CN116733942A - Rotating support structure of electric cylinder - Google Patents

Abstract

The invention provides a simple and convenient rotary support structure of an electric cylinder with excellent assembly and action stability. Comprises a cylindrical housing (H), a motor (M) having an output shaft (A1), and a reduction mechanism (K) connected to the output shaft. The speed reducing mechanism includes: a gear unit (U) composed of a first gear (G1) driven to rotate by an output shaft, a shaft support part (2) for supporting the first gear, balls (1) arranged on the shaft support part, and an outer member (4); and a ring-shaped second gear (G2) meshed with the first gear. One end of the outer member along the axis (X) of the output shaft is opposite to the inner surface of the housing or a gasket (S) mounted on the housing, and the other end is opposite to the second gear, and a gap is formed between at least one of the other end side of the outer member and the second gear, and between one end side of the outer member and the housing or the gasket, and a gap is formed between the outer surface of the outer member and the inner surface of the housing.

Description

Rotating support structure of electric cylinder

Technical field

The present invention relates to a rotation support structure of an electric cylinder, for example, in which a speed reduction mechanism is connected to an output shaft of a motor.

Background technique

Conventionally, as such a rotation support structure, there is, for example, a structure shown in Patent Document 1 (see [0024] to [0029] and FIGS. 1 and 2 ).

The rotating support structure is a hydraulic module of an electro-hydraulic servo brake, which uses a motor-driven piston to supply operating fluid to the brake.

In this rotation support structure, a pinion gear 511 as a sun gear is mounted on the shaft 52 of the motor 5 , and the pinion gear 511 meshes with a plurality of planetary gears 512 . The plurality of planetary gears 512 are supported by a sleeve 62 constituting a piston, and the sleeve 62 becomes a so-called planetary gear carrier. A ring gear (not shown) is arranged on the outer peripheral side of the planetary gear 512 , and these planetary gear mechanisms are covered by a bottomed cylindrical cover 513 . The sleeve 62 functioning as a planet carrier is held by the housing 7 via a bearing 72 .

The sleeve 62 makes the piston 3 reciprocate along the inner wall of the cylinder 2 via the ball 63 and the threaded core 61 . A ring 35 protruding in the radially outward direction is attached to an end of the piston 3. The plurality of notches 351 provided in the ring 35 move along the needle 21 attached to the housing 7, so that the piston 3 can reciprocate without rotation.

With such a structure, the rotation support structure can have a simple and highly reliable construction method for guiding the piston 3 and preventing the rotation of the piston 3 without increasing the required space.

Patent Document 1: Japanese Patent Publication No. 2020-536784

In the above-mentioned conventional rotation support structure of the electric cylinder, in the bearing 72 that axially supports the planet carrier (sleeve 62 ) of the planet gear 512 , the outer ring also serves as the wall portion of the housing 7 . Therefore, the extension direction of the rotation axis of the sleeve 62 as the planet carrier is accurately defined and is substantially parallel to the extension direction of the housing 7 .

On the other hand, the piston 3 also reciprocates along the inner wall of the cylinder 2 integrated with the housing 7 , and the threaded core 61 integrated with the piston 3 is engaged with the sleeve 62 via the ball 63 . In the ball screw structure, there is usually no backlash between the threaded core 61 and the sleeve 62 with the balls 63 interposed therebetween. Therefore, the axial direction of the piston 3 also substantially coincides with the extending direction of the sleeve 62 . In this way, the structural members from the planetary gear mechanism to the piston 3 are correctly assembled with each other without wobbling, which is effective for correctly and maximally transmitting the rotational drive from the motor to the piston 3 .

However, in order to reliably supply the operating fluid using the piston 3 , excessive assembly accuracy between the structural members is not necessarily required like that of the piston. Even when there is a certain amount of play between structural members, the machining accuracy of structural components such as gears can be reduced unless the timing of starting the drive of the motor is strictly required. In this case, the installation work of the rotation support member becomes easy, and an inexpensive rotation support member can be obtained as a whole.

On the other hand, for example, even if the processing accuracy of the planetary gear mechanism is high, if the processing accuracy of the housing 7 is not high, the installation posture of the planetary gear mechanism will become inappropriate and the piston may reciprocate along the cylinder. Will create unnecessary resistance.

In this way, there are various problems that need to be solved in the above-mentioned conventional rotation support structure, and there is a need for a rotation support structure for an electric cylinder that has a simple component structure, excellent installation properties, and excellent operational stability and mountability to various devices.

In addition, in the above-mentioned conventional rotation support structure of the electric cylinder, the planetary gear mechanism consists of the pinion gear 511 of the sun gear, the sleeve 62 that serves as a planetary gear carrier that supports the planetary gear 512 and functions as a piston, and the sleeve 62 that is fixed to the planetary gear 512. It is composed of a ring gear on the outer peripheral side. In addition, the sleeve 62 forms a thread mechanism together with the thread core 61 and the balls 63, and these planetary gear mechanisms are integrated with the thread mechanism.

However, among these structural members, since the sleeve 62 serving as the planet gear carrier has a hollow structure, the position of the rotation axis on which the planet gear 512 is mounted is limited. Therefore, it is necessary to enlarge the size of the member such as the sleeve 62 having a predetermined wall thickness. In addition, the bearing 72 and the ring gear that are integrally formed on the outer peripheral portion of the sleeve 62 that are disposed close to each other become easily in contact with each other. In order to avoid this situation, the meshing diameter of the planetary gear 512 and the ring gear needs to be close to the PCD (pitch circle diameter) of the bearing 72, so that the shape of the component is limited, so the component size still becomes larger.

As described above, there are various problems that need to be solved in the above-mentioned conventional rotation support structure, and there is a need for a compact electric cylinder rotation support structure that increases the degree of freedom of component structure and eliminates interference between components.

Contents of the invention

(feature structure)

The characteristic structure of the rotation support structure of the electric cylinder of the present invention is that it has: a cylindrical casing; a motor installed in the casing and having an output shaft; and a reduction mechanism built in the casing and connected to the casing. The output shaft is connected. The reduction mechanism includes a gear unit having a first gear that rotates driven by the output shaft on one side, and a shaft support portion that rotates together with the first gear on the other side. The shaft support portion is equipped with balls and an outer member facing the inner surface of the housing; and an annular second gear fixed to the inner surface of the housing and meshed with the first gear. One end of the outer member along the axis of the output shaft faces the inner surface of the housing or a gasket installed on the housing, and the other end of the outer member faces the second gear. Oppositely, at least any of between the other end side of the outer member and the second gear, and between the one end side of the outer member and the housing or the gasket. A gap is formed on one side, and a gap is formed between the outer surface of the outer member and the inner surface of the housing.

(Effect)

In a general electric cylinder, a bearing that supports a rotating body such as a gear is mounted on the casing without any clearance in order to prevent rotational oscillation of the gear. However, in this structure, the posture of the gear unit can be changed within a predetermined range inside the housing.

Therefore, even if there is a shape error in the second gear, the gear unit, etc., or in a case where there is a shape error or mounting error in other members further connected to the gear unit, the gear can be adjusted while absorbing these various errors. The unit is housed in the casing. Therefore, load fluctuation accompanying the rotation of the electric cylinder can be prevented, and an electric cylinder that can operate stably can be obtained.

In addition, since the gear unit also functions as a bearing, the components of the electric cylinder can be reduced. Therefore, the electric cylinder can be made compact and the mountability in various devices can be improved.

(feature structure)

In the rotation support structure of the electric cylinder of the present invention, the gear unit and the second gear are inserted into the housing from an opening on one side of the housing in this order. The second gear is fixed to the housing by a flange portion protruding radially outward from its outer peripheral portion.

(Effect)

In the gear unit of this structure, since the shaft support part has the function of a ball bearing and is integrated with the first gear, the rotation support structure is simplified compared with a gear unit having an independent ball bearing. Furthermore, in assembling the electric cylinder of this structure, the gear unit and the second gear are inserted from one side of the housing, and the second gear is fixed to the housing by an integral flange portion protruding in the radial direction.

Generally, gear members assembled in motors and the like and transmitting driving force are often made of materials different from structural members in consideration of durability and strength. Therefore, various gear components are mostly composed of a single product having only a gear function. However, in this structure, the annular second gear is provided with a flange portion, thereby having its own fixing function in addition to the drive transmission function of the second gear.

Thereby, there is no need to prepare a fixing member related to the second gear, the installation work of the second gear becomes easy, and the structure of the electric cylinder is simplified. In particular, since the flange portion is disposed outside the gear portion in the radial direction, when the second gear is rotated due to the reaction force of the rotational driving force acting from the first gear to the second gear, the flange portion is used to prevent the second gear from rotating. The moment arm that generates the reaction force in the edge becomes longer. Therefore, the mounting strength of the member that fixes the flange portion to the housing only needs to be small.

In addition, since it is fixed to the casing at a position further outside than the gear portion, even if the machining accuracy of the mounting portion of the flange portion is low and the second gear rotates relative to the casing, the amount of backlash of the second gear will be small. It decreases as the distance from the center of rotation becomes longer.

(feature structure)

In the rotation support structure of the electric cylinder of the present invention, the portion of the inner surface of the housing that faces the outer surface of the outer member and the outer surface of the second gear is a cylindrical surface, and the outer surface of the outer member is a cylindrical surface. The outer diameter of the outer surface may be configured to be smaller than the outer diameter of the outer surface of the second gear.

(Effect)

The second gear is mounted together with the outer member in a state facing the cylindrical surface that is the inner surface of the housing. At this time, if the outer diameter of the outer surface of the outer member is smaller than the outer diameter of the second gear, the gap between the cylindrical surface and the outer member will inevitably become larger. Therefore, the structure in which the gear unit has a gap relative to the housing can be easily formed.

In addition, as shown in this structure, if the inner surface of the housing is formed only as a cylindrical surface, when the gear unit and the second gear are inserted into the housing, there is no obstruction by these members, and the insertion operation becomes easy.

(feature structure)

In the rotation support structure of the electric cylinder of the present invention, a second output shaft is fittedly connected to the end of the gear unit, and the second output shaft can be screwed tightly with the inner surface of the housing. A piston that contacts and moves reciprocally along the axis.

(Effect)

In this structure, the second output shaft is fittingly connected to the end of the gear unit, and the piston is screwed to the second output shaft. The fitting connection of the second output shaft only involves fitting the end of the second output shaft into the gear unit, but the pressing force toward the gear unit via the piston acts on the second output shaft. Therefore, even when a simple fitting connection is used, the second output shaft can be appropriately fixed to the gear unit.

On the other hand, when the piston reciprocates, a certain degree of shaft vibration occurs in the piston. In order for the piston to reciprocate while in close contact with the housing, a gap is required between the inner surface of the housing and the piston. Therefore, a sealing ring, etc. is provided between the two to maintain a close contact state.

Therefore, the second output shaft is also affected by the piston and performs shaft oscillation rotation, which also affects the gear unit that is fittedly connected to the second output shaft. However, in this structure, a gap that allows the shaft of the gear unit to oscillate is actively provided between the gear unit and the housing, so that smooth operation of the piston can be exerted.

(feature structure)

The characteristic structure of the rotation support structure of the electric cylinder of the present invention has: a cylindrical casing; a motor installed in the casing and having an output shaft; and a reduction mechanism built in the casing and connected with the output Shaft connection. The reduction mechanism includes a gear unit having a first gear that rotates driven by the output shaft on one side, and a shaft support portion that rotates together with the first gear on the other side, and a ball is mounted on the shaft support portion. and an outer member facing the inner surface of the housing; and an annular second gear fixed to the inner surface of the housing and meshing with the first gear. When viewed in a direction orthogonal to the axis of the output shaft, the second gear and the shaft support are configured to be separated in the extending direction of the axis. When viewed in the direction of , the outer member and the first gear are arranged in a radially separated state.

(Effect)

In the rotation support structure of the electric cylinder of the present invention, a speed reduction mechanism is provided, and a plurality of members constituting the speed reduction mechanism inside the housing relatively rotate. Therefore, it is necessary to reliably prevent the components from interfering with each other.

Therefore, in this structure, the arrangement state between the rotating member and the fixed member arranged near it is limited. Specifically, the installation state of the first gear and the shaft support part that rotate integrally is specified.

For the first gear, the arrangement state of the outer member located in an adjacent area along the axis center of the output shaft is defined. In addition, the shaft support portion is specified to have a different radial dimension from the second gear. Accordingly, even if the first gear and the shaft support portion move along the axis due to an installation error, a positional shift during motor driving, or the like, mutual interference between the members can be reliably prevented.

Furthermore, in this structure, there is no need to match the meshing diameter of the first gear and the second gear with the ball position (PCD: Pitch Circle Diameter) of the bearing to prevent interference between the components.

(feature structure)

In the rotation support structure of the electric cylinder of the present invention, in the shaft support portion and the outer member facing each other across the balls, the length of the shaft support portion in the extending direction of the shaft center is smaller than the length of the shaft support portion. The length of the outer member is such that the side surface of the shaft support portion facing the second gear is further away from the second gear than the side surface of the outer member facing the second gear.

(Effect)

In this structure, the length of the shaft support portion along the axis center of the output shaft is smaller than the length of the outer member in the same direction, and the side surfaces of the shaft support portion are further away from the second gear than the side surfaces of the outer member. Since the positional relationship between the side surface of the shaft support portion and the side surface of the outer member can be reliably and simply defined by installing the ball between them, it is possible to reliably prevent the shaft support portion as the rotating member and the second fixed member as the fixed member. Interference between gears.

(feature structure)

In the rotation support structure of the electric cylinder of the present invention, the gear unit is a planetary gear mechanism, the first gear is a planetary gear, and the shaft support part is a planetary gear carrier that supports a plurality of the planetary gears, and the The output shaft is a sun gear, and a front end of the output shaft is provided with a tapered inclined portion, and a recessed portion for accommodating the inclined portion is provided in the shaft support portion at a position opposite to the output shaft.

(Effect)

This structure is a structure that compacts the rotation support structure of the electric cylinder when the gear unit is a planetary gear mechanism.

That is, when the output shaft of the motor is a sun gear and the first gear is a planetary gear, there is a case where the motor is installed after the gear unit including the first gear or the like is attached to the casing. At this time, the output shaft as the sun gear protruding from the motor is inserted into a predetermined position of the first gear as the planetary gear. In order to properly transmit the driving force, it is preferable that no backlash or the like is generated between the output shaft and the first gear. Therefore, the clearance between the output shaft and the first gear is set small, and when the motor is installed, the front end of the output shaft easily interferes with the end of the first gear.

In this structure, the front end of the output shaft is provided with a tapered inclined portion to facilitate installation of the motor. The meshing between the inclined portion formed at the front end of the output shaft and the first gear as the planetary gear becomes smaller. Therefore, the inclined portion is configured to penetrate the first gear and protrude toward the shaft support portion. Therefore, by forming a recessed portion in a portion of the shaft support portion facing the front end of the output shaft, and using the recessed portion to surround the inclined portion, the influence of the elongation of the output shaft caused by forming the inclined portion is absorbed, and the rotation support structure is maintained Compact without reducing the meshing length of the output shaft and first gear.

As described above, according to this structure, it is possible to obtain a rotation support structure of an electric cylinder that simplifies the structure of the gear unit and the piston and outputs the power of the motor appropriately.

Description of drawings

FIG. 1 is a cross-sectional view showing the rotation support structure of the electric cylinder according to the first embodiment.

FIG. 2 is an explanatory diagram showing the state of each gap provided in the rotation support structure of the first embodiment.

3 is a cross-sectional view showing the rotation support structure of the electric cylinder according to the second embodiment.

Explanation of reference signs

1: Ball 2: Shaft support part

23: Recessed portion 4: Outer member

A1: Output shaft A1a: Inclined portion

A2: Second output shaft D: Electric cylinder

G1: First gear G2: Second gear

G2a: Flange H: Housing

K: reduction mechanism L1: clearance

L4: Gap M: Motor

P: Piston U: Gear unit

X: axis

Detailed ways

[First Embodiment]

(summary)

The rotation support structure of the electric cylinder D of the present invention is a structure that transmits the rotational driving force from the motor M to other driven objects through the reduction mechanism K. The reduction mechanism K has a shaft support portion 2 using balls 1. During transmission, the posture of the reduction mechanism K can change relative to the housing H.

(reduction mechanism)

For example, Figures 1 and 2 show the specific structure of the first embodiment of the rotation support structure. Here, the reduction mechanism K is installed inside the cylindrical casing H, and the piston P as a drive object is arranged on one side of the reduction mechanism K, that is, in the inner part of the casing H. In addition, the motor M is connected to the other side of the speed reduction mechanism K so as to cover the speed reduction mechanism K.

The rotation of the motor M is transmitted from the output shaft A1 of the motor M to the reduction mechanism K. After the rotation speed is greatly reduced, it is transmitted to the piston P via the second output shaft A2 protruding toward the back of the reduction mechanism K. In the piston P, for example, the base portion P2 on the motor M side and the head portion P1 on the front end side are connected by screwing or fitting. The outer diameter of the base part P2 is formed slightly smaller than the outer diameter of the head part P1.

The piston P slides along the inner surface of the housing H. A male thread portion A23 is formed on the outer surface of the second output shaft A2 and is threadedly engaged with the female thread portion P2b formed on the inner surface of the base portion P2 of the piston P. In addition, a guide groove P2a is formed on the outer surface of the base P2, and a protrusion 3 is formed protruding from the wall surface of the housing H to engage with the guide groove P2a, so that the piston P can be pushed along the inner surface of the housing H. This protrusion 3 can be formed by screwing a threaded member from the outside of the wall surface of the housing H, for example.

The reduction mechanism K is constituted by a planetary gear mechanism, for example. As shown in FIG. 1 , the first gear G1 as a planetary gear meshes with the output shaft A1 of the motor M as a sun gear, and the plurality of first gears G1 are held by the shaft support 2 as a planetary gear carrier. An annular groove 2 a that supports the balls 1 constituting the bearing is formed in the circumferential direction on the outer peripheral portion of the shaft support portion 2 . An outer member 4 serving as an outer support portion of the bearing is disposed on the outer circumferential side of the ball 1 via the ball 1 .

The first gear G1, the shaft support part 2, the ball 1 and the outer member 4 are preassembled and integrated as the gear unit U. In this way, by integrally forming the shaft support portion 2 of the planetary gear mechanism and the outer member 4 of the bearing, the rotation support structure is simplified compared to mounting an independent ball bearing on the shaft support portion 2 . Therefore, the components of the electric cylinder D can be reduced and compacted, thereby improving the mountability of the electric cylinder D in various devices.

The gear unit U is inserted into the housing H together with the second output shaft A2 and the piston P. A boss portion 2 b protruding toward the piston P is formed in the center of the shaft support portion 2 . A two-stage fitting hole 21 and a sawtooth hole 22 are formed inside the boss 2b. A fitting convex part A21 and a sawtooth convex part A22 are formed in two stages at one end of the second output shaft A2. The second output shaft A2 and the shaft support part 2 are fitted and connected so that they always rotate together.

The fitting connection between the second output shaft A2 and the shaft support part 2 is only to embed the end of the second output shaft A2 into the shaft support part 2, but the pressing force toward the shaft support part 2 via the piston P acts on the second output shaft A2. Therefore, even when a simple fitting connection is used, the second output shaft A2 can be appropriately fixed to the shaft support portion 2 .

In addition, a seal ring 5 formed of a rubber member or the like is installed between the outer peripheral surface of the head P1 and the inner surface of the housing H. In FIG. 1 , a seal ring 5 is embedded in an annular groove Ha formed on the inner surface of the housing H. It should be noted that the two can also be interchanged, that is, an annular groove Ha is provided on the outer peripheral surface of the head P1 and the sealing ring 5 is embedded.

When the second output shaft A2 is fitted into the shaft support part 2 , as shown in FIG. 1 , a spacer S made of an annular plate material is inserted between the shaft support part 2 and the second output shaft A2 . One side of the gasket S faces the stepped portion Hb of the housing H, and the other side faces the outer member 4 . By using the spacer S, the position setting of the gear unit U in the axis X direction with respect to the housing H becomes correct. However, as will be described later, the spacer S is not completely fixed in position between the outer member 4 and the housing H, but can move slightly.

It should be noted that the gasket S can also be omitted. For example, the surface shape of the step portion Hb of the housing H is formed so that the outer member 4 can contact the step portion Hb in an appropriate posture without wobbling, or the gear unit U can be accurately contacted with the step portion Hb. When the position of the gear unit U along the axis X direction is accurately set, the spacer S may be omitted.

(Installation structure of the second gear)

After inserting the gear unit U into the housing H, the second gear G2 is installed. The second gear G2 is inserted into the housing H while meshing the internal tooth portion of the second gear G2 with the plurality of first gears G1. The outer surface of the second gear G2 is a cylindrical surface, and its shape is set to be in contact with or extremely close to the inner surface of the housing H in order to prevent shaking when rotating relative to the first gear G1.

A radially extending flange portion G2 a is provided near the end of the second gear G2 on the side opposite to the piston P. Fixing holes G2b are provided in multiple locations of the flange portion G2a, and the second gear G2 is fixed to the housing H using fixing members 6 such as bolts.

Generally, in consideration of durability and strength, a material different from that of the structural member is often selected for the gear member that is assembled in the motor M and the like and transmits driving force. Therefore, various gear components are mostly composed of a single product having only a gear function. However, in this structure, the annular second gear G2 is provided with the flange portion G2a, so that in addition to the drive transmission function of the second gear G2, it also has a fixing function to itself. After the gear unit U, such a second gear G2 is inserted and arranged from the opening on one side of the housing H.

Thereby, there is no need to prepare any special fixing parts except the second gear G2, the installation work of the gear unit U and the second gear G2 becomes easy, and the structure of the electric cylinder D is simplified. In particular, since the flange portion G2a is located radially outside with respect to the internal tooth portion, when the second gear G2 is rotated by the reaction force of the rotational driving force acting on the second gear G2 from the first gear G1 , the moment arm from the axis X to the flange part G2a becomes longer. Therefore, the mounting strength of the fixing member 6 that fixes the flange portion G2a to the housing H only needs to be small.

In addition, since the second gear G2 is fixed to the housing H at a position further outside than the internally toothed portion, even if the processing accuracy of the fixing hole G2b and the like is low and the second gear G2 rotates relative to the housing H, the second gear G2 rotates relative to the housing H. The amount of backlash of the gear G2 also decreases as the distance from the axis center X becomes longer.

(Motor installation structure)

After installing the second gear G2, install the motor M in the housing H. The motor M has an output shaft A1 which is engaged and installed with the first gear G1 of the mounted gear unit U. In order to properly transmit the driving force, it is preferable that no backlash or the like occurs between the output shaft A1 and the first gear G1. Therefore, the clearance between the output shaft A1 and the first gear G1 is set to be small, and when the motor M is installed, the front end of the output shaft A1 easily interferes with the end of the first gear G1. In order to avoid this interference, an inclined portion A1a processed into a tapered shape is provided at the front end of the output shaft A1. This inclined portion A1a allows the front end of the output shaft A1 to be easily engaged with the center positions of the plurality of first gears G1, making it easy to install the motor M.

In addition, even when the inclined portion A1a meshes with the first gear G1, the meshing between the two becomes small. Therefore, the inclined portion A1a is configured to penetrate the first gear G1 and protrude toward the shaft support portion 2 side. In order to cope with this protrusion, a recessed portion 23 is formed in the shaft support portion 2 at a portion facing the front end of the output shaft A1. By having the recessed portion 23 surround the inclined portion A1a, the influence of the elongation of the output shaft A1 caused by forming the inclined portion A1a is absorbed, so that the rotation support structure can be kept compact without reducing the meshing of the output shaft A1 and the first gear G1. length.

(Change in posture of the gear unit)

In the rotation support structure of this embodiment, the gear unit U can change a predetermined attitude with respect to the housing H. That is, as shown in the lower part of FIG. 1 , a predetermined angle of deviation is allowed between the axis Xu of the gear unit U and the axis X of the motor M. In this structure, for example, when the piston P is reciprocated, the electric cylinder D can be driven smoothly even if there are component size errors or installation errors in the speed reduction mechanism K and the piston P.

When the piston P reciprocates, a certain degree of shaft oscillation may occur in the piston P. Even in this case, in order to make the piston P and the housing H come into close contact and reciprocate, a prescribed gap is provided between the inner surface of the housing H and the piston P, and a sealing ring 5 is provided between them to maintain state of close contact.

In this structure, if the second output shaft A2 is affected by the change in the posture of the piston P and the shaft oscillates and rotates, it may affect the gear unit U that is fitted and connected to the second output shaft A2, making it impossible to operate smoothly. Maintains the rotational drive of the gear unit U. However, in this structure, a gap that allows the shaft of the gear unit U to oscillate is actively provided between the gear unit U and the housing H, so that the electric cylinder D can operate smoothly.

(radial clearance)

In the present embodiment, in particular, the gap L1 is actively provided between the outer surface of the outer member 4 and the inner surface of the housing H. Specifically, as shown in FIG. 2(a) , the portion of the inner surface of the housing H that faces the outer surface of the outer member 4 and the outer surface of the second gear G2 is formed into a cylindrical surface, and the outer member The outer diameter of the outer surface of G2 is configured to be smaller than the outer diameter of the outer surface of second gear G2. This ensures that the gap L1 between the cylindrical surface and the outer member 4 is always larger than the gap L2 between the cylindrical surface and the second gear G2.

By forming this gap, as shown in the lower part of FIG. 1 , the gear unit U and the piston P can swing around a position near the joint portion of the first gear G1 and the second gear G2 . The piston P and the inner surface of the casing H are sealed by a sealing ring 5, and the outer surface of the piston P and the inner surface of the casing H are not in direct contact. Therefore, as described above, the gear unit U and the piston P can sufficiently swing.

The gap L1 between the outer member 4 and the inner surface of the housing H is formed to be about 80 μm, for example. The reason is that in a general mechanical structure, the gap size when the outer ring of the bearing is inserted and arranged in the bearing portion without rattling is about 5 to 10 μm.

Therefore, even if there is a shape error of the second gear G2 or the gear unit U, or there is a shape error or installation error of other members such as the spacer S connected to the gear unit U, it is possible to absorb these. The gear unit U is housed in the casing H while maintaining various tolerances. In addition, when the gear unit U and the piston P are driven, any components do not interfere with each other at a predetermined rotation angle, and load fluctuations due to the rotation of the motor M can be prevented. Furthermore, by not completely fixing the outer member 4 that functions as a bearing, it is possible to reduce the work of fixing the outer member 4 to the housing H that has been required in the past. For example, the welding process can be eliminated, and the occurrence of thermal deformation caused by welding can be prevented.

(Gap along the axis direction)

In this embodiment, the outer member 4 can move a predetermined distance even in the direction of the axis X. Therefore, a gap L3 is actively formed between the outer member 4 and the second gear G2, and between the outer member 4 and the spacer S, or between the spacer S and the housing H. Specifically, the outer member 4 can move about 300 to 400 μm along the axis X. This makes it easier to change the postures of the gear unit U and the piston P.

(The gaps between the components form the structure)

In addition, in the rotation support structure of this embodiment, even when the posture of the gear unit U changes, the members constituting the gear unit U and the second gear G2 do not interfere with each other. Specifically, it is possible to prevent the relatively rotating outer member 4 or the second gear G2 from interfering with the integrally rotating shaft support portion 2 and the first gear G1.

Specifically, as shown in (b) of FIG. 2 , interference between the shaft support portion 2 and the second gear G2 is first prevented. When viewed in a direction orthogonal to the axis Xg1 of the first gear G1, the second gear G2 and the shaft support portion 2 are arranged in a state separated in the extending direction of the axis X. That is, in FIG. 2( b ), the right end surface of the second gear G2 and the left end surface of the shaft support portion 2 have a gap L4 in the direction of the axis Xg1 . This gap L4 is mainly formed by the distance by which the end surface of the shaft support portion 2 facing the first gear G1 is retreated from the end surface of the outer member 4 facing the second gear G2 .

Accordingly, even when the shaft support portion 2 is displaced toward the second gear G2, the outer member 4 is in contact with the second gear G2, and the shaft support portion 2 maintains a predetermined relative position with the outer member 4 via the balls 1. Therefore, With respect to the end surface of the outer member 4 , the left end surface of the shaft support portion 2 is always positioned away from the second gear G2 . As a result, the second gear G2 and the shaft support portion 2 never interfere with each other.

In addition, regarding the shaft support part 2, although there is a concern that the rotating shaft support part 2 may come into contact with the gasket S, in FIG. 2(b), the end portion of the shaft support part 2 facing the right side of the gasket S is constituted. This is a state in which the end surface of the outer member 4 facing the spacer S is retreated toward the first gear G1 side. That is, the length L6 of the outer peripheral surface of the shaft support part 2 is configured to be narrower than the length L5 of the outer member 4 along the axis Xg1, and the end surfaces on both sides of the shaft support part 2 are configured to be smaller than the both sides of the outer member 4 The end face recedes. Thereby, the shaft support part 2 does not interfere with the spacer S.

Furthermore, as shown in FIG. 2( b ), in order to prevent interference between the first gear G1 and the outer member 4 , the inner diameter of the outer member 4 is larger than the outer diameter of the first gear G1 , and a gap L7 is provided between them. . In this structure, the outer member 4 and the first gear G1 do not overlap in the direction along the axis Xg1. Therefore, even if the ball 1 between the shaft support part 2 and the outer member 4 wobbles and the first gear G1 moves toward the outer member 4 in the direction of the axis Xg1 relative to the outer member 4, the first gear G1 and the outer member 4 The outer elements 4 also do not interfere.

As described above, in this structure, it is not necessary to correctly position the position of the meshing diameter of the first gear G1 and the second gear G2 and the diameter size of the portion that functions as a bearing in order to avoid interference between the relatively rotating members. (PCD: Pitch Circle Diameter), that is, the radial position of ball 1, greatly expands the allowable range of component sizes or installation positions that should be considered. Therefore, the rotating members are less likely to interfere with each other, and a highly reliable rotating support member can be obtained.

As described above, according to this structure, the structure of the gear unit U and the piston P is simplified, and the rotation support structure of the electric cylinder D which outputs the power of the motor M appropriately can be obtained.

[Second Embodiment]

As shown in FIG. 3 , a wave gear mechanism may be used as the reduction mechanism K. The wave generator W1 is meshed with the output shaft A1, and the pressing roller W2 provided at the front end of the wave generator W1 presses the external teeth of the flexspline W3 in the radial direction. This external tooth meshes with the rigid wheel W4 arranged outside it. A boss portion W3a is formed at the end of the flexspline W3 opposite to the external teeth, and is axially supported by the housing H via a bearing B inserted outside the boss portion W3a. The same second output shaft A2 as in the first embodiment is fitted into the fitting hole W3b in the center of the boss portion W3a. The fitting hole W3b is provided with saw teeth and the like so that the two can rotate integrally with each other reliably.

In this case, the wave generator W1 is included in the output shaft A1, and the external teeth of the flexspline W3 correspond to the first gear G1. Rigid wheel W4 is equivalent to the second gear G2. In addition, the bearing B of the boss portion W3a corresponds to the shaft support portion 2 to which the outer member 4 and the balls 1 are mounted in the first embodiment. That is, the gear unit U is composed of the flexspline W3 and the bearing B.

In this embodiment, regarding the outer ring of the bearing B, between both end surfaces along the axis X direction and the side surfaces of the housing H or the rigid wheel W4, or between the outer ring Ba of the bearing B and the inner surface of the housing H Between them, or between the inner ring Bb of the bearing B and the boss portion W3a of the flexspline W3, a predetermined gap L1 is actively provided.

Flexspline W3 is inherently elastically deformable and may form different axes at various locations. For example, the axis X1 formed by the area of the external teeth whose position is restricted by meshing with the rigid wheel W4 and the axis X2 formed by the area of the boss portion W3a located at the opposite end may not be parallel. Therefore, even when the bearing B of the shaft support boss portion W3a is fixed to the housing H without any backlash, rotation failure caused by dimensional errors of components or the like can be dealt with.

However, as shown in this embodiment, by allowing the bearing B that supports the boss portion W3 a to actively change its posture, the rotation state of the flexspline W3 can be made more stable.

[Other embodiments]

In each of the above embodiments, the gap L1 is provided between the outer member 4 and the inner surface of the housing H. As another configuration, for example, a predetermined gap may be provided between the ball 1 and the outer member 4. In this case, the outer member 4 and the inner surface of the housing H may be welded and fixed, or the outer member 4 may be screwed and fixed to the inner surface of the housing H, or may be fastened with bolts.

Industrial availability

The rotation support structure of the electric cylinder of the present invention can be widely used as a device that significantly reduces the rotation speed of the motor and transmits rotational driving force to other driven objects.

Claims (7)

1. A rotary support structure of an electric cylinder, wherein,

the device comprises:

a cylindrical housing;

a motor mounted on the housing and having an output shaft; and

the speed reducing mechanism is arranged in the shell and is connected with the output shaft,

the speed reducing mechanism includes:

a gear unit having a first gear driven to rotate with the output shaft on one side and a shaft support portion rotating together with the first gear on the other side, the shaft support portion being provided with balls and an outer member facing an inner surface of the housing; and

an annular second gear fixed on the inner surface of the shell and meshed with the first gear,

one end of the outer member along the axis of the output shaft is opposite to the inner surface of the housing or a gasket mounted on the housing, the other end is opposite to the second gear,

gaps are formed between at least one of the other end side portion of the outer member and the second gear, and between the one end side portion of the outer member and the housing or the spacer,

a gap is formed between an outer surface of the outer member and an inner surface of the housing.

2. The rotary support structure of an electric cylinder according to claim 1, wherein,

the gear unit and the second gear are inserted and arranged in the housing from an opening at one side of the housing in the order of the gear unit and the second gear,

the second gear is fixed to the housing by a flange portion protruding radially outward from an outer peripheral portion thereof.

3. The rotary support structure of an electric cylinder according to claim 1 or 2, wherein,

the portion of the inner surface of the housing facing the outer surface of the outer member and the outer surface of the second gear is a cylindrical surface, and the outer diameter of the outer surface of the outer member is smaller than the outer diameter of the outer surface of the second gear.

4. A rotary support structure for an electric cylinder according to any one of claims 1 to 3, wherein,

a second output shaft is fitted to and connected to an end portion of the gear unit, and a piston that is in close contact with an inner surface of the housing and reciprocates along the shaft center is screwed to the second output shaft.

5. A rotary support structure of an electric cylinder, wherein,

the device comprises:

a cylindrical housing;

a motor mounted on the housing and having an output shaft; and

the speed reducing mechanism is arranged in the shell and is connected with the output shaft,

the speed reducing mechanism includes:

a gear unit having a first gear driven to rotate with the output shaft on one side and a shaft support portion rotating together with the first gear on the other side, the shaft support portion being provided with balls and an outer member facing an inner surface of the housing; and

an annular second gear fixed on the inner surface of the shell and meshed with the first gear,

the second gear and the shaft support portion are arranged in a state of being separated in an extending direction of the shaft center when viewed in a direction orthogonal to the shaft center of the output shaft, and the outer member and the first gear are arranged in a state of being separated in a radial direction when viewed in a direction along the shaft center.

6. The rotary support structure of an electric cylinder according to claim 5, wherein,

in the shaft support portion and the outer member facing each other with the balls interposed therebetween, a length of the shaft support portion along an extending direction of the shaft center is smaller than a length of the outer member, and a surface of the side surface of the shaft support portion facing the second gear is farther from the second gear than a surface of the side surface of the outer member facing the second gear.

7. The rotary support structure of an electric cylinder according to claim 5 or 6, wherein,

the gear unit is a planetary gear mechanism, the first gear is a planetary gear, the shaft support portion is a planetary carrier that supports a plurality of the planetary gears, the output shaft is a sun gear,

the front end of the output shaft is provided with an inclined part with a thinner front end,

a recess for accommodating the inclined portion is provided in the shaft support portion at a position opposite to the output shaft.