A single-rod symmetrical hydraulic cylinder with a rod end and stepped buffer

Abstract

The present invention discloses a single-rod symmetrical hydraulic cylinder with a rod end and a stepped buffer. The base and the rear end cover are fixedly connected, and the two sides of the base are respectively provided with oil ports A and T; the front and rear ends of the cylinder barrel are respectively connected with the front end cover and the base, and the rear end of the front end cover is provided with an annular boss, which is connected to the inner side wall of the annular cylinder barrel, and the front end cover is provided with an oil port B; the piston rod can be slidably connected to the inner side wall of the outer shell, and the front end of the piston rod passes through the front end cover; the oil pipe in the cylinder is located inside the piston rod and is fixedly connected to the outer shell, the piston rod bracket is fixedly connected to the front end of the piston rod, and a hysteresis telescopic displacement sensor is provided at the rear end, and the hysteresis telescopic displacement sensor is fixedly connected to the outer shell. The hydraulic cylinder of the present invention requires a small installation space, and moves normally within the normal working stroke. Once an emergency occurs and exceeds the normal working stroke, it immediately enters the buffer state to avoid collision between the piston rod and the front end cover.

Description

Technical Field

[0001] The invention belongs to the field of hydraulic servo actuators, and in particular relates to a single-rod symmetrical hydraulic cylinder with a rod end having a stepped buffer. Background Art

[0002] The swing table is a performance test equipment used to simulate spatial motion. It is mainly driven and controlled by a hydraulic servo system. Due to the spatial structure limitations of the swing table, the commonly used double-rod symmetrical hydraulic cylinder is limited in use. When a single-rod asymmetrical cylinder is used for control, the cross-sectional area of ​​the working chamber is not equal, which has a greater impact on the control performance of the swing table. At the same time, although the swing table has electrical protection measures, the inertia of the swing table is large. In an emergency, the hydraulic cylinder will not stop moving immediately, and the piston and cylinder head of the hydraulic cylinder will mechanically collide and produce an impact.

[0003] In general, the inertia of the target object driven and controlled by the hydraulic cylinder in the hydraulic servo system is relatively small, and the safety protection function can be achieved by using electrical protection measures. Therefore, the single-rod symmetrical hydraulic cylinder used rarely considers the emergency buffer function. At the same time, when considering the emergency buffer function, the existing single-rod symmetrical hydraulic cylinder generally connects a spring in series with the rod end or the rodless end of the hydraulic cylinder to achieve the purpose of buffering, but this will cause problems such as complex structure, increased diameter of the hydraulic cylinder, and introduction of spring nonlinear factors that affect the servo control accuracy. Summary of the invention

[0004] In order to solve the problems in the background technology, the purpose of the present invention is to provide a single-rod symmetrical hydraulic cylinder with a rod end stepped buffer, so as to solve the problem that the double-rod symmetrical cylinder cannot be used due to limited space on the swing platform and the piston and cylinder cover of the hydraulic cylinder may collide mechanically in an emergency.

[0005] The technical solution adopted by the present invention is as follows:

[0006] The symmetrical hydraulic cylinder includes an outer shell, a piston rod, an inner oil pipe, a piston rod bracket and a hysteresis telescopic displacement sensor; the piston rod is connected to the inner wall of the outer shell in a manner that it can slide back and forth, the inner oil pipe is located inside the piston rod and is fixedly connected to the outer shell, the front end of the piston rod bracket is fixedly connected to the front end of the piston rod, the rear end of the piston rod bracket is provided with a hysteresis telescopic displacement sensor, the rear end of the hysteresis telescopic displacement sensor is connected to the outer shell, and the hysteresis telescopic displacement sensor is used to measure the displacement of the piston rod bracket and the piston rod.

[0007] The housing comprises a rear end cover, a base, an annular cylinder and a front end cover; the rear end of the base is fixedly connected to the rear end cover, and oil ports A and T are respectively provided on both sides of the base; the front and rear ends of the cylinder are respectively fixedly connected to the rear end of the front end cover and the front end of the base, and an annular boss is provided at the rear end of the front end cover, and the annular boss on the front end cover is connected to the inner side wall of the annular cylinder, and an oil port B is provided on the front end cover;

[0008] The piston rod is located inside the cylinder, the rear end of the piston rod is connected to the inner wall of the cylinder in a forward and backward sliding manner, the front part of the piston rod is connected to the inner wall of the front end cover in a forward and backward sliding manner, and the front end of the piston rod passes through the front end cover; the outer wall of the front end of the oil pipe in the cylinder is sealed and connected to the inner wall of the piston rod, and the rear end of the oil pipe in the cylinder is fixedly connected to the front end of the base through a flange; the piston rod bracket is located inside the oil pipe in the cylinder, the rear end of the bracket is connected to the magnetic ring of the hysteresis telescopic displacement sensor, the rear end of the hysteresis telescopic displacement sensor is fixedly installed on the base, and the front end of the hysteresis telescopic displacement sensor passes into the interior of the piston rod bracket.

[0009] The inner wall of the piston rod and the inner wall of the oil pipe in the cylinder together form an inner working chamber, and the bottom of the inner working chamber is connected to the oil port A; the front end cover wall, the outer wall of the piston rod and the inner wall of the cylinder barrel form an outer working chamber, and the outer working chamber is connected to the oil port B; the front end of the base, the rear end of the piston rod, the outer wall of the oil pipe in the cylinder and the inner wall of the cylinder barrel together form an oil replenishing chamber, and the oil replenishing chamber is connected to the oil port T; the oil ports A, B and T are all connected to the external oil tank.

[0010] The outer wall of the rod end of the piston rod has a three-step structure, and the step structure is a first step, a second step and a third step from front to back; the annular boss of the front end cover cooperates with the second step or the third step of the piston rod to form a gap throttling, thereby realizing the first and second step buffering of the piston rod, preventing the piston rod and the front end cover from colliding under abnormal use.

[0011] The front and rear ends of the piston rod bracket are each provided with three rows of circular through holes with equal spacing, and the circular through holes of the piston rod bracket allow oil to enter the interior of the piston rod bracket, thereby allowing the oil to fill the inner working chamber.

[0012] The cross-sectional area of ​​the inner working chamber is equal to the cross-sectional area of ​​the annular outer working chamber. The lengths of the secondary step and the tertiary step are the primary buffer stroke L2 and the secondary buffer stroke L3 respectively; the distance from the annular boss of the front end cover to the front end of the secondary step is taken as the normal working stroke L1; when the symmetrical hydraulic cylinder is in normal use, the normal working stroke L1>primary buffer stroke L2>secondary buffer stroke L3.

[0013] The hydraulic cylinder of the present invention requires a small installation space and moves normally within a normal working stroke. Once an emergency occurs and the normal working stroke is exceeded, the hydraulic cylinder immediately enters a buffer state to avoid collision between the piston rod and the front end cover.

[0014] The beneficial effects of the present invention are:

[0015] 1. The present invention provides three rows of equally spaced circular holes at the front and rear ends of the piston rod internal bracket, so that the oil enters the interior of the piston rod internal bracket, ensuring that the cross section of the inner working chamber is always circular. Therefore, the effect of a single-rod symmetrical hydraulic cylinder can be achieved by only making the circular cross-sectional area of ​​the inner working chamber equal to the annular cross-sectional area of ​​the outer working chamber, thereby reducing the requirement for installation space.

[0016] 2. Without affecting the normal operation of the hydraulic cylinder, by setting steps with lengths of L2 and L3 respectively at the rod end of the piston rod, in an emergency, they cooperate with the annular boss of the front cover to form gap throttling, realize primary and secondary buffering, and improve the safety of the single-rod symmetrical hydraulic cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a cross-sectional view of a single-rod symmetrical hydraulic cylinder of the present invention.

[0018] Figure 2 It is a partial enlarged view of the single-rod symmetrical hydraulic cylinder of the present invention during step buffering.

[0019] In the figure: 1-bottom end cover; 2-base; 3-piston rod; 4-oil pipe in cylinder; 5-cylinder barrel; 6-front end cover; 7-piston rod bracket; 8-hysteresis telescopic displacement sensor; 9-inner working chamber; 10-outer working chamber; 11-oil replenishing chamber. DETAILED DESCRIPTION

[0020] The present invention is described in detail below in conjunction with specific implementation cases. The following implementation cases will help those skilled in the art to further understand the present invention, but will not limit the present invention in any form.

[0021] like Figure 1 As shown, the hydraulic cylinder includes a shell, a piston rod 3, an inner oil pipe 4, a piston rod bracket 7 and a hysteresis telescopic displacement sensor 8; the piston rod 3 is connected to the inner wall of the shell slidably forward and backward, the inner oil pipe 4 is located inside the piston rod 3 and is fixedly connected to the shell, the front end of the piston rod bracket 7 is fixedly connected to the front end of the piston rod 3 by bolts, the rear end of the piston rod bracket 7 is provided with a hysteresis telescopic displacement sensor 8, the rear end of the hysteresis telescopic displacement sensor 8 is connected to the shell by bolts, and the hysteresis telescopic displacement sensor 8 is used to measure the displacement of the piston rod bracket 7 and the piston rod 3.

[0022] The housing includes a rear end cover 1, a base 2, an annular cylinder 5 and a front end cover 6; the rear end of the base 2 is fixedly connected to the rear end cover 1 by bolts, and oil ports A and T are respectively provided on both sides of the base 2; the front and rear ends of the cylinder 5 are respectively fixedly connected to the rear end of the front end cover 6 and the front end of the base 2 by bolts, and an annular boss is provided at the rear end of the front end cover 6, and the annular boss on the front end cover 6 is connected to the inner side wall of the annular cylinder 5, and an oil port B is provided on the front end cover 6;

[0023] The piston rod 3 is located inside the cylinder 5, and the rear end of the piston rod 3 can be slidably connected to the inner wall of the cylinder 5 in a sealed manner. The rear end of the piston rod 3 and the inner wall of the cylinder 5 are slidably sealed to form a piston, and the front part of the piston rod 3 can be slidably connected to the inner wall of the front end cover 6 in a sealed manner, and the front end of the piston rod 3 passes through the front end cover 6; the outer wall of the front end of the in-cylinder oil pipe 4 is sealed to the inner wall of the piston rod 3, and the rear end of the in-cylinder oil pipe 4 is fixedly connected to the front end of the base 2 through a flange; the piston rod bracket 7 is located inside the in-cylinder oil pipe 4, and the rear end of the bracket 7 is connected to the magnetic ring of the hysteresis telescopic displacement sensor 8, and the rear end of the hysteresis telescopic displacement sensor 8 is fixedly installed on the base 2, and the front end of the hysteresis telescopic displacement sensor 8 passes into the interior of the piston rod bracket 7, and the piston rod bracket 7 and the hysteresis telescopic displacement sensor 8 can move relative to each other back and forth.

[0024] The inner wall of the piston rod 3 and the inner wall of the oil pipe 4 in the cylinder together form an inner working chamber 9, and the bottom of the inner working chamber 9 is connected to the oil port A; the wall surface of the front end cover 6, the outer wall of the piston rod 3 and the inner wall of the cylinder 5 form an outer working chamber 10, and the outer working chamber 10 is connected to the oil port B; the front end of the base 2, the rear end of the piston rod 3, the outer wall of the oil pipe 4 in the cylinder and the inner wall of the cylinder 5 together form an oil replenishing chamber 11, and the oil replenishing chamber 11 is connected to the oil port T; the oil ports A, B and T are all connected to the external oil tank.

[0025] The outer wall of the rod end of the piston rod 3 has a three-step structure, and the step structure is a first step, a second step and a third step from front to back; the front end cover 6 is located at the step structure position of the piston rod 3, and the annular boss of the front end cover 6 can cooperate with the second step or the third step of the piston rod 3 to form a gap throttling, thereby realizing the first and second step buffering of the piston rod 3, and preventing the piston rod 3 and the front end cover 6 from colliding under abnormal use.

[0026] In the specific implementation, there is a gap between the inner wall of the annular boss and the outer wall of the piston rod 3, so that the hydraulic oil flows into the outer working chamber 10 through the oil port B; the wall thickness of the piston rod 3 at the first step, the second step and the third step increases successively, so that the distance between the outer wall of the piston rod 3 and the inner wall of the annular boss decreases successively. The distance between the outer wall of the piston rod 3 and the inner wall of the annular boss at the first step is larger, so that the flow area between the outer wall of the piston rod 3 and the inner wall of the annular boss is larger, ensuring the normal movement of the piston rod 3. The distance between the outer wall of the piston rod 3 and the inner wall of the annular boss at the second step and the third step is smaller, so that the flow area between the outer wall of the piston rod 3 and the inner wall of the annular boss is reduced, so that the pressure in the outer working chamber 10 gradually increases, the movement speed of the piston rod 3 is reduced, and the buffering of the piston rod 3 is achieved.

[0027] Three rows of equally spaced circular through holes are provided at the front and rear ends of the piston rod bracket 7. The circular through holes of the piston rod bracket 7 allow oil to enter the interior of the piston rod bracket 7, thereby filling the inner working chamber 9 with oil to ensure that the cross-section of the inner working chamber 9 is circular after being filled with oil.

[0028] The maximum cross-sectional area of ​​the circular inner working chamber 9 is equal to the maximum cross-sectional area of ​​the annular outer working chamber 10 .

[0029] In a specific implementation, the maximum cross-sectional area of ​​the inner working chamber 9 is equal to the cross-sectional area of ​​the internal cavity of the piston rod 3; the maximum cross-sectional area of ​​the outer working chamber 10 is equal to the difference between the internal cavity area of ​​the cylinder 5 and the maximum cross-sectional area of ​​the piston rod 3 at the first step.

[0030] The lengths of the secondary step and the tertiary step are the primary buffer stroke L2 and the secondary buffer stroke L3 respectively; the distance from the annular boss of the front end cover 6 to the front end of the secondary step is taken as the normal working stroke L1; when the symmetrical hydraulic cylinder is in normal use, the normal working stroke L1>primary buffer stroke L2>secondary buffer stroke L3.

[0031] The single-rod symmetrical hydraulic cylinder moves normally within the normal working stroke L1. When it exceeds the normal working stroke, the steps with lengths L2 and L3 will cooperate with the annular boss of the front end cover 6 to form a gap throttling, such as Figure 2 As shown, the flow area between the outer wall of the piston rod 3 and the inner wall of the annular boss gradually decreases, so that the pressure of the outer working chamber 10 gradually increases, thereby causing the movement speed of the piston rod 3 to gradually drop to 0, achieving primary and secondary buffering, and avoiding collision between the piston rod 3 and the front end cover 6.

[0032] When oil is supplied from oil port A, piston rod 3 drives piston rod bracket 7 to extend together, oil port B discharges oil, and oil port T replenishes oil from the oil tank; when oil is supplied from oil port B, piston rod 3 drives piston rod bracket 7 to retract together, oil port A discharges oil, and oil port T discharges oil to the oil tank.

[0033] The above embodiments are only used to illustrate the present invention, but not to limit the present invention. Ordinary technicians in the relevant technical field can make various changes without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also belong to the scope of the present invention.

Claims

1. A single-rod symmetrical hydraulic cylinder with a rod end step buffer, characterized in that: The invention comprises a housing, a piston rod (3), an in-cylinder oil pipe (4), a piston rod support (7) and a magnetostrictive displacement sensor (8); the piston rod (3) is connected to the inner side wall of the housing in a manner that it can slide back and forth; the in-cylinder oil pipe (4) is located inside the piston rod (3) and is fixedly connected to the housing; the front end of the piston rod support (7) is fixedly connected to the front end of the piston rod (3); the rear end of the piston rod support (7) is provided with a magnetostrictive displacement sensor (8); the rear end of the magnetostrictive displacement sensor (8) is connected to the housing; the magnetostrictive displacement sensor (8) is used to measure the displacement of the piston rod support (7) and the piston rod (3); The housing comprises a rear end cover (1), a base (2), an annular cylinder barrel (5) and a front end cover (6); the rear end of the base (2) is fixedly connected to the rear end cover (1), and the two sides of the base (2) are respectively provided with an oil port A and an oil port T; the front and rear ends of the cylinder barrel (5) are respectively fixedly connected to the rear end of the front end cover (6) and the front end of the base (2), the rear end of the front end cover (6) is provided with an annular boss, the annular boss on the front end cover (6) is connected to the inner side wall of the annular cylinder barrel (5), and the front end cover (6) is provided with an oil port B; The piston rod (3) is located inside the cylinder (5), the rear end of the piston rod (3) is connected to the inner wall of the cylinder (5) in a manner that it can slide forward and backward, the front part of the piston rod (3) is connected to the inner wall of the front end cover (6) in a manner that it can slide forward and backward, and the front end of the piston rod (3) passes through the front end cover (6); the outer wall of the front end of the in-cylinder oil pipe (4) is sealedly connected to the inner wall of the piston rod (3), and the rear end of the in-cylinder oil pipe (4) is fixedly connected to the front end of the base (2) through a flange; the piston rod bracket (7) is located inside the in-cylinder oil pipe (4), the rear end of the piston rod bracket (7) is connected to the magnetic ring of the hysteresis telescopic displacement sensor (8), the rear end of the hysteresis telescopic displacement sensor (8) is fixedly mounted on the base (2), and the front end of the hysteresis telescopic displacement sensor (8) passes through the inside of the piston rod bracket (7); The inner wall of the piston rod (3) and the inner wall of the oil pipe (4) in the cylinder together form an inner working chamber (9), and the bottom of the inner working chamber (9) is connected to the oil port A; the wall surface of the front end cover (6), the outer wall of the piston rod (3) and the inner wall of the cylinder barrel (5) together form an outer working chamber (10), and the outer working chamber (10) is connected to the oil port B; the front end of the base (2), the rear end of the piston rod (3), the outer wall of the oil pipe (4) in the cylinder and the inner wall of the cylinder barrel (5) together form an oil replenishing chamber (11), and the oil replenishing chamber (11) is connected to the oil port T; the oil ports A, B and T are all connected to an external oil tank; The piston rod (3) has an outer wall of a rod end in a three-step structure, the step structure being a first step, a second step and a third step from front to back; the annular boss of the front end cover (6) cooperates with the second step or the third step of the piston rod (3) to form a gap throttling, thereby achieving a first-level buffer and a second-level buffer of the piston rod (3), thereby preventing the piston rod (3) and the front end cover (6) from colliding in an abnormal use state; The lengths of the secondary step and the tertiary step are the primary buffer stroke L2 and the secondary buffer stroke L3 respectively; the distance from the annular boss of the front end cover (6) to the front end of the secondary step is taken as the normal working stroke L1; when the symmetrical hydraulic cylinder is in normal use, the normal working stroke L1>the primary buffer stroke L2>the secondary buffer stroke L3.

2. A single-rod symmetrical hydraulic cylinder with a rod end step buffer according to claim 1, characterized in that: The front and rear ends of the piston rod support (7) are each provided with three rows of circular through holes at equal intervals, and the circular through holes of the piston rod support (7) allow oil to enter the interior of the piston rod support (7), thereby allowing the oil to fill the inner working chamber (9).

3. A single-rod symmetrical hydraulic cylinder with a rod end step buffer according to claim 1, characterized in that: The cross-sectional area of ​​the inner working chamber (9) is equal to the cross-sectional area of ​​the annular outer working chamber (10).

Images