An actuator cylinder whose output pressure is proportional to stroke

Abstract

The present application relates to the technical field of wheel brake, particularly relates to an output pressure proportional to stroke actuating cylinder, which comprises a push rod, a nut, a piston, a cylinder, an oil cup, a sealing ring, a shell, a pressure regulating spring, a small piston, a buffer spring, a spring seat and an exhaust nozzle assembly, the push rod is connected with the piston through threads, the nut is used for locking, the exhaust nozzle assembly is installed in the radial threaded hole of the push rod, the piston is installed in the cylinder, the sealing ring is installed in the lower installation groove in the middle of the outer circle of the piston, the cylinder is connected with the shell through threads, the oil cup is sleeved on the outer cylinder, the upper end of the small piston is inserted into the axial hole in the lower end of the piston, the pressure regulating spring is sleeved on the outer circle of the small piston, the spring seat is installed at the bottom of the cavity of the shell, the buffer spring is sleeved on the spring seat, the moving distance of the small piston is proportional to the displacement of the piston and inversely proportional to the stiffness of the pressure regulating spring, the input pressure is proportional to the piston stroke during braking, and the steering force is moderate.

Description

Technical Field

[0001] This invention relates to the field of wheel brake technology, and in particular to an actuator whose output pressure is proportional to its stroke. Background Technology

[0002] The actuator, a crucial component of the brake system, is used in the helicopter wheel brake system. Installed under the helicopter's foot pedals, it converts the force applied by the pilot to the brake pedals into hydraulic pressure. This output pressure is transmitted through system piping to the brake distribution valve, controlling the valve's output braking pressure to enable the helicopter to taxi, turn, and stop on the ground. A typical utility helicopter is equipped with one brake distribution valve, four actuators, and four brake pedals, one for the driver's left foot and one for the co-pilot's right foot. The brake distribution valve has four control pressure input ports, which are connected to the output ports of the four actuators via piping. The hydraulic fluid output from the actuators enters the four brake control chambers of the brake distribution valve. The brake distribution valve has one system pressure input port and two brake pressure output ports. The two brake pressure output ports of the brake distribution valve are connected to the left and right wheel brake systems, respectively. When the helicopter needs to taxi and turn on the ground, the pilot or co-pilot applies different forces to the left and right brake pedals with their feet. This results in different pressures from the left and right actuators, and the brake distribution valve outputs different brake pressures from its two brake pressure output ports, causing the left and right wheels to rotate at different speeds, thus achieving the turn. When braking is required, the pilot or co-pilot simultaneously presses the left and right brake pedals with both feet. The brake distribution valve then outputs the same maximum brake pressure from its two brake pressure output ports, bringing the helicopter to a stop.

[0003] When applying the wheel brakes, the pilot depresses the treadle, requesting the actuator to output 6 MPa pressure. Pilots reported that the brakes were too stiff; with only a small depressor stroke, the foot hadn't reached the optimal force application point before the actuator outputted high pressure, making it difficult to depress the pedal and requiring significant operational force. A review of similar products revealed this problem in all of them. Controlling the output pressure of the actuator within its specified stroke is a technical problem that needs to be solved. Summary of the Invention

[0004] To address the problems mentioned in the background section, this invention provides an actuator whose output pressure is proportional to its stroke, thus solving the problems of excessively stiff braking and high operating force.

[0005] This invention discloses the following technical solution: an actuating cylinder whose output pressure is proportional to its stroke, comprising a push rod, a nut, a piston, a cylinder, an oil cup, a sealing ring, a housing, a pressure regulating spring, a small piston, a buffer spring, a spring seat, and an exhaust nozzle assembly. The push rod and the piston are connected by threads and locked with a nut. The radial threaded hole of the push rod communicates with the axial exhaust hole of the piston. The exhaust nozzle assembly is installed in the radial threaded hole of the push rod. The piston is installed in the cylinder and is limited by a shoulder on the upper part of the piston. A sealing ring is installed in a mounting groove near the lower center of the outer circumference of the piston. The sealing ring is located between the piston and the cylinder. Between them, the cylinder is connected to the shell by a threaded connection, the oil cup is sleeved on the outside of the cylinder, and the upper and lower end faces of the oil cup abut against the boss end face of the cylinder and the end face of the shell, respectively. The small piston has a cavity inside with an open top and a sealed bottom. The upper end of the small piston is inserted into the axial hole at the lower end of the piston. The pressure adjusting spring is sleeved on the outer circumference of the small piston, and the upper and lower ends of the pressure adjusting spring abut against the lower end face of the piston and the bottom boss end face of the small piston, respectively. The spring seat is installed at the bottom of the cavity of the shell, and the buffer spring is sleeved on the spring seat. The upper and lower ends of the buffer spring abut against the bottom boss end face of the small piston and the bottom boss end face of the spring seat, respectively.

[0006] Furthermore, a nozzle assembly is installed in the radial mounting hole at the bottom of the housing;

[0007] Furthermore, sealing elements are provided on both the upper and lower sides between the cylinder and the oil cup;

[0008] Furthermore, the push rod is hinged to the brake pedal;

[0009] Furthermore, a spherical bearing is installed at the bottom of the housing;

[0010] Furthermore, the piston is provided with a radial exhaust hole near the shoulder, which is connected to the inner cavity of the cylinder. Oil passage holes are distributed around the middle of the piston, and a radial hole is provided in the middle of the cylinder, which is connected to the inner cavity of the oil cup.

[0011] Beneficial effects: Compared with the prior art, the actuating cylinder of the present invention, whose output pressure is proportional to the stroke, works in conjunction with the action of the cylinder body, oil cup, housing, buffer spring and exhaust nozzle assembly through the pressure regulating spring set between the piston and the small piston. When the operating force of the brake pedal is transmitted to the piston, the movement distance of the small piston is proportional to the displacement of the piston and inversely proportional to the stiffness of the pressure regulating spring. When the pedal is pressed to the optimal force state, the displacement of the piston reaches the maximum stroke, and the output pressure of the high pressure chamber reaches the highest braking pressure. During the braking process, the input pressure is proportional to the piston stroke, and the operating force is moderate. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the actuator structure of the present invention, where the output pressure is proportional to the stroke.

[0013] Figure 2This is a schematic diagram of the piston structure of the actuator cylinder of the present invention, in which the output pressure is proportional to the stroke.

[0014] Figure 3 This is a schematic diagram of the cylinder structure of the actuator cylinder of the present invention, in which the output pressure is proportional to the stroke.

[0015] Figure 4 This is a schematic diagram of the push rod structure of the actuator cylinder of the present invention, in which the output pressure is proportional to the stroke.

[0016] Figure 5 This is a schematic diagram of the housing structure of the actuator cylinder of the present invention, where the output pressure is proportional to the stroke.

[0017] In the diagram: 1-Push rod, 2-Nut, 3-Piston, 4-Cylinder, 5-Oil cup, 6-Sealing ring, 7-Housing shell, 8-Pressure adjusting spring, 9-Small piston, 10-Buffer spring, 11-Spring seat, 12-Spherical bearing, 13-Connecting nozzle assembly, 14-Exhaust nozzle assembly;

[0018] 101-Radial threaded hole, 301-Axial vent hole, 302-Shoulder, 303-Mounting groove, 304-Axial hole, 305-Oil passage hole, 306-Radial vent hole, 401-Radial hole, 701-Radial mounting hole. Detailed Implementation

[0019] like Figures 1 to 5As shown, an actuated cylinder with output pressure proportional to stroke includes a push rod 1, a nut 2, a piston 3, a cylinder 4, an oil cup 5, a sealing ring 6, a housing 7, a pressure regulating spring 8, a small piston 9, a buffer spring 10, a spring seat 11, and an exhaust nozzle assembly 14. The push rod 1 and piston 3 are connected by threads and locked with the nut 2. The radial threaded hole 101 of the push rod 1 communicates with the axial exhaust hole 301 of the piston 3. The exhaust nozzle assembly 14 is installed in the radial threaded hole 101 of the push rod 1. The piston 3 is installed in the cylinder 4 and is limited by the upper shoulder 302 of the piston 3. The piston 3 can move axially within the cylinder 4. The sealing ring 6 is installed in the mounting groove 303 near the lower center of the outer circle of the piston 3. The sealing ring 6 is located between the piston 3 and the cylinder 4. The cylinder 4 is connected to the housing 7 by threads. Next, the oil cup 5 is sleeved outside the cylinder 4, and the upper and lower end faces of the oil cup 5 abut against the boss end face of the cylinder 4 and the end face of the shell 7, respectively. The small piston 9 has a hollow cavity with an open top and a sealed bottom. The upper end of the small piston 9 is inserted into the axial hole 304 at the lower end of the piston 3. The small piston 9 can move linearly within the axial hole 304. A sealing element is provided between the small piston 9 and the piston 3. The pressure regulating spring 8 is sleeved on the outer circular surface of the small piston 9, and the upper and lower ends of the pressure regulating spring 8 abut against the lower end face of the piston 3 and the bottom boss end face of the small piston 9, respectively. The spring seat 11 is installed at the bottom of the cavity of the shell 7, and the buffer spring 10 is sleeved on the spring seat 11. The upper and lower ends of the buffer spring 10 abut against the bottom boss end face of the small piston 9 and the bottom boss end face of the spring seat 11, respectively. The buffer spring 10 provides support force to the small piston 9.

[0020] The nozzle assembly 13 is installed in the radial mounting hole 701 at the bottom of the housing 7 for connecting the brake system pipeline, allowing oil to enter and exit the actuator cylinder, and transmitting hydraulic pressure to the brake distribution valve.

[0021] The upper and lower sides of the cylinder 4 and the oil cup 5 are equipped with sealing elements to prevent oil leakage.

[0022] The push rod 1 is hinged to the brake pedal, and the push rod 1 receives the force from the pedal and transmits it to the piston 3;

[0023] A spherical bearing 12 is installed at the bottom of the housing 7, and the actuator cylinder is mounted on the machine body using the spherical bearing 12.

[0024] The piston 3 is provided with a radial exhaust hole 306 near the shoulder 302, which is connected to the inner cavity of the cylinder 4. The piston 3 has oil passage holes 305 distributed around its middle circumference, and the cylinder 4 has a radial hole 401 connected to the inner cavity of the oil cup 5. This makes the position between the piston 3 and the cylinder 4 below the sealing ring 6 and the inner cavity of the housing 7 and the small piston 9 form a high-pressure chamber, while the position between the piston 3 and the cylinder 4 above the sealing ring 6 and the inner cavity of the oil cup 5 and the small piston 9 forms an oil storage chamber.

[0025] When braking is required, the pilot depresses the pedal. Push rod 1 pushes piston 3 downwards a certain distance, causing pressure to build up in the high-pressure chamber. Simultaneously, this pressure acts on the lower end face of small piston 9. Under this pressure, small piston 9 moves upwards, pressure regulating spring 8 compresses, and buffer spring 10 extends. The distance small piston 9 moves is directly proportional to the displacement of piston 3 and inversely proportional to the stiffness of pressure regulating spring 8. As small piston 9 moves upwards, the oil inside piston 3 flows back to the oil reservoir through the oil passage 305 in its center. Continuing to depress the pedal, as piston 3's displacement increases, the compression of pressure regulating spring 8 increases, its elasticity increases, and the output pressure of the high-pressure chamber also increases. When the pedal is depressed to the optimal force application state, piston 3 reaches its maximum stroke, and the output pressure of the high-pressure chamber reaches the highest braking pressure. During the downward movement of piston 3, the volume of the oil reservoir increases. Air is drawn in through the axial exhaust port 301, radial exhaust port 306 of piston 3, and the exhaust nozzle assembly 14 installed in the radial threaded hole 101 of push rod 1 to balance the air pressure, preventing a vacuum from forming in the oil reservoir and creating negative pressure. During braking, the output pressure

[11] is proportional to the piston stroke 3, and the operating force is moderate.

[0026] When the brake needs to be released, the pilot releases the pedal, the pressure regulating spring 8 releases its elastic force to push the piston 3 upward and the small piston 9 downward. When the piston 3 moves to its limit position, the high pressure chamber and the oil reservoir of the actuator cylinder are connected through the radial hole 401 of the cylinder body 4, and the pressure in the high pressure chamber drops to zero. During the process of the piston 3 moving upward as a whole, the volume of the oil reservoir decreases, and it is connected to the atmosphere through the axial exhaust hole 301, the radial exhaust hole 306 and the exhaust nozzle assembly 14 of the piston 3 to balance the pressure and prevent pressure from being generated in the oil reservoir.

[0027] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An actuator cylinder with output pressure proportional to stroke, comprising a push rod (1), a nut (2), a piston (3), a cylinder body (4), an oil cup (5), a sealing ring (6), a housing (7), a pressure regulating spring (8), a small piston (9), a buffer spring (10), a spring seat (11) and an exhaust nozzle assembly (14), characterized in that: The push rod (1) is connected with the piston (3) through thread, and is locked by the nut (2). The radial threaded hole (101) of the push rod (1) is communicated with the axial exhaust hole (301) of the piston (3). The exhaust nozzle assembly (14) is installed in the radial threaded hole (101) of the push rod (1). The piston (3) is installed in the cylinder (4) and is limited by the shaft shoulder (302) of the upper part of the piston (3). The sealing ring (6) is installed in the lower installation groove (303) of the outer circle of the piston (3). The sealing ring (6) is located between the piston (3) and the cylinder (4). The cylinder (4) is connected with the shell (7) through thread. The oil cup (5) is sleeved outside the cylinder (4). The upper and lower end faces of the oil cup (5) are respectively abutted with the boss end face of the cylinder (4) and the end face of the shell (7). The small piston (9) is a cavity with an open upper end and a sealed bottom. The upper end of the small piston (9) is inserted into the axial hole (304) of the lower end of the piston (3). The pressure regulating spring (8) is sleeved on the outer circle of the small piston (9). The upper and lower ends of the pressure regulating spring (8) are respectively abutted with the lower end face of the piston (3) and the boss end face of the bottom of the small piston (9). The spring seat (11) is installed at the bottom of the cavity of the shell (7). The buffer spring (10) is sleeved on the spring seat (11). The upper and lower ends of the buffer spring (10) are respectively abutted with the boss end face of the bottom of the small piston (9) and the boss end face of the bottom of the spring seat (11).

2. The force outputting cylinder whose output pressure is proportional to stroke according to claim 1, characterized in that: The radial mounting hole (701) at the bottom of the shell (7) is installed with the pipe nozzle assembly (13).

3. The force outputting cylinder whose output pressure is proportional to stroke according to claim 1, characterized in that: Sealing elements are arranged between the cylinder (4) and the oil cup (5) on both upper and lower sides.

4. The force outputting cylinder whose output pressure is proportional to stroke according to claim 1, characterized in that: The push rod (1) is hinged with the brake pedal.

5. The force outputting cylinder according to claim 1, wherein: The bottom of the shell (7) is installed with the knuckle bearing (12).

6. The force outputting cylinder whose output pressure is proportional to stroke according to claim 1, characterized in that: The piston (3) is provided with the radial exhaust hole (306) near the shaft shoulder (302). The piston (3) is provided with the oil through hole (305) distributed on the circumference. The middle part of the cylinder (4) is provided with the radial hole (401).

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