A threaded plug-in adjustable shunt current collecting valve

Abstract

The present application relates to the technical field of synchronous valve, in particular to a threaded plug-in adjustable shunt and collecting valve, which comprises a valve body, a plurality of main oil passage holes are formed in the valve body, a first throttling hole and a second throttling hole are formed in the valve body, the first throttling hole and the second throttling hole are respectively located on both sides of the main oil passage hole, and each has two, through linkage of components of the valve core assembly, the device automatically balances the flow of two paths when the pressure difference is small, the pressure is dynamically compensated through the tapered hole of the synchronous mechanism and the electric control valve when the pressure difference is large, the pressure difference value on both sides of the first valve core and the second valve core is greatly reduced under high load operation; the clearance between the V-shaped groove and the corresponding first valve core or second valve core increases under low temperature state (lower than 40 DEG C), so as to avoid the device from being stuck during cold start; under high temperature state (higher than 80 DEG C), the clearance between the sealing surfaces is reduced, so as to avoid leakage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of synchronous valve, in particular to a threaded cartridge adjustable split and combine valve. BACKGROUND

[0002] As the core component of hydraulic synchronous control system, split and combine valve is widely used in the field of engineering machinery, metallurgical equipment and other fields requiring multi-actuator cooperative operation. It realizes the synchronous movement of hydraulic cylinder / motor by dividing or combining the flow of oil circuit. The traditional threaded cartridge split and combine valve adopts fixed orifice structure to cooperate with the displacement compensation of the valve core for synchronous adjustment. However, in actual application, the following defects are found:

[0003] Firstly, the synchronization accuracy of the existing structure excessively depends on the machining accuracy. Due to the inevitable size tolerance (usually the tolerance band is ±0.02mm) of the fixed orifice in the manufacturing process, when the load pressure difference of the two working oil circuits exceeds 3MPa, the coupling effect of the asymmetric hydraulic force on both sides of the valve core and the spring pre-tightening force deviation will cause the split flow difference to expand exponentially. Experimental data shows that under the working condition of 8MPa pressure difference, the synchronization error can reach 10%-15%, which seriously restricts the dynamic response performance of high-precision synchronous system.

[0004] Secondly, the adaptability of the traditional valve body-valve core assembly to wide temperature range working conditions is insufficient. The valve core and valve body are made of homogeneous metal materials (such as 40Cr steel and copper alloy valve sleeve). When cold starting in low temperature environment below 40℃, the metal shrinkage effect causes the fitting clearance to decrease to 3-6μm. At this time, the elastic modulus of the nitrile rubber sealing ring increases to 2-3 times of that at room temperature, and the starting torque of the valve core increases by more than 60%, which easily causes motion jamming. While in high temperature working condition above 80℃, the radial expansion amount of the valve body can reach 1.3-1.8 times of that at low temperature. The increased fitting clearance leads to abnormally high internal leakage, and the cross leakage of the two working chambers can reach 12%-18% of the rated flow, and the synchronization accuracy decays by more than 20%.

[0005] Based on the above defects, we propose a threaded cartridge adjustable split and combine valve. SUMMARY

[0006] To solve the above technical problems, the present application provides a threaded cartridge adjustable split and combine valve, which comprises a valve body, a plurality of main oil passage holes are formed in the valve body, a first orifice and a second orifice are formed in the valve body, the first orifice and the second orifice are respectively located on both sides of the main oil passage hole, and there are two of each, and further comprising:

[0007] A valve core assembly is installed inside the valve body, and when the pressure difference between the first and second throttle holes is small, the same flow of hydraulic oil is extracted or injected into the first and second throttle holes, respectively;

[0008] A synchronization mechanism is installed inside the valve body to compensate for the hydraulic oil pressure on the side with greater pressure when the pressure difference between the first and second throttle holes is large.

[0009] The valve core assembly includes a first fixed cylinder installed inside the valve body near the handheld end, a first spring installed on the inner wall of the side of the first fixed cylinder near the main oil passage hole, a first valve core slidingly installed inside the valve body, the first valve core being cylindrical, one end of the first spring being fixed to the first fixed cylinder and the other end being fixed to the inner wall of the side of the first valve core near the first fixed cylinder, a third throttle hole and a first damping hole being formed in the first valve core, the third throttle hole overlapping the first throttle hole, and the first damping hole being located between the third throttle hole and the main oil passage hole, the valve core assembly further including a second fixed cylinder installed inside the valve body, a second valve core slidingly installed inside the valve body, the second valve core being identical in shape to the first valve core and being connected to the second fixed cylinder via a second spring, a fourth throttle hole and a second damping hole being formed in the second valve core, the fourth throttle hole overlapping the second throttle hole, and the second damping hole being located between the fourth throttle hole and the main oil passage hole, the number of third throttle holes, fourth throttle holes, first damping holes, and second damping holes being equal to the number of first throttle holes;

[0010] The synchronization mechanism has two identical structures, including a through pipe connecting the two third throttle holes, a square block fixed on the through pipe, a groove formed in the square block and communicating with the through pipe, four tapered holes formed in the square block and arranged in a straight line, the front two tapered holes and the rear two tapered holes being opposite in direction, a guide plate fixed in each tapered hole and arranged in a spiral, a through hole formed in the square block and aligned with the four tapered holes, and the other synchronization mechanism being arranged in a plane mirror image of the center point of the main oil passage hole near the second valve core, the synchronization mechanism further including a conversion piece.

[0011] The conversion piece includes an electric control valve oppositely installed in the groove, and a single electric control valve can only block two tapered holes or one through hole at a time.

[0012] As a preferred embodiment, the valve core assembly further includes a fixed cover installed on the side of the first valve core near the main oil passage hole, a support rod installed on the side of the second valve core near the main oil passage hole, a sliding block fixed to the end of the support rod away from the second valve core, the sliding block being located on the inner wall of the fixed cover and being in sliding connection with the fixed cover, a third spring sleeved on the fixed cover, and the two ends of the third spring being fixed to the sides of the first valve core and the second valve core, respectively.

[0013] Preferably, the first valve core and the second valve core are both provided with annular grooves, and the annular grooves are multiple.

[0014] Preferably, the first valve core and the second valve core are both provided with sealing assemblies, the sealing assemblies increase the sealing performance between the first valve core, the second valve core and the inner wall of the valve body according to different temperatures of the environment, and the sealing assemblies comprise bimetallic compensation rings respectively sleeved on the first valve core and the second valve core, and the expansion coefficient of the outer layer is higher than that of the inner layer, and the bimetallic compensation ring is in the shape of "⊥".

[0015] Preferably, the outer layer of the bimetallic compensation ring is a manganese-copper alloy layer with a thickness of 0.8 mm, and the inner layer is an invar alloy layer with a thickness of 1.5 mm. The two layers are formed by explosion welding, and the outer wall and the inner wall of the bimetallic compensation ring are both provided with V-shaped grooves, and the V-shaped groove in the inner wall is filled with a fluororubber pad.

[0016] The present application has at least the following advantages:

[0017] 1. Through the linkage of the components of the valve core assembly, the device automatically balances the flow of the two paths when the pressure difference is small, and through the tapered hole of the synchronous mechanism and the dynamic compensation of the electric control valve when the pressure difference is large, the pressure difference between the two sides of the first valve core and the second valve core is greatly reduced under high load operation;

[0018] 2. In the low temperature state (lower than 40℃), the inner layer invar alloy shrinks, the ring body shrinks radially, the gap between the V-shaped groove and the corresponding first valve core or second valve core increases, and the device is prevented from being stuck during cold start;

[0019] In the high temperature state (higher than 80℃), the expansion amount of the outer layer manganese-copper alloy is much larger than that of the inner layer, the ring body expands radially outward after being heated, and the fluororubber pad in the V-shaped groove is extruded, so that the gap between the sealing surfaces is reduced, and leakage is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the present application;

[0021] Figure 2 It is a schematic diagram of the first cross-sectional structure inside the present application;

[0022] Figure 3 It is a schematic diagram of the second cross-sectional structure inside the present application;

[0023] Figure 4 It is a schematic diagram of the third cross-sectional structure inside the present application;

[0024] Figure 5 It is a schematic diagram of the cross-sectional structure of the bimetallic compensation ring of the present application;

[0025] Figure 6A cross-sectional structure schematic diagram of the flow distribution and collection valve in a flow distribution state;

[0026] Figure 7 A cross-sectional structure schematic diagram of the flow distribution and collection valve in a flow distribution state.

[0027] In the figure: 1, valve body; 11, main oil passage hole; 12, first throttle hole; 13, second throttle hole; 3, valve core assembly; 31, first fixed cylinder; 32, first spring; 33, first valve core; 34, third throttle hole; 35, first damping hole; 36, second fixed cylinder; 37, second spring; 38, second valve core; 39, fourth throttle hole; 310, second damping hole; 311, fixed cover; 312, support rod; 313, sliding block; 314, third spring; 4, synchronization mechanism; 41, through pipe; 42, square block; 43, groove; 44, tapered hole; 45, flow guide plate; 46, through hole; 47, conversion piece; 471, electric control valve; 5, annular groove; 6, bimetallic compensation ring; 61, manganese-copper alloy layer; 62, invar alloy layer; 63, V-shaped groove; 64, fluorine rubber pad. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0029] Embodiment 1:

[0030] Please refer to Figures 1-7 The present application provides a technical solution: a threaded plug-in adjustable flow distribution and collection valve, comprising a valve body 1, the valve body 1 is provided with a main oil passage hole 11, the main oil passage hole 11 has a plurality of holes, which are located at the middle position of the valve body 1, and further comprising a first throttle hole 12 and a second throttle hole 13 provided on the valve body 1, the first throttle hole 12 and the second throttle hole 13 are respectively located on both sides of the main oil passage hole 11, and each has two holes, and further comprising:

[0031] A valve core assembly 3 is installed inside the valve body 1, when the pressure difference between the first throttle hole 12 and the second throttle hole 13 is small, the same flow of hydraulic oil is extracted or injected into the first throttle hole 12 and the second throttle hole 13 respectively;

[0032] A synchronization mechanism 4 is installed inside the valve body 1, which is used to compensate the hydraulic oil pressure on the side with larger pressure when the pressure difference between the first throttle hole 12 and the second throttle hole 13 is large.

[0033] The valve core assembly 3 comprises a first fixed cylinder 31 installed in the valve body 1 near the hand-held end, a first spring 32 installed near the inner wall of the first fixed cylinder 31, a first valve core 33 slidably installed in the valve body 1, the first valve core 33 being cylindrical, one end of the first spring 32 being fixed with the first fixed cylinder 31 and the other end being fixed with the inner wall of the first valve core 33 near the first fixed cylinder 31, the first valve core 33 being provided with a third throttling hole 34 and a first damping hole 35, the third throttling hole 34 overlapping the first throttling hole 12, the first damping hole 35 being located between the third throttling hole 34 and the main oil passage hole 11, the valve core assembly 3 further comprising a second fixed cylinder 36 installed in the valve body 1, a second valve core 38 slidably installed in the valve body 1, the second valve core 38 being identical in shape with the first valve core 33 and being connected with the second fixed cylinder 36 through a second spring 37, the second valve core 38 being provided with a fourth throttling hole 39 and a second damping hole 310, the fourth throttling hole 39 overlapping the second throttling hole 13, the second damping hole 310 being located between the fourth throttling hole 39 and the main oil passage hole 11, the number of the third throttling hole 34, the fourth throttling hole 39, the first damping hole 35 and the second damping hole 310 being equal to the number of the first throttling hole 12.

[0034] For the convenience of understanding, as shown in Figure 6 , 7 The first damping hole 35 and the second damping hole 310 are fixed throttling holes in the valve, the hydraulic oil pressure at the position is P1 and P2 respectively, the first throttling hole 12 and the third throttling hole 34, and the second throttling hole 13 and the fourth throttling hole 39 respectively form two variable throttling holes, the hydraulic oil pressure at the position is P3 and P4 respectively, and the hydraulic oil pressure at the position of the main oil passage hole 11 is P0.

[0035] The valve core assembly 3 further comprises a fixed cover 311 installed on the side of the first valve core 33 near the main oil passage hole 11, a support rod 312 installed on the side of the second valve core 38 near the main oil passage hole 11, a sliding block 313 fixed on the end of the support rod 312 away from the second valve core 38, the sliding block 313 being located on the inner wall of the fixed cover 311 and being in sliding connection with the fixed cover 311, a third spring 314 sleeved on the fixed cover 311, and the two ends of the third spring 314 being fixed with the first valve core 33 and the second valve core 38 respectively.

[0036] The sliding block 313 and the fixed cover 311 are arranged in sliding connection with each other to ensure the relative position of the first valve core 33 and the second valve core 38, and the states (expansion or reduction) of P3 and P4 are opposite during the movement of the first valve core 33 and the second valve core 38.

[0037] The synchronization mechanism 4 has two and the same structure, including the communication pipe 41 connecting the two third throttling holes 34, the square block 42 fixed on the communication pipe 41, the recess 43 provided in the square block 42 and communicated with the communication pipe 41, the tapered hole 44 provided in the square block 42, the four tapered holes 44 distributed in a straight line, the front two tapered holes 44 and the rear two tapered holes 44 opposite to each other, the flow guide plate 45 fixed in each tapered hole 44, the flow guide plate 45 spirally distributed, the through hole 46 provided in the square block 42 and in the same straight line with the four tapered holes 44, and the other synchronization mechanism 4 distributed in the plane mirror of the center point of the main oil way hole 11 near the second valve core 38, and the conversion piece 47.

[0038] The conversion piece 47 includes the electric control valve 471 oppositely installed in the recess 43, the single electric control valve 471 only capable of plugging two tapered holes 44 or one through hole 46 at a time, the adjacent two tapered holes 44 and the single through hole 46 plugged according to the different pressure changes in the valve body 1, the pressure difference between the corresponding sides of the first valve core 33 and the second valve core 38 reduced when the pressure difference is large, and the precision of the equipment operation improved.

[0039] The annular grooves 5 are provided on the surfaces of the first valve core 33 and the second valve core 38, and the annular grooves 5 are multiple, which can effectively reduce the friction force of the first valve core 33 and the second valve core 38 when sliding in the valve body 1, and reduce the error range of the device.

[0040] The sealing assembly is sleeved on the first valve core 33 and the second valve core 38, the sealing assembly increases the sealing property between the first valve core 33, the second valve core 38 and the inner wall of the valve body 1 according to different temperatures of the environment, includes the bimetallic compensation ring 6 sleeved on the first valve core 33 and the second valve core 38 respectively, and the expansion coefficient of the outer metal layer is higher than that of the inner metal layer, and the whole is in the shape of “⊥”.

[0041] The outer layer of the bimetallic compensation ring 6 is the manganese copper alloy layer 61 with a thickness of 0.8 mm, and the inner layer is the invar alloy layer 62 with a thickness of 1.5 mm. The two are formed by explosion welding, and the outer wall and the inner wall of the bimetallic compensation ring 6 are provided with V-shaped grooves 63, and the V-shaped grooves 63 in the inner wall are filled with fluororubber pads 64.

[0042] The expansion coefficient (α=20×10⁻ 6 / ℃) of the manganese copper alloy layer 61 is much higher than that of the invar alloy layer 62 (α=1.2×10⁻ 6In a low-temperature operating environment (below 40 DEG C), the inner layer of the bimetallic compensation ring 6 shrinks due to the shrinkage of the inner Invar alloy layer 62, the radial inner shrinkage increases the gap between the V-shaped groove 63 and the corresponding first valve core 33 or second valve core 38, and the starting jamming is avoided; and once the temperature of the operating environment is increased (higher than 80 DEG C), the bimetallic compensation ring 6 expands radially outward after being heated, extruding the fluororubber pad 64 in the V-shaped groove 63, so that the gap between the sealing surfaces is reduced, and leakage is avoided.

[0043] The working principle of the present application is that: the core control components of the device are left-right symmetrical, and the connecting components between the first valve core 33 and the second valve core 38 are slidingly connected and are constrained by the third spring 314, the variable throttling ports P3 and P4 are always in an open state, but the opening size will change with the pressure, that is, when the pressure difference of the fixed throttling ports P1 and P2 is equal, the flow is also equal, so that:

[0044] The flow state is:

[0045] As shown in Figure 6 , the pressure of the inlet P3 and P4 is greater than that of the outlet P0, and the first valve core 33 and the second valve core 38 are extruded, so as to drive the sliding block 313 to slide in the fixed cover 311, and finally tightly adhere to one side of the first valve core 33;

[0046] When the difference between P3 and P4 is small (set according to the actual application scene and the pressure value detected by the pressure detection system), the two electric control valves 471 block the four tapered holes 44, and the hydraulic oil is drawn into the main oil passage hole 11 through the through hole 46, without compensating P2 or P1, at this time, two situations will occur:

[0047] 1. When the loads are the same: P3=P4, that is, P1=P2, the pressure difference before and after the left and right fixed throttling ports is the same, and the flow is the same.

[0048] 2. When the loads are different: assuming that P4 is greater than P3, that is, P2 is greater than P1, the first valve core 33 and the second valve core 38 move to the left, the right variable throttling port becomes smaller, and the left variable throttling port becomes larger, when the right throttling port becomes smaller, the pressure of P2 is reduced, when P2 pressure=P1 pressure, the valve core stops moving, and the pressure difference before and after the fixed throttling ports on both sides is consistent, that is, the flow on both sides is the same.

[0049] When the difference between P3 and P4 exceeds the set value: assuming P4 is greater than P3, that is, P2 is greater than P1, the first valve core 33 and the second valve core 38 move to the left, the right variable throttle orifice becomes smaller, and the left variable throttle orifice becomes larger. After the right throttle orifice becomes smaller, the pressure of P2 decreases. The solenoid valve 471 on the P1 side blocks the through hole 46 on the corresponding side and the two tapered holes 44 that become wider along the direction of hydraulic oil flow. The solenoid valve 471 on the P2 side blocks the through hole 46 on the corresponding side and the two tapered holes 44 that become narrower along the direction of hydraulic oil flow. At this time, the tapered holes 44 on P1 and P2 respectively form a low-resistance acceleration channel and a high-resistance compensation channel, forming a self-balancing flow distribution to reduce the error value.

[0050] During traffic splitting:

[0051] like Figure 7 As shown, the pressure at the inlet P0 is greater than the pressure at the outlets P3 and P4. Under the action of the pressure at P0, the first valve core 33 and the second valve core 38 separate to the left and right, and finally the slider 313 and the fixed cover 311 are attached to the inner wall away from the first valve core 33.

[0052] When the load is the same: P3=P4, that is, P1=P2, the pressure difference before and after the left and right fixed throttling orifices is the same, and the flow rate is the same.

[0053] When the loads are different: Assuming P4 is greater than P3, that is, P2 is greater than P1, the valve core moves to the left, the variable throttle orifice on the left becomes smaller, and the throttle orifice on the right becomes larger, the pressure of P1 increases. When the pressure of P1 increases to the pressure of P2, the valve core is in a balanced state. Since P1=P2, the pressure difference before and after the fixed throttle orifices on the left and right sides is constant, that is, the flow rates on both sides are the same.

[0054] Similarly, when the difference between P3 and P4 exceeds the set value, the solenoid valve 471 blocks the corresponding conical orifice 44 or through orifice 46 to achieve self-balancing flow distribution.

[0055] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0056] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A threaded cartridge type adjustable diverter valve, comprising a valve body (1), wherein the valve body (1) has a main oil passage hole (11), there are multiple main oil passage holes (11) located in the middle of the valve body (1), and further comprising a first throttling hole (12) and a second throttling hole (13) opened on the valve body (1), wherein the first throttling hole (12) and the second throttling hole (13) are respectively located on both sides of the main oil passage hole (11), and there are two of each, characterized in that: Also includes: Valve core assembly (3), which is installed inside the valve body (1), when the pressure difference between the first throttle hole (12) and the second throttle hole (13) is small, hydraulic oil of the same flow rate is drawn out or injected into the first throttle hole (12) and the second throttle hole (13) respectively. Synchronization mechanism (4), which is installed inside the valve body (1), is used to compensate the hydraulic oil pressure on the side with greater pressure when the pressure difference between the first throttle orifice (12) and the second throttle orifice (13) is large. The valve core assembly (3) includes a first fixed cylinder (31) installed inside the valve body (1) near the hand-held end. A first spring (32) is installed on the inner wall of the first fixed cylinder (31) near the main oil passage (11). A first valve core (33) is slidably installed inside the valve body (1). The first valve core (33) is cylindrical. One end of the first spring (32) is fixed to the first fixed cylinder (31), and the other end is fixed to the inner wall of the first valve core (33) near the first fixed cylinder (31). A third throttling hole (34) and a first damping hole (35) are provided on the first valve core (33). The third throttling hole (34) overlaps with the first throttling hole (12), and the first damping hole (35) is located between the third throttling hole (34) and the main oil passage (11). The valve core assembly (3) further includes a second fixed cylinder (36) installed in the valve body (1). A second valve core (38) is slidably installed in the valve body (1). The second valve core (38) has the same shape as the first valve core (33) and is connected to the second fixed cylinder (36) by a second spring (37). A fourth throttling hole (39) and a second damping hole (310) are provided on the second valve core (38). The fourth throttling hole (39) and the second throttling hole (13) overlap. The second damping hole (310) is located between the fourth throttling hole (39) and the main oil passage hole (11). The number of the third throttling hole (34), the fourth throttling hole (39), the first damping hole (35), and the second damping hole (310) are all equal to the number of the first throttling hole (12). There are two synchronization mechanisms (4) with the same structure. One includes a pipe (41) that connects the two third throttle holes (34). A square block (42) is fixed on the pipe (41). The square block (42) has a groove (43) that is connected to the pipe (41). The square block (42) has a conical hole (44). There are four conical holes (44) that are arranged in a straight line. The first two conical holes (44) and the last two conical holes (44) are oriented in opposite directions. A guide plate (45) is fixed inside each conical hole (44). The guide plate (45) is arranged in a spiral. A through hole (46) is opened on the square block (42). The through hole (46) and the four conical holes (44) are on the same straight line. The other synchronization mechanism (4) is arranged in a plane mirror image formed by the center point of the main oil passage hole (11) near the second valve core (38). The synchronization mechanism (4) also includes a conversion component (47). The conversion element (47) includes an electrically controlled valve (471) mounted relative to the groove (43), and a single electrically controlled valve (471) can only block two conical holes (44) or one through hole (46) at a time.

2. The threaded cartridge type adjustable diverter / combiner valve according to claim 1, characterized in that: The valve core assembly (3) also includes a fixed cover (311) installed on the side of the first valve core (33) near the main oil passage (11). A support rod (312) is installed on the side of the second valve core (38) near the main oil passage (11). A slider (313) is fixed at the end of the support rod (312) away from the second valve core (38). The slider (313) is located on the inner wall of the fixed cover (311) and the two are slidably connected. A third spring (314) is sleeved on the fixed cover (311). The two ends of the third spring (314) are fixed to the side of the first valve core (33) and the second valve core (38) respectively.

3. A threaded cartridge-type adjustable diverter / combiner valve according to claim 2, characterized in that: The first valve core (33) and the second valve core (38) are both provided with annular grooves (5), and there are multiple annular grooves (5).

4. A threaded cartridge-type adjustable diverter / combiner valve according to claim 3, characterized in that: A sealing assembly is fitted on both the first valve core (33) and the second valve core (38). The sealing assembly increases the sealing between the first valve core (33), the second valve core (38) and the inner wall of the valve body (1) according to different ambient temperatures. It includes a bimetallic compensation ring (6) fitted on the first valve core (33) and the second valve core (38) respectively, and the metal expansion coefficient of the outer layer is higher than that of the inner layer. The whole is in the shape of "⊥".

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