JPS639144B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an electric cylinder in which a linear actuating member, an actuating part having a threaded shaft, a driving part having a transmission mechanism for rotating the threaded shaft, and a control part having an overload detection mechanism are made oil-tight. The lubricating oil sealed in the actuating part and the grease sealed in the driving part are prevented from leaking in any mounting position of the electric cylinder, thereby improving the overload detection function.

Conventionally, electric cylinders include those in which a reduction motor is directly connected to the rear end of a screw shaft, or those in which the screw shaft and motor are arranged in parallel.
As stated in the publication, not only are the actuating part and the driving part not oil-tight, but also the overload detection limit switch must be oil-tight from both the actuating part and the driving part due to its structure. In the latter case, as shown in Fig. 1, the striker S of the limit switch for overload detection is provided on the spring receiving member A, so the operating section and the control section are separated from each other in an oil-tight manner due to their structure. If the lubricating oil from the actuating part leaks into the control part and significantly impairs the control function of the control part, and if the lead wire C coming out of the limit switch is installed on the lower side, do not install the electric cylinder. Sometimes, the lead wire becomes stuck under the wire, which can easily cause accidents such as wire breakage.Furthermore, when the electric cylinder is supported by a trunnion, it becomes difficult to inspect the limit switch. required many constraints.

The present invention eliminates the above-mentioned conventional drawbacks, and an embodiment of the present invention will be described below with reference to FIG. The shaft 1 is caused to rotate forward and reverse by the forward and reverse rotation drive of the motor through the transmission mechanism. A linear actuating member 2 having a front end connected to an actuated member is screwed onto the screw shaft 1, and the linear actuating member 2 allows a cylinder 3 fixed to the case B to move linearly in the front and back direction, but does not rotate. It is immovably inserted and forms the working part.

The cylinder 3 has a chamber 5 in which a buffer compression spring 4 is housed.
A front spring bearing member 8 is formed in the chamber 5 and has an outer ring 6 of a front conical bearing that rotatably supports the screw shaft 1 and is in sliding contact with the screw shaft 1 via a seal member 7. A rear spring bearing member 10 having an outer ring 9 of a rear inverted conical bearing that rotatably supports the screw shaft 1 is inserted by applying preload to both ends of the spring 4 and clamping it. 10 holds the spring 4 under preload by using the front wall 11 and the rear wall 12 of the spring storage chamber 5 as stoppers, respectively. It is in sliding contact with. The inner rings 14 and 15 of the front conical bearing and the rear inverted conical bearing are fixed to the screw shaft 1, respectively.

Therefore, the linear actuating member 2 is moved in the compression direction (second direction).
When an overload (to the left in the figure) is applied, the screw shaft 1 moves to the left together with the linear actuating member 2, and the front conical bearing pushes the front spring bearing member 8 to the left. 4 is compressed to the left to buffer overload, and as the screw shaft 1 moves to the left, only the inner ring 15 of the rear inverted conical bearing separates from its outer ring 9 and moves to the left. At this time, the rear spring receiving member 1
0 does not move to the left using the rear wall of the spring storage chamber 5 as a stopper, so the outer ring 9 of the rear inverted conical bearing does not move to the left.

Further, when an overload is applied to the linear actuating member 2 in the tensile direction (rightward in FIG. 2), the screw shaft 1 moves to the right together with the linear actuating member 2, and the rear inverted conical bearing moves towards the rear spring bearing member 10. is pushed to the right, the compression spring 4 is compressed to the right to buffer the overload, and as the screw shaft 1 moves to the right, only the inner ring 14 of the front conical bearing is compressed to the outer ring 6. Move further away and to the right. At this time, since the spring bearing member 8 does not move to the right using the front wall of the spring storage chamber 5 as a stopper, the outer ring 6 of the front conical bearing does not move to the right.

Then, the actuating portion includes seal members 7 and 13.
It is completely oil-tight with the drive part.

A striker 17 of an overload detection limit switch (not shown) is attached to a striker holder 17' that is slidably inserted into the case B via a seal member 16 on the outside of the drive unit case B. The holder 17' rotatably supports the rear end of the screw shaft 1 via a bearing 18, and is in sliding contact with the peripheral surface of the rear end of the screw shaft 1 via a seal member 19. Therefore, the control section having an overload detection limit switch operated by the striker 17 is made oil-tight with the drive section by the seal members 16 and 19. The control unit is in drive unit case B.
In addition to an overload detection limit switch attached to the outer surface of the case B, control devices such as stroke adjustment means and stroke position detection means for the linear actuating member 2 are attached to the cover 20 detachably attached to the case B. It is therefore protected.

When the above-mentioned overload is applied to the linear actuating member 2, the screw shaft 1 moves to the left or to the right. It operates a limit switch.

As described above, the present invention includes attaching the operating striker of the overload detection limit switch to the rear end of the screw shaft, screwing the linear actuating member to the front end of the screw shaft,
The spring bearing member that clamps the compression spring from both ends is composed of a front spring bearing member and a rear spring bearing member, and a transmission gear from the motor drive shaft is fixed to the middle part of the screw shaft, so that the operating part and the drive The parts and the control part can be arranged on the same axis along the screw shaft, and each part is completely oil-tightly separated by a seal member, so fluid lubricating oil can be applied to the operating part and the drive Even if the parts are filled with viscous oil such as grease to form an oil bath and a grease bath, respectively, these oils will not mix with each other regardless of the mounting orientation of the electric cylinder, making it optimal. According to the present invention, it is possible to freely select and seal oil in each part, and it is possible to provide an electric cylinder that does not require maintenance. In addition, since the control unit is placed all together at the end, the collie wire is not exposed to the outside of the machine, which prevents accidents such as the lead wire becoming caught or broken during operation during transportation or installation. However, it has the advantage that inspection and adjustment of the control section can be done at once by simply removing the dustproof cover.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a conventional electric cylinder, and FIG. 2 is a sectional view of a main part of the present invention. DESCRIPTION OF SYMBOLS 1... Threaded shaft, 2... Linear operating member, 3... Cylinder, 4... Compression spring, 6, 14... Front conical bearing, 9, 15... Rear inverted conical bearing, 8...
Front spring bearing member, 10... Rear spring bearing member, 7,
13, 16, 19... Seal member, 17... Striker, 17'... Striker holder.

Claims (1)

[Claims] 1. In an electric cylinder having a linear actuating member that is screwed onto a screw shaft rotationally driven by a motor and is prevented from rotating, a buffer compression spring housed in the cylinder is preloaded from both ends and clamped to tighten the screw shaft. a front spring bearing member and a rear spring bearing member each having a front conical bearing and a rear inverted conical bearing that rotatably support the compression spring; A stopper of the receiving member, a sealing member interposed between the front spring receiving member, the inner wall of the cylinder and the outer periphery of the screw shaft, and a transmission mechanism interposed between the drive shaft and the screw shaft of the motor. a striker holder that is slidably inserted into a housing case via a sealing member, rotatably supports the rear end of the screw shaft via a bearing, and has a sealing member interposed between it and the outer periphery of the screw shaft; An overload detection device for an electric cylinder, comprising: a striker for an overload detection limit switch provided on the holder on the outside of the case.