oil supply device

Abstract

The present invention provides an oil supply device that can ensure the necessary (minimum) hydraulic pressure even when the piston oil jet is in operation, and that can suppress an increase in the (total) friction of the oil pump. [Solution] The oil supply device 1 includes a main oil pump 20 that pressurizes oil and supplies it to the lubricated member and the cooled member, a sub-oil pump 30 that pressurizes oil and supplies it to a piston oil jet 12 that injects oil onto the back surface of the piston, and a hydraulic pipe 40 that connects the discharge port 27 of the main oil pump 20 to the side surface of the outer rotor 33 of the sub-oil pump 30, and injects a portion of the oil discharged from the main oil pump 20 onto the side surface of the outer rotor 33 of the sub-oil pump 30.

Description

Technical Field

[0001] The present invention relates to an oil supply device.

Background Art

[0002] An engine includes, for example, an oil pump that boosts and discharges the oil stored in an oil pan, and lubricates and cools each part (lubricated part and cooled part) by supplying the oil discharged from the oil pump to each part.

[0003] For example, Patent Document 1 discloses an internal combustion engine including a piston oil jet that injects the oil supplied by an oil pump toward the back surface of a piston to cool the piston.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, for example, in a high-output engine, in order to ensure reliability and performance, there are some that include a plurality (for example, three per cylinder) of piston oil jets per cylinder. Since the oil pump needs to ensure a predetermined necessary (minimum) oil pressure even during the operation of the piston oil jet (when oil is injected), when the number of piston oil jets increases and the amount of oil (oil pressure) required for the piston oil jets increases, it is necessary to increase the size of the oil pump (that is, increase the discharge amount to ensure the oil pressure), and the friction increases (thus deteriorating the fuel efficiency).

[0006] The present invention was made to solve the above-mentioned problems, and aims to provide an oil supply device that can ensure the necessary (minimum) hydraulic pressure even when the piston oil jet is in operation, and that can suppress an increase in friction of the oil pump. [Means for solving the problem]

[0007] An oil supply device according to one aspect of the present invention is characterized by comprising: a main oil pump that pressurizes oil and supplies it to a lubricated member and a cooled member; a sub-oil pump that pressurizes oil and supplies it to a piston oil jet that injects oil onto the back surface of a piston; and hydraulic piping that connects the discharge port of the main oil pump to the side surface of the outer rotor of the sub-oil pump, and injects a portion of the oil discharged from the main oil pump onto the side surface of the outer rotor of the sub-oil pump.

[0008] According to one aspect of the present invention, the sub-oil pump supplies oil to the piston oil jet, and the discharge pressure (discharge volume) characteristics of the sub-oil pump (discharge pressure (discharge volume) as a function of rotational speed) can be optimized to match (specialize for) the required hydraulic pressure (flow rate) of the piston oil jet. Therefore, friction can be reduced (increased) compared to the case where the size of the main oil pump is increased.

[0009] Next, (in addition), the discharge port of the main oil pump and the side of the outer rotor of the sub-oil pump are connected, and a portion of the oil discharged from the main oil pump is injected onto the side of the outer rotor of the sub-oil pump. Here, at low oil temperatures where there is no need to cool the piston, i.e., when the piston oil jet does not need to be operated, the oil viscosity is high and the discharge pressure of the main oil pump is high. Therefore, the tilt (inclination) of the outer rotor of the sub-oil pump increases due to the injection of oil onto its side. As a result, the sealing performance between the inner rotor and the outer rotor decreases, making it difficult to form an oil film (the oil film breaks and sealing becomes impossible), and oil cannot be drawn in (the intake resistance decreases). Consequently, the discharge capacity decreases. In other words, the sub-oil pump ends up spinning freely, resulting in decreased friction.

[0010] On the other hand, at high oil temperatures when the piston oil jet is operating, the viscosity of the oil decreases, the discharge pressure of the main oil pump decreases, and the tilt of the outer rotor of the sub-oil pump, caused by oil being sprayed onto its side, becomes smaller (almost zero). As a result, the sealing performance between the inner rotor and the outer rotor is restored, and the intake and discharge capabilities are restored. Thus, oil can be supplied to the piston oil jet, and the required oil pressure (flow rate) can be satisfied. Furthermore, since the oil pressure (oil volume) required for the piston oil jet can be secured by the sub-oil pump, a decrease in the oil pressure of the main oil pump can be prevented (avoided) without increasing the size of the main oil pump, and the necessary (minimum) oil pressure can be secured (guaranteeed). [Effects of the Invention]

[0011] According to the present invention, it is possible to ensure the necessary (minimum) hydraulic pressure even when the piston oil jet is in operation, and to suppress the increase in friction of the oil pump (as a whole). [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows the lubrication system (oil passages) of an engine to which the oil supply device according to the embodiment is applied. [Figure 2] This diagram shows the configuration of an oil supply device according to an embodiment. [Figure 3] This diagram illustrates the tilt (tilting) of the outer rotor of the sub-oil pump according to the embodiment. (a) shows the state at high oil temperature, and (b) shows the state at low oil temperature. [Figure 4] This diagram illustrates the reduction in workload (at high oil temperatures) for the entire oil pump system (main oil pump and sub-oil pump). [Figure 5] This diagram illustrates the reduction in workload (at low oil temperatures) for the entire oil pump system (main oil pump and sub-oil pump). [Figure 6] This is a diagram (graph) showing the relationship between rotational speed and hydraulic pressure in an oil supply device according to a modified example. [Modes for carrying out the invention]

[0013] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts will be denoted by the same reference numerals. In addition, in each drawing, the same elements will be denoted by the same reference numerals, and redundant explanations will be omitted.

[0014] First, the configuration of the oil supply device 1 according to this embodiment will be explained using Figures 1 to 3 together. Figure 1 is a diagram showing the lubrication system (oil passage) of the engine 10 to which the oil supply device 1 is applied. Figure 2 is a diagram showing the configuration of the oil supply device 1. Figure 3 is a diagram for explaining the tilt (tilt) of the rotor of the sub-oil pump 30, where (a) shows the state at high oil temperature and (b) shows the state at low oil temperature.

[0015] The engine 10 to which the oil supply device 1 is applied can be of any type, but for example, it is a horizontally opposed four-cylinder engine.

[0016] The oil supply device 1, for example, pressurizes the oil stored in the oil pan 11 and supplies it to each part (lubricated parts and cooled parts) such as a valve operating mechanism and a crankshaft, etc., to lubricate and cool these parts. Further, the oil supply device 1 supplies oil to the piston oil jet 12 that sprays oil toward the back surface of the piston to cool the piston. The oil used for lubricating and cooling each of the above parts drops into the oil pan 11 and is recovered and temporarily stored.

[0017] Here, the piston oil jet 12, for example, pressurizes the oil stored in the oil pan 11 by a sub-oil pump 30 (details will be described later), pumps it to a nozzle through an oil passage (hydraulic circuit) 43, and sprays it from the nozzle toward the back surface of the piston. Note that it may be configured to include a plurality of (for example, three per cylinder) piston oil jets 12 per cylinder.

[0018] Each piston oil jet 12 is provided with a check valve 121, for example, which includes a spring and a valve, and opens at a predetermined pressure or higher to allow oil to flow (turn on) into the piston oil jet 12. Therefore, the check valve 121 controls (switches) the operation (execution) and stop of the piston oil jet 12.

[0019] In particular, the oil supply device 1 has a function of ensuring the necessary (minimum) oil pressure even when the piston oil jet 12 is operating, and suppressing an increase in the (total) friction of the oil pump. Therefore, the oil supply device 1 mainly includes a main oil pump 20, a sub-oil pump 30, a hydraulic pipe 40 that communicates the main oil pump 20 and the side surface of the outer rotor 33 of the sub-oil pump 30, and a relief valve 41 interposed in the hydraulic pipe 40.

[0020] The main oil pump 20, for example, boosts the pressure of the oil stored in the oil pan 11 and supplies it mainly to the cooled and lubricated members except the piston oil jet 12. The sub oil pump 30, for example, boosts the pressure of the oil stored in the oil pan 11 and supplies it only to the piston oil jet 12 that injects oil onto the back surface of the piston.

[0021] More specifically, as the main oil pump 20 and the sub oil pump 30, for example, a trochoid pump (internal gear pump) that forms an oil film on the seal part to enhance the sealing performance and sucks up the oil is preferably used. The main oil pump 20 and the sub oil pump 30 are, for example, mechanical oil pumps driven by the engine 10.

[0022] Also, in order to reduce the overall size (to fit compactly), it is preferable that the main oil pump 20 and the sub oil pump 30 are arranged coaxially (that is, in a coaxial type).

[0023] More specifically, the main oil pump 20 and the sub oil pump 30 are, for example, driven by the engine output, suck up the oil stored in the oil pan 11 through the suction ports 26 and 36, boost the pressure, and discharge it from the discharge ports 27 and 37.

[0024] The main oil pump 20 and the sub oil pump 30 include pump housings 21 and 31 and covers 22 and 32 joined to the joint surfaces of the pump housings 21 and 31. Inside the pump housings 21 and 31, cylindrical (circular cross-section) rotor accommodating parts are formed.

[0025] Also, the covers 22 and 32 are formed with suction ports 26 and 36 that communicate with the rotor accommodating part so as to penetrate the covers 22 and 32 and suck up the oil, and discharge ports 27 and 37 that discharge the oil.

[0026] Inside the rotor housing, outer rotors 23 and 33, each having internal teeth on its inner circumferential surface, are rotatably arranged (housed). Inside the outer rotors 23 and 33, inner rotors 24 and 34, each having external teeth on its outer circumferential surface that mesh with the internal teeth of the outer rotors 23 and 33, are rotatably arranged (housed). The outer rotors 23 and 33 and the inner rotors 24 and 34 mesh with each other in an eccentric manner, and multiple working chambers with varying volumes are defined between them.

[0027] A pump shaft (drive shaft) 25 is connected to the center of the inner rotors 24 and 34. Here, a support hole is formed in the center of each of the pump housings 21 and 31 and covers 22 and 32, and the pump shaft 25 is rotatably supported, for example, via a bearing. On the other hand, a driven pulley (not shown) is fixed to the base end of the pump shaft 25 that protrudes from the support hole of the pump housings 21 and 31. This driven pulley is connected, for example, to a drive pulley provided at the end of the crankshaft (output shaft) of the engine 10 via an endless belt, and is rotationally driven via the endless belt.

[0028] Then, the pump shaft 25 is rotated, causing the inner rotors 24 and 34 to rotate, and the volume of the working chamber defined by the tooth grooves of the outer rotors 23 and 33 and the adjacent teeth of the inner rotors 24 and 34 changes, thereby drawing in, pressurizing, and discharging oil.

[0029] The main oil pump 20 and the sub-oil pump 30 have the same basic configuration, but the volume of the working chambers of the main oil pump 20 and the sub-oil pump 30 are set (optimized) according to the characteristics required for each of them (for example, the discharge pressure (discharge volume) characteristics with respect to rotational speed). The volume of the working chambers can be changed, for example, by changing the number of teeth of the outer rotors 23, 33 and the inner rotors 24, 34.

[0030] The hydraulic piping 40 (injection port) connects the discharge port 27 of the main oil pump 20 to the side of the outer rotor 33 of the sub-oil pump 30, injecting a portion of the oil discharged from the main oil pump 20 onto the side of the outer rotor 33 of the sub-oil pump 30.

[0031] Here, Figure 3(b) shows the state (tilt (overturn)) of the outer rotor 33 of the sub-oil pump 30 at low oil temperature (high oil pressure). Also, Figure 3(a) shows the state (tilt (overturn)) of the outer rotor 33 of the sub-oil pump 30 at high oil temperature (low oil pressure or injection stop).

[0032] As shown in Figure 3(b), at low oil temperatures, the oil viscosity is high, and the discharge pressure of the main oil pump 20 increases. Therefore, the tilt (inclination) of the outer rotor 33 of the sub-oil pump 30 increases due to oil being sprayed onto its side surface. As a result, the sealing performance between the inner rotor 34 and the outer rotor 33 decreases, making it difficult to form an oil film (the oil film breaks down and sealing becomes impossible), and preventing oil from being drawn in (the intake resistance decreases). Consequently, the discharge capacity decreases. In other words, the sub-oil pump 30 ends up running idly.

[0033] On the other hand, as shown in Figure 3(a), at high oil temperatures, the viscosity of the oil decreases, the discharge pressure of the main oil pump 20 decreases, the injection of oil onto the side of the outer rotor 33 of the sub-oil pump 30 stops, or the oil injection pressure decreases (if there is no relief valve 41, which will be described later), and the tilt (inclination) of the outer rotor 33 caused by the injection of oil onto the side of the outer rotor 33 of the sub-oil pump 30 becomes zero (or small). As a result, the sealing performance between the inner rotor 34 and the outer rotor 33 is restored, and the intake and discharge capabilities are restored. Thus, oil can be supplied to the piston oil jet 12.

[0034] Here, the diameter (injection volume) of the hydraulic piping 40 is set such that, at low oil temperatures (for example, below 90°C), an oil film cannot be formed between the inner rotor 34 and the outer rotor 33, and the pushing force (hydraulic pressure × area (∝ diameter)) is such that the outer rotor 33 is tilted to the extent that the work of the sub-oil pump 30 becomes almost zero, and at high oil temperatures (for example, above 90°C), the pushing force (=hydraulic pressure × area (∝ diameter)) is such that the outer rotor 33 tilts to the extent that the sub-oil pump 30 can operate (i.e., does not tilt at all).

[0035] The relief valve 41 is interposed in the hydraulic piping 40. The relief valve 41 is composed of, for example, a valve body and a coil spring, and opens (connects the hydraulic piping 40) when the hydraulic pressure in the hydraulic piping 40 is above a predetermined pressure. When the valve is open, oil is sprayed onto the side surface of the outer rotor 33.

[0036] On the other hand, the relief valve 41 closes (blocks communication in the hydraulic piping 40) when the hydraulic pressure in the hydraulic piping 40 is below a predetermined pressure. When the valve is closed, the injection of oil onto the side of the outer rotor 33 is stopped. Furthermore, by installing the relief valve 41, the operating state of the sub-oil pump 30 can be switched (on and off) more reliably and abruptly.

[0037] As described above, the sub-oil pump 30 supplies oil only to the piston oil jet 12, allowing the discharge pressure (discharge volume) characteristics of the sub-oil pump 30 (discharge pressure (discharge volume) as a function of rotational speed) to be optimized to match (specialize in) the required oil pressure (flow rate) of the piston oil jet 12. Therefore, as shown in Figure 4, friction can be reduced (increased) compared to the case where the size of the main oil pump 20 is enlarged. Figure 4 is a diagram illustrating the reduction in the workload of the entire oil pump (main oil pump 20 and sub-oil pump 30) at high oil temperatures.

[0038] Next, the discharge port 27 of the main oil pump 20 is connected to the side of the outer rotor 33 of the sub-oil pump 30, and a portion of the oil discharged from the main oil pump 20 is injected onto the side of the outer rotor 33 of the sub-oil pump 30. Here, at low oil temperatures where there is no need to cool the piston, that is, when the piston oil jet 12 does not need to be operated, the viscosity of the oil is high and the discharge pressure of the main oil pump 20 is high. Therefore, the tilt (inclination) of the outer rotor 33 of the sub-oil pump 30 increases due to the injection of oil onto its side (see Figure 3(b)).

[0039] As a result, the sealing performance between the inner rotor 34 and the outer rotor 33 deteriorates, making it difficult to form an oil film (the oil film breaks down and sealing becomes impossible), and preventing oil from being drawn in (the intake resistance decreases). Consequently, the discharge capacity decreases. In other words, as shown in Figure 5, the sub-oil pump 30 ends up running idle (not doing any work). Figure 5 is a diagram illustrating the reduction in the amount of work done by the entire oil pump (main oil pump 20 and sub-oil pump 30) at low oil temperatures.

[0040] On the other hand, at high oil temperatures when the piston oil jet 12 is driven (operating), the viscosity of the oil decreases, the discharge pressure of the main oil pump 20 decreases, and the tilt (inclination) of the outer rotor 33 of the sub-oil pump 30, caused by oil being sprayed onto the side of the outer rotor 33, becomes zero (or small) (see Figure 3(a)).

[0041] Therefore, the sealing performance between the inner rotor 34 and the outer rotor 33 is restored, and the intake and discharge capabilities are restored (recovered) (see Figure 4). As a result, oil is supplied to the piston oil jet 12.

[0042] As explained in detail above, according to this embodiment, firstly, since the sub-oil pump 30 supplies oil only to the piston oil jet 12, the discharge pressure (discharge volume) characteristics of the sub-oil pump 30 (discharge pressure (discharge volume) as a function of rotational speed) can be optimized to match (specialize for) the required oil pressure (flow rate) of the piston oil jet 12. Therefore, compared to the case where the size of the main oil pump 20 is increased, friction can be reduced (its increase can be suppressed).

[0043] Next, (in addition), the discharge port 27 of the main oil pump 20 is connected to the side of the outer rotor 33 of the sub-oil pump 30, and a portion of the oil discharged from the main oil pump 20 is injected onto the side of the outer rotor 33 of the sub-oil pump 30. Here, at low oil temperatures where there is no need to cool the piston, that is, when the piston oil jet 12 does not need to be operated, the viscosity of the oil is high and the discharge pressure of the main oil pump 20 is high. Therefore, the tilt (inclination) of the outer rotor 33 of the sub-oil pump 30 increases due to the injection of oil onto its side. As a result, the sealing performance between the inner rotor 34 and the outer rotor 33 decreases, making it difficult to form an oil film (the oil film breaks and sealing becomes impossible), and it becomes impossible to draw in oil (the intake resistance decreases). Consequently, the discharge capacity decreases. In other words, the sub-oil pump 30 ends up spinning freely, resulting in decreased friction.

[0044] On the other hand, when the piston oil jet 12 is operating at high oil temperatures, the viscosity of the oil decreases, the discharge pressure of the main oil pump 20 decreases, and the tilt of the outer rotor 33 caused by oil being sprayed onto the side of the outer rotor 33 of the sub-oil pump 30 becomes smaller (almost zero). As a result, the sealing performance between the inner rotor 34 and the outer rotor 33 is restored, and the intake and discharge capacities are restored. Thus, oil can be supplied to the piston oil jet 12, and the required oil pressure (flow rate) can be satisfied. Furthermore, since the oil pressure (oil volume) required for the piston oil jet 12 can be secured by the sub-oil pump 30, a decrease in the oil pressure of the main oil pump 20 can be prevented (avoided) without increasing the size of the main oil pump 20, and the necessary (minimum) oil pressure can be secured (guaranteeed).

[0045] As a result, according to this embodiment, it is possible to secure the necessary (minimum) hydraulic pressure even when the piston oil jet 12 is in operation, and to suppress the increase in friction (total) of the oil pumps 20 and 30.

[0046] Furthermore, according to this embodiment, compared to, for example, the case of employing an electronically controlled variable oil pump, costs can be reduced, and reliability against heat, vibration, etc., can be easily ensured.

[0047] Furthermore, according to this embodiment, a relief valve 41 is interposed that opens when the hydraulic pressure in the hydraulic piping 40 is above a predetermined pressure (i.e., injects oil onto the side surface of the outer rotor 33 of the sub-oil pump 30), and closes when it is below the predetermined pressure (i.e., stops the injection of oil). Therefore, the operating state of the sub-oil pump 30 can be switched more reliably and more abruptly.

[0048] Furthermore, according to this embodiment, since the main oil pump 20 and the sub-oil pump 30 are arranged coaxially, the overall size can be reduced (made more compact).

[0049] (modified version) Incidentally, in addition to the above-described configuration of the oil supply device 1, a check valve that opens at a predetermined pressure or higher may be interposed in the oil passage 42 that connects the main oil pump 20 to the lubricated member or the cooled member.

[0050] More specifically, in the modified oil supply device 1, for example, the piston oil jet 12 consists of multiple (e.g., three) piston oil jets 12 per cylinder, and the main oil pump 20 supplies oil to a portion (e.g., one of the three) of the multiple piston oil jets 12, including the check valve 121. Therefore, the sub-oil pump 30 supplies oil to the piston oil jets 12 other than the piston oil jet 12 supplied with oil by the main oil pump 20 (e.g., two of the three).

[0051] The other components are the same as or similar to those of the oil supply device 1 described above, so a detailed explanation is omitted here.

[0052] According to this modified example, as shown in Figure 6, when the check valve 121 is opened (piston oil jet 12 is activated) at a rotational speed of 2000 rpm, for example, the pressure (injection pressure) of the oil injected onto the side of the outer rotor 33 of the sub-oil pump 30 decreases, and the sub-oil pump 30 is activated. Therefore, the sub-oil pump 30 can be reliably operated in sync with (synchronized with) the operation (execution) of the piston oil jet 12 (i.e., it can be operated in conjunction with the sub-oil pump 30).

[0053] Furthermore, according to this modified configuration, since the piston oil jet 12 including the check valve 121 is used, there is no need to add a dedicated check valve, which is superior (advantageous) in terms of cost, weight, layout flexibility, etc., compared to the case where a dedicated check valve is added.

[0054] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications are possible. For example, in the above embodiments, the main oil pump 20 and the sub-oil pump 30 are arranged coaxially, but the main oil pump 20 and the sub-oil pump 30 do not necessarily have to be arranged coaxially. Also, the configuration (structure) of the relief valve 41 and the like is not limited to the above embodiments, and other configurations (structures) may be used.

[0055] Furthermore, in the above embodiment, trochoidal pumps were used as the main oil pump 20 and sub-oil pump 30, but instead of trochoidal pumps, for example, internal gear pumps with other tooth shapes may be used. [Explanation of Symbols]

[0056] 1. Oil supply device 10 Engines 11 Oil pan 12 Piston Oil Jet 121 Check valve 20 Main oil pump 30 Sub-oil pump 21, 31 Pump Housing 22, 32 cover 23, 33 Outer rotors 24, 34 Inner Rotor 25 Pump shaft 26, 36 inhalation ports 27, 37 Discharge ports (discharge outlets) 40 Hydraulic piping 41 Relief valve 42, 43 Oil road

Claims

1. A main oil pump that pressurizes the oil and supplies it to the lubricated and cooled components, A sub-oil pump that pressurizes the oil and supplies it to the piston oil jet that injects the oil onto the back surface of the piston, An oil supply device characterized by comprising: a hydraulic pipe that connects the discharge port of the main oil pump to the side surface of the outer rotor of the sub-oil pump, and injects a portion of the oil discharged from the main oil pump onto the side surface of the outer rotor of the sub-oil pump.

2. The oil supply device according to claim 1, further comprising a relief valve interposed in the hydraulic piping, which opens when the hydraulic pressure in the hydraulic piping is equal to or greater than a predetermined pressure.

3. The oil supply device according to claim 2, characterized in that the main oil pump and the sub-oil pump are arranged coaxially.

4. The oil supply device according to claim 3, further comprising a check valve interposed in an oil passage connecting the main oil pump and the lubricated member or the cooled member, which opens at a predetermined pressure or higher.

5. The aforementioned piston oil jet consists of multiple piston oil jets per cylinder. The oil supply device according to claim 4, characterized in that the main oil pump supplies oil to some of the piston oil jets, which include the check valve, among the plurality of piston oil jets.

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