A lubrication system

Abstract

The present invention relates to a lubrication system, including an oil pump module, the oil pump module including a grease pump and an oil tank, the lubrication system also including at least one dual-oil circuit controlled suction and discharge device, the oil pump module controls the dual-oil circuit controlled suction and discharge device through a reversing module, the lubrication system also including at least one oil injection module powered by the oil pump module, the oil injection module including a distributor. New lubricating grease can be pumped into lubrication points through the distributor by the grease injection pump; and after being pressurized by the grease injection pump, it is used as the power medium of the dual-oil circuit controlled suction and discharge device. When the lubricating grease is replaced, once the grease injection pump is turned on, the operations of adding new lubricating grease and sucking out waste grease will be carried out simultaneously, thereby realizing the operation of extracting waste grease from the lubrication points while injecting new lubricating grease into the lubrication points, realizing the operation of extracting waste grease from the lubrication points when injecting new lubricating grease, so the lubrication system of the present invention has the advantages of facilitating the injection of lubricating grease and improving the lubrication effect.

Description

Technical Field

[0001] The invention relates to a lubrication system. Background Art

[0002] At present, in the lubrication points with sealing structures such as gearboxes and bearing seats of wind turbines, after adding lubricating grease, after a period of operation, the lubricating grease will oxidize and deteriorate, and the base oil will precipitate and harden due to the problem. At the same time, the wear debris generated during the operation of the lubricating point will also enter the lubricating grease, causing the lubricating grease to operate in a state of deterioration, hardening and carrying wear debris. In order to ensure the good lubrication effect of the lubricating grease, it is necessary to replace it regularly. However, when adding new lubricating grease to the lubricating point, if the waste grease is not discharged, on the one hand, it is difficult to add new lubricating grease due to the pressure of the waste grease; on the other hand, even if the new lubricating grease is squeezed into the lubricating point, the new lubricating grease will be contaminated by the waste grease, making the oil change effect in the lubricating point not obvious and the lubrication effect poor. Summary of the invention

[0003] The object of the present invention is to provide a lubrication system to solve the technical problems of obstruction in injecting new lubricating grease and poor oil changing effect.

[0004] In order to achieve the above purpose, the technical solution of the present invention is as follows:

[0005] Solution 1: A lubrication system includes an oil pump module, the oil pump module includes a grease pump and an oil tank; the lubrication system also includes at least one dual-oil circuit controlled suction and discharge device, the oil pump module controls the dual-oil circuit controlled suction and discharge device through a reversing module; the lubrication system also includes at least one oil injection module powered by the oil pump module, the oil injection module includes a distributor.

[0006] Solution 2: Based on Solution 1, the following improvement is made: the oil injection module and the dual oil circuit controlled suction and exhaust device share the main oil pipe.

[0007] Solution 3: Based on Solution 2, the following improvement is made: the oil injection module and the dual oil circuit control suction and exhaust device are connected in parallel behind the same reversing module.

[0008] Solution 4: Based on Solution 3, the following improvement is made: the distributor of the oil injection module is a double-line distributor.

[0009] Solution 5: Based on Solution 4, the improvement is as follows: the reversing module is a four-way reversing valve or a five-way reversing valve.

[0010] Scheme 6: Based on Scheme 5, the following improvements are made: the reversing module is a two-position four-way reversing valve, one of the two channels on one side of the two-position four-way reversing valve is connected to the oil tank, and the other is connected to the grease pump, and the two channels on the other side of the two-position four-way reversing valve are respectively connected to the two oil inlets of the dual-line distributor.

[0011] Solution 7: Based on Solution 6, the following improvement is made: the dual oil circuit control suction and exhaust device shares a valve body with the dual-line distributor.

[0012] Scheme 8: Based on any one of Schemes 1-7, the following improvement is made: there are multiple dual-oil circuit controlled suction and exhaust devices, and each dual-oil circuit controlled suction and exhaust device is connected in parallel.

[0013] Solution 9: Based on any one of Solutions 4-7, the following improvement is made: there are multiple two-wire distributors, and each two-wire distributor is connected in parallel.

[0014] Solution 10: Based on Solution 2, the following improvement is made: at least two reversing modules are connected in parallel to the oil pump module, and the oil injection module and the dual-oil circuit control suction and exhaust device are respectively connected behind different reversing modules.

[0015] Scheme 11: Based on Scheme 1, it is further improved as follows: the oil pump module is provided with at least two main oil pipes, and the oil pump module and the dual-oil channel control suction and exhaust device are respectively located on different main oil pipes.

[0016] Scheme 12: Based on Scheme 1, the following improvement is made: a waste grease collector is connected to the dual oil circuit controlled suction and exhaust device.

[0017] Scheme 13: Based on Scheme 1, further improvements are made as follows: the grease pump is a double-plunger pump, and the reversing module includes two three-way valves, which are respectively connected in series in the two oil circuits between the double-plunger pump and the double-oil circuit control suction and exhaust device, and the third outlet of the three-way valve is connected to the oil tank.

[0018] The lubrication system of the present invention can realize centralized lubrication and waste oil collection at the same time. The oil pump module can drive the dual-oil circuit controlled suction and discharge device to suck the waste grease. At the same time, the oil pump module also drives the oil pump module to inject new grease into the lubrication point. Waste oil collection and centralized lubrication are carried out simultaneously. Specifically, the new grease can be pumped into the lubrication point through the distributor by the grease injection pump; and after being pressurized by the grease injection pump, it is used as the power medium of the dual-oil circuit controlled suction and discharge device, that is, the new grease is pressurized by the grease injection pump, and the energy is converted on the suction and discharge device to output mechanical power to carry out the suction operation of the waste grease. In this way, when the grease is replaced, once the grease injection pump is turned on, the operations of adding new grease and sucking waste grease will be carried out simultaneously, thereby realizing the extraction of waste grease from the lubrication point while filling new grease into the lubrication point, and realizing the operation of extracting waste grease in the lubrication point when filling new grease. Therefore, the lubrication system of the present invention has the advantages of easy filling of grease and improved lubrication effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of embodiment 1 of the lubrication system of the present invention;

[0020] Figure 2 yes Figure 1 Schematic diagram of the oil circuit of the middle distributor in the first state;

[0021] Figure 3 yes Figure 1 Schematic diagram of the oil circuit of the middle distributor in the second state;

[0022] Figure 4 yes Figure 1 Schematic diagram of the oil circuit of the central suction and exhaust device under the oil suction station;

[0023] Figure 5 yes Figure 1 Schematic diagram of the oil circuit of the central suction and discharge device under the oil discharge station;

[0024] Figure 6 is a schematic structural diagram of Embodiment 2 of the lubrication system of the present invention;

[0025] Figure 7 is a schematic structural diagram of Embodiment 3 of the lubrication system of the present invention;

[0026] Figure 8 is a schematic structural diagram of a lubrication system according to a fourth embodiment of the present invention;

[0027] Fig. 9 is a schematic structural diagram of a lubrication system according to a fifth embodiment of the present invention;

[0028] Fig.10 is a schematic structural diagram of a sixth embodiment of a lubrication system of the present invention;

[0029] Fig.11 is a schematic structural diagram of a seventh embodiment of a lubrication system of the present invention;

[0030] Fig.12 is a schematic structural diagram of an embodiment 8 of the lubrication system of the present invention;

[0031] Fig.13 is a schematic structural diagram of a ninth embodiment of a lubrication system of the present invention;

[0032] Fig.14 is a schematic structural diagram of a lubrication system according to an embodiment 10 of the present invention;

[0033] Fig.15 is a schematic structural diagram of an embodiment 11 of the lubrication system of the present invention;

[0034] Fig.16 is a schematic structural diagram of a twelfth embodiment of a lubrication system of the present invention;

[0035] Fig.17 is a schematic structural diagram of embodiment 13 of the lubrication system of the present invention;

[0036] Figure 1-5 And 8-17: 100-lubrication unit, 101-oil tank, 102-grease pump, 103-reversing valve, 104-distributor, 105-suction and discharge device, 121-three-way valve, 122-oil return line, 131-double plunger pump, 141-adjusting screw, 142-indicator rod, 143-control piston, 144-working piston, 145-first oil filling port 145, 146-second oil filling port 146, 151-control unit, 152-actuator unit, 153-piston, 154-plunger, 155-suction port, 156-oil discharge port, 157-collector; 171-on-off valve, 181-progressive distributor, 191-single-line distributor; first oil supply port C, second oil supply port D;

[0037] Figure 6 Middle: 303- reversing valve, 304- distributor, 305- suction and exhaust device, 309- suction and exhaust device module;

[0038] Figure 7 Middle: 500-lubrication unit, 503-reversing valve, 504-distributor, 505-suction and exhaust device. DETAILED DESCRIPTION

[0039] Embodiment 1 of the lubrication system of the present invention: The lubrication system is a centralized lubrication dual-line lubrication device for adding new lubricating grease to the lubrication points of a wind turbine and draining waste grease from the lubrication points at the same time. That is, it is not just a traditional lubrication system, but a multifunctional lubrication system integrating centralized lubrication and waste oil collection. Figure 1As shown, the lubrication system is mainly composed of a double-line grease pump station, a distributor 104, a suction and discharge device 105, new lubricating oil, and lubrication points. The grease pump 102, the drive motor, and the reversing valve 103 in the double-line grease pump station are connected to the distributor 104 and the suction and discharge device 105 through an oil circuit to form a lubrication device connected between the oil tank 101 and the lubrication points. The reversing valve 103 in the lubrication device forms a lubrication unit 100 with the distributor 104 and the suction and discharge device 105. The inlet of the lubrication unit 100 is the oil inlet P of the reversing valve 103, and the outlet of the lubrication unit is the oil return port T of the reversing valve 103.

[0040] The double-line grease pump station includes an oil tank 101, a grease injection pump 102, a drive motor, and a reversing valve 103. The oil tank 101 contains new grease to be added to the lubrication point. The inlet of the grease injection pump 102 is connected to the pump suction port on the oil tank 101, and the outlet is connected to the pump pressure port on the reversing valve 103. Under the drive of the drive motor, the grease injection pump 102 sucks the new grease in the oil tank 101 from the pump suction port and pumps it out from the pump pressure port. The reversing valve 103 is a two-position four-way reversing valve. The four oil ports of the reversing valve 103 are respectively the oil inlet P connected to the pump oil port of the grease pump 102, the oil return port T of the direct oil tank 101, and the first working port A and the second working port B connected to the two ports of the new oil pipeline. One working position of the reversing valve 103 is the first working position where the oil inlet P is connected to the first working port A and the oil return port T is connected to the second working port B. The other working position is the second working position where the oil inlet P is connected to the second working port B and the oil return port T is connected to the first working port A.

[0041] Distributor 104 is a two-wire distributor, which is an existing product. Figure 2 and Figure 3As shown, the double-line distributor includes an adjustment screw 141, an indicator rod 142, a first oil supply port C, a second oil supply port D, a control piston 143, a working piston 144, a first oil filling port 145, and a second oil filling port 146. The first oil supply port C is connected to the first working port of the reversing valve through a first filling oil circuit, and the second oil supply port D is connected to the second working port of the reversing valve through a second filling oil circuit, so that when one of the first and second filling oil circuits is pressurized, the other is unloaded; the first and second oil filling ports 146 are respectively connected to two lubrication points on the lubrication point. The working principle of the distributor is as follows: the new lubricating grease delivered by the grease injection pump enters the first oil supply port C of the distributor through the first oil filling circuit, and the new lubricating grease is pressurized at the first oil supply port C to move the control piston 143 toward the second oil supply port D, so that the first oil filling port 145 is closed, the second oil filling port 146 is opened, and the second oil supply port D is unloaded. At the same time, the pressure at the first oil supply port C will act on the working piston 144 through the new lubricating grease, and the working piston 144 will press the new lubricating grease out of the second oil filling port 146 and inject it into a lubrication point of the lubrication point. When the new lubricating grease enters the second oil supply port D through the second oil filling passage, the new lubricating grease is pressurized at the second oil supply port D. On the one hand, this pressure will push the control piston 143 to move toward the first oil supply port C, so that the second oil filling port 146 is closed, the first oil filling port 145 is opened, and the first oil supply port C is unloaded; on the other hand, it will act on the working piston 144, and the working piston 144 presses the new lubricating grease to be injected from the first oil filling port 145 and act on another lubrication point. Therefore, the distributor has a first state in which the second oil filling port 146 is filled with oil when the first oil supply port C is pressurized and the second oil supply port D is unloaded, and a second state in which the first oil filling port 145 is filled with oil when the second oil supply port D is pressurized and the first oil supply port C is unloaded.

[0042] The suction and exhaust device 105 is a dual-control oil channel suction and exhaust device, which is an existing product. Figure 4 and Figure 5As shown, the dual-control oil channel suction and discharge device mainly consists of a control unit 151 and an execution unit 152, and the control unit 151 and the execution unit 152 share a housing. The control unit 151 is a double-acting piston cylinder, including a first control port E, a second control port F and a piston 153. The first control port E is connected to the first working port of the reversing valve through a first control oil circuit, and the second control port F is connected to the second working port of the reversing valve through a second control oil circuit, so that when the first control port E pressurizes the piston 153, the second control port F is unloaded, and vice versa. The execution unit 152 is similar to an existing syringe, that is, the execution unit 152 is a plunger 154 cylinder, including a plunger 154 and an oil suction port 155 and an oil discharge port 156, so that as the plunger 154 is reciprocated, the oil suction port 155 and the oil discharge port 156 are alternately opened to perform alternate oil suction and oil discharge actions, and a collector 157 for storing waste grease is connected to the oil discharge port 156. A one-way valve is provided at the oil discharge port 156 of the suction and discharge device 105. The working principle of the suction and discharge device is as follows: when the reversing valve is switched to the first control oil circuit to connect to the grease injection pump and the second control oil circuit to connect to the oil tank, the grease injection pump delivers new lubricating grease to the first control port E through the first control oil circuit, the new lubricating grease in the first control port E is pressurized, the pressure of the first piston 153 cavity connected to the first control port E rises, the piston 153 compresses the second piston 153 cavity under the action of the pressure in the first piston 153 cavity, the new lubricating grease in the second piston 153 cavity is unloaded from the second control port F and flows back to the oil tank, and at the same time the piston 153 drives the plunger 154 to extend and move in the plunger 154 cylinder to close the piston 153. When the oil suction port 155 is in the state, the waste grease stored in the plunger 154 cylinder is transported to the collector from the oil discharge port 156; when the reversing valve is switched to the first control oil circuit to connect to the oil tank and the second control port F to connect to the grease injection pump, the grease injection pump transports new grease to the second control port F through the second control oil circuit, the second piston 153 cavity is pressurized, and the piston 153 compresses the first piston 153 cavity under the action of pressure to unload the first control port E, and at the same time, the piston 153 drives the plunger 154 to retract and move in the plunger 154 cylinder to open the oil suction port 155, and suck out the waste grease from the lubrication point through the oil suction port 155.

[0043] The distributor 104 and the suction and exhaust device 105 share a valve body, so that the distributor 104 and the suction and exhaust device 105 are integrally arranged to form a combination valve. Correspondingly, the new oil pipeline in the entire lubrication system can be divided into an external pipeline outside the combination valve and an internal pipeline inside the combination valve, and the internal pipeline is a grease flow channel arranged on the common valve body.

[0044] The working principle of the lubrication system in this embodiment is as follows: after the grease injection pump 102 is turned on, the grease injection pump 102 delivers the new lubricating grease in the oil tank 101 into the oil inlet of the reversing valve 103. After the new lubricating grease is discharged from the reversing valve 103, it enters the distributor 104 and is injected into the lubrication points, and enters the control unit of the suction and discharge device 105 as a pressure medium. As the first station and the second station of the reversing valve 103 are alternately changed, the control unit of the suction and discharge device 105 drives the execution unit to reciprocately suck and discharge oil, so that the waste grease in the lubrication points is sucked out and discharged into the collector 157. At the same time, the distributor 104 continuously injects new lubricating grease into the lubrication points to realize the replacement of waste grease and new grease in the lubrication points.

[0045] Embodiment 2 of the lubrication system of the present invention: Figure 6 As shown, the difference between this embodiment and embodiment 1 is that there are multiple suction and exhaust devices 305, and each suction and exhaust device 305 is connected in parallel to form a suction and exhaust device module 309, such as the first control port E of the control unit of each suction and exhaust device 305 is connected to the first working port A of the reversing valve 303, and the second control port F is connected to the second working port B of the reversing valve 303. The distributor module and the suction and exhaust device module 309 are still arranged in parallel between the first and second working ports A and B of the reversing valve 303, that is, the first oil supply port C of each distributor 304 is connected to the first working port A of the reversing valve 303 together with one end of the suction and exhaust device module, and the second oil supply port D is connected to the second working port B of the reversing valve 303 together with the other end of the suction and exhaust device module.

[0046] Embodiment 3 of the lubrication system of the present invention: Figure 7 As shown, the difference between this embodiment and embodiment 1 is that there are multiple lubrication units 500 consisting of a reversing valve 503, a distributor 504 and a suction and exhaust device 505, and each lubrication unit 500 is arranged in parallel.

[0047] Embodiment 4 of the lubrication system of the present invention: Figure 8 As shown, the difference between this embodiment and embodiment 1 is that the grease pump 102 directly supplies oil to two parallel branches, one of which is provided with a reversing valve 103 and a distributor 104 thereafter. The distributor is a double-line distributor as in embodiment 1. The first oil supply port C and the second oil supply port D of the double-line distributor are respectively connected to the E and F ports of the double-oil-circuit control suction and discharge device 105. The distributor 104 is connected in parallel with the suction and discharge device 105, which is the same as the connection between the suction and discharge device and the distributor in embodiment 1. The collector 157 is still provided on the oil discharge port 156 of the suction and discharge device 105. The collector 157 is a collection bottle or a collection bag. A reversing valve 103 is provided on the other oil circuit, followed by more than one suction and discharge device 105, but only one is shown in this embodiment.

[0048] Embodiment 5 of the lubrication system of the present invention: Fig. 9 As shown, the difference between this embodiment and embodiment 4 is that, of the two oil circuits, one of the oil circuits is only connected in parallel with at least one dual-line distributor 104 behind the reversing valve 103, and one is drawn in this embodiment, and the other oil circuit is only connected in parallel with at least one dual-oil circuit control suction and discharge device 105 behind the reversing valve 103, and only one is drawn in this embodiment. That is, the distributor 104 and the suction and discharge device 105 are located in different oil circuits, one oil circuit is only used to add grease, and the other oil circuit is only used to suck out old grease.

[0049] Embodiment 6 of the lubrication system of the present invention: Fig.10 As shown, the difference between this embodiment and embodiment 5 is that the grease pump 102 is provided with two oil outlets on the front and back sides respectively, and each oil outlet is connected to an oil circuit, that is, two independent main oil circuits; while in embodiment 5, the two oil circuits share one main oil circuit, and the grease pump in embodiment 5 also uses only one oil outlet.

[0050] Embodiment 7 of the lubrication system of the present invention: Fig.11 As shown, the difference between this embodiment and embodiment 6 is that the two-line distributor is replaced by two parallel progressive distributors 181, that is, a progressive distributor 181 is respectively provided in the two oil circuits after the reversing valve 103. In other embodiments, it is not limited to provide one progressive distributor in each oil circuit.

[0051] Embodiment 8 of the lubrication system of the present invention: Fig.12 As shown, the difference between this embodiment and Embodiment 7 is that the progressive distributor is replaced by a single-line distributor 191 .

[0052] Embodiment 9 of the lubrication system of the present invention: Fig.13 As shown, the difference between this embodiment and Embodiment 6 is that there is at least one distributor 104 on the left oil circuit, and the right oil circuit is a combination of the distributor 104 and the suction and exhaust device 105. Functionally, the left side is a centralized lubrication subsystem, and the right side is a subsystem combining waste oil collection and centralized lubrication.

[0053] Embodiment 10 of the lubrication system of the present invention: Fig.14 As shown, the difference between this embodiment and embodiment 1 is that this embodiment uses two grease pumps 102 to supply two oil circuits respectively, and three-way valves 121 are respectively provided on the two oil circuits. The third channel of the three-way valve 121 is an oil return circuit 122 connected to the oil tank 101.

[0054] Embodiment 11 of the lubrication system of the present invention: Fig.15 As shown, the difference between this embodiment and embodiment 10 is that the two oil routes are supplied with oil by two plungers of a double plunger pump 131, and the double plunger pump 131 is a grease pump with two plungers on the same valve body.

[0055] Embodiment 12 of the lubrication system of the present invention: Fig.16 As shown, the difference between this embodiment and embodiment 10 is that the reversing valve 103 is replaced by two three-way valves 121, and a single-line distributor 191 is connected in series on the oil circuit corresponding to each three-way valve 121 and behind the three-way valve 121, and one of the outlets of the single-line distributor 191 on one oil circuit is connected to the E port of the dual oil circuit control suction and discharge device 105, and one of the outlets of the single-line distributor 191 on the other oil circuit is connected to the F port of the dual oil circuit control suction and discharge device 105. That is, the reversing valve 103 and the dual-line distributor 104 are replaced by a pair of three-way valves 121 and a pair of single-line distributors 191 on two oil circuits.

[0056] Embodiment 13 of the lubrication system of the present invention: Fig.17 As shown, the difference between this embodiment and embodiment 12 is that the single-line distributor is replaced by a progressive distributor 181. At the same time, in order to ensure that the progressive distributor 181 has sufficient pressure, an on-off valve 171 is arranged between the three-way valve 121 and the progressive distributor 181.

[0057] Other embodiments of the lubrication system of the present invention: Each lubrication unit or waste oil collection unit shares an oil tank, which can lubricate the same lubrication point or multiple lubrication points. The reversing valve can be a solenoid valve, a hydraulically controlled or pneumatically controlled pilot valve, or even a manually controlled valve. In a single lubrication unit, there can be multiple distributors, but the distributors should be arranged in parallel.

Claims

1. A lubrication system, comprising an oil pump module, the oil pump module comprising a grease pump for pumping grease and an oil tank for storing grease, characterized in that: The lubrication system also includes at least one dual-oil circuit controlled suction and discharge device, which includes a shell and a plunger movable in the shell. The shell is provided with a first control port and a second control port respectively corresponding to the two ends of the plunger. The oil pumping module pumps grease to one of the first and second control ports alternately through the reversing module to drive the piston to reciprocate and suck out the waste grease. The lubrication system also includes at least one oil injection module powered by the oil pumping module. The oil injection module includes a distributor. The grease pump can simultaneously pump grease to the distributor and the dual-oil circuit controlled suction and discharge device to respectively realize the addition of new grease for lubrication and the suction of waste grease.

2. The lubrication system according to claim 1, characterized in that: The oil injection module and the dual-oil-circuit controlled suction and exhaust device share a main oil pipe.

3. The lubrication system according to claim 2, characterized in that: The oil injection module and the dual oil circuit control suction and exhaust device are connected in parallel behind the same reversing module.

4. The lubrication system according to claim 3, characterized in that: The distributor of the oil injection module is a double-line distributor.

5. The lubrication system according to claim 4, characterized in that: The reversing module is a four-way reversing valve or a five-way reversing valve.

6. The lubrication system according to claim 5, characterized in that: The reversing module is a two-position four-way reversing valve, one of the two channels on one side of the two-position four-way reversing valve is connected to the oil tank, and the other is connected to the grease pump, and the two channels on the other side of the two-position four-way reversing valve are respectively connected to the two oil inlets of the dual-line distributor.

7. The lubrication system according to claim 6, characterized in that: The dual-oil-circuit controlled suction and exhaust device shares a valve body with the dual-line distributor.

8. The lubrication system according to any one of claims 1 to 7, characterized in that: There are multiple dual-oil-circuit controlled suction and exhaust devices, and each dual-oil-circuit controlled suction and exhaust device is connected in parallel.

9. The lubrication system according to any one of claims 4 to 7, characterized in that: There are multiple two-wire distributors, and each two-wire distributor is connected in parallel.

10. The lubrication system according to claim 2, characterized in that: At least two reversing modules are connected in parallel to the oil pump module, and the oil injection module and the dual oil circuit control suction and exhaust device are respectively connected behind different reversing modules.

11. The lubrication system according to claim 1, characterized in that: The oil pump module is provided with at least two main oil pipes, and the oil pump module and the dual-oil-circuit controlled suction and exhaust device are respectively located on different main oil pipes.

12. The lubrication system according to claim 1, characterized in that: The dual oil circuit controlled suction and exhaust device is connected with a waste grease collector.

13. The lubrication system according to claim 1, characterized in that: The grease pump is a double-plunger pump, and the reversing module includes two three-way valves, which are respectively connected in series in two oil circuits between the double-plunger pump and the double-oil circuit control suction and exhaust device, and the third outlet of the three-way valve is connected to the oil tank.

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