Electric cylinder and working machine

Abstract

To efficiently lubricate a connection part of an electric cylinder.SOLUTION: An electric cylindrical comprises a shaft, a bearing arranged on an external periphery of the shaft, and a holder which surrounds the shaft via the bearing. The holder comprises a holder main body which is open in an axial direction of the shaft and supports the shaft via the bearing, and a cylindrical trunnion part protruding from the holder main body in an outward direction intersecting with the axial direction. The holder is configured to enable a lubricant to be circulated from the outer side of the axial direction of the holder main body toward an internal periphery of the trunnion part.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to an electric cylinder and a working machine. [Background technology]

[0002] Patent Document 1 discloses an electric shovel as an example of a work machine. The electric shovel includes a vehicle body, a boom rotatably provided with respect to the vehicle body, and an electric cylinder. The boom is driven by the electric cylinder. Patent Document 2 discloses an electric cylinder having an inner cylinder that houses a screw shaft extending in the vertical direction and an outer cylinder that houses the inner cylinder so that the inner cylinder can be projected and retracted. The inner cylinder is fixed to a nut that screws onto the screw shaft. A lubricant is sealed in the lower half of the inner cylinder, which flows through a flow hole and into the outer cylinder. An air chamber is formed in the upper half of the inner cylinder, and has an air communication hole formed at the upper end of the inner cylinder. Patent Document 3 discloses a configuration including a body long along the axial direction and a displacement mechanism provided inside the body. The displacement mechanism includes a screw shaft accommodated inside the body, a displacement nut screwed onto the screw shaft, a piston attached to the outer periphery of the displacement nut, and a piston rod connected to the piston. One end of the screw shaft is connected to a connector. The connector is supported rotatably by a bearing. The other end of the screw shaft is connected to a holder. A support ring is provided on the outer periphery of the holder. The outer periphery of the support ring is formed in an uneven shape with a plurality of support parts. The support parts are in sliding contact with the inner periphery of the piston rod and support the piston rod displaceably along the axial direction. A stirring groove for guiding a lubricant is formed on the outer periphery of the support ring. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-204172 A [Patent Document 2] Publication No. 3-4962 [Patent Document 3] JP 2009-275914 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the case of Patent Document 1, the boom rotates by driving an electric cylinder. The electric cylinder has a connection hole through which a pin is inserted. The boom has a through hole through which the pin is inserted. The boom is supported rotatably around the central axis of the pin by inserting the pin into the through hole of the boom and the connection hole of the electric cylinder. In Patent Document 1, efficient lubrication of the connection part of the electric cylinder is required to rotate the boom smoothly. In the case of Patent Document 2, a lubricant is enclosed within the inner cylinder and the outer cylinder. In the case of US Pat. No. 5,399,636, the lubricant is agitated by agitating grooves in a support ring. In Patent Documents 2 and 3, when an electric cylinder is rotatably connected to a target member such as a pin, there is room for improvement in terms of efficiently lubricating the connection portion of the electric cylinder.

[0005] Therefore, an object of the present invention is to provide an electric cylinder and a working machine that can efficiently lubricate the connecting parts of the electric cylinder. [Means for solving the problem]

[0006] An electric cylinder according to one aspect of the present invention includes a shaft, a bearing provided on an outer periphery of the shaft, and a holder surrounding the shaft via the bearing, the holder including a holder body that opens in an axial direction of the shaft and supports the shaft via the bearing, and a cylindrical trunnion portion that protrudes outward from the holder body in a direction intersecting with the axial direction, and the holder includes a holder body that is provided with a bearing that is provided on an outer periphery of the shaft, the holder body being ... Through the gap of the bearing A lubricant can be circulated toward the inner periphery of the trunnion portion. Effect of the Invention

[0007] According to the above aspect, the connection portion of the electric cylinder can be efficiently lubricated. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a side view of the shovel according to the embodiment. [Diagram 2] FIG. 2 is a side view of the work machine according to the embodiment, showing the inside of the boom and the arm in a see-through manner. [Diagram 3] FIG. 2 is a perspective view of the boom according to the embodiment, showing the inside of the boom in a see-through manner. [Figure 4] FIG. 2 is a perspective view of the arm according to the embodiment, showing the inside of the arm in a see-through manner. [Diagram 5] FIG. 1 is a perspective view of an electric cylinder according to an embodiment. [Figure 6] FIG. 2 is a diagram showing the electric cylinder according to the embodiment as viewed from one side in the axial direction. [Figure 7] FIG. 4 is a view of the electric cylinder according to the embodiment as viewed from the other axial side. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII of FIG. 7. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX of FIG. 8 . [Figure 10] 9 is a view equivalent to an enlarged view of a portion X in FIG. 8, illustrating a head-side space and a bottom-side space in a state in which the nut of the embodiment is separated from the holder. FIG. [Figure 11] An enlarged view of part XI in Figure 9. [Figure 12] FIG. 12 is a cross-sectional view including the XII-XII section of FIG. [Figure 13] FIG. [Figure 14] FIG. 2 is a perspective view including a cross section of the holder according to the embodiment cut along a plane including a cylinder axis and a trunnion axis. [Figure 15] FIG. 2 is a perspective view of a piston according to an embodiment. [Figure 16] FIG. 2 is a perspective view including a cross section of a piston according to an embodiment, cut along a plane including a cylinder axis and a trunnion axis. [Figure 17]FIG. 11 corresponds to FIG. 10 and is a diagram for explaining an example of a flow of a lubricant according to the embodiment. [Figure 18] FIG. 12 corresponds to FIG. 11 and is a diagram for explaining an example of a flow of a lubricant according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the embodiment, a shovel will be described as an example of a work machine (work vehicle).

[0010] <Shovel (working machine)> As shown in FIG. 1, a shovel 1 as a work machine includes a vehicle body 2 and a work implement 3 connected to the vehicle body 2. Hereinafter, the forward direction, reverse direction and vehicle width direction of the shovel 1 will be referred to as the "front of the vehicle (one side in the fore-and-aft direction of the vehicle)", the "rear of the vehicle (the other side in the fore-and-aft direction of the vehicle)" and the "vehicle width direction". The vehicle width direction may also be referred to as the "left side (one side in the vehicle width direction)" or the "right side (the other side in the vehicle width direction)". The right side with respect to the forward direction of the shovel 1 will be referred to as the right side, and the left side with respect to the forward direction of the shovel 1 will be referred to as the left side. The up-down direction, upward and downward when the shovel 1 is arranged on a horizontal plane will be referred to simply as the "up-down direction", "up" and "down".

[0011] <Vehicle body> The vehicle body 2 includes a self-propelled lower traveling body 5 and an upper rotating body 6 provided on the lower traveling body 5 so as to be capable of rotating freely.

[0012] The lower traveling body 5 has a pair of left and right crawlers 7. The lower traveling body 5 is equipped with an electric motor (not shown) that drives the crawlers 7. The lower traveling body 5 travels when the crawlers 7 are driven by the electric motor. Note that the lower traveling body 5 may be equipped with a hydraulic motor instead of the electric motor.

[0013] A blade 8 is provided at the front of the lower traveling body 5 as a blade extending in the vehicle width direction of the lower traveling body 5. The lower traveling body 5 includes an electric actuator (not shown) that drives the blade 8. The height position of the blade 8 can be adjusted by driving the electric actuator.

[0014] The upper rotating body 6 is provided on the upper part of the lower traveling body 5. The upper rotating body 6 is provided with an electric motor for traveling which is the drive source of the lower traveling body 5, a motor of an electric cylinder which is the drive source of the work machine 3, and a battery, an inverter, etc. (not shown) which serve as the power source of each motor. The upper rotating body 6 is capable of rotating about an axis extending in the vertical direction relative to the lower traveling body 5.

[0015] A canopy 10 is provided on the upper rotating body 6. The canopy 10 has an operating space 11 capable of accommodating a driver. The canopy 10 includes a hood 12 forming a ceiling of the operating space 11, rear supports 13 provided on both sides in the vehicle width direction at the rear of the hood 12 and extending downward from the hood 12, and front supports 14 provided on both sides in the vehicle width direction at the front of the hood 12 and extending downward from the hood 12.

[0016] A bracket 15 supporting the boom 20 is provided at the front of the upper rotating body 6. As shown in Fig. 2, the bracket 15 has a first hole 15a and a second hole 15b that open in the vehicle width direction of the upper rotating body 6. The first hole 15a is located near the upper end of the bracket 15. The second hole 15b is located below and forward of the first hole 15a.

[0017] <Work equipment> As shown in FIG. 1, the work machine 3 is provided so as to be movable relative to the upper rotating body 6 so as to be freely bent and raised. The work machine 3 includes a boom 20, an arm 30, a bucket 40 (working tool), and a plurality of electric cylinders 100A to 100C (for example, three in this embodiment). The three electric cylinders 100A to 100C are a first electric cylinder 100A that operates the boom 20, a second electric cylinder 100B that operates the arm 30, and a third electric cylinder 100C that operates the bucket 40. A base end of the boom 20 is rotatably connected to the upper rotating body 6. A tip end of the boom 20 is rotatably connected to a base end of the arm 30. A tip end of the arm 30 is rotatably connected to the bucket 40.

[0018] <boom> In the posture of FIG. 1, the boom 20 extends upward from the bracket 15 when viewed from the vehicle width direction of the upper rotating body 6, and then bends and extends toward the front and upper side. Hereinafter, the direction in which the boom 20 extends when viewed from the vehicle width direction of the upper rotating body 6 is referred to as the "boom extension direction", and the direction perpendicular to the boom extension direction is referred to as the "boom plate width direction". One end of the boom 20 in the boom extension direction (the end on the bracket 15 side) is referred to as the "boom base end". The other end of the boom 20 in the boom extension direction (the end opposite to the boom base end) is referred to as the "boom tip". The dimension in the boom plate width direction gradually increases from the boom base end toward the center of the boom extension direction, and then gradually decreases toward the boom tip.

[0019] As shown in FIG. 3, the boom 20 comprises a pair of boom side plates 21 arranged at a distance in the vehicle width direction of the upper rotating body 6, a boom bottom plate 22 extending in the vehicle width direction of the upper rotating body 6 and connecting the pair of boom side plates 21 to each other, a boom base end connecting plate 23 connected to the boom base end side of the boom bottom plate 22, a boom tip side connecting plate 24 connected to the boom tip side of the boom bottom plate 22, a boom partition member 25 partitioning the space sandwiched between the pair of boom side plates 21 near the center in the boom extension direction, a boom base end support member 26 supporting the boom base end on the upper rotating body 6, and an arm support plate 27 supporting the arm 30.

[0020] The boom side plate 21 has a first cylinder base end side hole 21a and a second cylinder base end side hole 21b that open in the vehicle width direction of the upper rotating body 6. As shown in Fig. 2, the first cylinder base end side hole 21a is disposed on the lower side near the center in the boom extension direction when viewed from the vehicle width direction of the upper rotating body 6, at a portion overlapping with a part of the first electric cylinder 100A (near the upper end in Fig. 2). The second cylinder base end side hole 21b is disposed on the upper side near the center in the boom extension direction when viewed from the vehicle width direction of the upper rotating body 6, at a portion overlapping with a part of the second electric cylinder 100B (near the lower end in Fig. 2).

[0021] 3, the boom bottom plate 22 is provided on an edge of the boom side plate 21 on the opposite side to the upper rotating body 6 in the boom plate width direction. The boom bottom plate 22 extends along the boom extension direction. The boom bottom plate 22 is curved toward between the first cylinder base end side hole 21a and the second cylinder base end side hole 21b near the center in the boom extension direction.

[0022] The boom base end side connecting plate 23 extends in the vehicle width direction of the upper rotating body 6 on the boom base end side and connects the pair of boom side plates 21. The boom base end side connecting plate 23 extends toward the boom base end as it moves away from the connection portion with the boom bottom plate 22 in the boom plate width direction, and then bends and extends toward the boom base end.

[0023] The boom tip side connecting plate 24 extends in the vehicle width direction of the upper rotating body 6 on the boom tip side and connects the pair of boom side plates 21 together. The boom tip side connecting plate 24 extends closer to the boom tip as it moves away from the connection with the boom bottom plate 22 in the boom plate width direction, and then bends and extends toward the boom tip. The boom tip side connecting plate 24 has an opening 24a that opens in the boom extension direction at a position adjacent to one of the boom side plates 21.

[0024] The boom partition member 25 extends in the vehicle width direction of the upper rotating body 6 near the center in the boom extension direction and connects the pair of boom side plates 21 together. The boom partition member 25 extends along the boom plate width direction. The boom partition member 25 is disposed between the first cylinder base end side hole 21a and the second cylinder base end side hole 21b. The boom partition member 25 is spaced apart from the boom bottom plate 22 in the boom plate width direction.

[0025] The boom base end support member 26 is provided on the boom base end side. The boom base end support member 26 has a first through hole 26a that opens in the vehicle width direction of the upper rotating body 6. A first pin 28 (see FIG. 2) extending in the vehicle width direction of the upper rotating body 6 is inserted into the first through hole 26a. The boom 20 is supported rotatably around the central axis O1 of the first pin 28 by inserting the first pin 28 into the first through hole 26a of the boom base end support member 26 and the second hole 15b of the bracket 15.

[0026] The arm support plate 27 is provided on the boom tip side. The arm support portion 16 is provided on the outer surfaces of the boom side plates 21 so as to sandwich the pair of boom side plates 21 from the outer sides in the vehicle width direction of the upper rotating body 6. The arm support plate 27 protrudes outward in the boom extension direction beyond the boom side plates 21. The arm support plate 27 has a second through hole 27a that opens in the vehicle width direction of the upper rotating body 6. The second through hole 27a is provided in a portion of the arm support plate 27 that protrudes outward in the boom extension direction beyond the boom side plates 21. A second pin 29 (see FIG. 2) extending in the vehicle width direction of the upper rotating body 6 is inserted into the second through hole 27a.

[0027] <Arm> In the posture of FIG. 1, the arm 30 extends downward and forward from a portion overlapping with a part of the second electric cylinder 100B (near the upper end in FIG. 1) as viewed in the vehicle width direction of the upper rotating body 6. Hereinafter, the direction in which the arm 30 extends as viewed in the vehicle width direction of the upper rotating body 6 is referred to as the "arm extension direction", and the direction perpendicular to the arm extension direction is referred to as the "arm plate width direction". One end of the arm 30 in the arm extension direction (the end on the second electric cylinder 100B side) is referred to as the "arm base end". The other end of the arm 30 in the arm extension direction (the end opposite to the arm base end) is referred to as the "arm tip". The dimension in the arm plate width direction gradually increases from the arm base end toward the vicinity of the boom connection part in the arm extension direction, and then gradually decreases toward the arm tip.

[0028] As shown in Figure 4, the arm 30 comprises a pair of arm side plates 31 arranged at a distance in the vehicle width direction of the upper rotating body 6, an arm bottom plate 32 extending in the vehicle width direction of the upper rotating body 6 and connecting the pair of arm side plates 31 to each other, an arm side connecting plate 33 connected to the arm bottom plate 32, an arm partition member 34 that partitions the space sandwiched between the pair of arm side plates 31 near the arm base end, a boom tip connecting member 35 connected to the boom tip, a bucket support member 36 that supports a bucket 40 (see Figure 2), and a link support member 37 that supports one end of a first link member 41 (see Figure 2).

[0029] The arm side plate 31 has a second cylinder tip side hole 31a and a third cylinder base end side hole 31b that open in the vehicle width direction of the upper rotating body 6. As shown in Fig. 2, the second cylinder tip side hole 31a is arranged in a portion that overlaps with a part of the second electric cylinder 100B (near the upper end in Fig. 2) near the arm base end when viewed from the vehicle width direction of the upper rotating body 6. The third cylinder base end side hole 31b is arranged in a portion that overlaps with a part of the third electric cylinder 100C (near the upper end in Fig. 2) on the opposite side to the portion that overlaps with the boom tip in the arm plate width direction when viewed from the vehicle width direction of the upper rotating body 6.

[0030] 2, the arm bottom plate 32 is provided on the edge of the arm side plate 31 on the upper rotating body 6 side (the boom 20 side) in the arm plate width direction. The arm bottom plate 32 extends along the arm extension direction. As shown in Fig. 4, the arm bottom plate 32 extends between the boom tip connection member 35 and the bucket support member 36 in the arm extension direction.

[0031] The arm-side connecting plate 33 extends in the vehicle width direction of the upper rotating body 6 on the arm tip side and connects the pair of arm side plates 31. The arm-side connecting plate 33 extends closer to the arm tip as it moves away from the connection portion with the arm bottom plate 32 in the arm plate width direction, and then bends and extends toward the arm tip.

[0032] The arm partition member 34 extends in the vehicle width direction of the upper rotating body 6 near the arm base end and connects the pair of arm side plates 31 together. The arm partition member 34 is disposed between the second cylinder tip side hole 31a and the third cylinder base end side hole 31b. The arm partition member 34 is disposed spaced apart from the boom tip connection member 35. When viewed from the vehicle width direction of the upper rotating body 6, the arm partition member 34 extends from the vicinity of the boom tip connection member 35 toward the arm tip side and then bends to extend across between the second cylinder tip side hole 31a and the third cylinder base end side hole 31b.

[0033] The boom tip connection member 35 is formed in a cylindrical shape extending in the vehicle width direction of the upper rotating body 6. The boom tip connection member 35 has a boom connection hole 35a that opens in the vehicle width direction of the upper rotating body 6. As shown in FIG. 2, the boom connection hole 35a overlaps with the second through hole 27a of the arm support plate 27 when viewed from the vehicle width direction of the upper rotating body 6. The arm 30 is supported rotatably around the central axis O2 (see FIG. 4) of the second pin 29 by inserting the second through hole 27a of the arm support plate 27 and the boom connection hole 35a of the boom tip connection member 35.

[0034] As shown in Fig. 4, bucket support member 36 is provided at the tip of the arm. Bucket support member 36 is formed in a cylindrical shape extending in the vehicle width direction of upper rotating body 6. Bucket support member 36 has a third through hole 36a that opens in the vehicle width direction of upper rotating body 6. A third pin 38 (see Fig. 2) extending in the vehicle width direction of upper rotating body 6 is inserted into third through hole 36a.

[0035] As shown in Fig. 4, the link support member 37 is disposed between the arm bottom plate 32 and the arm side connecting plate 33. The link support member 37 is disposed near the bucket support member 36. The link support member 37 is formed in a cylindrical shape extending in the vehicle width direction of the upper rotating body 6. The link support member 37 protrudes outward in the vehicle width direction of the upper rotating body 6 beyond the pair of arm side plates 31. The link support member 37 has a first link connection hole 37a that opens in the vehicle width direction of the upper rotating body 6.

[0036] <bucket> 2, the bucket 40 is inclined from the arm tip toward near the center in the boom extension direction. The bucket 40 has a bucket connection hole 40a and a second link connection hole 40b that open in the vehicle width direction of the upper rotating body 6.

[0037] When viewed from the vehicle width direction of the upper rotating body 6, the bucket connection hole 40a overlaps with the third through hole 36a of the bucket support member 36. The bucket 40 is supported rotatably around the central axis O3 (see FIG. 4 ) of the third pin 38 by inserting the third through hole 36a of the bucket support member 36 and the bucket connection hole 40a of the bucket 40. In the attitude of FIG. 2, the second link connection hole 40b is disposed at a position lower and further rearward than the bucket connection hole 40a.

[0038] <First electric cylinder> 2, the first electric cylinder 100A is disposed closer to the boom base end side than the boom partition member 25. The first electric cylinder 100A includes a first cylinder body 103A configured to be extendable and retractable along the boom extension direction, a first motor 101A as a drive source, and a first power transmission unit 102A that transmits the drive force of the first motor 101A to the first cylinder body 103A.

[0039] The first cylinder body 103A and the first motor 101A extend parallel to each other. A first end of the first cylinder body 103A is connected to a pin 51 inserted into a first hole 15a of a bracket 15. The first electric cylinder 100A is supported by the upper rotating body 6 via the bracket 15 so as to be rotatable around the central axis of the pin 51 extending in the width direction of the upper rotating body 6.

[0040] A second end of the first cylinder body 103A is connected to a pin 52 inserted into a first cylinder base end side hole 21a of the boom 20. The first electric cylinder 100A is supported by the boom 20 so as to be rotatable around the central axis of the pin 52 extending in the width direction of the upper rotating body 6.

[0041] The first motor 101A is disposed on the second end side of the first cylinder body 103A. The first motor 101A is disposed on the inside of the first cylinder body 103A in the boom plate width direction. The first motor 101A operates the first cylinder body 103A using a battery (not shown) provided in the upper rotating body 6 as a power source. The boom 20 rotates around the central axis O1 (see FIG. 3) of the first pin 28 relative to the upper rotating body 6 as the first motor 101A drives the first cylinder body 103A to extend and retract.

[0042] A first wiring 61 extends from the first motor 101A. The first wiring 61 extends along the boom base end side connecting plate 23 and leads into the bracket 15. The first wiring 61 is connected to a battery (not shown) through the bracket 15.

[0043] <Second electric cylinder> The second electric cylinder 100B is disposed closer to the boom tip side than the boom partition member 25. The second electric cylinder 100B includes a second cylinder body 103B configured to be extendable and retractable along the boom extension direction, a second motor 101B as a drive source, and a second power transmission unit 102B that transmits the drive force of the second motor 101B to the second cylinder body 103B.

[0044] The second cylinder body 103B and the second motor 101B extend parallel to each other. A first end of the second cylinder body 103B is connected to a pin 53 inserted into the second cylinder base end side hole 21b of the boom 20. The second electric cylinder 100B is supported by the boom 20 so as to be rotatable around the central axis of the pin 53 extending in the width direction of the upper rotating body 6 relative to the boom 20.

[0045] A second end of the second cylinder body 103B is connected to a pin 54 inserted into a second cylinder tip side hole 31a of the arm 30. The second electric cylinder 100B is supported by the arm 30 so as to be rotatable around the central axis of the pin 54 extending in the width direction of the upper rotating body 6 relative to the arm 30.

[0046] The second motor 101B is disposed on the first end side of the second cylinder body 103B. The second motor 101B is disposed on the inside of the second cylinder body 103B in the boom plate width direction. The second motor 101B operates the second cylinder body 103B using a battery (not shown) provided in the upper rotating body 6 as a power source. The second motor 101B drives the second cylinder body 103B to extend and retract, causing the arm 30 to rotate around the central axis O2 (see FIG. 3) of the second pin 29 relative to the boom 20.

[0047] A second wiring 62 extends from the second motor 101B. The second wiring 62 extends toward the first motor 101A, and then extends along the boom base end side connecting plate 23 together with the first wiring 61, and leads into the bracket 15. The second wiring 62 is connected to a battery (not shown) through the bracket 15.

[0048] <Third electric cylinder> The third electric cylinder 100C is disposed closer to the arm tip end side than the arm partition member 34. The third electric cylinder 100C includes a third cylinder body 103C configured to be extendable and retractable along the arm extension direction, a third motor 101C as a drive source, and a third power transmission unit 102C that transmits the drive force of the third motor 101C to the third cylinder body 103C.

[0049] The third cylinder body 103C and the third motor 101C extend parallel to each other. A first end of the third cylinder body 103C is connected to a pin 55 inserted into the third cylinder base end side hole 31b of the arm 30. The third electric cylinder 100C is supported by the arm 30 so as to be rotatable around the central axis of the pin 55 extending in the width direction of the upper rotating body 6 relative to the arm 30.

[0050] A second end of the third cylinder body 103C is connected to a first end of the first link member 41. The first end of the first link member 41 has a first link hole 41a that opens in the width direction of the upper rotating body 6. The second end of the third cylinder body 103C is connected to a pin 56 inserted into the first link hole 41a. The third electric cylinder 100C supports the first link member 41 rotatably about the central axis of the pin 56 that extends in the width direction of the upper rotating body 6 relative to the first link member 41.

[0051] A second end of the first link member 41 has a second link hole 41b that opens in the width direction of the upper rotating body 6. A pin 57 is inserted into the second link hole 41b together with the first link connection hole 37a of the arm 30. The first link member 41 is supported by the arm 30 so as to be rotatable around the central axis of the pin 57 that extends in the width direction of the upper rotating body 6 relative to the arm 30.

[0052] A second end of the third cylinder body 103C is connected to a first end of the second link member 42. The first end of the second link member 42 has a third link hole 42a that opens in the width direction of the upper rotating body 6. The second end of the third cylinder body 103C is connected to a pin 56 inserted into the third link hole 42a together with the first link hole 41a. The second link member 42 is provided rotatably around the central axis of the pin 56 extending in the width direction of the upper rotating body 6 relative to the second end of the third cylinder body 103C and the first end of the first link member 41.

[0053] A second end of the second link member 42 has a fourth link hole 42b penetrating in the width direction of the upper rotating body 6. A pin 58 is inserted into the fourth link hole 42b together with the second link connection hole 40b of the bucket 40. The second link member 42 is provided rotatably around the central axis of the pin 58 extending in the width direction of the upper rotating body 6 relative to the bucket 40.

[0054] The third motor 101C is disposed on the first end side of the third cylinder body 103C. The third motor 101C is disposed on the inside of the third cylinder body 103C in the arm plate width direction. The third motor 101C operates the third cylinder body 103C using a battery (not shown) provided in the upper rotating body 6 as a power source. The bucket 40 rotates around the central axis O3 (see FIG. 4) of the third pin 38 relative to the arm 30 as the third cylinder body 103C extends and retracts due to the driving of the third motor 101C.

[0055] A third wiring 63 extends from the third motor 101C. The third wiring 63 extends toward the boom 20, and then passes through an opening 24a (see FIG. 3) of the boom tip side connecting plate 24. The third wiring 63 then extends toward the first motor 101A, and then extends along the boom base end side connecting plate 23 together with the first wiring 61 and the second wiring 62, and leads into the bracket 15. The third wiring 63 is connected to a battery (not shown) through the bracket 15.

[0056] <Electric cylinder> 1, a first electric cylinder 100A, a second electric cylinder 100B, and a third electric cylinder 100C are a common electric cylinder 100. As shown in FIG. 5, the electric cylinder 100 includes a motor 101, a power transmission unit 102, and a cylinder body 103.

[0057] The motor 101 is a drive source of the electric cylinder 100. For example, the motor 101 is a servo motor. As shown in Fig. 8, the motor 101 and the cylinder body 103 extend parallel to each other. The motor 101 and the cylinder body 103 are arranged side by side with a gap between them.

[0058] The electric cylinder 100 has an output shaft 105 that rotates when driven by the motor 101. The output shaft 105 is provided coaxially with the central axis of the motor 101. The output shaft 105 protrudes axially outward from an axial end face 101f of the motor 101. In the drawing, reference symbol C1 indicates a motor axis line that is aligned with the central axis of the motor 101.

[0059] The power transmission unit 102 transmits the driving force of the motor 101 to the piston 182. The power transmission unit 102 includes a planetary gear mechanism 110 that changes the speed (e.g., reduces the speed) of the driving force of the output shaft 105, and a transmission gear mechanism 120 that transmits the driving force whose speed has been changed by the planetary gear mechanism 110 to the piston 182.

[0060] The planetary gear mechanism 110 includes a sun gear 111 connected to the output shaft 105, a plurality of planetary gears 112 arranged adjacent to the sun gear 111, carriers 114 and 115 that rotatably support central shafts of the plurality of planetary gears 112, and a ring gear 116 that surrounds the plurality of planetary gears 112. The planetary gear mechanism 110 is covered by a cylindrical case 106 arranged adjacent to an axial end face 101f of the motor 101. A spacer 118 is provided between the axial end face 101f of the motor 101 and the carriers 114 and 115.

[0061] The transmission gear mechanism 120 includes a transfer gear 121 that transmits the rotational force of the carriers 114, 115 to the piston 182, a transfer shaft 122 that extends axially outward from a position facing the axially outer end of the sun gear 111, an idler gear 123 arranged adjacent to the transfer gear 121, and a driven gear 124 arranged on the opposite side of the idler gear 123 to the transfer gear 121. The transmission gear mechanism 120 is covered by a cover unit 160 arranged adjacent to the case 106.

[0062] The transfer gear 121 is provided coaxially with the output shaft 105. The transfer gear 121 is formed in a cylindrical shape having an opening that allows the transfer shaft 122 to be inserted therethrough. The transfer gear 121 is supported by an inner bearing 130 and an outer bearing 131 to be rotatable around the motor axis C1 relative to the cover unit 160.

[0063] The transfer shaft 122 is provided coaxially with the output shaft 105. The carrier 114 is connected to one axial end of the transfer shaft 122 by a spline. The transfer gear 121 is connected to the other axial end of the transfer shaft 122 by a spline.

[0064] The idler gear 123 rotates due to the rotation of the transfer gear 121. The idler gear 123 is rotatable about an axis extending parallel to the transfer shaft 122.

[0065] The driven gear 124 is disposed adjacent to the idler gear 123. The driven gear 124 rotates due to the rotation of the idler gear 123. The driven gear 124 is provided coaxially with the cylinder shaft 180 housed inside the cylinder body 103. In the drawing, symbol C2 indicates the cylinder axis line along the cylinder shaft 180.

[0066] The driven gear 124 is formed in a cylindrical shape with an opening allowing the first end of the cylinder shaft 180 to be inserted therethrough. The driven gear 124 includes a cylindrical gear body 124a having external teeth that mesh with the idler gear 123, an inner cylinder body 124b that protrudes axially inward from the gear body 124a, and an outer cylinder body 124c that protrudes axially outward from the gear body 124a. The gear body 124a, the inner cylinder body 124b, and the outer cylinder body 124c are integrally formed from the same member.

[0067] The driven gear 124 is supported rotatably around the cylinder axis C2 relative to the cover unit 160 by an inner bearing 155 provided on the outer periphery of the inner cylinder body 124b and an outer bearing 156 provided on the outer periphery of the outer cylinder body 124c.

[0068] <Cover unit> The cover unit 160 comprises a first cover 161 that covers the transfer gear 121 from the axially outer side, a second cover 162 that covers the driven gear 124 from the axially outer side, and a third cover 163 that covers the transfer gear 121, the idler gear 123, and the driven gear 124 from the radially outer side of each gear.

[0069] As shown in Fig. 7, the first cover 161 has a rectangular shape when viewed from the axial direction. As shown in Fig. 8, the first cover 161 has a first supply opening 161a that opens to allow lubricant to be supplied from the outside to the other axial end side of the transfer shaft 122. The first supply opening 161a is formed on the motor axis C1. A gap through which the lubricant can flow is formed between the axial outer end of the transfer gear 121 and the first cover 161. A first lid member 165 is detachably attached to the first cover 161 so as to open and close the first supply opening 161a.

[0070] As shown in Fig. 8, the second cover 162 has a second supply opening 162a that opens to allow lubricant to be supplied from the outside to the first end of the cylinder shaft 180. The second supply opening 162a is formed on the cylinder axis C2. A gap through which the lubricant can flow is formed between the axial outer end of the tributary gear 124 and the second cover 162. A second lid member 166 is detachably attached to the second cover 162 to open and close the second supply opening 162a.

[0071] 7, the second cover 162 includes an idler cover portion 162b provided at a position overlapping with the idler gear 123 when viewed in the axial direction, and a driven cover portion 162c provided at a position overlapping with the driven gear 124. The idler cover portion 162b and the driven cover portion 162c are integrally formed from the same member. The idler cover portion 162b fixes the central axis of the idler gear 123 with a bolt 170.

[0072] As shown in FIG. 5, the third cover 163 includes a case side cover portion 163a provided between the case 106 and the first cover 161, and a screw side cover portion 163b provided between the cylinder body 103 and the second cover 162.

[0073] The first cover 161 is fastened to the case 106 via the case side cover portion 163a by a plurality of (for example, four in this embodiment) bolts 171. An axially inner end portion of the case side cover portion 163a is connected to an axially outer end portion of the case 106 by fastening the bolts 171 together.

[0074] The driven cover portion 162c is fixed to the screw side cover portion 163b by a plurality of (e.g., eight in this embodiment) bolts 172. The screw side cover portion 163b is fixed to the cylinder body 103 by a plurality of (e.g., four in this embodiment) bolts 173.

[0075] <Cylinder body> As shown in FIG. 9, the cylinder body 103 includes a cylinder shaft 180 (hereinafter also simply referred to as "shaft 180"), a bearing 189 provided on the outer periphery of the shaft 180, a holder 186 surrounding the shaft 180 via the bearing 189, a nut 181 screwed onto a screw shaft 180a of the shaft 180, a piston 182 connected to the nut 181, a cylindrical piston rod 183 connected to the piston 182, a joint member 184 provided at the tip of the piston rod 183, a cylindrical cylinder tube 185 accommodating the piston rod 183, and a rod cover 187 provided at a second end of the cylinder tube 185.

[0076] The shaft 180 includes a threaded shaft 180a onto which a nut 181 is screwed, a splined shaft 180b coupled to the driven gear 124 by a spline, and a connecting shaft 180c connecting the splined shaft 180b and the threaded shaft 180a. The splined shaft 180b, the connecting shaft 180c, and the threaded shaft 180a are coaxially arranged with one another. The splined shaft 180b, the connecting shaft 180c, and the threaded shaft 180a are integrally formed from the same member.

[0077] The screw shaft 180a is disposed in a cylinder tube 185. The screw shaft 180a has a larger diameter than the connecting shaft 180c. The screw shaft 180a is longer in the axial direction than the connecting shaft 180c. The screw shaft 180a is longer in the axial direction than the cylinder tube 185.

[0078] The spline shaft 180b is disposed within the threaded side cover portion 163b of the third cover 163. The outer periphery of the spline shaft 180b is provided with external teeth having tooth surfaces parallel to the axial direction of the spline shaft 180b and meshing with the internal teeth of the gear body 124a of the driven gear 124. A gap is formed between the external teeth of the spline shaft 180b and the internal teeth of the gear body 124a, through which a lubricant can flow.

[0079] The connecting shaft 180c is disposed within the holder 186. The connecting shaft 180c is formed in a cylindrical shape with a larger diameter than the spline shaft 180b. The connecting shaft 180c is longer in the axial direction than the spline shaft 180b.

[0080] The bearing 189 is provided on the outer periphery of the connecting shaft 180c. A plurality of bearings 189 are provided on the connecting shaft 180c. The plurality of bearings 189 (for example, three in this embodiment) are disposed adjacent to each other in the axial direction.

[0081] In the drawing, reference numeral 195 denotes a spacer provided on the connecting shaft 180c between the bearing 189 and the screw shaft 180a, and reference numeral 196 denotes a lock nut provided on the connecting shaft 180c between the bearing 189 and the driven gear 124. A gap through which a lubricant can flow is formed between the spacer 195 and the holder 186. A gap through which a lubricant can flow is formed between the lock nut 196 and the driven gear 124.

[0082] The piston 182 is configured to be movable on the screw shaft 180a integrally with the nut 181. The piston rod 183 is configured to be movable integrally with the piston 182 along the cylinder axis C2.

[0083] As shown in Fig. 6, the joint member 184 protrudes outward beyond the outer circumferential edge of the rod cover 187. As shown in Fig. 8, the joint member 184 has a connection hole 184a that opens in a direction perpendicular to the cylinder axis C2. A bearing 188 is provided between the inner circumferential surface of the cylinder tube 185 and the outer circumferential surface of the piston 182.

[0084] <Holder> 9, the holder 186 is provided on the radially outer side of the connecting shaft 180c. The holder 186 is provided between the first end of the cylinder tube 185 and the threaded side cover portion 163b. The holder 186 surrounds the shaft 180 via a plurality of bearings 189.

[0085] The holder 186 includes a holder body 190 that opens in the axial direction of the shaft 180 and supports the shaft 180 via a plurality of bearings 189, and a cylindrical trunnion portion 191 that protrudes radially outward from the holder body 190. The holder 186 is configured to allow a lubricant to flow from the outside of the holder body 190 in the axial direction toward the inner periphery of the trunnion portion 191.

[0086] The outer shape of the holder main body 190 has a rectangular shape that follows the outer shape of the screw-side cover portion 163b when viewed in the axial direction. As shown in Fig. 11, the holder 186 includes a protruding cylindrical body 210 that protrudes outward in the axial direction from the holder main body 190 and is formed in a cylindrical shape coaxial with the shaft 180, and an annular convex portion 211 that is formed in an annular shape with a larger diameter than the protruding cylindrical body 210. The protruding cylindrical body 210 and the annular convex portion 211 are integrally formed of the same material as the holder main body 190.

[0087] The protruding cylindrical body 210 protrudes toward the nut 181. The protruding cylindrical body 210 protrudes in the axial direction farther than the annular convex portion 211. An inner peripheral surface 210a of the protruding cylindrical body 210 is spaced radially outward from the shaft 180 over the outer periphery of the shaft 180. A gap is formed between the inner peripheral surface 210a of the protruding cylindrical body 210 and the outer periphery of the shaft 180, through which a lubricant can flow.

[0088] The annular protrusion 211 protrudes toward the inner circumference of the first end of the cylinder tube 185. The holder 186 has an annular surface 212 that follows the outer periphery of the annular protrusion 211. The annular surface 212 of the holder 186 is joined to the first end of the cylinder tube 185 by welding (for example, full-circumference welding).

[0089] The holder 186 has an annular recess 213 that is open axially outward so as to be able to store lubricant and that is formed in a ring shape along the outer periphery of the protruding cylindrical body 210. The annular recess 213 is provided between the protruding cylindrical body 210 and the annular protrusion 211. The annular recess 213 has a uniform depth (axial length) around the outer periphery of the protruding cylindrical body 210.

[0090] 13, the protruding cylinder 210 has an outer guide groove 210b that extends from the axial outside of the annular recess 213 toward the inner circumference of the protruding cylinder 210 and is recessed to allow the flow of lubricant. The depth (axial length) of the outer guide groove 210b is shallower than the depth (axial length) of the annular recess 213. A plurality of outer guide grooves 210b (for example, two in this embodiment) are provided at intervals in the circumferential direction. The two outer guide grooves 210b are formed on a virtual line perpendicular to the cylinder axis C2.

[0091] 11, the holder 186 has an inclined surface 214 that inclines from the axial inner end (the end on the bearing 189 side) of the inner circumferential surface 210a of the protruding cylindrical body 210 toward the axial inner side (the bearing 189 side) so as to be positioned radially outward (toward the trunnion portion 191). The inclined surface 214 is provided around the inner circumference of the axial inner end of the protruding cylindrical body 210.

[0092] 14, the holder 186 has an inner guide groove 215 that extends along the axial direction of the inner circumferential surface 190a of the holder body 190 and is recessed to allow the flow of lubricant, and an opening hole 216 that opens radially outward from the inner guide groove 215 in the radial center of the trunnion portion 191. The opening hole 216 opens onto a central axis C3 of the trunnion portion 191 (hereinafter also referred to as the "trunnion axis C3").

[0093] The inner peripheral surface 190a of the holder body 190 is spaced radially outward from the outer peripheral edge of the inclined surface 214. An intermediate groove 217 that connects the inclined surface 214 and the inner guide groove 215 is provided on the axially inner side surface 190b of the holder body 190. The intermediate groove 217 curves from the inclined surface 214 toward the axial end of the inner guide groove 215. A plurality of inner guide grooves 215 (for example, two in this embodiment) are provided at intervals in the circumferential direction. As shown in FIG. 11, the opening hole 216 is arranged at a position overlapping with the axial center portions of the plurality of bearings 189 when viewed from the radial direction.

[0094] As shown in Fig. 13, a pair of trunnion portions 191 are provided on both side surfaces of the holder body 190. The trunnion portions 191 extend in a direction perpendicular to the direction in which the outer guide grooves 210b extend. The trunnion portions 191 have a connection hole 191a that opens in a direction perpendicular to the cylinder axis C2 (direction along the trunnion axis C3). As shown in Fig. 9, the connection hole 191a of the trunnion portion 191 opens in parallel to the connection hole 184a of the joint member 184.

[0095] 11, the above-mentioned pin (in the illustrated example, the pin 52 inserted into the first cylinder base end side hole 21a of the boom 20 illustrated in FIG. 2) is inserted into the connection hole 191a of the trunnion portion 191. When the electric cylinder 100 is mounted on the boom 20, the connection hole 191a of the trunnion portion 191 opens in the vehicle width direction of the upper rotating body 6. The electric cylinder 100 is supported rotatably around the central axis of the pin 52 by inserting the pin 52 into the first cylinder base end side hole 21a as a through hole of the boom 20 and the connection hole 191a of the trunnion portion 191 as a connection hole of the electric cylinder 100.

[0096] 12, the trunnion portion 191 has a supply hole 191b that opens to allow lubricant to be supplied from the outside to the connection hole 191a. The supply hole 191b opens in a direction perpendicular to each of the cylinder axis C2 and the trunnion axis C3. The supply hole 191b is provided on one radial side of the trunnion portion 191. A grease nipple 192 that can be opened and closed to allow lubricant to be supplied from the outside to the supply hole 191b is provided on one radial side of the trunnion portion 191.

[0097] <Nut> 8, the screw shaft 180a and the nut 181 constitute a ball screw that converts the rotational motion of the motor 101 into linear motion. Between the screw shaft 180a and the nut 181, a ball (not shown) is interposed.

[0098] As shown in FIG. 9, the nut 181 includes a cylindrical nut body 220 provided on the screw shaft 180a, a nut flange 221 extending radially outward from one axial end (the end on the holder 186 side) of the nut body 220, and a circulation part 222 for circulating balls (not shown).

[0099] As shown in FIG. 10, the inner peripheral surface of the nut body 220 is provided with a spiral recess 220a into which a ball is inserted. The nut flange 221 has a bolt hole 221a that opens in the axial direction to allow the insertion of the bolt 198. The outer circumferential edge of the nut flange 221 is spaced radially inward from the inner circumferential surface of the cylinder tube 185. As shown in FIG. 9, the circulation part 222 is provided on one radial side of the nut body 220.

[0100] <Piston> 10, the piston 182 is connected to the nut 181 by a bolt 198 extending in the axial direction. The piston 182 has a bolt hole 182a that opens to allow the bolt 198 to be inserted therethrough, a nut side recess 182b that opens to allow the nut body 220 and the circulating part 222 to be housed therein, a rod side recess 182c that opens toward the piston rod 183, and a piston shaft hole 182d that opens to allow the screw shaft 180a to be inserted therethrough. The piston 182 is configured to allow the lubricant to flow from a position facing the outer periphery of the screw shaft 180a toward the inner periphery of the cylinder tube 185.

[0101] 15, a plurality of bolt holes 182a (for example, six in this embodiment) are provided. The bolt holes 182a are arranged on both radial sides of the piston 182, sandwiching the nut side recess 182b. The plurality of bolt holes 182a are provided radially outward from the nut side recess 182b, three on each side. The three bolt holes 182a on each side are arranged at equal intervals from each other along the circumferential direction of the piston 182.

[0102] The nut side recess 182b is recessed axially inward from a first end (the end on the nut 181 side) of the piston 182. The outer shape of the nut side recess 182b has a shape that combines a circular shape and two trapezoidal shapes when viewed from the axial direction. The nut body 220 is accommodated in the circular space of the nut side recess 182b when viewed from the axial direction. The circulation part 222 is accommodated in one of the trapezoidal spaces of the nut side recess 182b when viewed from the axial direction.

[0103] 10, the rod-side recess 182c is recessed axially inward from a second end (an end on the piston rod 183 side) of the piston 182. The inner peripheral edge of the rod-side recess 182c extends linearly axially inward from the second end of the piston 182, and then inclines toward the screw shaft 180a as it extends axially inward.

[0104] The piston shaft hole 182d is formed in a circular shape coaxial with the screw shaft 180a when viewed in the axial direction. The piston shaft hole 182d communicates the nut side recess 182b and the rod side recess 182c in the axial direction.

[0105] 16, the piston 182 includes a cylindrical piston body 230 along the cylinder axis C2, a bottom-side convex portion 231 that protrudes radially outward from a first end portion (end portion on the holder 186 side) of the piston body 230, and a head-side convex portion 232 that protrudes radially outward from a second end portion (piston rod 183 side) of the piston 182 further than the bottom-side convex portion 231. The piston body 230, the bottom-side convex portion 231, and the head-side convex portion 232 are integrally formed from the same member.

[0106] The bottom side convex portion 231 and the head side convex portion 232 are provided around the outer periphery of the piston body 230. As shown in Fig. 10, a bearing 188 is provided between the bottom side convex portion 231 and the head side convex portion 232. A gap through which a lubricant can flow is formed between the outer periphery of the bottom side convex portion 231 and the inner periphery of the cylinder tube 185. A gap through which a lubricant can flow is formed between the outer periphery of the head side convex portion 232 and the inner periphery of the cylinder tube 185.

[0107] A head side space 201 (first space) through which a lubricant can flow is formed between the piston rod 183 and the cylinder tube 185. The head side space 201 is a space surrounded by the cylinder tube 185, the piston rod 183, and the piston 182 (the piston body 230 and the head side protrusion 232 on the piston rod 183 side). An end of the head side protrusion 232 opposite the bearing 188 in the axial direction of the piston 182 faces the head side space 201.

[0108] A bottom-side space 202 (second space) through which a lubricant can flow is formed between the piston 182 and the holder 186. The bottom-side space 202 is a space surrounded by the cylinder tube 185, the screw shaft 180a, the nut 181, and the piston 182 (bottom-side protrusion 231). An end of the bottom-side protrusion 231 opposite the bearing 188 in the axial direction of the piston 182 faces the bottom-side space 202.

[0109] The piston 182 has a first guide hole 230a extending from a position facing the outer periphery of the screw shaft 180a toward the inner periphery of the cylinder tube 185, and a second guide hole 230b and a third guide hole 230c provided at a position different from the first guide hole 230a and arranged spaced apart from each other in the axial direction. The first guide hole 230a, the second guide hole 230b and the third guide hole 230c each have an opening to allow the flow of lubricant.

[0110] As shown in Fig. 16, a pair of first guide holes 230a are arranged on both radial sides of the piston 182 with the piston shaft hole 182d in between. The pair of first guide holes 230a are formed on an imaginary line perpendicular to the cylinder axis C2. The first guide holes 230a extend radially outward from the piston shaft hole 182d and open to the outer circumferential surface of the piston body 230. As shown in Fig. 10, the first guide holes 230a communicate between the piston shaft hole 182d and the head side space 201.

[0111] The second guide hole 230b extends from a position facing the outer periphery of the bolt 198 toward the inner periphery of the cylinder tube 185. The second guide hole 230b extends parallel to the first guide hole 230a. The second guide hole 230b extends radially outward from the bolt hole 182a and opens to the outer periphery surface of the head side protrusion 232. The second guide hole 230b communicates between the bolt hole 182a and the head side space 201.

[0112] The third guide hole 230c extends parallel to the second guide hole 230b from a position facing the outer periphery of the bolt 198 toward the inner periphery of the cylinder tube 185. The third guide hole 230c extends radially outward from the bolt hole 182a and opens into the outer periphery surface of the bottom-side protrusion 231. The third guide hole 230c communicates between the bolt hole 182a and the bottom-side space 202.

[0113] The bolt hole 182a extends in the axial direction between a first end (an end on the holder 186 side) of the piston 182 and the first guide hole 230a. A female threaded portion 182e into which a male threaded portion of the bolt 198 is screwed is formed on the inner periphery between the first guide hole 230a and the second guide hole 230b in the axial direction of the bolt hole 182a. A gap through which a lubricant can flow is formed on the inner periphery between the second guide hole 230b and the third guide hole 230c in the axial direction of the bolt hole 182a (in other words, the outer periphery of the bolt 198).

[0114] <Cover material>

[0115] As shown in Fig. 11, a cover member 137 that covers the axially outer end of the shaft 180 from the outside is removably attached to the outer cylinder body 124c of the driven gear (rotating body). The cover member 137 has a supply hole 137a that opens to allow lubricant to be supplied from the outside to the axially outer end of the shaft 180. The supply hole 137a is formed on the cylinder axis C2. A gap is formed between the axially outer end of the shaft 180 and the cover member 137, allowing the lubricant to flow therethrough.

[0116] The cover member 137 is provided with a grease nipple 138 that can be opened and closed to supply lubricant to the supply hole 137a from the outside. The grease nipple 138 is provided on the cylinder axis C2. The grease nipple 138 extends axially outward beyond the cover member 137. The grease nipple 138 has a lubricant injection port (not shown) that communicates with the supply hole 137a. The grease nipple 138 has a check valve in which a ball is pressed against the injection port from the inside by a spring. For example, by connecting a grease gun or the like to the grease nipple 138 and applying pressure, the grease nipple 138 can be opened and the lubricant can be supplied to the supply hole 137a through the injection port.

[0117] <Operation of electric cylinder> An example of the operation of the electric cylinder 100 will now be described. As shown in Fig. 8, the driving force from the motor 101 is decelerated through the power transmission unit 102 and transmitted to the cylinder shaft 180. Specifically, the driving force from the motor 101 is converted into a rotational force about the motor axis C1 and is decelerated by the output shaft 105, the sun gear 111, the plurality of planetary gears 112, and the carriers 114 and 115. The rotational force decelerated by the carriers 114 and 115 is transmitted to the transfer gear 121 through the transfer shaft 122. The rotational force transmitted to the transfer gear 121 is transmitted to the cylinder shaft 180 through the idler gear 123 and the driven gear 124.

[0118] For example, when the motor 101 is rotated forward, the cylinder shaft 180 rotates in one direction around the cylinder axis C2. The rotation of the cylinder shaft 180 in one direction causes the nut 181 screwed onto the threaded shaft 180a of the cylinder shaft 180 to move in the direction of arrow M1 on the cylinder axis C2. The movement of the nut 181 in the direction of arrow M1 causes the piston 182, piston rod 183, and joint member 184 to move together in the direction of arrow M1. This causes the cylinder body 103 to extend.

[0119] On the other hand, when the motor 101 is rotated in the reverse direction from the state in which the cylinder body 103 is extended, the cylinder shaft 180 rotates in the other direction around the cylinder axis C2. The rotation of the cylinder shaft 180 in the other direction causes the nut 181 screwed onto the screw shaft 180a of the cylinder shaft 180 to move on the cylinder axis C2 in the direction opposite to the direction of arrow M1. The movement of the nut 181 in the direction opposite to the direction of arrow M1 causes the piston 182, piston rod 183, and joint member 184 to move together in the direction opposite to the direction of arrow M1. This causes the cylinder body 103 to retract. In this manner, the electric cylinder 100 is configured such that the cylinder body 103 extends and contracts as the motor 101 rotates forward and backward.

[0120] <Lubricant flow> An example of the flow of the lubricant will now be described. First, an example of the flow of the lubricant when the cylinder body 103 expands will be described. 17, when the cylinder body 103 extends, the piston 182 moves in the direction of the arrow M1. This causes the head-side space 201 to shrink. Then, the lubricant and air that can no longer fit into the head-side space 201 flows in the direction of the arrow K1 through the first guide hole 230a and enters the outer periphery (gap) of the screw shaft 180a.

[0121] On the other hand, the lubricant and air that cannot enter the head-side space 201 due to the reduction in the head-side space 201 flows in the direction of arrow K2 through the second guide hole 230b, the outer periphery of the bolt 198, and the third guide hole 230c, and enters the bottom-side space 202. The lubricant that has flowed into the bottom-side space 202 is reused for lubrication of the destination.

[0122] Next, an example of the flow of the lubricant when the cylinder body 103 contracts will be described. When the cylinder body 103 contracts, the piston 182 moves in the direction opposite to the direction of the arrow M1. This expands the head side space 201. Therefore, air enters the head side space 201 through the first guide hole 230a and the second guide hole 230b.

[0123] On the other hand, as the piston 182 moves in the direction opposite to the direction of the arrow M1, the bottom-side space 202 shrinks. Then, part of the lubricant flows through the second guide hole 230b in the direction opposite to the direction of the arrow K2 and enters the head-side space 201. The lubricant that has flowed into the head-side space 201 is reused for lubrication of the destination.

[0124] On the other hand, when the bottom-side space 202 shrinks, another part of the lubricant flows through the third guide hole 230c in the direction of arrow K2 and enters the bottom-side space 202. The lubricant that has flowed into the bottom-side space 202 is reused for lubrication of the destination.

[0125] A portion of the lubricant that has flowed into the bottom-side space 202 flows along the protruding cylindrical body 210 of the holder 186 in the direction of arrow K3 and enters the inner periphery of the holder 186. This allows the bearing 189 in the holder 186 to be lubricated.

[0126] 18, the lubricant then flows in the direction of arrow K4 through the gaps in the bearing 189 in the holder 186 and enters the trunnion portion 191 through the opening 216 of the holder 186. This lubricates the inner periphery of the trunnion portion 191 and also lubricates the pin inserted into the connection hole 191a of the trunnion portion 191 (in the illustrated example, the pin 52 inserted into the first cylinder base end side hole 21a of the boom 20 shown in FIG. 2).

[0127] Next, an example of the flow of the lubricant when the lubricant is supplied from the second supply opening 162a after the electric cylinder 100 is assembled will be described. As shown in FIG. 18, first, the second cover member 166 is removed from the cover unit 160 to open the second supply opening 162a. Then, the grease nipple 138 is exposed through the second supply opening 162a. Next, for example, a grease gun or the like is connected to the grease nipple 138 to apply pressure to open the grease nipple 138, and lubricant is supplied to the inner periphery (gap) of the driven gear 124 through the supply hole 137a (in the direction of the arrow K5 in the figure). Then, the lubricant flows along the outer periphery (gap of the spline) of the spline shaft 180b of the shaft 180 in the direction of the arrow K6 and enters the inner periphery (gap) of the holder 186. This allows the bearing 189 in the holder 186 to be lubricated.

[0128] The lubricant then flows in the direction of arrow K7 through the gaps in the bearing 189 inside the holder 186 and enters the trunnion portion 191 through the opening 216 of the holder 186. This lubricates the inner periphery of the trunnion portion 191 and also lubricates the pin inserted into the connection hole 191a of the trunnion portion 191 (in the illustrated example, the pin 52 inserted into the first cylinder base end side hole 21a of the boom 20 shown in FIG. 2).

[0129] Meanwhile, part of the lubricant flowing in the direction of arrow K6 along the outer periphery (spline gaps) of the spline shaft 180b of the shaft 180 flows in the direction of arrow K8 along the outer periphery of the driven gear 124 and flows toward the bearings 155, 156 of the driven gear 124. This allows the bearings 155, 156 of the driven gear 124 to be lubricated.

[0130] <Action and effect> As described above, the electric cylinder 100 of this embodiment includes the shaft 180, the bearing 189 provided on the outer periphery of the shaft 180, and the holder 186 surrounding the shaft 180 via the bearing 189. The holder 186 includes a holder body 190 that opens in the axial direction of the shaft 180 and supports the shaft 180 via the bearing 189, and a cylindrical trunnion portion 191 that protrudes radially outward from the holder body 190. The holder 186 is configured to allow a lubricant to flow from the outside in the axial direction of the holder body 190 toward the inner periphery of the trunnion portion 191. According to this configuration, the lubricant can be circulated inside the holder 186 through the inner circumference of the holder body 190 that opens in the axial direction of the shaft 180, and the lubricant can flow into the trunnion portion 191. When the electric cylinder 100 is rotatably connected to the work machine 3, a pin is inserted into the trunnion portion 191. In this case, the lubricant is present in the gap between the trunnion portion 191 and the pin. Therefore, the connection portion of the electric cylinder 100 can be efficiently lubricated.

[0131] In this embodiment, the holder 186 includes a protruding cylindrical body 210 that protrudes outward in the axial direction from the holder body 190 and is formed in a cylindrical shape coaxial with the shaft 180. An inner peripheral surface 210a of the protruding cylindrical body 210 is spaced radially outward from the shaft 180 over the outer periphery of the shaft 180. According to this configuration, the lubricant can be caused to flow into the holder 186 through the inner periphery of the protruding cylinder 210 (the gap between the inner periphery 210a of the protruding cylinder 210 and the outer periphery of the shaft 180), and the lubricant can be caused to flow into the trunnion portion 191. In addition, by causing the lubricant to flow along the inner periphery of the protruding cylinder 210, a portion of the lubricant flows toward the bearing 189 in the holder 186, and therefore the bearing 189 can be efficiently lubricated.

[0132] In this embodiment, the holder 186 has an annular recess 213 that is open axially outward and is formed in an annular shape along the outer periphery of the protruding cylindrical body 210 so as to be able to store a lubricant. According to this configuration, a part of the lubricant flowing from the axial outside of the holder main body 190 toward the protruding cylinder 210 can be stored in the annular recess 213. Therefore, it is possible to prevent the lubricant flowing from the axial outside of the holder main body 190 toward the protruding cylinder 210 from excessively flowing into the holder 186 through the inner circumference of the protruding cylinder 210.

[0133] In this embodiment, the protruding cylinder 210 has an outer guide groove 210b that extends from the outside of the annular recess 213 in the axial direction toward the inner periphery of the protruding cylinder 210 and is recessed to allow the flow of lubricant. According to this configuration, the lubricant that cannot fit into the annular recess 213 can flow through the outer guide groove 210b toward the inner circumference of the protruding cylindrical body 210. Therefore, the lubricant flowing from the outside in the axial direction of the holder main body 190 toward the protruding cylindrical body 210 can flow into the holder 186 through the inner circumference of the protruding cylindrical body 210 in stages.

[0134] In this embodiment, the holder 186 has an inclined surface 214 that inclines from the inner end of the inner circumferential surface 210a of the protruding cylinder body 210 in the axial direction toward the inside in the axial direction so as to be positioned radially outward. According to this configuration, by circulating the lubricant along the inner circumference of the protruding cylinder 210, a portion of the lubricant flows along the inner circumferential surface 210a and the inclined surface 214 of the protruding cylinder 210 toward the bearing 189 in the holder 186, thereby efficiently lubricating the bearing 189. In addition, a portion of the lubricant flows along the inner circumferential surface 210a and the inclined surface 214 of the protruding cylinder 210 through the bearing 189 in the holder 186 into the trunnion portion 191, thereby efficiently lubricating the inside of the trunnion portion 191.

[0135] In this embodiment, the holder 186 has an inner guide groove 215 that extends axially along the inner surface 190a of the holder body 190 and is recessed to allow the flow of lubricant, and an opening hole 216 that opens radially outward from the inner guide groove 215 at the radial center of the trunnion portion 191. According to this configuration, by circulating lubricant along the inner circumference of the protruding cylindrical body 210, a portion of the lubricant flows toward the inner surface 190a of the holder main body 190 and flows into the trunnion portion 191 through the inner guide groove 215 and the opening hole 216, thereby efficiently lubricating the inside of the trunnion portion 191.

[0136] In this embodiment, the electric cylinder 100 includes a nut 181 screwed onto a screw shaft 180a of a shaft 180, a piston 182 connected to the nut 181, a cylindrical piston rod 183 connected to the piston 182, and a cylindrical cylinder tube 185 that houses the piston rod 183. The piston 182 is configured to allow a lubricant to flow from a position facing the outer periphery of the screw shaft 180a toward the inner periphery of the cylinder tube 185. According to this configuration, the lubricant can be present in the gap on the outer periphery of the screw shaft 180a, the gap on the inner periphery of the cylinder tube 185, the gap between the part of the piston 182 facing the outer periphery of the screw shaft 180a and the inner periphery of the cylinder tube 185, etc. Therefore, each part including the piston 182 can be efficiently lubricated.

[0137] In this embodiment, the piston 182 extends from a position facing the outer periphery of the screw shaft 180a toward the inner periphery of the cylinder tube 185, has an opening to allow the flow of lubricant, and has a first guide hole 230a that leads to the head side space 201 formed between the piston rod 183 and the cylinder tube 185. According to this configuration, the lubricant can be caused to flow into the head side space 201 through the first guide hole 230a. Therefore, the lubricant that has flowed into the head side space 201 can efficiently lubricate each part.

[0138] In this embodiment, the piston 182 is connected to the nut 181 by a bolt 198 extending in the axial direction. The piston 182 has a second guide hole 230b and a third guide hole 230c that are arranged spaced apart from each other in the axial direction and open to allow the flow of lubricant. The second guide hole 230b extends from a position facing the outer periphery of the bolt 198 toward the inner periphery of the cylinder tube 185 and communicates with the head side space 201. The third guide hole 230c extends from a position facing the outer periphery of the bolt 198 toward the inner periphery of the cylinder tube 185 and communicates with a bottom side space 202 formed between the piston 182 and the holder 186. According to this configuration, the lubricant can be introduced into the head side space 201 through the second guide hole 230b, so that the lubricant introduced into the head side space 201 can efficiently lubricate each part. In addition, the lubricant can be introduced into the bottom side space 202 through the third guide hole 230c, so that the lubricant introduced into the bottom side space 202 can efficiently lubricate each part. In addition, when the head side space 201 shrinks when the cylinder body 103 expands, the lubricant and air that cannot be contained in the head side space 201 enter the outer periphery (gap) of the screw shaft 180a through the first guide hole 230a, and enter the bottom side space 202 through the second guide hole 230b, the outer periphery of the bolt 198, and the third guide hole 230c. Therefore, the lubricant and air enclosed in the cylinder body 103 are compressed or expanded, so that it is possible to suppress the cylinder body 103 from being subjected to an unintended load.

[0139] In this embodiment, one axial end side of the shaft 180 is connected to the driven gear 124 by a spline. The electric cylinder 100 includes a cover member 137 that has a supply hole 137a that opens to allow lubricant to be supplied from the outside to the one axial end side of the shaft 180 and covers the one axial end side of the shaft 180 from the outside in the axial direction, and a grease nipple 138 that is provided on the cover member 137 and can be opened and closed to allow lubricant to be supplied to the supply hole 137a from the outside. According to this configuration, after the electric cylinder 100 is assembled, the grease nipple 138 can be opened and the connection portion of the electric cylinder 100 can be lubricated from the outside through the supply hole 135a. For example, the lubricant can be supplied in the following manner. First, the grease nipple 138 is exposed to the outside. Next, the grease nipple 138 is opened by connecting, for example, a grease gun or the like to the grease nipple 138 and applying pressure to it, and the lubricant is supplied to the inner periphery (gap) of the driven gear 124 through the supply hole 137a. Then, the lubricant flows along the outer periphery (gap of the spline) of the spline shaft 180b of the shaft 180 and enters the inner periphery (gap) of the holder 186. After that, the lubricant enters the trunnion portion 191 through the gap of the bearing 189 in the holder 186 and the opening hole 216 of the holder 186. This allows the inner periphery of the trunnion portion 191 to be lubricated, and the pin inserted into the connection hole 191a of the trunnion portion 191 to be lubricated (the connection portion of the electric cylinder to be lubricated).

[0140] In this embodiment, the excavator 1 includes a vehicle body 2 and a work implement 3 connected to the vehicle body 2. The work implement 3 includes the electric cylinder 100 described above. Therefore, it is possible to provide a shovel 1 capable of efficiently lubricating the connection portion of the electric cylinder 100.

[0141] In this embodiment, the work machine 3 includes a common electric cylinder 100 serving as a first electric cylinder 100A, a second electric cylinder 100B, and a third electric cylinder 100C. Therefore, compared to a case in which different electric cylinders are provided as the first electric cylinder 100A, the second electric cylinder 100B, and the third electric cylinder 100C, the number of parts can be reduced, resulting in lower costs.

[0142] <Other embodiments> In the above-described embodiment, an example has been described in which the trunnion portion is formed in a cylindrical shape that protrudes radially outward from the holder body, but this is not limited thereto. For example, the trunnion portion may be formed in a cylindrical shape that protrudes outward from the holder body diagonally intersecting the axial direction. For example, it is sufficient that the trunnion portion is formed in a cylindrical shape that protrudes outward from the holder body intersecting the axial direction. For example, the form of the trunnion portion can be changed according to the required specifications.

[0143] In the above-described embodiment, the holder is described by way of example with a protruding cylindrical body that protrudes outward in the axial direction from the holder body and is formed in a cylindrical shape coaxial with the shaft, but this is not limited thereto. For example, the protruding cylindrical body may not protrude outward in the axial direction from the holder body. For example, the protruding cylindrical body may protrude inward in the axial direction from the holder body. For example, the holder may not have the above-described protruding cylindrical body. For example, the protruding cylindrical body may be provided on a member different from the holder. For example, the form of the protruding cylindrical body may be changed according to the required specifications.

[0144] In the above-described embodiment, the holder has an annular recess that is open axially outward and is formed in a ring shape along the outer periphery of the protruding cylinder so as to be able to store the lubricant, but is not limited thereto. For example, the holder may not have an annular recess. For example, the annular recess may be provided in a member different from the holder. For example, the form of the annular recess may be changed according to the required specifications.

[0145] In the above-described embodiment, the protruding cylindrical body has an outer guide groove that extends from the axial outside of the annular recess toward the inner circumference of the protruding cylindrical body and is recessed to allow the lubricant to flow, but the present invention is not limited to this. For example, the protruding cylindrical body may not have an outer guide groove. For example, the outer guide groove may be provided in a member different from the protruding cylindrical body. For example, the form of the outer guide groove may be changed according to the required specifications.

[0146] In the above-mentioned embodiment, the holder has an inclined surface that is inclined so as to be positioned radially outward as it moves from the axial inner end of the inner circumferential surface of the protruding cylindrical body to the axial inner side, but is not limited thereto. For example, the inclined surface may not be inclined so as to be positioned radially outward as it moves from the axial inner end of the inner circumferential surface of the protruding cylindrical body to the axial inner side. For example, the inclined surface may be inclined so as to be positioned radially inward as it moves from the axial inner end of the inner circumferential surface of the protruding cylindrical body to the axial inner side. For example, the holder may not have the inclined surface described above. For example, the form of the inclined surface can be changed according to the required specifications.

[0147] In the above-mentioned embodiment, the holder has an inner guide groove that extends in the axial direction of the inner peripheral surface of the holder body and is recessed to allow the lubricant to flow, and an opening hole that opens radially outward from the inner guide groove at the radial center of the trunnion part, but is not limited to this. For example, the holder may not have an inner guide groove. For example, the opening hole may open radially outward from the inner peripheral surface of the holder body at the radial outside of the trunnion part. For example, the opening hole may open outward from the inner peripheral surface of the holder body in a direction that obliquely intersects with the axial direction. For example, the form of the inner guide groove and the form of the opening hole can be changed according to the required specifications.

[0148] In the above-described embodiment, the electric cylinder includes a nut screwed onto the screw shaft of the shaft, a piston connected to the nut, a cylindrical piston rod connected to the piston, and a cylindrical cylinder tube that houses the piston rod. The piston is configured to allow a lubricant to flow from a position facing the outer periphery of the screw shaft toward the inner periphery of the cylinder tube. However, the present invention is not limited to this. For example, the piston does not have to be configured to allow a lubricant to flow from a position facing the outer periphery of the screw shaft toward the inner periphery of the cylinder tube. For example, a member different from the piston, such as a nut, may be configured to allow a lubricant to flow from a position facing the outer periphery of the screw shaft toward the inner periphery of the cylinder tube. For example, the flow mode of the lubricant can be changed according to the required specifications.

[0149] In the above-described embodiment, the piston extends from a position facing the outer periphery of the screw shaft toward the inner periphery of the cylinder tube, has an opening to allow the lubricant to flow, and has a first guide hole that leads to a head-side space formed between the piston rod and the cylinder tube. However, the present invention is not limited to this. For example, the piston does not need to have a first guide hole. For example, the first guide hole may be formed in a member different from the piston. For example, the form of the first guide hole can be changed according to the required specifications.

[0150] In the above-described embodiment, the piston is connected to the nut by a bolt extending in the axial direction, the piston has a second guide hole and a third guide hole that are arranged axially apart from each other and open to allow the lubricant to flow, the second guide hole extends from a position facing the outer periphery of the bolt toward the inner periphery of the cylinder tube and communicates with the head side space, and the third guide hole extends from a position facing the outer periphery of the bolt toward the inner periphery of the cylinder tube and communicates with the bottom side space formed between the piston and the holder. However, the present invention is not limited to this. For example, the piston may not have the second guide hole and the third guide hole. For example, at least one of the second guide hole and the third guide hole may be formed in a member different from the piston. For example, the form of the second guide hole and the form of the third guide hole can be changed according to the required specifications.

[0151] In the above-described embodiment, an example was described in which the axial end side of the shaft is connected to the driven gear by a spline, the electric cylinder has a supply hole that opens to allow lubricant to be supplied from the outside to the axial end side of the shaft, a cover member that covers the axial end side of the shaft from the outside in the axial direction, and a grease nipple that is provided on the cover member and can be opened and closed to allow lubricant to be supplied from the outside to the supply hole, but this is not limited to this. For example, the electric cylinder may not be provided with a cover member and a grease nipple. For example, the axial end side of the shaft may be covered by the driven gear. For example, the supply hole may be provided in a member other than the cover member such as the driven gear. For example, the grease nipple may be provided in a member other than the cover member such as the driven gear. For example, the installation mode of the supply hole and the installation mode of the grease nipple can be changed according to the required specifications.

[0152] In the above embodiment, the working machine is described as having a common electric cylinder as the first electric cylinder, the second electric cylinder, and the third electric cylinder, but is not limited thereto. For example, the working machine may have different electric cylinders as the first electric cylinder, the second electric cylinder, and the third electric cylinder. For example, the installation mode of the electric cylinders can be changed according to the required specifications.

[0153] In the above embodiment, a shovel has been described as an example of a work machine (work vehicle), but the present invention is not limited to this. For example, the present invention may be applied to other work vehicles such as a dump truck, a bulldozer, a wheel loader, etc.

[0154] Although the embodiments of the present invention have been described above, the present invention is not limited to these, and additions, omissions, substitutions, and other modifications of the configuration are possible without departing from the spirit of the present invention, and the above-described embodiments can also be combined as appropriate. [Explanation of symbols]

[0155] 1... Shovel (working machine), 2... Vehicle body, 3... Work machine, 100... Electric cylinder, 100A... First electric cylinder (electric cylinder), 100B... Second electric cylinder (electric cylinder), 100C... Third electric cylinder (electric cylinder), 137... Cover member, 137a... Supply hole, 138... Grease nipple, 180... Shaft, 180a... Screw shaft, 181... Nut, 182... Piston, 183... Piston rod, 185... Cylinder tube, 18 6...holder, 189...bearing, 190...holder body, 190a...inner circumferential surface of holder body, 191...trunnion portion, 198...bolt, 201...head side space (first space), 202...bottom side space (second space), 210...projecting cylinder, 210a...inner circumferential surface of projecting cylinder, 210b...outer guide groove, 213...annular recess, 214...inclined surface, 215...inner guide groove, 216...opening hole, 230a...first guide hole, 230b...second guide hole, 230c...third guide hole

Claims

1. A shaft, A bearing provided on an outer periphery of the shaft; a holder surrounding the shaft via the bearing, The holder includes: a holder body that opens in an axial direction of the shaft and supports the shaft via the bearing; a cylindrical trunnion portion protruding outward from the holder body in a direction intersecting with the axial direction, The holder is configured to allow a lubricant to flow from the outside of the holder body in the axial direction toward the inner periphery of the trunnion portion through a gap in the bearing. Electric cylinder.

2. The holder further includes a protruding cylindrical body that protrudes outward in the axial direction from the holder body and is formed in a cylindrical shape coaxial with the shaft, The inner circumferential surface of the protruding cylinder is spaced radially outward from the shaft along the outer periphery of the shaft. The electric cylinder according to claim 1.

3. The holder further has an annular recess that is open outward in the axial direction and is formed in an annular shape along an outer periphery of the protruding cylindrical body so as to be able to store the lubricant. The electric cylinder according to claim 2.

4. The protruding cylindrical body has an outer guide groove that extends from the outside of the annular recess in the axial direction toward the inner circumference of the protruding cylindrical body and is recessed to allow the lubricant to flow therethrough. The electric cylinder according to claim 3.

5. The holder has an inclined surface that is inclined from an inner end portion of an inner circumferential surface of the protruding cylinder toward an inner side in the axial direction so as to be positioned radially outward. The electric cylinder according to any one of claims 2 to 4.

6. The holder includes: an inner guide groove extending in the axial direction of an inner circumferential surface of the holder body and recessed to allow the lubricant to flow therethrough; an opening hole that opens outwardly from the inner guide groove in a direction intersecting with the axial direction at the radial center of the trunnion portion; The electric cylinder according to any one of claims 2 to 5.

7. A nut that is screwed onto the threaded shaft of the shaft; A piston connected to the nut; A cylindrical piston rod connected to the piston; A cylindrical cylinder tube that accommodates the piston rod, The piston is configured to allow the lubricant to flow from a position facing the outer periphery of the screw shaft toward the inner periphery of the cylinder tube. The electric cylinder according to any one of claims 1 to 6.

8. The piston extends from a position facing the outer periphery of the screw shaft toward the inner periphery of the cylinder tube, has a first guide hole that opens to allow the lubricant to flow and communicates with a first space formed between the piston rod and the cylinder tube. The electric cylinder according to claim 7.

9. The piston is connected to the nut by a bolt extending in the axial direction, The piston further includes a second guide hole and a third guide hole that are disposed apart from each other in the axial direction and open to allow the lubricant to flow therethrough, the second guide hole extends from a position facing an outer periphery of the bolt toward an inner periphery of the cylinder tube and communicates with the first space, The third guide hole extends from a position facing the outer periphery of the bolt toward the inner periphery of the cylinder tube and communicates with a second space formed between the piston and the holder. The electric cylinder according to claim 8.

10. One axial end of the shaft is connected to a rotor by a spline, a cover member having a supply hole that opens to allow the lubricant to be supplied from the outside to one axial end side of the shaft and that covers the one axial end side of the shaft from the outside in the axial direction; a grease nipple that is provided on the cover member and that can be opened and closed to supply the lubricant to the supply hole from the outside. The electric cylinder according to any one of claims 1 to 9.

11. A vehicle body, A working machine connected to the vehicle body, The working machine is provided with the electric cylinder according to any one of claims 1 to 10. Working machinery.

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