Rotary actuator and tilt device using the rotary actuator

Abstract

The present invention provides a rotary actuator that can prevent grease and foreign matter from entering the space in which the piston sleeve reciprocates under harsh environmental conditions. [Solution] The piston sleeve 3 has a first oil seal member 31a and a sleeve 32 and is reciprocating. The shaft 4 has a second oil seal member 41a, a first dust seal member 42a and an output shaft 43 that passes through the piston sleeve 3. The end cap 5 has a third oil seal member 51a and a second dust seal member 52a and the output shaft 43 passes through it. The inner circumferential surface of the piston sleeve 3 and the outer circumferential surface of the output shaft 43 each have spiral grooves. The rotary actuator 1 further includes a third dust seal member 41b between the second oil seal member 41a and the first dust seal member 42a, and a fourth dust seal member 51b between the third oil seal member 51a and the second dust seal member 52a.

Description

Technical Field

[0001] The present invention relates to motion conversion technology, and more specifically, to an apparatus that converts the reciprocating motion of a piston sleeve housed inside a cylinder of a housing into rotational motion of an output shaft, and has a configuration capable of reducing internal wear and the frequency of maintenance, and to a tilt device using such a rotary actuator.

Background Art

[0002] In various household and industrial mechanical appliances, a tilt device is used as a device for rotating one device with respect to another device within a certain angular range. The tilt device includes a rotary actuator for converting the reciprocating motion of a piston into rotational motion using a pressure fluid such as hydraulic pressure.

[0003] A typical rotary actuator currently in use has a structure shown in Non-Patent Document 1. A conventional rotary actuator includes a housing having a cylinder inside, a piston sleeve, a shaft, and an end cap. The piston sleeve has a first oil seal member for sealing between the inner peripheral surface of the cylinder and a sleeve, and is reciprocable in the axial direction of the cylinder. The shaft has a second oil seal member for sealing between the inner peripheral surface of the cylinder, a first dust seal member for sealing between the inner peripheral surface of the cylinder, a piston sleeve, and an output shaft passing through an opening. The end cap has a third oil seal member for sealing between the inner peripheral surface of the cylinder, a second dust seal member for sealing between the inner peripheral surface of the cylinder, and an opening centered on the axis. Spiral screw grooves are formed on each of the inner peripheral surface of the piston sleeve and the outer peripheral surface of the output shaft so as to mesh with each other facing each other. The rotary actuator converts the reciprocating motion of the piston sleeve generated by the supply and discharge of pressure fluid to a first section formed between the first oil seal member and the second oil seal member and a second section formed between the first oil seal member and the third oil seal member into rotational motion of the output shaft. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] "PowerTilt Series Service and Repair Manual" (https: / / promo.parker.com / parkerimages / Parker.com / Literature / Industrial%20Cylinder / Helac / PDF%20files / Helac_Series_PowerTilt_Service_Manual_HY34-1410.pdf), Parker Hannifin Corporation [Overview of the project] [Problems that the invention aims to solve]

[0005] In conventional rotary actuators, there is a grease reservoir between the dust seal and the oil seal. When grease is injected, it is injected until the grease that has been pressed into the grease reservoir flows out from the dust seal. During such grease injection, the internal pressure of the grease reservoir increases, causing grease to flow from the reservoir into the oil seal and into the space where the piston sleeve reciprocates within the cylinder. In addition, as the grease passes through the oil seal, foreign matter that has entered from the dust seal may enter the space along with the grease.

[0006] Furthermore, construction vehicles, for example, are often used in harsh environments where muddy water and dust are present. When conventional rotary actuators are used in such environments, foreign matter such as muddy water and dust can enter the inside of the rotary actuator, more specifically the space in the cylinder where the piston sleeve reciprocates, leading to accelerated wear.

[0007] To solve the above problems, the present invention aims to provide a rotary actuator having a structure that can prevent grease and foreign matter from flowing into the space in which the piston sleeve reciprocates when grease is injected or when used in harsh environments. Another objective of the present invention is to provide a tilt device using such a rotary actuator. [Means for solving the problem]

[0008] The present invention provides a rotary actuator that converts reciprocating motion generated by the supply and discharge of pressurized fluid into rotational motion. The rotary actuator has a housing with a cylinder inside, and inside the cylinder are a piston sleeve, a shaft, and an end cap. The piston sleeve has a first oil seal member that seals between itself and the inner surface of the cylinder, and is reciprocating in the direction of the cylinder's axis. The shaft has a second oil seal member that seals between itself and the inner surface of the cylinder, a first dust seal member that seals between itself and the inner surface of the cylinder, and an output shaft that passes through the piston sleeve. The end cap has a third oil seal member that seals between itself and the inner surface of the cylinder, a second dust seal member that seals between itself and the inner surface of the cylinder, and the output shaft of the shaft passes through it. The inner surface of the piston sleeve and the outer surface of the output shaft each have spiral grooves formed to interlock with each other. The rotary actuator converts the reciprocating motion of a piston sleeve, which is generated by the supply and discharge of pressurized fluid to a first compartment formed between a first oil seal member and a second oil seal member, and to a second compartment formed between a first oil seal member and a third oil seal member, into rotational motion of an output shaft. The rotary actuator further comprises a third dust seal member disposed between the second oil seal member and the first dust seal member, and a fourth dust seal member disposed between the third oil seal member and the second dust seal member.

[0009] In one embodiment, the rotary actuator housing has a first passage connecting the space between a first dust seal member and a third dust seal member to the outside of the housing; a second passage connecting the space between a second dust seal member and a fourth dust seal member to the outside of the housing; a third passage located radially opposite the first passage to the housing and connecting the space between the first dust seal member and the third dust seal member to the outside of the housing; and a fourth passage located radially opposite the second passage to the housing and connecting the space between the second dust seal member and the fourth dust seal member to the outside of the housing. Grease nipples are provided in the first and second passages, and relief nipples are provided in the third and fourth passages.

[0010] The present invention further provides a tilt device comprising the aforementioned rotary actuator. The tilt device connects a first device to the housing of the rotary actuator and a second device to the output shaft of the rotary actuator, thereby supplying and discharging pressurized fluid to the rotary actuator, and allowing the angle of the second device relative to the first device to be arbitrarily changed. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a rotary actuator that is highly durable and requires less frequent maintenance. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view showing the external appearance of a rotary actuator according to one embodiment of the present invention, where (a) is a perspective view from the front at an oblique angle and (b) is a perspective view from the rear at an oblique angle. [Figure 2] This is a longitudinal cross-sectional view of the rotary actuator shown in Figure 1. [Figure 3] This is a cross-sectional view of the rotary actuator shown in Figure 1. [Figure 4]Figure 1 shows the grease supply and discharge state in the rotary actuator, and Figure 3 shows a cross-section along line AA. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described in detail below with reference to the drawings.

[0014] The rotary actuator according to the present invention can be used in a variety of applications, including changing the position of a second device relative to a first device, specifically, changing the angle of the second device relative to the first device. The rotary actuator according to the present invention can be used, for example, as a device for swinging an attachment mounted on the boom end of a construction machine, as a replacement for the cylinder of a bucket device used in a construction machine, or as an elevator or rudder in an aircraft. The following embodiment will be described using a rotary actuator for swinging an attachment in a construction machine as an example.

[0015] [Structure of a rotary actuator] Figure 1 is a perspective view showing the external appearance of a rotary actuator 1 (hereinafter referred to as actuator 1) according to one embodiment of the present invention, where (a) is a perspective view from the front at an oblique angle and (b) is a perspective view from the rear at an oblique angle. Figure 2 is a longitudinal cross-sectional view of actuator 1, and Figure 3 is a transverse cross-sectional view of actuator 1.

[0016] (housing) The actuator 1 has a housing 2. Inside the housing 2 is a cylinder 21 that is open at both ends, and inside the cylinder 21 are a piston sleeve 3, a shaft 4, and an end cap 5. Both ends of the shaft 4 protrude from the housing 2, and a shaft fixing portion 71 of a coupler 7 is attached to one end of the protruding shaft 4, and a lock ring 6 is attached to the other end. The lock ring 6 is fixed to a lock ring fixing portion 72 of the coupler 7.

[0017] The housing 2 has flanges 22 and 23 fixed to both ends of its outer periphery. A connecting blade 8 connected to a boom (not shown) of a construction vehicle is fixed to the flanges 22 and 23. The flanges 22 and 23 further have grease injection passages 22a (first passage) and 23a (second passage), and pressure relief passages 22b (third passage) and 23b (fourth passage). Grease nipples 91a and 92a are attached to the grease injection passages 22a and 23a, and relief nipples 91b and 92b are attached to the pressure relief passages 22b and 23b. Note that since the grease nipples 91a and 92a are arranged inside the grease injection passages 22a and 23a, and the relief nipples 91b and 92b are arranged inside the pressure relief passages 22b and 23b, neither is shown in FIG. 1. The housing 2 has working oil supply and discharge ports 24 and 25 that communicate the outside with the inside of the cylinder 21 in order to reciprocate the piston sleeve

[0018] (Piston sleeve) A piston sleeve

[0019] 3 is arranged inside the cylinder 21. The piston sleeve 3 has an annular seal portion 31 with a diameter corresponding to the inner diameter of the cylinder 21, and a cylindrical sleeve 32 that extends in the axial direction of the cylinder 21 from the seal portion 31 and has a smaller diameter than the seal portion 31. The seal portion 31 has an outer periphery that contacts the inner peripheral surface 21a of the cylinder 21 and an inner periphery that contacts the outer peripheral surface 43b of the output shaft 43 of the shaft 4. An annular outer peripheral oil seal member 31a (first oil seal member) that seals between the outer periphery of the seal portion 31 and the inner peripheral surface 21a of the cylinder 21 is attached, and an annular inner peripheral oil seal member 31b that seals between the inner periphery of the seal portion 31 and the outer peripheral surface 43b of the output shaft 43 is attached. The outer peripheral oil seal member 31a and the inner peripheral oil seal member 31b can be appropriately used, for example, nitrile rubber, acrylic rubber, silicone rubber, etc., although not limited thereto.

[0020] In this embodiment, as shown in FIGS. 2 and 3, the outer peripheral oil seal member 31a and the inner peripheral oil seal member 31b are attached in pairs to the outer and inner perimeters of the seal portion 31, but the present invention is not limited to this. Between the first compartment S1 and the second compartment S2 located on both sides of the outer peripheral oil seal member 31a and the inner peripheral oil seal member 31b, as long as there is no leakage of the hydraulic oil that functions as the pressure fluid, there may be one or three or more. The first compartment S1 and the second compartment S2 will be described later in the description of the operation of the actuator 1.

[0021] The sleeve 32 extending in the axial direction of the cylinder 21 from the seal portion 31 has an inner peripheral spiral groove 32a1 formed on its inner peripheral surface 32a. The inner peripheral spiral groove 32a1 is a groove formed to extend in an oblique direction with respect to the axial direction of the cylinder 21, and the space between adjacent grooves forms a ridge. The inner peripheral surface 32a faces the outer peripheral surface 43b of the output shaft 43 of the shaft 4, and the inner peripheral spiral groove 32a1 is engaged with an outer peripheral spiral groove 43b1 formed in a portion of the outer peripheral surface 43b facing the inner peripheral surface 32a. The outer peripheral spiral groove 43b1 is a groove formed to extend in an oblique direction with respect to the axial direction of the cylinder 21, and the space between adjacent grooves forms a ridge. Therefore, the inner peripheral spiral groove 32a1 and the outer peripheral spiral groove 43b1 are engaged with each other such that one ridge enters the other groove and one groove receives the other ridge.

[0022] The sleeve 32 has an outer circumferential groove 32b1 formed on its outer circumferential surface 32b. The outer circumferential groove 32b1 is a groove formed to extend obliquely with respect to the axial direction of the cylinder 21, with a peak between adjacent grooves. The outer circumferential surface 32b faces a groove forming portion 21a2 provided on the inner circumferential surface 21a of the cylinder 21, and the outer circumferential groove 32b1 engages with an inner circumferential groove 21a1 formed on the portion of the groove forming portion 21a2 facing the outer circumferential surface 32b. The inner circumferential groove 21a1 is a groove formed to extend obliquely with respect to the axial direction of the cylinder 21, with a peak between adjacent grooves. Therefore, the outer circumferential groove 32b1 and the inner circumferential groove 21a1 engage by one peak fitting into the other groove and the other peak fitting into the other groove. Furthermore, the inner circumference groove 32a1 and the outer circumference groove 32b1 provided in the sleeve 32 extend in opposite directions with respect to the axial direction of the cylinder 21.

[0023] (shaft) A shaft 4 is positioned inside the cylinder 21. The shaft 4 has a cylindrical inner seal portion 41 whose outer circumference is in contact with the inner surface 21a of the cylinder 21, and an annular outer seal portion 42 which has a larger diameter than the inner seal portion 41 and whose outer circumference is in contact with the inner surface 21a. An annular oil seal member 41a (second oil seal member) is attached to the outer circumference of the inner seal portion 41 to seal the space between it and the inner surface 21a of the cylinder 21, and an annular outer dust seal member 42a (first dust seal member) is attached to the outer circumference of the outer seal portion 42 to seal the space between it and the inner surface 21a. The oil seal member 41a is not limited, but can be made of the same material as the outer oil seal member 31a and the inner oil seal member 31b. The outer dust seal member 42a is not limited, but can be made of nitrile rubber, acrylic rubber, silicone rubber, etc. as appropriate.

[0024] The shaft 4 has an output shaft 43 that extends in the axial direction of the cylinder 21, passing through the inner seal portion 41 and the outer seal portion 42. The output shaft 43 is positioned to pass through the inside of the piston sleeve 3. A gap is provided between the inner seal portion 41 and the output shaft 43, into which the piston sleeve 3 fits.

[0025] In the actuator 1 according to the present invention, in addition to the oil seal member 41a and the outer dust seal member 42a, an annular inner dust seal member 41b (third dust seal member) is attached to the outer circumference of the inner seal portion 41, outside the oil seal member 41a, that is, between the oil seal member 41a and the outer dust seal member 42a. The inner dust seal member 41b can be made of the same material as the outer dust seal member 42a, although this is not limited to the inner dust seal member 41b. In conventional rotary actuators without the inner dust seal member 41b, a problem arose in which foreign matter that could not be captured by the dust seal member located outside the oil seal member entered the space inside the cylinder where the piston sleeve reciprocates. In actuator 1, since the inner dust seal member 41b is attached between the oil seal member 41a and the outer dust seal member 42a, foreign matter that could not be captured by the outer dust seal member 42a is captured by the inner dust seal member 41b, so that foreign matter does not enter the space inside the cylinder 21 where the piston sleeve 3 reciprocates. As a result, maintenance time can be extended.

[0026] The output shaft 43 is positioned inside the cylinder 21 such that its central axis is coaxial with the axis of the cylinder 21. The output shaft 43 extends from the outside of one end of the cylinder 21, through the sleeve 32 and seal portion 31 of the piston sleeve 3 and the end cap 5 (described later), to the outside of the other end of the cylinder 21. The projection 43a at one end of the output shaft 43 is fixed to the shaft fixing portion 71 of the coupler 7, and the projection 43c at the other end is fixed to the lock ring 6.

[0027] A spiral groove 43b1 is formed on a portion of the outer circumferential surface 43b of the output shaft 43. The spiral groove 43b1 is formed to extend obliquely with respect to the axial direction of the cylinder 21, and there are peaks between adjacent grooves. A portion of the outer circumferential surface 43b faces the inner circumferential surface 32a of the sleeve 32, and the spiral groove 43b1 engages with an inner spiral groove 32a1 formed on the inner circumferential surface 32a. The inner spiral groove 32a1 is formed to extend obliquely with respect to the axial direction of the cylinder 21, and there are peaks between adjacent grooves. Therefore, the spiral groove 43b1 and the inner spiral groove 32a1 engage by the peaks of one groove fitting into the other groove, and vice versa. The groove 43b1 on the outer circumference of the output shaft 43 and the groove 32a1 on the inner circumference of the sleeve 32 engage with each other, causing the output shaft 43 to rotate in conjunction with the reciprocating linear motion of the piston sleeve 3.

[0028] On the projection 43c of the output shaft 43, opposite to the projection 43a, there are external teeth 43c1 formed on its outer circumference. The external teeth 43c1 mesh with the internal teeth 6a1 formed on the inner surface 6a of the lock ring 6, and as a result, the rotation of the output shaft 43 causes the lock ring 6 to rotate. The lock ring 6 is fixed to the lock ring fixing portion 72 of the coupler 7, and therefore, the coupler 7 swings as the output shaft 43 rotates.

[0029] The output shaft 43 preferably has a pressure control valve 44 inside. The pressure control valve 44 is in communication with the first compartment S1 and the second compartment S2 via a passage provided inside the output shaft 43. The pressure control valve 44 has the function of adjusting the internal pressure of the first compartment S1 and the second compartment S2 through which the working oil is supplied and discharged.

[0030] (End cap) The end cap 5 has a cylindrical inner seal portion 51 whose outer circumference is in contact with the inner circumferential surface 21a of the cylinder 21, and an annular outer seal portion 52 which has a larger diameter than the inner seal portion 51 and whose outer circumference is in contact with the inner circumferential surface 21a of the cylinder 21, and is positioned inside the cylinder 21 at the end of the shaft 4 opposite to the outer seal portion 42. An annular oil seal member 51a (third oil seal member) is attached to the outer circumference of the inner seal portion 51 to seal the space between it and the inner circumferential surface 21a, and an annular outer dust seal member 52a (second dust seal member) is attached to the outer circumference of the outer seal portion 52 to seal the space between it and the inner circumferential surface 21a. The oil seal member 51a is not limited, but can be made of the same material as, for example, the outer oil seal member 31a and the inner oil seal member 31b. The outer dust seal member 52a is not limited, but can be made of the same material as the outer dust seal member 42a. The inner sealing portion 51 and the outer sealing portion 52 of the end cap 5 are both annular in shape, and the output shaft 43 of the shaft 4 passes through the opening in the center of the annule.

[0031] In the actuator 1 according to the present invention, in addition to the oil seal member 51a and the outer dust seal member 52a, an annular inner dust seal member 51b (a fourth dust seal member) is attached to the outer circumference of the inner seal portion 51, outside the oil seal member 51a, that is, between the oil seal member 51a and the outer dust seal member 52a. The inner dust seal member 51b is not limited to, but can be made of the same material as the outer dust seal member 42a and the inner dust seal member 41b. In conventional rotary actuators without the inner dust seal member 51b, a problem arose in which foreign matter that could not be captured by the dust seal member located outside the oil seal member entered the space inside the cylinder where the piston sleeve reciprocates. In actuator 1, an inner dust seal member 51b is installed between the oil seal member 51a and the outer dust seal member 52a. As a result, any foreign matter that could not be captured by the outer dust seal member 52a is captured by the inner dust seal member 51b, preventing foreign matter from entering the space inside the cylinder 21 where the piston sleeve 3 reciprocates. Consequently, maintenance time can be extended.

[0032] (Lock ring) The lock ring 6 is attached to the projection 43c of the output shaft 43, in contact with the end cap 5. The lock ring 6 has inner teeth 6a1 formed on its inner circumferential surface 6a, and these inner teeth 6a1 mesh with the outer teeth 43c1 formed on the projection 43c. The meshing of the inner teeth 6a1 and the outer teeth 43c1 causes the lock ring 6 to rotate in conjunction with the rotation of the output shaft 43.

[0033] (Capra) The actuator 1 may further include a coupler 7. The coupler 7 swings around the central axis of the output shaft 43 as the output shaft 43 rotates. Therefore, by using the actuator 1 to attach, for example, a construction vehicle attachment to the coupler 7, the angle of the attachment relative to the boom can be freely changed in accordance with the supply and discharge of the working oil.

[0034] The coupler 7 has a shaft fixing portion 71 that is attached to the protruding portion 43a of the shaft 4. The shaft fixing portion 71 has a shaft fixing screw 71a, a screw insertion portion 71b, and a screw receiving portion 71c, the screw insertion portion 71b is fixed to the protruding portion 43a of the shaft 4. By passing the shaft fixing screw 71a through the screw insertion portion 71b and tightening it into the screw receiving portion 71c, the coupler 7 is fixed to the shaft 4 at one end of the housing 2.

[0035] The coupler 7 has a lock ring fixing portion 72 that is attached to the lock ring 6. The lock ring fixing portion 72 is provided with a hole 72a with a diameter corresponding to the outer circumference of the lock ring 6. The coupler 7 is fixed to the shaft 4 at the other end of the housing 2 by inserting the lock ring 6 into the hole 72a and fixing the lock ring 6 and the lock ring fixing portion 72 together, for example, with a bolt, although this is not limited to the coupler 7. The coupler 7 further has attachment connecting portions 73a and 73b for attaching attachments used in construction vehicles.

[0036] (Connecting blades) The connecting blade 8 is fixed to the flanges 22 and 23 of the housing 2. The connecting blade 8 has boom connecting sections 8a and 8b for attaching the boom of a construction vehicle.

[0037] (Grease injection passage, pressure release passage, and nipple) As described above, the housing 2 has flanges 22 and 23 fixed to both ends of its outer circumference. Flange 22 has a grease injection passage 22a and a pressure release passage 22b, respectively, located at radially opposite positions on its outer circumference, and flange 23 has a grease injection passage 23a and a pressure release passage 23b, respectively, located at radially opposite positions on its outer circumference.

[0038] The grease injection passages 22a, 23a and the pressure release passages 22b, 23b have a structure that connects the inside and outside of the cylinder 21. Specifically, the grease injection passage 22a and the pressure release passage 22b each open at radially opposing positions on the inner circumferential surface 21a of the cylinder 21, and the openings are located between the inner dust seal member 41b and the outer dust seal member 42a of the shaft 4. The opening of the grease injection passage 22a and the opening of the pressure release passage 22b communicate through the space in the cylinder 21 between the inner dust seal member 41b and the outer dust seal member 42a. The space formed by these seal members, the outer circumferential surface of the shaft 4, and the inner circumferential surface 21a of the cylinder 21 becomes a grease reservoir.

[0039] Similarly, the grease injection passage 23a and the pressure release passage 23b each open at radially opposing positions on the inner circumferential surface 21a of the cylinder 21, and the openings are located between the inner dust seal member 51b and the outer dust seal member 52a of the end cap 5. The openings of the grease injection passage 23a and the pressure release passage 23b communicate with each other through the space in the cylinder 21 between the inner dust seal member 51b and the outer dust seal member 52a. The space formed by these seal members, the outer circumferential surface of the end cap 5, and the inner circumferential surface 21a of the cylinder 21 becomes a grease reservoir.

[0040] Grease nipples 91a and 92a are attached to grease injection passages 22a and 23a, respectively, and relief nipples 91b and 92b are attached to pressure release passages 22b and 23b, respectively. Grease nipples 91a and 92a are inlets for injecting grease and are equipped with check valves inside, allowing grease to be injected into grease injection passages 22a and 23a without backflow due to the pressure applied during grease injection. Relief nipples 91b and 92b release unnecessary internal pressure in the grease reservoir during grease injection and allow excess grease to be discharged.

[0041] Here, during grease injection, the grease in the grease reservoir moves as shown in Figure 4. Figure 4 is a view of the actuator 1 from the direction of the lock ring 6. As indicated by arrow A, during grease injection, the grease is injected into the cylinder 21 from the grease nipple 92a through the grease injection passage 23a. As described above, the grease is injected into the grease reservoir from between the inner dust seal member 51b and the outer dust seal member 52a.

[0042] The injected grease moves through the grease reservoir inside the cylinder 21 as indicated by arrows B1 and B2, spreading between the oil seal member 51a and the outer dust seal member 52a. Excess grease flows through the opening formed between the inner dust seal member 51b and the outer dust seal member 52a into the pressure release passage 23b, and is discharged through the relief nipple 92b as indicated by arrow C. Thus, the relief nipple 92b releases the internal pressure of the grease reservoir and discharges excess grease.

[0043] Although not shown in the diagram, the same applies to the opposite side of the cylinder 21 (the seal portion of the shaft 4). Grease is injected into the cylinder 21 from the grease nipple 91a through the grease injection passage 22a. Grease is injected into the grease reservoir from between the inner dust seal member 41b and the outer dust seal member 42a.

[0044] The injected grease moves through the grease reservoir inside the cylinder 21. Excess grease flows through an opening formed between the inner dust seal member 41b and the outer dust seal member 42a into the pressure release passage 22b and is discharged through the relief nipple 91b. Thus, the relief nipple 91b releases the internal pressure of the grease reservoir and discharges excess grease.

[0045] In conventional rotary actuators, each of the two flanges of the housing has a grease injection passage at an opposing position on the outer circumference of the flange, and a grease nipple equipped with a check valve is attached to each grease injection passage. When grease is injected from one of the two grease nipples in each flange, the check valve of the other grease nipple acts to increase the internal pressure of the grease reservoir (the space between the dust seal and the oil seal), and grease is injected until it overflows the dust seal. At this time, the increased internal pressure of the grease reservoir causes grease to flow from the oil seal into the space where the piston sleeve reciprocates, and along with this, foreign matter may also enter the inside of the cylinder.

[0046] In contrast, the actuator 1 according to the present invention, as described above, has grease injection passages 22a, 23a and pressure release passages 22b, 23b at opposing positions on the outer circumference of each of the two flanges 22, 23. Grease nipples 91a, 92a are attached to the grease injection passages 22a, 23a, and relief nipples 91b, 92b are attached to the pressure release passages 22b, 23b. Furthermore, the inner seal portions 41, 51 are provided with inner dust seal members 41b, 51b in addition to oil seal members 41a, 51a. Therefore, in the actuator 1, the rise in internal pressure can be suppressed by releasing the internal pressure of the grease reservoir with the relief nipples 91b, 92b when grease is injected, and the intrusion of grease into the cylinder 21 can be prevented by the inner dust seal members 41b, 51b. As a result, the intrusion of foreign matter into the cylinder 21 can be avoided and the decrease in grease over time can be prevented, thus extending the maintenance time.

[0047] [Rotary actuator operation] The actuator 1 having the structure described above operates as follows. Inside the cylinder 21, there are two compartments: a first compartment S1 and a second compartment S2. The first compartment is located between the inner seal portion 41 of the shaft 4 and the seal portion 31 of the piston sleeve 3, more specifically between the oil seal member 41a of the inner seal portion 41 and the outer oil seal member 31a of the seal portion 31. The second compartment S2 is located between the seal portion 31 of the piston sleeve 3 and the inner seal portion 51 of the end cap 5, more specifically between the outer oil seal member 31a and the inner oil seal member 31b of the seal portion 31 and the oil seal member 51a of the inner seal portion 51. Therefore, the first compartment S1 and the second compartment S2 are separated from each other by the outer oil seal member 31a and the inner oil seal member 31b so as not to communicate with each other.

[0048] For the first compartment S1, hydraulic oil can be supplied and discharged from the hydraulic oil inlet / outlet 24 provided in the housing 2, and for the second compartment S2, hydraulic oil can be supplied and discharged from the hydraulic oil inlet / outlet 25 provided in the housing 2. In this embodiment, two hydraulic oil inlet / outlet 24 and two hydraulic oil inlet / outlet 25 are provided at corresponding positions on opposite radial sides of the housing 2, but the embodiment is not limited to this, and there may be one of each.

[0049] The piston sleeve 3 reciprocates linearly in the direction of the axis extending along the length of the cylinder 21 due to the pressure of the hydraulic oil supplied and discharged from the hydraulic oil inlet and outlet ports 24 and 25. When hydraulic oil is supplied from one of the two hydraulic oil inlet and outlet ports 24 (while the other of the two is closed) and hydraulic oil is discharged from one of the two hydraulic oil inlet and outlet ports 25 (similarly, the other of the two is closed), the internal pressure in the first compartment S1 becomes high and the internal pressure in the second compartment S2 becomes low, causing the piston sleeve 3 to move toward the end cap 5.

[0050] An inner circumferential groove 32a1 is formed on the inner circumferential surface 32a of the sleeve 32 of the piston sleeve 3, and an outer circumferential groove 43b1 is formed on the outer circumferential surface 43b of the output shaft 43 of the shaft 4 which is opposite the inner circumferential surface 32a, and the inner circumferential groove 32a1 and the outer circumferential groove 43b1 are engaged. Also, an outer circumferential groove 32b1 is formed on the outer circumferential surface 32b of the sleeve 32, and an inner circumferential groove 21a1 is formed on the groove-forming portion 21a2 of the inner circumferential surface 21a of the cylinder 21 which is opposite the outer circumferential surface 32b, and the outer circumferential groove 32b1 and the inner circumferential groove 21a1 are engaged. Therefore, as the piston sleeve 3 moves linearly in the direction toward the end cap 5, the output shaft 43, which has an outer circumferential groove 43b1 engaged with the inner circumferential groove 32a1 of the piston sleeve 3, rotates around its central axis.

[0051] Conversely, when hydraulic oil is discharged from one of the two hydraulic oil inlet / outlet ports 24 and hydraulic oil is supplied from one of the two hydraulic oil inlet / outlet ports 25, the internal pressure in the first compartment S1 becomes low and the internal pressure in the second compartment S2 becomes high, causing the piston sleeve 3 to move away from the end cap 5. As the piston sleeve 3 moves linearly away from the end cap 5, the output shaft 43, which has a spiral groove 43b1 on its outer circumference that engages with a spiral groove 32a1 on its inner circumference, rotates around its central axis in the opposite direction to when the piston sleeve 3 approaches the end cap 5.

[0052] In this way, by supplying and discharging hydraulic oil to the hydraulic oil inlet / outlet port 24 and discharging and supplying hydraulic oil to the hydraulic oil inlet / outlet port 25, the linear motion of the piston sleeve 3 is converted into the rotational motion of the output shaft 43, causing the coupler 7 connected to the output shaft 43 to swing around the central axis of the housing 2, and the angle of the coupler with respect to the direction of motion of the piston sleeve can be freely changed. [Explanation of Symbols]

[0053] 1 Rotary Actuator 2 Housing 21 Cylinders 21a Inner surface 21a1 Inner circumference spiral groove 21a2 Groove forming part 22 Flange 22a Grease injection passage 22b Pressure release passage 23 Flange 23a Grease injection passage 23b Pressure release passage 24, 25 Operating oil inlet / outlet 3 Piston sleeves 31 Seal part 31a Outer peripheral oil seal member 31b Inner circumferential oil seal member 32 sleeves 32a Inner surface 32a1 Inner circumference spiral groove 32b Outer surface 32b1 Outer circumference spiral groove 4 shafts 41 Inner seal section 41a Oil seal member 41b Inner dust seal member 42 Outer seal portion 42a Outer dust seal member 43 Output shaft 43a Protrusion 43b Outer surface 43b1 Outer circumference with spiral groove 43c Protrusion 43c1 Peripheral teeth 44 Pressure control valve 5 End caps 51 Inner sealing part 51a Oil seal member 51b Inner dust seal member 52 Outer seal portion 52a Outer dust seal member 6 lock rings 6a Inner surface 6a1 Peripheral tooth 6b Outer surface 7 Couplers 71 Shaft fixing part 71a Shaft fixing screw 71b Screw insertion section 71c Screw receiver 72 Lock ring fixing part 72a hole 73a, 73b Attachment connection part 8-linked blades 8a, 8b Boom connection section 9 Nipples 91a, 92a Grease Nipple 91b, 92b Relief nipple S1 First section S2 Second Section

Claims

1. A housing having a cylinder inside, A piston sleeve having a first oil seal member that seals the space between the cylinder and the inner circumferential surface, and a sleeve, and being capable of reciprocating motion in the axial direction of the cylinder, A shaft having a second oil seal member that seals the space between the cylinder and the inner circumferential surface, a first dust seal member that seals the space between the cylinder and the inner circumferential surface, and an output shaft that penetrates the piston sleeve, The end cap has a third oil seal member that seals the space between the cylinder and the inner circumferential surface, and a second dust seal member that seals the space between the cylinder and the inner circumferential surface, through which the output shaft passes. On the inner circumferential surface of the piston sleeve and the outer circumferential surface of the output shaft, a spiral groove is formed so as to face each other and mesh with each other. A rotary actuator comprising a first oil seal member and a second oil seal member, wherein the reciprocating motion of the piston sleeve, which is generated by the supply and discharge of pressurized fluid to a first compartment formed between the first oil seal member and the second oil seal member and a second compartment formed between the first oil seal member and the third oil seal member, is converted into rotational motion of the output shaft, The present invention further comprises a third dust seal member disposed between the second oil seal member and the first dust seal member, and a fourth dust seal member disposed between the third oil seal member and the second dust seal member. The third dust seal member prevents grease from flowing from the grease reservoir formed between the first dust seal member and the third dust seal member to the second oil seal member, and the fourth dust seal member prevents grease from flowing from the grease reservoir formed between the second dust seal member and the fourth dust seal member to the third oil seal member. The aforementioned housing is A first passage for injecting grease connects the grease reservoir between the first dust seal member and the third dust seal member to the outside of the housing, A second passage for injecting grease connects the grease reservoir between the second dust seal member and the fourth dust seal member to the outside of the housing, A third passage for pressure relief and grease discharge is provided on the radially opposite side of the housing to the first passage, and connects the grease reservoir between the first dust seal member and the third dust seal member to the outside of the housing, A fourth passage for pressure relief and grease discharge is provided on the radially opposite side of the housing to the second passage, and connects the grease reservoir between the second dust seal member and the fourth dust seal member to the outside of the housing. It has, Grease nipples are provided in the first passage and the second passage, and relief nipples are provided in the third passage and the fourth passage. The relief nipple provided in the third passage releases the internal pressure of the grease reservoir formed between the first dust seal member and the third dust seal member and discharges excess grease when grease is injected, thereby suppressing a pressure increase that could cause grease to flow into the first compartment beyond the third dust seal member and the second oil seal member. The relief nipple provided in the fourth passage releases the internal pressure of the grease reservoir formed between the second dust seal member and the fourth dust seal member and discharges excess grease when grease is injected, thereby suppressing a pressure increase that could cause grease to flow into the second compartment beyond the fourth dust seal member and the third oil seal member. Characterized by, Rotary actuator.

2. The rotary actuator is provided as described in claim 1, By connecting a first device to the housing of the rotary actuator and a second device to the output shaft of the rotary actuator, and by supplying and discharging pressurized fluid to the rotary actuator, the angle of the second device relative to the first device can be arbitrarily changed. Tilt device.

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