JPH0925912A - Operating speed detecting sensor of cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the operating speed of a cylinder with high accuracy. SOLUTION: A operating speed detecting sensor is constituted in such a way that the cylinder cover 7 is provided with a coil 9 which can be projected into the cylinder 2 toward the lengthwise direction of the rod, and also the piston rod 5 is provided with a permanent magnet 13 opposing to the outer circumference of the coil, so that the induced electromotive force produced in the coil by the relative movement to the coil of the permanent magnet due to the expansive and contractive motion of the hydraulic cylinder 1 is measured for detecting the operating speed of the cylinder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operating speed detecting sensor for a cylinder such as a hydraulic cylinder provided in a construction machine.

[0002]

2. Description of the Related Art In general,
For example, in a hydraulic cylinder or the like provided in a construction machine, in order to appropriately control the hydraulic pressure supply to the hydraulic cylinder, the expansion / contraction operation speed of the hydraulic cylinder is detected and fed back to the flow rate control device of the hydraulic pump. There is one configured.

As means for detecting the operating speed of such a hydraulic cylinder, a displacement sensor for detecting the amount of displacement of the hydraulic cylinder is provided and means for differentiating the amount of displacement to obtain the speed, or a straight line of the hydraulic cylinder. There is known a means for converting a motion into a rotary motion, linking the rotary motion with a generator such as a tachogenerator, and measuring the electric power generated by the generator to detect the speed.

In the former case, however, the sampling interval for data extraction may be shortened in order to detect the speed with high accuracy, but in such a case or when the hydraulic cylinder is operating at a low speed, the displacement data Since the absolute value of becomes small, the small noise included in the detected displacement data
There is a problem that the speed calculation value obtained by differentiating the displacement data is greatly affected, and the accuracy of the calculated detection speed deteriorates.

On the other hand, the latter has a large number of parts to be attached to the outside of the hydraulic cylinder, and in order to protect these external parts from the external environment, a protective device such as a cover is further required, and the number of parts is further increased. As in the former case, there is also a problem that when the hydraulic cylinder operates at a low speed, the output electric power is small and it is easily affected by noise.

[0006]

SUMMARY OF THE INVENTION The present invention has been conceived in view of the above circumstances, with the object of providing a cylinder operating speed detection sensor capable of solving these problems. A cylinder cover and a movable side member including a piston slidably fitted in the cylinder cylinder and a piston rod to which the piston is fixed, the cylinder being configured to expand and contract, a head cover provided on the cylinder cylinder. A coil made of a conductive member protruding in the rod length direction, a cylindrical hole formed in the movable member so that the coil is loosely inserted, and a movable side facing the outer circumference of the coil. Based on the movement of the magnet, the magnet is provided integrally with the member, the inner peripheral surface side facing the coil is set to one of N and S poles, and the outer peripheral surface side is set to the other pole. It is characterized in being constituted by a detecting means for detecting the induction magnitude of electromotive force generated in the file. And the present invention, by this configuration,
The operating speed of the cylinder is simple,
It is made possible to detect with high accuracy.

[0007]

Next, an embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 denotes a hydraulic cylinder, and the hydraulic cylinder 1 includes a cylindrical cylinder tube 2, a piston 3 which is fitted in the cylinder tube 2 so as to be slidable in an axial direction, and a base end portion of the piston 3. Side is fixed via a nut 4, and a tip end side projects a piston rod 5 from the cylinder cylinder 2, a rod cover 6 that closes an end of the cylinder cylinder 2 on the protruding side of the piston rod 5, and a cylinder on the side opposite to the rod cover 6 side. It is composed of a member such as a head cover 7 that closes the end portion of the cylinder 2, and pressure oil is introduced into the cylinder cylinder 2 from the contraction side port 6a formed in the rod cover 6 or the expansion side port 7a formed in the head cover 7. Is supplied to the hydraulic cylinder 1 so that the hydraulic cylinder 1 expands and contracts, etc. In the figure, 8 and 8a are cushion rings.

Reference numeral 9 denotes a coil constituting the speed detecting sensor of the present invention, which is made of a conductive member. The coil 9 is solidified into a cylindrical shape by a non-magnetic insulating substance 10 such as resin or ceramics. Has been done. Further, at the base end of the non-magnetic insulating material 10, a screw groove 1 is formed on the outer peripheral surface.
A screw member 11 having an engraved 1a is integrally provided. By screwing the screw member 11 into a screw hole 7b formed in the center of the head cover 7, the nonmagnetic insulating material is formed. The coil 9 solidified by 10 is configured to be integrally attached to the head cover 7 in a state of protruding in the axial direction (the length direction of the piston rod 5) in the cylinder cylinder 2.

Further, a cylindrical auxiliary magnet 12 is installed inside the cylinder of the non-magnetic insulating material 10. In this embodiment, the auxiliary magnet 12 has an N pole on the outer peripheral surface side,
The inner peripheral surface side is set to the S pole. Of course, the N and S poles may be set in reverse, and in this case, the permanent magnet 1 described later will be used.
It goes without saying that the pole of 3 is also reversed.

On the other hand, at the axial center of the piston rod 5,
A cylindrical hole 5a into which the coil 9 is loosely fitted is formed. At the end of the cylindrical hole 5a on the head cover 7 side, a cylindrical permanent magnet 13 whose inner peripheral surface faces the outer peripheral surface of the nonmagnetic insulating material 10 with a slight gap is provided. The permanent magnet 13 is fixed by an adhesive or the like, but the inner peripheral surface of the permanent magnet 13 facing the coil 9 has an S pole,
The outer peripheral surface side is set to the N pole. The coil 9 solidified by the non-magnetic insulating material 10 can withstand the sliding resistance generated between the cylindrical hole 5a and the permanent magnet 13 and the fluid force of the pressure oil flowing in and out of the cylinder cylinder 2. It goes without saying that it has strength.

Further, 14 is a lead wire connected to both ends of the coil 9, and the lead wire 14 is drawn out from the end of the non-magnetic insulating material 10 on the side of the head cover 7,
It is connected to an amplifier 15 housed in a recess 7c formed in the head cover 7. The amplifier 14 is also connected to a voltmeter 17 outside the hydraulic cylinder 1 via a connector 16 that is also housed in the recess 7c.

In the embodiment of the present invention constructed as described above, the hydraulic cylinder 1 has a port 6a or a port 7a.
The expansion / contraction operation is performed by supplying the pressure oil to the coil. With the expansion / contraction operation, a slight gap is present in the coil 9 with respect to the coil 9 projecting from the head cover 7 in the cylinder cylinder 2 in the axial direction. Therefore, the cylindrical permanent magnet 13 fixed to the cylindrical hole 5a of the piston rod 5 moves back and forth in the axial direction in a state of facing each other, and accordingly, an induced current flows in the coil 9. The induced electromotive force generated in the coil 9 is measured by the voltmeter 17 after being amplified by the amplifier 15. The induced electromotive force e obtained at this time is the moving speed of the permanent magnet 13, That is, since it is proportional to the moving speed V of the piston rod 5 (e∝V), the moving speed of the piston rod 5 can be detected by measuring the magnitude of the induced electromotive force.

As described above, in the embodiment of the present invention, the moving speed of the piston rod 5 can be directly detected by measuring the magnitude of the induced electromotive force generated in the coil 9, which is different from the conventional case. In addition, compared to the one that obtains the speed by differentiating the displacement amount of the hydraulic cylinder, or obtains the speed by measuring the electric power generated by converting the linear motion of the hydraulic cylinder into the rotary motion, The effect is small, and high sensitivity and high dynamic characteristics can be obtained.

In addition, in this structure, the permanent magnet 13 is cylindrical, and the N pole is set to be polarized on the outer peripheral side and the S pole is polarized on the inner peripheral side. The induced electromotive force generated in 9 is the sum of the same current directions generated in the moving front side (the side where the magnetic flux increases and changes) and the moving rear side (the side where the magnetic flux decreases and changes) of the permanent magnet 13. Therefore, it is possible to contribute to the improvement of the detection accuracy while using the versatile coil 9 wound in the same direction.

Moreover, in this structure, each member constituting the speed detecting sensor such as the coil 9, the auxiliary magnet 12, the permanent magnet 13, the amplifier 15 and the connector 16 is the hydraulic cylinder 1.
Since it is housed inside, there is no need of a protective device for protecting external parts attached to the outside of the hydraulic cylinder 1, which contributes to simplification of the structure and reduction of the number of parts. Moreover, since the generated electromotive force is amplified by the amplifier 15 provided in the recess 7c formed in the head cover 7, the induced electromotive force is output as a weak voltage as it is. There is also an advantage that it is possible to contribute to the improvement of the detection accuracy by avoiding the influence of the increase.

Furthermore, the speed detecting sensors such as the coil 9, the auxiliary magnet 12 and the permanent magnet 13 are electromagnetically shielded by the cylinder cylinder 2, so that the cylinder cylinder 2 and the speed detecting sensor influence the external magnetic force. Since it can be effectively used as a shield member for preventing the above-mentioned, there is no need for a separate shield member.

Further, in this embodiment, since the inner cylinder portion of the coil 9 is internally provided with the auxiliary magnet 12 whose pole is opposite to the pole on the inner peripheral surface side of the permanent magnet 13, the auxiliary magnet 12 is provided. A stable magnetic field is formed between the magnet 12 and the permanent magnet 13, so that more accurate speed detection can be performed.

[0018]

In summary, since the present invention is constructed as described above, the expansion and contraction operation of the hydraulic cylinder causes
The magnet integrally provided on the movable side member moves relative to the coil protruding from the head cover in the rod length direction. At this time, the coil is proportional to the moving speed of the movable side member. Induced electromotive force is generated. As a result, it becomes possible to directly detect the moving speed of the piston rod by measuring the magnitude of the induced electromotive force generated in the coil.As in the conventional case, the displacement amount of the hydraulic cylinder is differentiated to obtain the speed, Compared to the one that obtains the speed by measuring the electric power generated by converting the linear motion of the hydraulic cylinder into the rotary motion, the influence of noise is small, and high sensitivity and high dynamic characteristics can be obtained. Become. In addition, since the coils, magnets, and other members that form the speed detection sensor are housed inside the hydraulic cylinder, a protective device for protecting external parts mounted outside the hydraulic cylinder is not required. This contributes to simplification of the structure and reduction of the number of parts.

[Brief description of drawings]

FIG. 1 is a sectional view of a hydraulic cylinder.

FIG. 2 is an enlarged sectional view of a main part.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is an output circuit diagram of a speed detection sensor.

[Explanation of symbols]

 1 Hydraulic Cylinder 2 Cylinder Tube 3 Piston 5 Piston Rod 7 Head Cover 9 Coil 10 Non-Magnetic Insulating Material 12 Auxiliary Magnet 13 Permanent Magnet 15 Amplifier 17 Voltmeter

Claims (7)

[Claims] 1. A cylinder configured to be expandable and contractible, comprising a cylinder cylinder and a movable side member including a piston slidably fitted in the cylinder cylinder and a piston rod to which the piston is fixed. A coil made of a conductive member protruding from the head cover provided in the cylinder in the rod length direction, a cylindrical hole formed in the movable member so that the coil is loosely inserted, and a coil outer circumference. A magnet that is integrally provided on the movable side member so as to face each other, and the inner circumferential surface side facing the coil is set to one of N and S poles and the outer circumferential surface side is set to the other pole, and based on the movement of the magnet. A cylinder operating speed detection sensor, comprising: a detection unit that detects the magnitude of an induced electromotive force generated in a coil. 2. The magnet according to claim 1, wherein the magnet has a cylindrical shape,
An operating speed detection sensor for a cylinder, wherein the inner cylinder surface side is set to either N or S pole and the outer cylinder surface side is set to the other pole. 3. The coil according to claim 1 or 2,
A cylinder operating speed detection sensor characterized by being solidified by an insulating material made of a non-magnetic material. 4. The cylinder operating speed detection sensor according to claim 3, wherein the insulating material is formed in a cylindrical shape. 5. The auxiliary magnet according to claim 4, wherein an auxiliary magnet whose outer peripheral surface side is set to a pole opposite to a pole on the inner peripheral surface side of the magnet is provided inside the cylinder of the insulating material. A cylinder operating speed detection sensor. 6. The detecting means according to claim 1, wherein:
An operating speed detection sensor for a cylinder, comprising: an amplifier for amplifying induced electromotive force; and a detector for detecting the magnitude of the amplified output power. 7. The cylinder operating speed detection sensor according to claim 6, wherein the amplifier is embedded in the head cover.