Full hydraulic steering mechanism implementing a by-wire lubrication system

Abstract

The present application relates to the technical field of drive-by-wire hydraulic steering system, and particularly relates to a drive-by-wire lubricating system realized by a full hydraulic steering mechanism, comprising a steering oil cylinder one and a steering oil cylinder two, the oil outlet ends of the oil pressure control valve one and the oil pressure control valve two are provided with lubricating systems, and the oil outlet end of the lubricating pump is connected with a lubricating distributor. In the process of switching the steering (i.e. the process of switching the large cavity and the small cavity, the pressure impact exists), the steering oil cylinder impacts the steering system, or the wheels bear the road impact on the bumpy road, the present application realizes that when the pressure of the steering hydraulic system exceeds the set pressure value of the oil pressure control valve (the oil pressure control valve one or the oil pressure control valve two), the pressure oil at the moment can make the oil pressure control valve open, and the pressure oil drives the lubricating pump, so as to realize that the lubricating system drives the lubrication of each lubricating point. Therefore, the instantaneous impact force generated during steering and the impact from the wheel side are used as the power source of the system to finally realize the lubrication of the lubricating points.

Description

The fully hydraulic steering mechanism achieves a drive-by-wire lubrication system. Technical Field

[0001] This invention relates to the field of steer-by-wire hydraulic systems, and more particularly to a steer-by-wire lubrication system implemented in a fully hydraulic steering mechanism. Background Technology

[0002] The fully hydraulic steering system consists of a steering wheel, steering column, steering motor, and steering gear, which achieve mechanical and intelligent steering of heavy vehicles through steering cylinders. Due to the structural limitations of the steering cylinders, they are composed of large and small chambers.

[0003] P=F / A; P is pressure; F is the force acting on the liquid surface; A is the flow area. As can be seen from the above formula, under the same system pressure, the steering driving force generated by the extension and retraction cylinders is very different. As can be seen from the composition configuration of the steering system, the steering of heavy vehicles is achieved through the combined action of the large and small chambers.

[0004] Referring to Figure 1, two connecting brackets 10 are mounted on the steering axle 9. Left and right angle limiting rods 11 are hinged between the two connecting brackets 10. Steering cylinders 12 are hinged between each connecting bracket 10 and the steering axle 9. Each steering cylinder 12 has a large cavity 13 and a small cavity 14. Let the mounting hinge point of the steering cylinder and the steering hinge point of the steering axle both be 'a'. Referring to point A in Figure 1, it can be seen that when the wheel experiences road impact (wheel-side impact) on a bumpy road surface, the steering cylinder cannot retract, causing the impact force to act directly on the steering cylinder. This indicates a rigid connection between the steering cylinder and the wheel (equivalent to Figure 2). Referring to Figure 2, the rigid connection between the steering cylinder and the wheel allows road impacts to directly impact the hydraulic system, causing an increase in hydraulic system pressure.

[0005] Furthermore, during the instantaneous process of steering, referring to Figure 3, the volume difference between the large cavity 13 and the small cavity 14 determines that there will be a pressure impact at the moment of left and right reversal. There will inevitably be a pressure impact during the switching process between the large and small cavities. When the left and right steering wheels are forced to turn synchronously by the tie rod, and during the process of numerous strong pulls and tugs, the mounting hinge point of the steering cylinder and the steering hinge point of the steering axle will experience excessive wear due to excessive friction, which will affect the steering accuracy and may also easily cause mechanical damage or mechanical connection breakage, resulting in safety accidents. Summary of the Invention

[0006] In view of this, the purpose of this invention is to propose a fully hydraulic steering mechanism to realize a steer-by-wire lubrication system, so as to solve the problem that in the existing system, during the instant of steering, i.e. the switching between the large and small chambers, there is a pressure shock. On the one hand, the shock force cannot be utilized, and on the other hand, the shock force will act on the mechanical fixed part instantly. During the continuous steering process, it will cause connection fatigue at the mechanical connection and is also prone to breakage at the mechanical connection.

[0007] To achieve the above objectives, this invention provides a fully hydraulic steering mechanism with a steer-by-wire lubrication system, comprising a steering cylinder one and a steering cylinder two, both having a large chamber and a small chamber. The combined action of the steering cylinder one and the steering cylinder two drives the steering axle and achieves synchronized left and right steering via a tie rod. An oil supply pipe one is provided on the small chamber of the steering cylinder one and the large chamber of the steering cylinder two, and an oil pressure control valve one is installed on the oil supply pipe one. An oil supply pipe two is provided on the large chamber of the steering cylinder one and the small chamber of the steering cylinder two, and an oil pressure control valve two is installed on the oil supply pipe two. Both the oil outlet ends of the oil pressure control valve one and the oil pressure control valve two are equipped with lubrication systems.

[0008] The lubrication system includes a lubrication pump, a lubrication tank, and a lubrication distributor. The inlet of the lubrication pump is connected to the outlet of either oil pressure control valve one or oil pressure control valve two, and the inlet of the lubrication pump is also connected to the lubrication tank. The outlet of the lubrication pump is connected to the lubrication distributor, which has multiple lubrication outlet ports. These lubrication outlet ports are connected to lubrication points that require lubrication via lubrication pipes, and pressure regulating springs are installed at the contact points between the lubrication pipes and the lubrication points. When the vehicle turns left by retracting steering cylinder one and extending steering cylinder two, the lubrication process of the automatic lubrication system includes the following steps:

[0009] Step 1: The piston rod of steering cylinder one retracts and the piston rod of steering cylinder two extends, thus achieving left turn of the entire vehicle;

[0010] Step 2: At the instant of making a left turn, when the pressure exceeds the set pressure value of the hydraulic control valve, the hydraulic pressure at that instant will cause the hydraulic control valve to open, allowing the hydraulic pressure at that moment of turning to enter the lubrication pump through the hydraulic control valve.

[0011] Step 3: The lubrication pump operates and draws lubricating oil from the lubrication tank into the lubrication distributor. The lubricating oil in the lubrication distributor enters the lubrication pipe through the lubrication outlet port, thereby lubricating the lubrication points on the left and right wheel sides that require lubrication.

[0012] Preferably, both the first hydraulic control valve and the second hydraulic control valve are safety relief valves, and the set pressure value of the safety relief valve is 7 MPa.

[0013] Preferably, the oil outlet end of the first oil pressure control valve is provided with a spring-type one-way pressure valve, and the oil outlet end of the second oil pressure control valve is provided with a spring-type one-way pressure valve. The first spring-type one-way pressure valve and the second spring-type one-way pressure valve are respectively connected to their adjacent lubrication pumps.

[0014] Preferably, a one-way valve for replenishing oil is provided between the lubricating oil tank and the lubricating distributor. If the lubricating distributor over-distributes oil and a vacuum negative pressure occurs at the lubrication point, the one-way valve for replenishing oil will open, allowing the lubricating distributor to draw lubricating oil from the lubricating oil tank to lubricate the lubrication point.

[0015] Preferably, the lubrication distributor is equipped with a hydraulic oil return tank. When the lubrication points are not lubricated, the hydraulic oil enters the lubrication pump through the oil pressure control valve. The lubrication pump runs idle. At this time, the power oil impacted by the steering system enters the lubrication distributor and flows back to the hydraulic oil return tank, automatically lubricating the idle state and realizing the return of the pressure oil impacted by the steering system.

[0016] Preferably, pressure gauges are provided at the inlet and outlet of the lubrication pump, and the pressure gauges are used to detect the lubrication pressure during the lubrication process.

[0017] Preferably, pressure detection point one is provided on oil supply pipe one, and pressure detection point two is provided on oil supply pipe two. When pressure detection point one detects that the pressure in oil supply pipe one exceeds 7 MPa, oil pressure control valve one will open, allowing hydraulic oil to enter the lubrication pump through oil pressure control valve one. When pressure detection point two detects that the pressure in oil supply pipe two exceeds 7 MPa, oil pressure control valve two will open, allowing hydraulic oil to enter the lubrication pump through oil pressure control valve two.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. During the instant of steering switching (i.e., during the switching between the large and small chambers, there is a pressure shock), the steering system is impacted by the steering cylinder, or the wheels are subjected to road impacts on bumpy roads. This invention enables the steering hydraulic system pressure to open when the pressure exceeds the set pressure value of the oil pressure control valve (oil pressure control valve one or oil pressure control valve two). The pressure oil drives the lubrication pump, thereby driving the lubrication system to lubricate each lubrication point. Thus, the instantaneous impact force generated during steering and the impact from the wheel side are used as the system power source to ultimately achieve lubrication of the lubrication points.

[0020] Second, by using a pressure gauge and a hydraulic oil return tank, when no lubrication points are being lubricated, the hydraulic oil entering the lubrication pump will run dry when the lubrication pump is not in operation. This allows the hydraulic oil entering the lubrication distributor to return to the hydraulic oil return tank for recirculation. When the pressure gauge detects that the hydraulic oil pressure reaches the preset pressure (the preset pressure is the maximum pressure that the lubrication pump or lubrication pipe can withstand), the lubrication distributor will connect to the hydraulic oil return tank, allowing the hydraulic oil to enter the hydraulic oil return tank and thus protecting the lubrication system.

[0021] Third, by setting up the oil replenishment check valve, when the lubrication distributor over-distributes and a vacuum negative pressure occurs at the lubrication point, the oil replenishment check valve opens, allowing the lubrication distributor to draw lubricating oil from the lubrication tank to lubricate the lubrication point. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 is a schematic diagram of the structure of the steering cylinder driving the steering axle for steering according to an embodiment of the present invention;

[0024] Figure 2 is a schematic diagram of the rigid connection (i.e., wheel-side impact) between the steering cylinder and the wheel in an embodiment of the present invention;

[0025] Figure 3 is a schematic diagram of the structure of the large and small cavities inside the steering cylinder according to an embodiment of the present invention;

[0026] Figure 4 is a schematic diagram showing the connection between hydraulic control valve one and hydraulic control valve two and steering cylinder one and steering cylinder two in an embodiment of the present invention.

[0027] Figure 5 is a schematic diagram of the lubrication system of the present invention.

[0028] In the diagram: 101, Steering cylinder one; 102, Steering cylinder two; 201, Hydraulic pressure control valve one; 202, Hydraulic pressure control valve two; 301, Lubrication pump; 302, Lubricating oil tank; 303, Lubrication distributor; 304, Lubrication outlet port; 305, Lubrication pipe; 306, Lubrication point; 307, Pressure regulating spring; 401, Spring-loaded one-way pressure valve one; 402, Spring-loaded one-way pressure valve two; 5, Oil replenishment check valve; 601, Pressure detection point one; 602, Pressure detection point two; 7, Pressure gauge; 8, Hydraulic oil return box; 9, Steering axle; 10, Connecting frame; 11, Left and right turning angle limit rods; 12, Steering cylinder; 13, Large chamber; 14, Small chamber. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0030] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this invention should have the ordinary meaning understood by those skilled in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0031] As shown in Figures 1, 2, 3, 4, and 5, the fully hydraulic steering mechanism implements a steerable lubrication system, including steering cylinder 101 and steering cylinder 202. Both steering cylinder 101 and steering cylinder 202 have a large cavity 13 and a small cavity 14 (the volume difference between the large cavity (rodless cavity) and the small cavity (rod cavity) determines the pressure impact at the moment of left and right reversal). The combined action of steering cylinder 101 and steering cylinder 202 can drive the steering axle and achieve left and right steering synchronization through a tie rod. Oil supply pipes are provided on the small cavity of steering cylinder 101 and the large cavity of steering cylinder 202. The first cylinder is equipped with a hydraulic control valve 201. The large chamber of the first steering cylinder 101 and the small chamber of the second steering cylinder 102 are provided with oil supply pipes 2, and hydraulic control valve 202 is installed on the oil supply pipes 2. Both the oil outlets of hydraulic control valve 201 and hydraulic control valve 202 are equipped with lubrication systems. The lubrication system includes a lubrication pump 301, a lubrication tank 302 and a lubrication distributor 303. The lubrication pump 301 is not a pump that rotates continuously. It can only operate when the hydraulic oil impacts. The working pressure of the lubrication pump 301 is usually between 0.3-0.6 MPa, which is in the low-pressure range. Gear pumps are often used. Therefore, when pressurized oil enters the lubrication pump 301, the lubrication pump 301 can operate normally. The oil inlet of the lubrication pump 301 is connected to the oil pressure control valve 1 201 or the oil pressure control valve 2 202, and the oil inlet of the lubrication pump 301 is also connected to the lubrication oil tank 302. The oil outlet of the lubrication pump 301 is connected to the lubrication distributor 303. The lubrication distributor 303 is provided with multiple lubrication outlet ports 304. The lubrication outlet ports 304 are connected to each lubrication point 306 that needs to be lubricated through lubrication pipes 305. A pressure regulating spring 307 is provided at the contact point between the lubrication pipe 305 and the lubrication point 306. By setting the pressure regulating spring 307, the output of the lubrication point can be adjusted according to the actual output of the lubrication point in the process. For optimal lubrication, oil pressure control valves 201 and 202 collect pressurized oil into the lubrication pump 301. When the lubrication pump 301 is working, the pressurized oil acts as the driving oil. If the lubrication pump 301 is not operating, the oil is unloaded and flows back to the hydraulic oil return tank 8 through the lubrication distributor 303, thus protecting the system. The function of oil pressure control valves 201 and 202 is to prevent hydraulic oil from flowing back into the lubrication system after a pressure shock, thus preventing the hydraulic oil from affecting the steering system during normal operation. Both oil pressure control valves 201 and 202 are equipped with springs (adjustable according to actual working conditions) to ensure the stability of the pressurized oil as it enters the lubrication pump.

[0032] The lubrication process of the lubrication system during left turn of the vehicle, achieved by retracting steering cylinder 101 and extending steering cylinder 102, includes the following steps:

[0033] Step 1: The piston rod of steering cylinder 101 retracts and the piston rod of steering cylinder 2 102 extends, thus achieving left turn of the entire vehicle;

[0034] Step 2: At the instant of making a left turn, when the pressure of the steering hydraulic system exceeds the set pressure value of the oil pressure control valve 201, the pressure oil at that instant will cause the oil pressure control valve 201 to open, so that the pressure oil at the instant of the turn can enter the lubrication pump 301 through the oil pressure control valve 201.

[0035] Step 3: The lubrication pump 301 operates and draws the lubricating oil from the lubrication tank 302 into the lubrication distributor 303. The lubricating oil in the lubrication distributor 303 enters the lubrication pipe 305 through the lubrication outlet port 304, thereby lubricating the lubrication points 306 on the left and right wheel sides that need lubrication.

[0036] In a preferred embodiment of the present invention, both hydraulic control valve 201 and hydraulic control valve 202 are safety relief valves, and the safety relief valve is set to a pressure of 7 MPa. A steering system pressure of 7 MPa is sufficient to generate thrust in the steering cylinders (steering cylinder 1 and steering cylinder 2 in this invention), enough to drive a steering system with a 20-ton front axle load. The maximum steering pressure of the entire vehicle is determined by the cylinder diameter and the steering load on the front axle of the vehicle. In other words, with a steering system hydraulic pressure of 7 MPa, the selected steering cylinders are sufficient to drive a steering system with a 20-ton front axle load while stationary, thus achieving the vehicle's steering function. The pressure set by the unloading valve (safety relief valve) is thus derived (7 MPa).

[0037] In another preferred embodiment of the present invention, a spring-type one-way pressure valve 401 is provided at the oil outlet end of the hydraulic control valve 201, and a spring-type one-way pressure valve 402 is provided at the oil outlet end of the hydraulic control valve 202. The spring-type one-way pressure valve 401 and the spring-type one-way pressure valve 402 are respectively connected to their adjacent lubrication pump 301. By setting the spring-type one-way pressure valve 401 and the spring-type one-way pressure valve 402, the stable output of instantaneous power can be ensured. The preset pressure of the spring-type one-way pressure valve 401 or the spring-type one-way pressure valve 402 can be adjusted according to the lubrication pump 301 and the instantaneous impact of steering. The spring-type one-way pressure valve 401 and the spring-type one-way pressure valve 402 have the purpose of one-way conduction, avoiding the mixing of hydraulic oil in the steering cylinder 101 and the steering cylinder 202.

[0038] In another preferred embodiment of the present invention, a replenishing oil check valve 5 is provided between the lubricating oil tank 302 and the lubrication distributor 303. If the lubrication distributor 303 over-distributes and a vacuum negative pressure occurs at the lubrication point 306, the replenishing oil check valve 5 opens, so that the lubrication distributor 303 can draw lubricating oil from the lubricating oil tank 302 to lubricate the lubrication point 306, thereby protecting the lubrication pump 301.

[0039] It should be noted that the lubrication distributor 303 is equipped with a hydraulic oil return tank 8. When the lubrication point 306 is not lubricated, the hydraulic oil enters the lubrication pump 301 through the oil pressure control valve 201. The lubrication pump 301 runs idle. At this time, the power oil impacted by the steering system enters the lubrication distributor 303 and flows back to the hydraulic oil return tank 8. Automatic lubrication is achieved under no-load conditions, and the pressure oil impacted by the steering system is returned, thereby achieving unloading and protecting the system.

[0040] It should be noted that pressure gauges 7 are installed at the inlet and outlet of the lubrication pump 301. The pressure gauges 7 are used to detect the lubrication pressure during the lubrication process to ensure the stable operation of the system. When the pressure gauge 7 detects that the pressure of the hydraulic oil exceeds the preset pressure of the pressure gauge 7 (the maximum preset pressure of the pressure gauge 7 is the maximum pressure that the lubrication pump 301 or the lubrication pipe 305 can withstand), the lubrication distributor 303 will connect with the hydraulic oil return tank 8, so that the hydraulic oil can enter the hydraulic oil return tank 8, which plays a protective role for the lubrication system.

[0041] In addition, a pressure detection point 601 is installed on oil supply pipe 1, and a pressure detection point 602 is installed on oil supply pipe 2. When pressure detection point 601 detects that the pressure in oil supply pipe 1 exceeds 7 MPa, oil pressure control valve 201 will open, allowing hydraulic oil to enter the lubrication pump 301 through oil pressure control valve 201. When pressure detection point 602 detects that the pressure in oil supply pipe 2 exceeds 7 MPa, oil pressure control valve 202 will open, allowing hydraulic oil to enter the lubrication pump 301 through oil pressure control valve 202, thereby protecting the system.

[0042] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0043] The embodiments of this invention are intended to cover all such substitutions, modifications, and variations falling within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A fully hydraulic steering mechanism with a steer-by-wire lubrication system, comprising a steering cylinder one (101) and a steering cylinder two (102), wherein the combined action of the steering cylinder one (101) and the steering cylinder two (102) drives the steering axle and achieves synchronized left and right steering via a tie rod, characterized in that, An oil supply pipe is provided on the small cavity of the first steering cylinder (101) and the large cavity of the second steering cylinder (102), and an oil pressure control valve (201) is installed on the first oil supply pipe. An oil supply pipe is provided on the large cavity of the first steering cylinder (101) and the small cavity of the second steering cylinder (102), and an oil pressure control valve (202) is installed on the second oil supply pipe. The oil outlets of the first oil pressure control valve (201) and the second oil pressure control valve (202) are both equipped with a lubrication system. The lubrication system includes a lubrication pump (301) and a lubrication oil tank (302). The lubrication pump (301) is connected to the oil pressure control valve 1 (201) or the oil pressure control valve 2 (202) at its inlet end, and is also connected to the lubrication oil tank (302). The lubrication pump (301) at its outlet end is connected to the lubrication distributor (303). The lubrication distributor (303) is provided with multiple lubrication outlet ports (304). The lubrication outlet ports (304) are connected to the lubrication points (305) that need to be lubricated through lubrication pipes (305). 6) Connected, and a pressure regulating spring (307) is provided at the contact point between the lubrication pipe (305) and the lubrication point (306); When the steering cylinder one (101) retracts and the steering cylinder two (102) extends, the lubrication process of the automatic lubrication system when the whole vehicle turns left includes the following steps: Step 1, when the piston rod of the steering cylinder one (101) retracts and the piston rod of the steering cylinder two (102) extends, the whole vehicle turns left; Step 2, at the instant of turning left, when the pressure exceeds the set pressure value of the oil pressure control valve one (201), the instantaneous pressure exceeds the set pressure value of the oil pressure control valve one (201). The pressure oil in the middle will cause the oil pressure control valve (201) to open, so that the pressure oil at the moment of steering can enter the lubrication pump (301) through the oil pressure control valve (201); Step 3, the lubrication pump (301) works and sucks the lubricating oil in the lubrication tank (302) into the lubrication distributor (303). The lubricating oil in the lubrication distributor (303) enters the lubrication pipe (305) through the lubrication outlet port (304), thereby realizing the lubrication of the lubrication points (306) that need to be lubricated on the left wheel side and the right wheel side.

2. The fully hydraulic steering mechanism implementing a steer-by-wire lubrication system according to claim 1, characterized in that, Both the first oil pressure control valve (201) and the second oil pressure control valve (202) are safety relief valves, and the set pressure value of the safety relief valve is 7 MPa.

3. The fully hydraulic steering mechanism implementing a steer-by-wire lubrication system according to claim 1, characterized in that, The oil outlet of the first oil pressure control valve (201) is provided with a spring-type one-way pressure valve (401), and the oil outlet of the second oil pressure control valve (202) is provided with a spring-type one-way pressure valve (402). The first spring-type one-way pressure valve (401) and the second spring-type one-way pressure valve (402) are respectively connected to their adjacent lubrication pumps (301).

4. The fully hydraulic steering mechanism implementing a steer-by-wire lubrication system according to claim 1, characterized in that, A one-way valve (5) for replenishing oil is provided between the lubricating oil tank (302) and the lubrication distributor (303). If the lubrication distributor over-distributes and a vacuum negative pressure occurs at the lubrication point (306), the one-way valve (5) for replenishing oil will open, so that the lubrication distributor (303) can draw lubricating oil from the lubricating oil tank (302) to lubricate the lubrication point (306).

5. The fully hydraulic steering mechanism realizing a steer-by-wire lubrication system according to claim 2, characterized in that, The lubrication distributor (303) is equipped with a hydraulic oil return tank (8). When the lubrication point (306) is not lubricated, the hydraulic oil enters the lubrication pump (301) through the oil pressure control valve (201). The lubrication pump (301) runs idle. At this time, the power oil impacted by the steering system enters the lubrication distributor (303) and flows back to the hydraulic oil return tank (8). Automatic lubrication is achieved under no-load, and the pressure oil impacted by the steering system is returned.

6. The fully hydraulic steering mechanism according to claim 5, realizing a steer-by-wire lubrication system, characterized in that, Pressure gauges (7) are provided at the inlet and outlet of the lubrication pump (301), and the pressure gauges (7) are used to detect the lubrication pressure during the lubrication process.

7. The fully hydraulic steering mechanism according to claim 6 realizes a steer-by-wire lubrication system, characterized in that, The first oil supply pipe is equipped with a pressure detection point 1 (601), and the second oil supply pipe is equipped with a pressure detection point 2 (602). When the pressure detection point 1 (601) detects that the pressure in the first oil supply pipe exceeds 7 MPa, the first oil pressure control valve 1 (201) will open, so that the hydraulic oil enters the lubrication pump (301) through the first oil pressure control valve 1 (201). When the pressure detection point 2 (602) detects that the pressure in the second oil supply pipe exceeds 7 MPa, the second oil pressure control valve 2 (202) will open, so that the hydraulic oil enters the lubrication pump (301) through the second oil pressure control valve 2 (202).

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