CN107839489B

CN107839489B - Pantograph

Info

Publication number: CN107839489B
Application number: CN201711240955.4A
Authority: CN
Inventors: 陈文韬; 王三槐; 戴谋军; 吴忠发
Original assignee: Zhuzhou Lince Group Shock Absorber Co ltd; Zhuzhou Lince Group Co Ltd
Current assignee: Zhuzhou Lince Group Shock Absorber Co ltd; Zhuzhou Lince Group Co Ltd
Priority date: 2017-11-30
Filing date: 2017-11-30
Publication date: 2023-09-12
Anticipated expiration: 2037-11-30
Also published as: CN107839489A

Abstract

The invention provides a pantograph, which comprises a damper, an underframe, a pantograph lifting device and other parts, wherein the damper comprises an oil storage cylinder, an oil cylinder, a guide bearing, a piston rod, a piston, hydraulic oil and a base valve seat, a plurality of throttle holes with one ends communicated with oil through holes are arranged on the piston rod, the other ends of the throttle holes face to openings outside the piston rod, the openings of the throttle holes can be exposed in a cavity I and/or covered by the guide bearing, and at least two throttle holes are distributed at different positions in the axial direction of the piston rod; a gasket is arranged between the axial inner end of the oil cylinder and the bottom valve seat and used for adjusting the stretching maximum damping force in the outward stretching stroke of the piston rod. The invention cancels the adjusting structure of adjusting the maximum damping force by the nut, the spring and the valve plate in the prior art, and adopts the method of adjusting the maximum damping force by adding gaskets with different thicknesses. The pantograph provided by the invention can well meet the service condition requirements of the pantograph. Simple and easy to operate and convenient to maintain.

Description

Pantograph

Technical Field

The invention relates to a pantograph, in particular to a pantograph applied to rail transit vehicles such as an electric locomotive, a city rail vehicle, a motor train unit and the like.

Background

The pantograph is a key component of rail transit vehicles such as an electric locomotive, a city rail vehicle, a motor train unit and the like, is arranged on the roof of the rail transit vehicle, and is used for collecting current from a contact net after the pantograph head rises to be contacted with the contact net and transmitting the current into the vehicle for the locomotive. The pantograph generally comprises: the device comprises a chassis, a damper, an arch lifting device, a lower arm, an arch assembly, a lower guide rod, an upper arm, an upper guide rod, an arch head, a sliding plate, an arch lifting air source control valve plate and other mechanisms, wherein the damper is arranged between the chassis and the lower arm. The fluency of the pantograph collecting current from the contact network is related to the contact pressure, the transition resistance and the contact area between the sliding plate and the contact line, and depends on the interaction between the pantograph and the contact network; the main function of the damper is that the vibration of the pantograph is attenuated, so that the pressure change of the pantograph and the overhead contact line is not great when the running speed of the locomotive is changed.

The damping performance requirement of the damper for the pantograph is shown in the figure 1, the damper is in a compression stroke when the pantograph ascends, and the damper is kept at a relatively stable small damping force at the speed of the pantograph ascending, so that the head of the pantograph ascends rapidly and stably and reaches and is kept at the height of a contact net; when the pantograph descends, the damper is in a stretching stroke, at the descending speed, most of the stroke in front of the damper is kept at a relatively stable small damping force, and the damping force is rapidly increased in the small stroke at the back, so that the pantograph head is ensured to have a buffering effect and stably descend on the underframe when descending to a certain height.

When the damper works, the piston rod drives the piston to do stretching and compression reciprocating motion in the oil cylinder, hydraulic oil rubs and flows to generate damping force through holes in the damper and the valve, and meanwhile, the damper converts vibration energy of the pantograph into heat of the hydraulic oil to be dissipated. The prior art scheme generally has the phenomenon that the damping characteristic and the sealing performance of the damper can not well meet the use requirement. The damping force can be influenced by the sealing effect of related parts in the damper, and the problems of easy oil leakage and weakening or disappearance of the damping force exist; the size processing precision and consistency of related parts of the damper can seriously influence the damping force and the sealing effect; the tolerance range of the maximum damping force (B in the figure 1) is large, and rebound phenomenon easily occurs in the bow lowering process when the maximum damping force is too large, so that damage is caused to the pantograph and the underframe; and the tensile maximum damping force (at B in fig. 1) cannot be adjusted and controlled.

The patent CN201220614261.9 provides a pantograph damper of a railway electric locomotive, which comprises an oil storage cylinder, wherein a chassis is welded at one end of the oil storage cylinder, so that the oil storage cylinder is a half-open oil storage cylinder, a guide supporting seat is arranged at the other end of the oil storage cylinder, and is arranged in the oil storage cylinder, axially positioned by a pressure cylinder and locked by a locking nut; a piston rod is inserted into the center of the guide supporting seat, a piston is arranged at the end of the piston rod positioned in the oil storage cylinder, and the piston can axially move along with the piston rod in the pressure cylinder; the piston is characterized in that a piston rod is in contact with a piston, a piston one-way valve is arranged on the end face close to one side of the piston rod, a damping hole is formed in the piston, an adjusting valve is arranged at the top end of the piston rod, and a pressure damping hole is formed in the piston rod; the pressure damping hole is positioned in one side of the piston rod, which is close to the high-pressure cavity of the pressure cylinder, and is communicated with the low-pressure cavity of the pressure cylinder on the other side of the piston through the regulating valve; a one-way valve and a bottom valve are arranged between the pressure cylinder and the chassis and are closely arranged together. The tensile maximum damping force of the damper in this patent cannot be adjusted and controlled.

In addition, patent CN201310381795.0 discloses a damping throttling device of a pantograph damper, one end of an oil cylinder is sealed by a guide, the guide is provided with a central hole for supporting and guiding a piston rod, and the other end of the oil cylinder is sealed by a bottom valve seat. The piston divides the oil cylinder into a cavity I and a cavity II, and the piston is provided with a stretching orifice and a compression orifice which are arranged in opposite directions. The compression valve plate of the piston, which is close to the end face of one side of the cavity I of the oil cylinder, is covered on the compression throttle hole, the compression valve plate is pressed by the spring, and the spring is fixed on the spring seat. The stretching spring valve plate positioned on the end surface of the piston, which is close to the cavity II of the oil cylinder, is covered on the stretching throttle hole, the stretching spring valve plate is pressed by the baffle plate, and the baffle plate is fixed on the piston rod by the lock nut. The invention can overcome the technical defect that the damping force cannot be adjusted and controlled at will when the piston rod stretches to the last stroke in the prior art. Although this patent shows a scheme for adjusting the maximum damping force of the damper, in this scheme, spring valve plates are disposed on the end face of the piston close to the cylinder i cavity and the end face of the piston close to the cylinder ii cavity, wherein the maximum damping force of the damper is finely adjusted by nuts, springs and valve plates, and such a structure is very easy to loosen, so that the use of this structure to adjust the maximum damping force of the damper is not reliable.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a damper for a pantograph and a pantograph correspondingly comprising the damper, wherein the size of the maximum tensile damping force of the damper can be conveniently adjusted, so that the operation of the pantograph is stable.

The invention provides a pantograph, which comprises a damper, a bottom frame, a pantograph lifting device, a lower arm, a pantograph assembly, a lower guide rod, an upper arm, an upper guide rod, a pantograph head, a sliding plate and a pantograph lifting air source control valve plate, wherein the damper comprises an oil storage cylinder, an oil cylinder, a guide, a piston rod, hydraulic oil and a base valve seat, the damper takes the hydraulic oil (9) as a working medium, two ends of the oil cylinder (7) are positioned and installed in the oil storage cylinder (8) through the guide (4) and the base valve seat (12), the guide (4) is provided with a central hole for supporting and guiding the piston rod (1), and the piston rod (1) drives the piston (22) to reciprocate in the oil cylinder under the action of external force; the guide (4), the oil cylinder (7), the piston (22) and the bottom valve seat (12) divide the oil storage cylinder (8) into an I cavity (81), an II cavity (82) and an III cavity (83), a space between the guide (4) and the piston (22) in the radial direction and the oil cylinder (7) in the axial direction is the I cavity, a space between the bottom valve seat (12) and the piston (22) in the radial direction and the oil cylinder (7) in the axial direction is the II cavity, the space between the outer side of the oil cylinder (7) and the inner side of the oil storage cylinder (8) in the radial direction is the III cavity, a channel through which hydraulic oil can flow between the I cavity and the II cavity is arranged on the piston (22), and a channel through which the hydraulic oil can flow between the II cavity and the III cavity is arranged on the bottom valve seat (12), and the hydraulic oil cannot flow between the I cavity and the III cavity under the condition that the hydraulic oil does not leak from the guide (4). When the piston rod stretches outwards, hydraulic oil enters the cavity II from the cavity I and the cavity III, when the piston rod compresses inwards, hydraulic oil enters the cavity I and the cavity III from the cavity II, an oil through hole (25) is arranged in the center of the piston rod (1), the oil through hole (25) is a blind hole arranged in the piston rod, the opening of the blind hole is communicated with the cavity II, a plurality of orifices (26) with one ends communicated with the oil through hole (25) are further arranged on the piston rod (1), the other ends of the orifices (26) face to the opening outside the piston rod, the openings of the orifices can be exposed in the cavity I and/or covered by the guide (4), at least two orifices (26) are distributed at different positions in the axial direction of the piston rod (1), and the orifices (26) are gradually covered by the guide (4) in the process of stretching outwards of the piston rod, and the orifices (26) are gradually exposed in the cavity I in the process of compressing inwards of the piston rod; a gasket (11) is arranged between the axial inner end of the oil cylinder (7) and the bottom valve seat (12) and used for adjusting the stretching maximum damping force in the outward stretching stroke of the piston rod.

In a specific embodiment, two dynamic sealing structures (6) for dynamically sealing the piston rod are arranged at the central hole of the guide (4), the two dynamic sealing structures (6) are arranged at different positions in the axial direction of the central hole, and the two dynamic sealing structures (6) are all gray rings.

In a specific embodiment, a central hole and a III cavity (83) which are communicated with the guide (4) are arranged at one end of the guide (4) far away from the piston (22) and are used for preventing hydraulic oil from leaking to an oil return leakage hole (27) outside the damper, and in the axial direction of the central hole, two dynamic sealing structures (6) are arranged on the same side of the oil return leakage hole (27).

In a specific embodiment, the gasket is a copper gasket, and the thickness of the gasket is 0.5-3 mm. Such as a polytetrafluoroethylene gasket or a copper gasket that can simultaneously exert a sealing effect and an effect of adjusting the maximum damping force of stretching, but a copper gasket is more preferable.

In a specific embodiment, the thickness of the spacer is 1-2 mm. Specifically, when the thickness of the gasket is 1-2 mm, the gasket is added or withdrawn, so that the magnitude of the maximum tensile damping force in the same damper is changed by about 1000-2000N.

In a specific embodiment, a plurality of compression orifices (19) and at least one stretching normal through hole (21) are arranged on the piston (22), the compression orifices (19) are in a through hole shape in the axial direction of the piston (22), a piston check valve (23) and a baffle plate (24) are arranged on one side, close to the I cavity, of the piston (22), the piston check valve (23) is fixed on the piston rod (1) through threads on the lock nut (18) and the piston rod, the piston check valve (23) is in a spring valve plate structure, is pressed through the baffle plate (24) and covers the compression orifices (19) on one side, close to the I cavity, of the piston (22), so that when the piston rod stretches outwards, the piston check valve (23) covers the compression orifices (19) without allowing hydraulic oil to flow into the II cavity from the I cavity through the piston check valve (23) and the plurality of compression orifices (19), and when the piston rod compresses inwards, hydraulic oil can jack the piston check valve (23) against the spring force to enable the hydraulic oil to flow into the II cavity from the compression orifices (23) from the I cavity to the II cavity; the stretching normal through hole (21) is an inclined hole, one end of the stretching normal through hole (21) is directly or indirectly communicated with the cavity I, and the other end of the stretching normal through hole is communicated with a certain compression throttle hole (19), so that hydraulic oil flows into the cavity II from the cavity I through the stretching normal through hole (21) and the compression throttle hole (19) communicated with the stretching normal through hole (21) when the piston rod stretches outwards. Specifically, in the present invention, the diameter of the tensile normal through hole is determined by the maximum tensile damping force in the damper.

In a specific embodiment, the bottom valve seat (12) is provided with a stretching throttle hole (17) and a compression throttle hole (15), and the end surface of the stretching throttle hole (17) close to the side of the II cavity is covered with a bottom valve stretching valve (10), so that hydraulic oil can flow into the II cavity from the III cavity through the stretching throttle hole (17) and the bottom valve stretching valve (10) when the piston rod stretches; a first bottom valve compression valve (13) and a second bottom valve compression valve (14) are covered on the end surface of one side of the compression throttle hole (15) away from the II cavity, so that hydraulic oil can flow into the III cavity from the II cavity through the compression throttle hole (15) and the two bottom valve compression valves when the piston rod is compressed inwards; the first bottom valve compression valve (13) and the second bottom valve compression valve (14) are arranged at the step of the bottom valve seat (12) at one side far away from the II cavity, the first bottom valve compression valve (13) and the second bottom valve compression valve (14) are covered on two step surfaces of the bottom valve seat (12), so that an axial gap is formed between the first bottom valve compression valve (13) and the second bottom valve compression valve (14), the bottom valve seat (12) is further provided with an oil return hole (16), one end of the oil return hole (16) is communicated with the axial gap, and the other end of the oil return hole is communicated with the II cavity, so that hydraulic oil can flow back into the II cavity from the axial gap when the piston rod is compressed inwards, and a relatively stable small damping force is kept in the whole process of inward compression of the piston rod. Specifically, the bottom valve extension valve 10 and the piston check valve 23 are configured identically or similarly, and are provided with wave springs, and the flow condition of hydraulic oil is changed by the pressure change in the two chambers partitioned by the valve. Neither the first base valve compression valve 13 nor the second base valve compression valve 14 is provided with a spring, but the flow of hydraulic oil is changed by the change in the rigidity of the own steel sheet.

In a specific embodiment, the guide (4) is provided with a first static sealing structure (3) and a second static sealing structure (5) at the contact surfaces with the oil storage cylinder (8) and the oil cylinder (7), respectively, and the first static sealing structure (3) and the second static sealing structure (5) are O-shaped rings.

In a specific embodiment, the outer surface of the piston (22) is in clearance fit with the inner surface of the oil cylinder (7), and a guide ring and a check ring (20) are arranged on the outer surface of the piston (22). A dynamic seal and positioning structure is formed between the outer surface of the piston and the inner surface of the cylinder.

The invention also provides a method for adjusting the maximum damping force of the stretching in the damper for the pantograph, which comprises the steps of adjusting the diameter of the stretching normal through hole in the piston, and adjusting the diameter of the stretching normal through hole by arranging gaskets with different thicknesses between 0 and 3mm between the oil cylinder and the base valve seat after the damper is designed.

The working principle of the technical scheme is described as follows: when the piston rod drives the piston to do stretching and compression reciprocating motion in the oil cylinder under the action of external force, hydraulic oil does reciprocating circulation flow in the oil cylinder, and damping force is generated due to friction when the hydraulic oil passes through a hole in the damper and the valve. When the piston rod stretches outwards, the pressure of the cavity I increases and the pressure of the cavity II decreases, so that the piston one-way valve 23 is closed, and hydraulic oil enters the cavity II through the stretching normal through hole 21 on the piston and the throttle hole 26 and the central oil through hole 25 on the piston rod; when the orifice 26 on the piston rod is gradually covered by the guide, the pressure in the i-chamber increases rapidly, resulting in a rapid increase in the tensile damping force; when all the orifices on the piston rod are covered by the guide, the hydraulic oil in the cavity I can only enter the cavity II through the stretching normal through hole 21 on the piston, and the stretching damping force reaches the maximum value. Simultaneously, as the piston rod stretches outwards, the volume occupied by the piston rod causes small hydraulic oil quantity in the cavity I, so that the cavity II cannot be filled with oil to form negative pressure, the bottom valve stretching valve 10 is opened, the bottom valve compression valves 13 and 14 are closed, and hydraulic oil enters the cavity II from the cavity III. Therefore, the technical scheme ensures that the damping force of most of the front travel in the stretching process keeps relatively stable smaller damping force, and the damping characteristic of the small rear travel in the stretching process is rapidly increased.

When the piston rod is compressed inwards, the pressure of the cavity II is increased, and the pressure of the cavity I is reduced, so that the piston check valve 23 is opened, hydraulic oil can enter the cavity I from a plurality of compression orifices 19, and when the hydraulic oil enters the oil cylinder along with the gradual withdrawal of the orifices on the piston rod from the guide bearing, the hydraulic oil can also enter the cavity I from the cavity II through the central oil through hole 25 and the orifices 26 on the piston rod; simultaneously, with the entering of the piston rod, redundant hydraulic oil in the cavity II pushes up the bottom valve compression valves 13 and 14 to enter the cavity III. The opening pressure of the bottom valve compression valve is larger than that of the piston check valve 23, so that hydraulic oil in the cavity II firstly enters the cavity I and then enters the cavity III, and the compression damping force is mainly determined by the opening pressure of the bottom valve compression valve. According to the invention, the two bottom valve compression valves are respectively provided with the valve plates, the two valve plates are respectively covered on the two step surfaces of one side of the bottom valve seat, which is far away from the II cavity, and the oil return hole leading to the II cavity is arranged between the two valve plates, so that the pressure difference between the two valve plates and the damping force generated by the pressure difference are reduced, and the damping force generation process is stable. Therefore, the technical scheme ensures that the damper maintains relatively stable small damping force in the whole compression process.

The guide is provided with the two static sealing structures and the two dynamic sealing structures, so that effective low-pressure external sealing and high-pressure internal sealing effects can be provided for the reciprocating motion of the piston rod, and the problem that the damper is easy to leak oil and the damping force generated by the damper is weakened or vanished is effectively solved. Before the dynamic sealing structure is used, the excessive flow area formed by the gap between the piston rod and the guide and the excessive flow area of the stretching normal through hole 21 on the piston are in the same order, so that the processing quality and consistency of related parts can seriously influence the stretching maximum damping force of a small part of the rear stroke when the damper stretches. The two dynamic sealing structures of the guide bearing can isolate high-pressure oil in the cavity I from entering the gap between the piston rod and the guide bearing, and prevent hydraulic oil entering the gap from entering the cavity II through the piston rod throttle 26 and the central oil through hole 25. Therefore, the invention eliminates the influence of the dimensional processing precision and consistency of related parts such as guide and the like on the maximum damping force of stretching, ensures the stability and consistency of the damping force, reduces the processing difficulty of parts and saves the cost.

The maximum damping force of the extension in the present invention is also affected by the depth of the orifice 26 in the piston rod from the end face of the guide (i.e., the end face of the guide that contacts the i-cavity) into the guide, the greater the depth of the orifice 26 from the end face of the guide into the guide, the greater the maximum damping force of the extension. When the thickness of the gasket between the oil cylinder and the bottom valve seat is larger, the guide is moved away from the bottom valve seat 12 under the same piston stroke, and the smaller the depth of the piston rod orifice which can enter the guide is, the smaller the stretching maximum damping force of the damper is; conversely, the smaller the thickness of the shim, the greater the maximum damping force of the extension. Therefore, the stretching maximum damping force of the damper can be adjusted and controlled within a certain range by changing the thickness of the gasket.

The pantograph damper disclosed by the invention can generate damping characteristics shown in the attached figure 1, well meets the service condition requirement of a pantograph, is simple in structure and easy to realize, and has the following advantages:

1) The invention cancels the adjusting structure of adjusting the maximum damping force by the nut, the spring and the valve plate in the prior art, and adopts the method of adjusting the maximum damping force by adding gaskets with different thicknesses. Simple and easy to operate and convenient to maintain.

2) The damper effectively realizes the functions of low-pressure external sealing and high-pressure internal sealing of the damper through structures such as guide sealing, piston sealing, gasket compensation and the like, and basically solves the problems that the damper is easy to leak oil and the damping force generated by the damper is weakened or vanished.

3) The damper makes full use of the dynamic sealing structure of the guide, can eliminate the influence of the dimensional machining precision and consistency of related parts such as the guide on the damping force, ensures the stability and consistency of the damping force, reduces the machining difficulty of the parts and saves the cost.

4) The magnitude of the maximum stretching damping force of the damper is mainly ensured by the stretching normal through hole 21 on the piston, the problems of damping force jumping and the like caused by valve system failure and clamping stagnation do not exist, and the consistency and stability of the damping force are ensured.

5) The damper is provided with an oil return hole 16 which is communicated with the cavity II between the first bottom valve compression valve 13 and the second bottom valve compression valve 14, so that the pressure difference on the two sides of the bottom valve and the damping force generated by the pressure difference are reduced, and the stability of the damping force generating process is ensured.

Drawings

Fig. 1 is a schematic diagram showing damping force requirements of a damper for a pantograph according to the present invention;

FIG. 2 is a schematic view of a damper structure according to an embodiment of the present invention;

FIG. 3 is a schematic view of the structure of a piston rod of a damper according to an embodiment of the present invention;

fig. 4 is a schematic view of a piston of a damper according to an embodiment of the present invention.

Fig. 5 is a schematic view of the structure of fig. 4, taken along the diagonal line and indicated by the circle in fig. 4.

Detailed Description

The invention will be further described with reference to the drawings and specific examples.

As shown in fig. 1, the tensile damping force and the compressive damping force of the damper for the pantograph according to the present invention are very asymmetric, and the damping force is required to be maintained at a relatively stable small damping force during the whole compression process, while the damping force is required to be maintained at a relatively stable small damping force during the most front stroke during the extension process, and the damping force is required to be rapidly increased during the most rear stroke, so that a peak value occurs.

As shown in fig. 2 to 5, a damper for a pantograph of the present embodiment includes: the hydraulic oil storage cylinder 8, the oil cylinder 7, the guide assembly, the piston rod assembly, the hydraulic oil 9 and the bottom valve assembly; the guide assembly comprises a guide 4 and a sealing structure thereof, wherein the sealing structure comprises two static sealing structures 3 and 5 arranged at the contact surface between the guide 4 and an oil storage cylinder 8 and the oil cylinder 7, and an O-shaped ring is adopted; two dynamic sealing structures 6 are arranged in a central hole which is in contact with the piston rod 1, and a check ring is adopted; the piston rod assembly comprises a piston rod 1, a baffle 24, a piston one-way valve 23, a piston assembly and a lock nut 18, wherein the piston assembly comprises a piston 22 and a guide ring and a check ring 20 arranged on the outer surface of the piston 22, the piston one-way valve 23 is fixed on the piston rod 1 by the lock nut 18, and the piston 22 and the lock nut 18 are fixed on the piston rod 1 through threaded connection; as shown in fig. 3, the piston rod 1 is provided with an oil through hole 25 and a plurality of orifices 26 at the center, the orifices 26 are progressively distributed along the axial direction of the piston rod 1, and the orifices 26 are progressively and completely covered by the guide 4 in the drawing process a-B shown in fig. 1; as shown in fig. 4 and 5, the piston 22 is provided with a circumferential compression orifice 19 and a tension constant through hole 21, and the tension constant through hole 21 is an inclined hole with a very short length, and the diameter thereof is determined by the maximum tension damping force; the piston check valve 23 is of a spring valve plate structure, is pressed by the baffle 24 and covers the compression throttle hole 19 on one side of the piston 22 close to the cavity I; the bottom valve assembly comprises a bottom valve seat 12, a gasket 11, a bottom valve stretching valve 10 and bottom valve compression valves 13 and 14, wherein the bottom valve seat 12 is provided with a stretching orifice 17, a compression orifice 15 and an oil return hole 16, the bottom valve stretching valve 10 is covered on the stretching orifice 17 of the bottom valve seat 12, which is close to the end face of the side of the II cavity, and the bottom valve compression valves 13 and 14 are covered on the compression orifice 15 of the bottom valve seat (12), which is close to the end face of the side of the III cavity. An oil return hole 16 leading to a cavity II is arranged between the two compression valve plates 13 and 14, and a gasket 11 is additionally arranged between the oil cylinder 7 and the bottom valve seat 12.

The two ends of the oil cylinder 7 are positioned, installed and sealed in the oil storage cylinder 8 through the guide 4 and the bottom valve seat 12, the guide 4 is provided with a central hole for supporting and guiding the piston rod 1, the guide 4, the oil cylinder 7, the piston 22 and the bottom valve seat 12 divide the oil storage cylinder 8 into a cavity I, a cavity II and a cavity III, the damping throttling and sealing device takes hydraulic oil 9 as a working medium, the piston rod 1 drives the piston 22 to reciprocate in the oil cylinder 7 under the action of external force, and the hydraulic oil 9 is forced to circularly flow in the cavity I, the cavity II and the cavity III, and generates damping force due to friction when passing through the damping hole and the valve system.

When the piston rod 1 stretches outwards, the pressure of the cavity I increases and the pressure of the cavity II decreases, so that the piston one-way valve 23 is closed, hydraulic oil 9 from the cavity I enters the cavity II through the normal through hole 21 on the piston 22 and enters the cavity II through the throttle hole 26 and the central oil through hole 25 on the piston rod 1; when the throttle hole 26 on the piston rod 1 is gradually covered by the guide 4, namely, the point A in the figure 1 is entered, the pressure in the cavity I is rapidly increased, and the stretching damping force is rapidly increased; when the throttle 26 on the piston rod 1 is entirely covered by the guide 4, the hydraulic oil 9 in the i chamber can only enter the ii chamber through the normal through hole 21 on the piston 22, and the tensile damping force reaches the maximum value, namely the point B in fig. 1. Simultaneously, as the piston rod 1 stretches outwards, the hydraulic oil 9 in the cavity II cannot be filled due to the occupied volume of the piston rod 1, the cavity II forms negative pressure, the bottom valve stretching valve 10 is opened, the bottom valve compression valves 13 and 14 are closed, and the hydraulic oil 9 enters the cavity II from the cavity III. Thus, this embodiment ensures that the front most stroke damping force remains a relatively stable, small damping force during stretching and the rear small stroke stretching force increases rapidly.

When the piston rod 1 is compressed inwards, the pressure of the cavity II is increased, the pressure of the cavity I is reduced, therefore, the piston check valve 23 is opened, hydraulic oil 9 can enter the cavity I from a plurality of compression orifices 19, and the hydraulic oil 9 can also enter the cavity I from the cavity II through the central oil through hole 25 and the orifices 26 on the piston rod 1 when the orifices 26 on the piston rod 1 gradually exit the guide 4; simultaneously, with the entering of the piston rod 1, redundant hydraulic oil 9 in the cavity II pushes up the bottom valve compression valves 13 and 14 to enter the cavity III. Wherein the opening pressure of the bottom valve compression valve 13 is larger than the piston check valve 23, and the compression damping force is mainly determined by the opening pressure of the bottom valve compression valve 13. In the invention, the bottom valve compression valves 13 and 14 are provided with two valve plates in total, the two step surfaces of one side of the bottom valve seat 12 close to the III cavity are covered, and the oil return hole 16 leading to the II cavity is arranged between the two valve plates, so that the pressure difference between the two valve plates and the damping force generated by the pressure difference are reduced, and the damping force generation process is stable. Thus, this embodiment ensures a relatively stable, low damping force throughout the compression process.

In the embodiment, the working surface of the piston rod 1 is treated by adopting a special metal ceramic spraying process, the guide 4 is provided with two O-shaped ring static sealing structures 3 and 5 and two check ring dynamic sealing structures 6, so that effective low-pressure external sealing and high-pressure internal sealing effects can be provided for the reciprocating motion of the piston rod 1, the problem that the damper is prone to oil leakage and the damping force generated by the problem is weakened or vanished is effectively solved, and the service life is greatly prolonged. When the dynamic seal structure 6 is not used, the processing quality and consistency of the relevant parts can seriously affect the tensile maximum damping force at the point B in fig. 1 because the overflow area formed by the gap between the piston rod 1 and the guide 4 and the overflow area of the piston normal through hole 21 are in the same order. In this embodiment, after the orifice 26 on the piston rod 1 is covered by the guide 4, the dynamic sealing structure 6 of the guide 4 can isolate the high-pressure oil 9 in the cavity i from entering the gap between the piston rod 1 and the guide 4, and prevent the oil from entering the cavity ii through the orifice 26 and the central oil through hole 25, thereby eliminating the influence of the dimensional processing precision and consistency of related parts such as the guide 4 on the damping force, ensuring the stability and consistency of the damping force, reducing the difficulty of part processing, and saving the cost.

In addition to the diameter dimension of the tensile normal through hole 21, the tensile maximum damping force in the present invention is also affected by the depth of the orifice 26 in the piston rod 1 from the end face of the guide (the face of the guide adjacent to the I-cavity) into the guide 4, the greater the depth the piston rod can enter the guide 4 from the end face of the guide, the greater the tensile maximum damping force. The magnitude of the tensile maximum damping force is adjusted and controlled within a certain range by changing the thickness of the spacer 11 in the present embodiment. When the thickness of the gasket 11 between the oil cylinder 7 and the bottom valve seat 12 is larger, the depth of the piston rod orifice 26 entering the guide 4 is smaller under the same stroke, and the stretching maximum damping force is smaller; conversely, the greater the tensile maximum damping force.

Therefore, the damper for the pantograph, which is described in the embodiment, can generate damping performance requirements as shown in the attached figure 1, meet the use requirements of the pantograph in the process of lifting, collecting and lowering the pantograph, and can effectively adjust the maximum damping force of stretching by arranging a gasket with a certain thickness. And the influence of the dimensional processing precision and consistency of related spare and accessory parts on the damping force can be eliminated, the problems that the damper is easy to leak oil and the damping force is weakened or vanished are effectively solved, the structure is simple, the damping force is easy to adjust, the processing difficulty is reduced, the consistency is improved, and the stability of the damping force is ensured.

In a specific embodiment, there are 7 total orifices 26 in this embodiment, in which the first group of three stepped orifices are arranged in sequence in the axial direction as shown in fig. 3, and the diameter of the large diameter section is 2mm, the small diameter section is directly connected to the oil hole 25, and the diameter of the small diameter section is 0.8mm. The second group of stepped orifices are also three stepped orifices arranged in sequence in the axial direction, but the radial positions of the second group of stepped orifices and the first group of stepped orifices are different from each other. And the six step-shaped orifices of the first group and the second group are distributed in a staggered way in the axial direction as a whole. Furthermore, a cylindrical orifice of diameter 2mm is distributed over the piston rod.

As can be seen from fig. 4, eleven compression orifices 19 of uniform size are through holes in the direction of movement of the piston, a through groove for communicating each compression orifice 19 is provided in the end face of the piston adjacent to the chamber i, the piston check valve 23 covers all the through groove and the compression orifices 19 from the chamber i 81, and the piston check valve 23 only allows hydraulic oil to flow from the chamber ii to the chamber i through a plurality of compression orifices 19, but does not allow hydraulic oil to flow from the chamber i to the chamber ii through a plurality of compression orifices 19. But the piston is provided with an inclined hole channel, namely a stretching normal through hole 21, one end of the stretching normal through hole 21 is communicated with the cavity I through a groove arranged on the radial inner side of the compression throttle hole 19, and the other end of the stretching normal through hole is communicated with the inside of the through hole of the twelfth compression throttle hole 19, so that hydraulic oil can flow from the cavity I into the cavity II in the outward stretching process of the piston rod.

In the damper, during the stretching process of the piston rod, hydraulic oil flows into the cavity II from the cavity I and then flows into the cavity II from the cavity III; in the compression process of the piston rod, hydraulic oil flows into the cavity I from the cavity II, and then flows into the cavity III from the cavity II.

During compression of the piston rod, when hydraulic oil flows from the second chamber into the first chamber, the hydraulic oil overcomes the spring force from the plurality of through-hole-shaped compression orifices 19 to jack the piston check valve 23, and the hydraulic oil flows from the plurality of compression orifices 19 and the piston check valve 23 into the first chamber through the second chamber. In addition, when the throttle 26 is partially or completely exposed from the guide during compression of the piston rod, hydraulic oil also enters the throttle 26 from the chamber II through the oil through hole 25 and is discharged to the chamber I. In addition, as can be seen in fig. 2, the damper further comprises a skeleton oil seal 2 arranged outside the guide in the axial direction.

The foregoing is a further detailed description of the invention in connection with specific preferred embodiments, and is not intended to limit the practice of the invention to such description. It will be apparent to those skilled in the art that several simple deductions and substitutions can be made without departing from the spirit of the invention, and these are considered to be within the scope of the invention.

Claims

1. A pantograph comprises a damper, a bottom frame, a pantograph lifting device, a lower arm, a pantograph assembly, a lower guide rod, an upper arm, an upper guide rod, a pantograph head, a sliding plate and a pantograph lifting air source control valve plate,

the damper comprises an oil storage cylinder (8), an oil cylinder (7), a guide (4), a piston rod (1), a piston (22), hydraulic oil (9) and a bottom valve seat (12), wherein the damper takes the hydraulic oil (9) as a working medium, two ends of the oil cylinder (7) are positioned and installed in the oil storage cylinder (8) through the guide (4) and the bottom valve seat (12), the guide (4) is provided with a central hole for supporting and guiding the piston rod (1), and the piston rod (1) drives the piston (22) to reciprocate in the oil cylinder under the action of external force; the guide (4), the oil cylinder (7), the piston (22) and the bottom valve seat (12) divide the oil storage cylinder (8) into an I cavity (81), an II cavity (82) and an III cavity (83), a space between the guide (4) and the piston (22) in the radial direction and the oil cylinder (7) in the axial direction is the I cavity, a space between the bottom valve seat (12) and the piston (22) in the radial direction and the oil cylinder (7) in the axial direction is the II cavity, the space between the outer side of the oil cylinder (7) and the inner side of the oil storage cylinder (8) in the radial direction is the III cavity, a channel through which hydraulic oil can flow between the I cavity and the II cavity is arranged on the piston (22), and a channel through which the hydraulic oil can flow between the II cavity and the III cavity is arranged on the bottom valve seat (12), and the hydraulic oil cannot flow between the I cavity and the III cavity under the condition that the hydraulic oil does not leak from the guide (4). When the piston rod stretches outwards, hydraulic oil enters the cavity II from the cavity I and the cavity III, when the piston rod compresses inwards, hydraulic oil enters the cavity I and the cavity III from the cavity II, an oil through hole (25) is arranged in the center of the piston rod (1), the oil through hole (25) is a blind hole arranged in the piston rod, the opening of the blind hole is communicated with the cavity II, a plurality of orifices (26) with one ends communicated with the oil through hole (25) are further arranged on the piston rod (1), the other ends of the orifices (26) face to the opening outside the piston rod, the openings of the orifices can be exposed in the cavity I and/or covered by the guide (4), at least two orifices (26) are distributed at different positions in the axial direction of the piston rod (1), and the orifices (26) are gradually covered by the guide (4) in the process of stretching outwards of the piston rod, and the orifices (26) are gradually exposed in the cavity I in the process of compressing inwards of the piston rod; a gasket (11) is arranged between the axial inner end of the oil cylinder (7) and the bottom valve seat (12) and used for adjusting the stretching maximum damping force in the outward stretching stroke of the piston rod.

2. The pantograph according to claim 1, characterized in that two dynamic sealing structures (6) for dynamic sealing the piston rod are provided at the central hole of the guide (4), and that the two dynamic sealing structures (6) are provided at different positions in the axial direction of the central hole, both dynamic sealing structures (6) being gurley circles.

3. A pantograph according to claim 2, characterized in that a central hole communicating with the guide (4) and the iii-chamber (83) and for preventing hydraulic oil from leaking to the outside of the damper is provided at the end of the guide (4) remote from the piston (22), and that both dynamic seal structures (6) are arranged on the same side of the oil return leak hole (27) in the axial direction of the central hole.

4. A pantograph according to any one of claims 1 to 3 wherein the pad is a copper pad and the thickness of the pad is 0.5 to 3mm.

5. The pantograph of claim 4, wherein the spacer has a thickness of 1-2 mm.

6. A pantograph according to any one of claims 1-3, characterized in that the piston (22) is provided with a plurality of circumferentially arranged compression orifices (19) and at least one tensile constant through hole (21), the compression orifices (19) are in a through hole shape in the axial direction of the piston (22), and a piston check valve (23) and a baffle plate (24) are arranged on one side of the piston (22) close to the i cavity, and the piston (22) and the piston check valve (23) are both fixed on the piston rod (1) by a lock nut (18) and threads on the piston rod, the piston check valve (23) is in a spring valve plate structure, and is pressed by the baffle plate (24) and covers the compression orifices (19) on one side of the piston (22) close to the i cavity, so that when the piston rod is stretched outwards, the piston check valve (23) is pressed and covers the compression orifices (19) without allowing hydraulic oil to flow from the i cavity into the ii cavity through the piston check valve (23) and the plurality of compression orifices (19), and when the piston rod is compressed inwards, the piston check valve (23) can be opened from the i cavity and the piston check valve (23) by the spring valve (23); the stretching normal through hole (21) is an inclined hole, one end of the stretching normal through hole (21) is directly or indirectly communicated with the cavity I, and the other end of the stretching normal through hole is communicated with a certain compression throttle hole (19), so that hydraulic oil flows into the cavity II from the cavity I through the stretching normal through hole (21) and the compression throttle hole (19) communicated with the stretching normal through hole (21) when the piston rod stretches outwards.

7. A pantograph according to any one of claims 1 to 3, wherein the base valve seat (12) is provided with a stretching orifice (17) and a compression orifice (15), and the end face of the stretching orifice (17) close to the side of the cavity ii is covered with a base valve stretching valve (10) so that hydraulic oil can flow from the cavity iii to the cavity ii through the stretching orifice (17) and the base valve stretching valve (10) when the piston rod is stretched; a first bottom valve compression valve (13) and a second bottom valve compression valve (14) are covered on the end surface of one side of the compression throttle hole (15) away from the II cavity, so that hydraulic oil can flow into the III cavity from the II cavity through the compression throttle hole (15) and the two bottom valve compression valves when the piston rod is compressed inwards; the first bottom valve compression valve (13) and the second bottom valve compression valve (14) are arranged at the step of the bottom valve seat (12) at one side far away from the II cavity, the first bottom valve compression valve (13) and the second bottom valve compression valve (14) are covered on two step surfaces of the bottom valve seat (12), so that an axial gap is formed between the first bottom valve compression valve (13) and the second bottom valve compression valve (14), the bottom valve seat (12) is further provided with an oil return hole (16), one end of the oil return hole (16) is communicated with the axial gap, and the other end of the oil return hole is communicated with the II cavity, so that hydraulic oil can flow back into the II cavity from the axial gap when the piston rod is compressed inwards, and a relatively stable small damping force is kept in the whole process of inward compression of the piston rod.

8. A pantograph according to any one of claims 1 to 3, wherein the guide (4) is provided with a first static seal structure (3) and a second static seal structure (5) at the contact surface with the reservoir cylinder (8) and the cylinder (7), respectively, and the first static seal structure (3) and the second static seal structure (5) are both O-rings.

9. A pantograph according to any one of claims 1 to 3, characterised in that the outer surface of the piston (22) is in clearance fit with the inner surface of the cylinder (7), and that a guide ring and a glaring (20) are provided on the outer surface of the piston (22).