a CPU (Central Processing Unit) copies the program stored in the storage device to a RAM (Random Access Memory), and sequentially reads and executes instructions included in the program from the RAM, thereby realizing the functions of the control unit 8.

[0029] Next, the operation of this embodiment will be described with reference to the flowchart of FIG.

[0030] First, when the engine 1 is driven in the vehicle, in step S1, the control unit 8 of the control device 2 drives the pump 9 so that the oil L flows through the oil passage 14, as shown in FIG. 2. In addition, in step S2, the control unit 8 repeatedly determines whether or not to supply the oil L to the piston 3 based on the temperature of the piston 3. That is, when the temperature of the piston 3 is equal to or higher than a predetermined threshold, the control unit 8 determines to supply the oil L to the piston 3. At this time, the control unit 8 may obtain piston temperature information indicating the temperature of the piston 3, for example, the operating range of the engine 1, from the control unit of the engine 1, and determine whether or not to supply the oil L to the piston 3 based on the operating range. For example, the control unit 8 may determine that the piston 3 has reached a high temperature and that the oil L is to be supplied to the piston 3 when a predetermined threshold is set in advance for the operating range and the operating range of the engine 1 indicates a predetermined threshold or higher (for example, high load).

[0031] When the control unit 8 determines to supply the oil L to the piston 3, the process proceeds to step S3, where it controls the discharge unit 4 or the flow rate control valve 12 to discharge the oil L. As a result, the oil L discharged from the discharge unit 4 is supplied to the piston 3. The supply of the oil L cools the piston 3 and allows the piston 3 to slide smoothly.

[0032] Subsequently, the oil L supplied to the piston 3 returns to and is stored in the oil pan 13. Then, the oil L stored in the oil pan 13 is pumped up by the pump 9 and reaches the switching unit 11 via the pressure regulating valve 10.

[0033] Here, when the control unit 8 determines in step S2 that the oil L is to be supplied to the piston 3, in step S4, the control unit 8 controls the switching unit 11 so that the oil L flows through the oil passage 14a passing through the heat exchange unit 6. That is, the control unit 8 switches the switching unit 11 so that the oil passage 14a, out of the oil passages 14a and 14b, is connected to the oil passage 14 through which the oil L flows. This causes heat exchange between the refrigerant flowing through the heat exchange unit 6 and the oil L flowing through the oil passage 14a, and it is possible to lower the temperature of the oil L that has risen due to its supply to the piston 3.

[0034] After impurities are removed from the oil L cooled by the heat exchange unit 6 by the filter 7, the oil L flows to the flow rate control valve 12 and is discharged from the discharge unit 4 toward the piston 3 as described above. In addition, a portion of the oil L from which impurities have been removed by the filter 7 flows through the oil passage 14c and is supplied to the engine sliding part 15. This allows the engine sliding part 15 to slide smoothly.

[0035] Here, it is assumed that the operating range of the engine 1 has been changed to low load. When the operating range of the engine 1 indicates a value less than a predetermined threshold (e.g., low load), the control unit 8 determines in step S2 to stop the supply of the oil L to the piston 3. When the control unit 8 determines to stop the supply of the oil L to the piston 3, the process proceeds to step S5, where it controls the discharge unit 4 or the flow rate control valve 12 to stop the discharge of the oil L. This makes it possible to reduce the cooling loss of the piston 3 and increase the illustrated work.

[0036] Then, when the control unit 8 determines that the supply of the oil L to the piston 3 is to be stopped, in step S6, the control unit 8 controls the switching unit 11 so that the oil L flows through the oil passage 14b that does not pass through the heat exchange unit 6. That is, the control unit 8 switches the switching unit 11 so that the oil passage 14b, out of the oil passages 14a and 14b, is connected to the oil passage 14 through which the oil L flows. This makes it possible to suppress a decrease in temperature of the oil L when the supply is stopped, and to maintain the oil L at an appropriate viscosity. Furthermore, by maintaining the oil L at an appropriate viscosity, it is possible to suppress a driving loss of the pump 9 that transfers the oil L. In addition, since the oil L is supplied to the engine sliding part 15 with an appropriate viscosity, it is possible to suppress damage to the engine sliding part 15 due to poor sliding or the like.

[0037] In addition, when the operating range of the engine 1 changes from high load to low load in a short time, the piston 3 may be at a high temperature even if the engine 1 is operated at a low load. Therefore, the control unit 8 may determine whether or not the operating range of the engine 1 has changed from high load to low load in a short time based on the history of the operating range of the engine 1, and when it is determined that the operating range has changed in a short time, the control unit 8 may control the discharge unit 4 or the flow rate control valve 12 so as to continue supplying the oil L to the piston 3, for example, until a time has passed during which the temperature of the piston 3 becomes less than a predetermined threshold value. At this time, in step S4, the control unit 8 controls the switching unit 11 so that the oil L flows through the oil passage 14a passing through the heat exchange unit 6. This allows the piston 3 to be appropriately cooled.

[0038] According to this embodiment, the control device 2 has a switching unit 11 that switches the flow of the pressure-fed oil L to either the oil passage 14a or the oil passage 14b. This allows the control device 2 to suppress a decrease in the temperature of the oil L.

[0039] (Embodiment 2) Hereinafter, a second embodiment of the present disclosure will be described. Here, differences from the first embodiment will be mainly described, and common reference numerals will be used for common points with the first embodiment, and detailed descriptions thereof will be omitted.

[0040] In the second embodiment, a new heat exchange unit is connected to the hydraulic circuit 5. This hydraulic circuit 5 is disposed in the vehicle in correspondence with a fluid having a higher temperature than the oil L, and is configured to exchange heat between the oil L flowing therethrough and the fluid. When the supply of the oil L from the discharge unit 4 to the piston 3 is stopped, the control unit 8 causes the oil L or the fluid to flow through the new heat exchange unit, thereby exchanging heat between the oil L and the fluid. For example, the new heat exchange unit may be disposed in an exhaust gas recirculation (EGR) passage that recirculates the exhaust gas of the engine 1 to the intake side, and configured to exchange heat between the oil L and the exhaust gas.

[0041] 4 shows the configuration of the control device 2 of the embodiment 2. The control device 2 may further include a heat exchanger 22, which may be connected to the filter 7 via an oil passage 14d.

[0042] The heat exchanger 22 is disposed in a location in the vehicle corresponding to a location where a fluid having a higher temperature than the oil L exists, and is configured to exchange heat between the oil L flowing inside and the fluid.

[0043] When oil L is supplied to the piston 3, the control unit 8 controls the switching unit 11 to cause the oil L to flow through the oil passage 14a passing through the heat exchange unit 6, and limits the amount of oil L or fluid flowing through the heat exchange unit 22 to a predetermined value or less. At this time, the predetermined value may be set based on the temperature of the fluid and does not affect the temperature of the piston 3. On the other hand, when the supply of oil L from the discharge unit 4 to the piston 3 is stopped, the control unit 8 controls the switching unit 11 to cause the oil L to flow through an oil passage that does not pass through the heat exchange unit 6, and causes the oil L or fluid to flow through the heat exchange unit 22, i.e., causes an amount of oil L or fluid that exceeds the predetermined value to flow.

[0044] 5 shows an example of a location in a vehicle where the heat exchanger 22 is disposed. The engine system has an intake passage 23, an exhaust passage 24, a recirculation passage 25, an air cleaner 26, a supercharger 27, an intercooler 28, an aftertreatment device 29, the heat exchangers 22 and 30, and a valve 31.

[0045] The intake passage 23 is disposed so as to extend from the engine 1 to the outside, and is formed so as to guide air taken in from the outside to the engine 1.

[0046] The exhaust passage 24 is disposed so as to extend from the engine 1 to the outside, and is formed so as to guide the exhaust gas flowing in from the engine 1 to the outside.

[0047] The recirculation passage 25 is disposed to connect the exhaust passage 24 and the intake passage 23, and guides a portion of the exhaust gas of the engine 1 flowing through the exhaust passage 24 to the intake passage 23 for recirculation.

[0048] The air cleaner 26 is disposed at the base end of the intake passage 23, and filters air flowing into the intake passage 23 from the outside to remove dust.

[0049] The turbocharger 27 has a turbine that is rotationally driven by the exhaust gas flowing through the exhaust passage 24, and a compressor that is coaxially connected to the turbine and pressurizes the intake air in the intake passage 23.

[0050] The intercooler 28 is disposed downstream of the turbocharger 27 in the intake passage 23, and cools the intake air compressed by the turbocharger 27 to increase the density of the intake air.

[0051] The aftertreatment device 29 treats the exhaust gas flowing through the exhaust passage 24, and may include, for example, a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), a selective catalytic reduction catalyst (SCR), etc. The DOC oxidizes unburned fuel to increase the exhaust temperature, and oxidizes NO (nitric oxide) in the exhaust to reduce NO 2The DPF traps particulate matter in the exhaust. The SCR selectively reduces and purifies nitrogen oxides (NOx) in the exhaust using ammonia, which is produced by hydrolysis of urea water using exhaust heat, as a NOx catalyst to purify the NOx in the exhaust.

[0052] The heat exchanger 30 is disposed in the recirculation passage 25 and cools the exhaust gas by exchanging heat between the refrigerant flowing inside the heat exchanger 30 and the exhaust gas flowing through the recirculation passage 25. The refrigerant may be, for example, the cooling water of the engine 1.

[0053] The heat exchange unit 22 is disposed in a recirculation passage that recirculates the exhaust gas of the engine 1 to the intake side, and is configured to use oil L flowing inside as a refrigerant and to cool the exhaust gas by exchanging heat between the oil L and the exhaust gas. In other words, the exhaust gas represents a fluid with a higher temperature than the oil L. The heat exchange unit 22 is also disposed in series with a heat exchange unit 30 that exchanges heat between the exhaust gas and the refrigerant in the recirculation passage 25.

[0054] Here, when the oil L is being supplied from the discharge portion 4 to the piston 3, the control portion 8 of the control device 2 controls the hydraulic circuit 5 so that the amount of the oil L or the exhaust gas flowing through the heat exchange portion 22 is equal to or less than a predetermined value. On the other hand, when the supply of the oil L from the discharge portion 4 to the piston 3 is stopped, the control portion 8 controls the hydraulic circuit 5 so that the oil L flows through the heat exchange portion 22, that is, so that an amount of the oil L flowing through the heat exchange portion 22 that exceeds the predetermined value flows through the heat exchange portion 22.

[0055] The valve 31 is disposed in the recirculation passage 25 and adjusts the amount of exhaust gas supplied to the intake passage 23 by changing the opening degree of the recirculation passage 25 .

[0056] Next, the operation of this embodiment will be described.

[0057] First, as shown in FIG. 4, when the control unit 8 determines in step S2 that the oil L is to be supplied to the piston 3, in step S3, the control unit 8 controls the discharge unit 4 or the flow rate control valve 12 so as to discharge the oil L. In addition, in step S4, the control unit 8 controls the switching unit 11 so as to cause the oil L to flow through the oil passage 14a passing through the heat exchange unit 6. Here, when the oil L is supplied from the discharge unit 4 to the piston 3, the control unit 8 controls the hydraulic circuit 5 so as to make the flow rate of the oil L in the heat exchange unit 22 equal to or less than a predetermined value. For example, the control unit 8 can automatically reduce the flow rate of the oil L in the heat exchange unit 22 equal to or less than a predetermined value in response to the control of the flow rate control valve 12 that causes the oil L to be discharged from the discharge unit 4. In addition, a control valve that controls the flow rate of the oil L may be disposed between the filter 7 and the heat exchange unit 22. Thereby, the control unit 8 can control the control valve so as to make the flow rate of the oil L in the heat exchange unit 22 equal to or less than a predetermined value.

[0058] On the other hand, when the control unit 8 determines in step S2 that the supply of the oil L to the piston 3 is stopped, in step S5, the control unit 8 controls the discharge unit 4 or the flow rate control valve 12 to stop the discharge of the oil L. In addition, in step S6, the control unit 8 controls the switching unit 11 to cause the oil L to flow through the oil passage 14b through which the oil L does not pass through the heat exchange unit 6. Here, when the supply of the oil L to the piston 3 is stopped, the control unit 8 controls the hydraulic circuit 5 so that the amount of the oil L flowing through the heat exchange unit 22 exceeds a predetermined value. For example, the control unit 8 can automatically increase the amount of the oil L flowing through the heat exchange unit 22 so that it exceeds a predetermined value in response to the control of the flow rate control valve 12 that stops the discharge of the oil L from the discharge unit 4. In addition, a control valve that controls the flow rate of the oil L may be disposed between the filter 7 and the heat exchange unit 22. Thereby, the control unit 8 can control the control valve so that the amount of the oil L flowing through the heat exchange unit 22 exceeds a predetermined value.

[0059] 5, in the engine system, the intake air flowing through the intake passage 23 is compressed by the turbocharger 27, cooled by the intercooler 28 to increase its density, and then sequentially supplied to the engine 1. In addition, the exhaust gas discharged from the engine 1 flows through the exhaust passage 24, is treated by the aftertreatment device 29, and is then discharged to the outside. In addition, a part of the exhaust gas flows through the recirculation passage 25 and is supplied to the intake passage 23. At this time, the exhaust gas flowing from the exhaust passage 24 into the recirculation passage 25 is at a high temperature and has a higher temperature than the oil L.

[0060] The heat exchanger 30 cools the exhaust gas flowing through the recirculation passage 25 by exchanging heat with the refrigerant. The heat exchanger 22 further cools the exhaust gas that has passed through the heat exchanger 30 by exchanging heat with the oil L.

[0061] In this way, the heat exchanger 22 is disposed in a location in the vehicle where a fluid with a higher temperature than the oil L is present. When the control unit 8 stops the supply of the oil L from the discharge unit 4 to the piston 3, the oil L is caused to flow through the heat exchanger 22, whereby heat is exchanged between the oil L flowing inside the heat exchanger 22 and the fluid. This allows the heat of the fluid to be conducted to the oil L, so that a drop in the temperature of the oil L can be reliably suppressed. By suppressing a drop in the temperature of the oil L, the oil L can be maintained at a more appropriate viscosity, and the drive loss of the pump 9 that transports the oil L can be reliably suppressed.

[0062] At this time, the heat exchanger 22 is disposed in the recirculation passage 25 and exchanges heat between the oil L and the exhaust gas. This reliably suppresses a decrease in the temperature of the oil L and reliably cools the exhaust gas flowing through the recirculation passage 25.

[0063] Moreover, the heat exchange unit 22 is disposed in series with the heat exchange unit 30 that exchanges heat between the exhaust gas and the refrigerant in the recirculation passage 25. When the supply of the oil L from the discharge unit 4 to the piston 3 is stopped, the control unit 8 controls the hydraulic circuit 5 so that the oil L flows through the heat exchange unit 22. This makes it possible to reliably cool the exhaust gas flowing through the recirculation passage 25 while suppressing a decrease in the temperature of the oil L.

[0064] The heat exchange section 22 may be disposed downstream of the heat exchange section 30 with respect to the flow direction of the exhaust gas in the recirculation passage 25. In this way, by disposing the heat exchange section 30, which has a high exhaust gas cooling capacity, downstream of the heat exchange section 22, it is possible to efficiently cool the exhaust gas flowing through the recirculation passage 25. Also, only the heat exchange section 22 may be disposed in the recirculation passage 25 without disposing the heat exchange section 30.

[0065] According to this embodiment, the heat exchanger 22 is disposed in the vehicle corresponding to a fluid having a higher temperature than the oil L, and exchanges heat between the oil L flowing inside and the fluid. When the supply of the oil L from the discharge portion 4 to the piston 3 is stopped, the control portion 8 causes the oil L to flow through the heat exchanger 22. This makes it possible to reliably suppress a decrease in the temperature of the oil L.

[0066] In the present embodiment, when the supply of the oil L from the discharge portion 4 to the piston 3 is stopped, the control portion 8 controls the heat exchange between the oil L and the fluid by circulating the oil L through the heat exchange portion 22. However, the heat exchange between the oil L and the fluid may be controlled by circulating the fluid through the heat exchange portion 22. For example, as shown in FIG. 6, the heat exchange portion 22 may be arranged in parallel to the heat exchange portion 30 in the recirculation passage 25. Specifically, the recirculation passage 25 may be provided with a recirculation passage 25a and a recirculation passage 25b extending in parallel from the exhaust passage 24. The heat exchange portion 30 and the valve 32 may be arranged in the recirculation passage 25a, and the heat exchange portion 22 and the valve 33 may be arranged in the recirculation passage 25b. The valves 32 and 33 may be configured to change the amount of exhaust gas flowing through the recirculation passages 25a and 25b, for example. The valves 32 and 33 may be electrically connected to the control portion 8 of the control device 2.

[0067] With this configuration, when the oil L is supplied from the discharge part 4 to the piston 3, the control part 8 controls the valve 32 so that the exhaust gas flows through the heat exchange part 30. Also, the control part 8 controls the valve 33 so that the exhaust gas does not flow through the heat exchange part 22. As a result, the control part 8 can maintain the temperature of the oil L cooled in the heat exchange part 6 because heat exchange between the oil L is not performed in the heat exchange part 22. On the other hand, when the supply of the oil L from the discharge part 4 to the piston 3 is stopped, the control part 8 controls the valves 32 and 33 so that the exhaust gas flows through the heat exchange part 30 and the heat exchange part 22, respectively. As a result, heat exchange is performed between the oil L and the exhaust gas in the heat exchange part 22, so that a decrease in the temperature of the oil L can be suppressed. Also, heat exchange is performed between the oil L and the exhaust gas in the heat exchange part 22, so that the exhaust gas can be reliably cooled. The valve 32 does not have to be disposed in the recirculation passage 25a.

[0068] 7, a directional control valve 34 may be disposed in place of the valves 32 and 33. For example, the recirculation passage 25a and the recirculation passage 25b may be formed so as to branch off from the exhaust passage 24. The directional control valve 34 may be disposed at the branch point of the recirculation passage 25a and the recirculation passage 25b. Here, the directional control valve 34 may be configured to control the flow direction of the exhaust gas in the recirculation passage 25 to at least one of the recirculation passages 25a and 25b. The directional control valve 34 may be electrically connected to the control unit 8 of the control device 2.

[0069] With this configuration, when the oil L is supplied from the discharge part 4 to the piston 3, the control part 8 controls the directional control valve 34 so that the exhaust gas flows through the heat exchange part 30, but the exhaust gas does not flow through the heat exchange part 22. As a result, the control part 8 can maintain the temperature of the oil L cooled in the heat exchange part 6 because heat exchange is not performed between the oil L in the heat exchange part 22. On the other hand, when the supply of the oil L from the discharge part 4 to the piston 3 is stopped, the control part 8 controls the directional control valve 34 so that the exhaust gas flows through the heat exchange part 30 and the heat exchange part 22. As a result, heat exchange is performed between the oil L and the exhaust gas in the heat exchange part 22, so that a drop in the temperature of the oil L can be suppressed. In addition, heat exchange is performed between the oil L and the exhaust gas in the heat exchange part 22, so that the exhaust gas can be reliably cooled.

[0070] (Embodiment 3) Hereinafter, a third embodiment of the present disclosure will be described. Here, the differences from the first and second embodiments will be mainly described, and common reference numerals will be used for common points with the first and second embodiments, and detailed descriptions thereof will be omitted.

[0071] In embodiment 2, the heat exchange section 22 is arranged in the recirculation passage 25 through which exhaust gas having a higher temperature than the oil L flows, but the heat exchange section 22 may be arranged in a location corresponding to a location in the vehicle where a fluid having a higher temperature than the oil L exists, and is not limited to this.

[0072] For example, the heat exchange unit 22 may be disposed corresponding to the turbocharger 27. Exhaust gas having a higher temperature than the oil L flows through this turbocharger 27. Furthermore, lubricating oil whose temperature becomes higher than the oil L in response to the rotation of the turbine is held in the shaft of the turbocharger 27. Thus, in the turbocharger 27, a fluid having a higher temperature than the oil L is present. The heat exchange unit 22 exchanges heat between the oil L flowing inside and the fluid present in the turbocharger 27.

[0073] With this configuration, when the oil L is supplied from the discharge section 4 to the piston 3, the control section 8 controls the hydraulic circuit 5 so that the flow rate of the oil L in the heat exchange section 22 is equal to or less than a predetermined value. This allows the control section 8 to maintain the temperature of the oil L cooled in the heat exchange section 6. On the other hand, when the supply of the oil L from the discharge section 4 to the piston 3 is stopped, the control section 8 controls the hydraulic circuit 5 so that the oil L flows through the heat exchange section 22. This allows heat exchange between the oil L and the fluid of the turbocharger 27 in the heat exchange section 22, so that a drop in the temperature of the oil L can be suppressed. In addition, heat exchange between the oil L and the fluid of the turbocharger 27 in the heat exchange section 22 allows the fluid of the turbocharger 27 to be reliably cooled.

[0074] According to this embodiment, the heat exchanger 22 is disposed in correspondence with the turbocharger 27, and exchanges heat between the oil L and the fluid present in the turbocharger 27. This makes it possible to reliably suppress a decrease in the temperature of the oil L.

[0075] In addition, the above-mentioned embodiments are merely examples of the embodiment of the present invention, and the technical scope of the present invention should not be interpreted as being limited by these. That is, the present invention can be implemented in various forms without departing from the gist or main features of the present invention. For example, the disclosure of the shape and number of each part described in the above-mentioned embodiments is merely an example, and can be implemented by appropriately changing them. [Industrial Applicability]

[0076] A control device according to the present disclosure can be used in a device that controls a hydraulic circuit that guides oil discharged toward a piston. [Explanation of symbols]

[0077] 1 Engine 2. Control device 3 Piston 4 Discharge part 4a Discharge port 5 Hydraulic Circuit 6,22,30 Heat exchange section 7 Filters 8. Control Unit 9. Pump 10. Pressure Regulating Valve 11 Switching section 12 Flow Control Valve 13 Oil pan 14,14a~14d Oil road 15 Engine sliding parts 23 Intake passage 24 Exhaust passage 25,25a,25b Recirculation passage 26 Air cleaner 27 Turbocharger 28 Intercooler 29 Aftertreatment device 31, 32, 33 Valve 34 Directional control valve L Oil

Claims

1. A control device for controlling a hydraulic circuit that guides oil to a discharge portion that discharges the oil toward a piston of an engine, A pump for pumping the oil; a first flow path for flowing the pumped oil; a first heat exchanger disposed in the first flow path and configured to lower a temperature of the oil by heat exchange with the oil flowing through the first flow path; a second flow path for flowing the pumped oil; a switching unit that switches the flow of the pressure-fed oil to either the first flow path or the second flow path; A control device having the above configuration.

2. The control device according to claim 1 , further comprising a control unit that controls the switching unit so that the oil flows through the second flow path when the supply of the oil from the discharge portion to the piston is stopped.

3. The second heat exchanger is disposed in a location in the vehicle where a fluid having a higher temperature than the oil is present, and exchanges heat between the oil flowing therethrough and the fluid, The control device according to claim 2 , wherein the control unit causes the oil or the fluid to flow through the second heat exchanger when the supply of the oil from the discharge portion to the piston is stopped.

4. 4. The control device according to claim 3, wherein the second heat exchanger is disposed in a recirculation passage that recirculates exhaust gas from the engine to an intake side, and exchanges heat between the oil and the exhaust gas.

5. the second heat exchange unit is disposed in series with a third heat exchange unit that exchanges heat between the exhaust gas and the refrigerant in the recirculation passage; The control device according to claim 4 , wherein the control unit controls the hydraulic circuit so that the oil flows through the second heat exchanger when the supply of the oil from the discharge unit to the piston is stopped.

6. the second heat exchange unit is disposed in parallel with a third heat exchange unit that exchanges heat between the exhaust gas and the refrigerant in the recirculation passage; The control device according to claim 4 , wherein the control unit controls the second heat exchange unit so that the exhaust gas flows through the second heat exchange unit when the supply of the oil from the discharge unit to the piston is stopped.

7. The control device according to claim 3 , wherein the second heat exchanger is disposed in correspondence with a turbocharger and exchanges heat between the oil and the fluid present in the turbocharger.

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