JPH0131806Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an electric cylinder. As is well known, an electric cylinder uses a mechanism consisting of a male thread and a female thread to cause the rotation of an electric motor to reciprocate in the axial direction of an operating rod engaged with the female thread.

As a means of increasing the thrust of the electric cylinder, generally, the lead of the screw is changed, or a reduction mechanism with a fixed ratio is installed between the electric motor and the screw mechanism (for example, a spur gear is installed between the electric motor and the male screw of the screw mechanism). The feed speed of the operating rod is constant.

There is also a device that uses a variable speed electric motor to make the feed speed of the operating rod variable. However, both have constant torque characteristics, and the thrust of the operating rod is determined by the rated output of the electric motor, which may result in insufficient thrust if the load is large. Therefore, to compensate for the lack of thrust, a large capacity electric motor must be used. Also, these devices cannot produce zero output. Furthermore, it is necessary to separately provide an overload protection device to protect against abnormal loads.

The present invention solves the above-mentioned drawbacks by making the drive unit more compact and capable of generating a large thrust when necessary. At the same time, the feed speed of the operating rod is automatically increased when the load is light, resulting in excellent workability. The object of the present invention is to provide an electric cylinder with constant horsepower characteristics.

The present invention will be described below with reference to the drawings. FIG. 1 shows an example of a continuously variable friction transmission developed by the applicant. In this figure, 1 and 2 are an input shaft and an output shaft having a common center axis, 3 is a conical rotor, 4 is a speed change ring, 5 is a transmission wheel on the input shaft,
6 is a transmission wheel on the output shaft.

As shown in FIG. 2, the conical rotor 3 has one conical surface 3a as a friction transmission surface that changes the effective half meridian and two friction transmission surfaces 3b and 3c whose effective half meridian is constant. The friction transmission surface 3b has an arc-shaped cross section, and the friction transmission surface 3c has a flat surface.
The former is frictionally engaged with a friction transmission wheel 5 on the input shaft, and the latter is frictionally engaged with a friction transmission wheel 6 on the output shaft. As shown in FIG. 2, the rotational speed N of the output shaft 2 is determined when the speed change ring 4 is on the large diameter side of the conical friction transmission surface 3a and between the dimensions a, b, c, and d, a:b= c:
It becomes 0 in a state where the relationship d holds true. An arrow S in the figure indicates the moving direction of the speed change ring that reduces the rotational speed N of the output shaft 2.

Before explaining the electric cylinder according to the present invention as shown in FIG. 3 using the friction continuously variable transmission as a base body, parts denoted by the same reference numerals as in FIGS. 1 and 2 are the same and will be omitted.

To explain the electric cylinder according to the present invention, 7
8 is a male thread provided on the output shaft 2, and a pressure generating device 9 is connected between the output shaft 2 and the transmission wheel 6. They are integrally engaged through. 1
0 is a female thread that screws into the male thread 8, 11 is a female thread 1
It is an operating rod that is engaged at zero. 12 is the operating rod 11
The upper key fits into a key groove 14 provided on the inner surface of the cylinder frame 13, thereby preventing the operating rod 11 from rotating. The end of the operating rod 11 projects from the hollow end of the cylinder frame 13 in the longitudinal direction. 15 is a male threaded bearing. Note that when the load is directly connected to the operating rod, the rotation preventing means between the cylinder frame and the operating rod can be omitted. Reference numeral 16 denotes a movement regulating device that controls the force that tries to move the speed change ring 4 to the high speed side.
The cam device 20 includes a spring 17 and a cam device 20 including a first cam surface 18 and a second cam surface 19 as shown in FIGS. When increases, spring 1
7 acts to move the speed change ring 4 toward the lower speed side.

21 is the first cam surface 18 or the second cam surface 19
This is a pin on the transmission ring 4 that engages with the transmission ring 4. This pin 21 is fixed to a bracket 23 on a casing 22 as shown in FIG.
It is possible to have a deformed structure in which the direction of is reversed. 24 is the first cam surface 18 and the second cam surface 19
This is the notch space. The spring 17 is provided between the casing 22 and the speed change ring 4 and is engaged with each other, and the cam device 20 is fixed to the casing 22. 4 and 5 are diagrams showing the operation regulating device 16 in different states, and FIG. 4 shows the output shaft 2.
Figure 5 shows the state where the rotational speed of the output shaft 2 is the lowest value (N=0), and FIG.
MAX) status.

When the input shaft 1 is rotated in the D direction and the output shaft 2, that is, the male thread 8 is rotated in the E direction, the speed change ring 4 receives a force (rotational force) in the F direction, so the first cam surface 18 becomes activated. When the rotation direction of the input shaft 1 and the output shaft 2, that is, the male screw 8, is opposite to the above-mentioned direction, the second cam surface 19 is activated.

The directions of the first and second cam surfaces 18 and 19 are selected so that the force acting on the speed change ring 4 due to the load on the operating rod 11 has a component force in the direction of moving the speed change ring 4 in the deceleration direction. ing. That is, the first
When the cam surface 18 is in the operating state, the force acting on the cam surface 18 due to the load applied to the operating rod 11 is the rotational force F and its component force F ₁ , as shown by the arrow.
It is represented by F ₂ (see Fig _. 5), and is a component force effective for moving the speed change ring 4 in the deceleration direction. In this configuration, switching of the reciprocating motion of the operating rod is performed by a position detector (not shown).

The operation of the present invention in the above configuration will be explained as follows based on the case where it is used in a compressor as shown in FIG.

As the electric motor is driven, the transmission wheel on the input shaft side,
Power is transmitted to the operating rod via the conical trochanter, the transmission wheel on the output shaft side, the output shaft, and the screw mechanism. Therefore, until the operating rod moves in the axial direction and starts the compression operation, there is no load, so the speed change ring is positioned on the high speed side by the spring of the movement regulating device. At this time, the operating rod is moved at a rapid traverse speed V ₁ in the no-load operating section from point a to point b.

Furthermore, when the cylinder operates and the operating rod starts compressing the object to be compressed, a load is applied to the operating rod, so the speed change ring is moved to the low speed side against the spring of the movement regulating device. Therefore, the feed speed V ₁ of the operating rod is b
The thrust force F ₁ decreases from point b to point c (load operation section), and conversely increases from point b to point c (load operation section) due to constant horsepower characteristics, increasing the compression operation. At this time, the operating rod is moved at a speed corresponding to the load. In addition, if an excessive load is applied to the operating rod, the speed change ring is brought to the lowest value (N = 0) against the force exerted by the spring of the movement regulating device, and the power rotation to the male screw becomes 0, and the operating rod is rotated. movement is stationary to prevent overloading. Note that even when the power rotation to the male screw becomes 0, the electric motor continues to rotate steadily.

As described above, the electric cylinder of the present invention moves the operating rod rapidly when the load on the operating rod is light (including no load), and when the load is other than light, the actuating rod is moved further with thrust and feed speed according to the load. When returning after completion, quick return operation is possible.

As a result, the drive unit can be made smaller and the thrust of the operating rod can be increased, so work efficiency can be greatly improved and overload protection can be achieved for automation, which is continuously used as a drive source for various equipment. Since the function is provided by the drive mechanism itself, the structure can be simplified.

[Brief explanation of drawings]

Fig. 1 is an explanatory longitudinal sectional view of the friction continuously variable transmission used in the device according to the present invention, and Fig.
An explanatory diagram of the state in which the rotational speed of the output shaft becomes zero in the one shown in the figure, Figure 3 is a longitudinal sectional view of the electric cylinder according to the present invention, and Figures 4 and 5 are the drive section of the electric cylinder in Figure 3. Fig. 6 is an explanatory diagram showing the relationship between the thrust of the actuating rod of the electric cylinder shown in Fig. 3 and the feed speed, and Fig. 7 shows a modification of the cam device. It is a drawing. 1... Input shaft, 2... Output shaft, 3... Conical trochanter, 4... Speed change ring, 5, 6... Operating wheel, 7...
...Electric motor, 8...Male thread, 10...Female thread, 11
... Operating rod, 13 ... Cylinder frame, 15
... Bearing, 16 ... Motion regulating device, 17 ... Spring, 18, 19 ... Cam surface, 20 ... Cam device,
21...Pin, 22...Casing, 23...Bracket, 24...Notch space.

Claims (1)

[Scope of utility model registration request] The transmission system from the input shaft to the output shaft has a plurality of conical rotors that perform planetary motion, and is commonly frictionally engaged with the conical surfaces of these conical rotors, and is moved in the axial direction to change the gear ratio. In addition to the conical surface, the conical trochanter includes a first friction transmission surface that engages with the transmission wheel on the input shaft and a second friction transmission surface that engages with the transmission wheel on the output shaft. A continuously variable friction transmission of the type provided with a friction transmission surface is drivingly connected to an electric motor, and reciprocating in the axial direction via a female thread that is engaged with a male thread that is linked to an output shaft that rotates in forward and reverse directions. a spring that exerts a force in the direction of moving the speed change ring of the frictionally continuously variable transmission to the high speed side, and a spring that resists the force exerted by the spring as the load applied to the operating rod increases due to the drive of the electric motor. and a cam device having a pair of cam surfaces that attempts to move the speed change ring in the deceleration direction by reducing the speed of the operating rod as the load applied to the operating rod increases. An electric cylinder that is characterized by increasing thrust.