JPS5962705A - Fluid pressure cylinder - Google Patents

Abstract

PURPOSE:To enable to measure the stroke of a piston against a cylinder by providing a concave part on the end face of the piston for obtaining the rate between propagation times of ultrasonic waves reflected and returned by the concave part and a non-concave part. CONSTITUTION:The ultrasonic wave transmitted from an ultrasonic-wave transmitting/receiving unit 5 provided on the side of a cylinder 1 is reflected at two spots on the end face of a piston 3, and times for these reflected ultrasonic waves to return to the ultrasonic-wave transmitting/receiving unit 5 are measured. By taking the product of the rate between these measured signals and the depth of a cocave 6, the position of the piston 3, that is, the stroke of a piston rod 2 can be obtained with high accuracy without reference to the change of fluid pressure and the like. At this stage, one spot among two on the end face of the piston 3 can be convexed besides being concaved.

Description

[Detailed description of the invention] Related to IE cylinder vc, especially IC in cylinder
L-rc is designed to be detected with high accuracy using an ultrasonic transceiver, regardless of the entry/exit position of the piston rod, changes in fluid pressure or fluid viscosity within the cylinder, etc.
k Regarding the body pressure cylinder.

Conventional force, automatic control means for the fluid pressure system [1] responds to the control command [2] detects the amount of movement in and out of the piston rod in the cylinder [7] uses the error data between the detected data and the control command data. Based on this, the in/out position of the piston rod is maintained at the set command position] Also, a fluid pressure pump is provided. , is there.

on the other hand,. As a means for detecting the amount of movement in and out of the piston rod, that is, as a sensor for detecting the movement position of the piston rod, an ultrasonic wave is emitted from an ultrasonic transmitter installed on the cylinder side toward one end surface of the moving piston. , The ultrasonic waves reflected from the piston (2) and returned are received by a receiver (2) also provided in the cylinder, which detects the in/out position of the piston rod from the propagation time of the ultrasonic waves. It has reached (1987-104)
No. 606).

However, the propagation velocity of the ultrasonic wave is 71. It is easy to be affected by pressure changes of the working fluid and viscosity changes due to temperature changes. 1. Therefore, it was not possible to accurately measure the amount of movement in and out of the piston rod.

The present invention aims to improve such conventional drawbacks, and uses an ultrasonic transmitter/receiver installed on the cylinder side to ensure accurate measurement of rl, zπ, and The overall purpose is to measure the in/out position of the piston rod.

Therefore, in the present invention, the ultrasonic transmitter/receiver is provided on all cylinder sides, and a recess or six locations are provided on the end face of the piston opposite to the ultrasonic transmitter/receiver. Calculate from the ratio of the propagation time of the ultrasonic waves that simultaneously emit all of the ultrasonic waves 1-1 f+, and both of which are reflected and return to the ultrasonic transmitter/receiver, and the dimensions of the recess or six locations in the ultrasonic traveling direction. A configuration in which the amount of movement of the piston or piston rod into and out of the cylinder is measured using a device;
It was.

Embodiments of the present invention will be specifically described below based on the drawings.

FIG. 1 shows an embodiment of a fluid pressure cylinder [2, partially cut away 7]. In the same figure, 1 is a cylinder Lm filled with a fluid such as hydraulic oil, 2 is one sealed end of this cylinder 1, 1/j is a seta piston rond that is slidably penetrated, and 3
111 is attached to the end of this piston rod 2, and 4 is a piston that comes into sliding contact with the inner circumferential surface of the cylinder; 4 is this piston 3;
A seal ring 5 fitted on the outer periphery is an ultrasonic transmitter/receiver supported by a liquid-tight Q at one end of the cylinder 1 so as to face one end surface of the piston 3.
It has a configuration that allows it to be used as both the transmitter and receiver.
It can be made independent. 6 is a recess formed in one end surface of the piston 3. Here, the ultrasonic transmitter/receiver 6 simultaneously emits ultrasonic waves to a portion with a recess and a portion without a recess on the end surface of the piston 3, and the ultrasonic wave is reflected by the end surface of the piston 3.
The configuration is such that the LLC ultrasonic waves are received again by the ultrasonic transceiver 5vc.

Next, the operation of this fluid pressure cylinder will be explained in detail. Now, at the piston 30 predetermined position, the ultrasonic transceiver 5
The distance from to the end surface of piston 3 is 1 as shown in Figure 2.
1 The depth of the recess is Δ11, and the thickness of the piston 3 is d. The magnitude of Kd is selected so that d>4Δl, so that the reflected wave from the bottom of the recess reaches the receiving section faster than the reflected wave from the back surface of the piston 3. Therefore, the propagation velocity of the ultrasonic wave kCs is reflected by the end surface of the piston 3 71. The respective propagation times of the reflected wave P1 at the bottom of the recess 6 and the reflected wave P2 at the bottom of the recess 6 are T□, ΔT□ [, and the distances l and Δl are calculated mathematically as follows: t7C'T□, Δl=CΔT1 Become. Since L, T□, and Δ1r1 vary depending on changes in fluid pressure and fluid viscosity, the above l and Δt2 cannot be determined accurately.

Therefore, substitute one ' and the other of the above two equations [,,,l=T□
/Δ'F□×Δl, the ratio between VcTI and ΔT□ remains constant as described later, despite changes in fluid pressure and fluid viscosity, so by calculating Tt /ΔTtk, , and the known Δl, it is possible to easily and accurately determine VC1, that is, the amount of movement in and out of the piston rod 2. In this way, regardless of the propagation speed C of the reflected wave, the general value of the propagation time /Δ'11□ and the known depth of the recess 6 Δ
γ1. I understand that.

FIG. 3 (α) shows the timing relationship between the transmission time of the ultrasonic signal Pα□ and the reception time of the two reflected wave signals “a11′ + PtL8” in the above case.
yards, and the propagation time of the ultrasonic wave in this case T1
．． The ratio of Δη is ET, /ΔT□− as described above. Here, when the fluid pressure or fluid viscosity changes E-, the propagation time becomes 71. responds equally to changes in [
2, as shown in Figure 3 Cb), T2゜ΔT2 changes, but T2/ΔT2 = i'□/ΔT1-, and the propagation time ratio remains the same regardless of changes in fluid pressure, fluid viscosity, etc. Always constant.

If necessary, the velocity and acceleration of the piston rod 2 can also be determined from VC by time-differentiating l determined by IcI as described above (!; VC.

FIG. 4 shows an electrical signal calculation device for calculating the signal in this manner. In the figure, reference numeral 11 denotes a receiving section of an ultrasonic transmitter/receiver 6 including an ultrasonic oscillator, and a signal Tl + ΔT0 corresponding to each of the reflected waves is outputted, and signals fl1, γl, and the like are input to a divider 12VC, γL. It has become. After calculating T□/ΔT1 in this divider 12, the result is input to the next stage multiplier 13VC, where it is output from the signal generator 14. T□/ΔT along with the depth signal Δl of the recess 6
After calculating 1xΔl, the result is displayed on the display 15Vc.
Input, input, or input 1 to an external control circuit. Naoko γ1. Each divider 12, multiplier 13, signal generator'
14t/f: Can be configured as a digital circuit.

In this way, the ultrasonic waves transmitted from the ultrasonic transceiver 5 provided on the cylinder 1 side are reflected at three locations on the end face of the piston 3, and these reflected ultrasonic waves return to the ultrasonic transceiver. By measuring the entire time in the ox and taking the product of the ratio of these measurement signals and the depth of the recess, the piston 3
, that is, the amount of movement in and out of the piston rod 2 can be determined with high accuracy regardless of changes in fluid pressure and the like.

In this case, one of the three locations on the end surface of the π piston 3 may be a recess in addition to the recess.

As described above in detail, the present invention provides γ1. a fluid pressure cylinder that responds to a control command (2) detects the amount of movement of the piston rod into and out of the cylinder, and controls the amount of movement of the piston rod based on the error between the detected data and the control command data; , a recess or recess is provided at one end of the piston rod, and ultrasonic waves are simultaneously emitted to both the recess or the part with and without the recess. [7] From the arrival time ratio of the ultrasonic waves returning to the ultrasonic transmitter/receiver and the dimensions of the recess or the recess in the ultrasonic emission direction, it is possible to accurately measure the amount of movement in and out of the piston rod. By using such a fluid pressure cylinder, it is said that it is possible to eliminate the conventional drawback that measurement results vary due to changes in fluid pressure or fluid accuracy within the cylinder. There are advantages to be gained.

[Brief explanation of the drawing]

Fig. 1 is a partially longitudinal front view showing one embodiment of a fluid cylinder according to the present invention, Fig. 2 is an enlarged explanatory view of the main part, and Fig. 3 (
α) and (b) are explanatory diagrams showing the propagation time of ultrasonic waves before and after changes in fluid pressure, etc., and FIG. FIG. 2 is a block circuit diagram of a signal calculation device. 1...Cylinder 2...Piston rod 3...Piston 5...Ultrasonic transmitter/receiver 6.・・・・・・Recess patent applicant Kayaba Kogyo Co., Ltd. Agent
Patent Attorney Amano Izumiko 3 Diagram Room 4 Zuba / 1 Diagram Kidney 2 I! 11

Claims (2)

[Claims] (1) Detect the amount by which the piston rod moves in and out of the cylinder in response to the control command, and based on the error data π between this detection data and the control command data, adjust the amount by which the piston rod moves in and out according to the control command. In a fluid pressure cylinder to be set at a position according to data, an ultrasonic transmitter/receiver is installed on the cylinder side, and a concave or convex PJi is provided on the end face of the piston facing the ultrasonic transmitter/receiver. The ultrasonic wave is emitted from the ultrasonic transmitter/receiver to both the concave PgT of the piston end surface or the area where there is crystallization and the area where there is no crystallization, and both of these waves are reflected back to the ultrasonic transmitter/receiver by reflection E-. The axial position of the piston' or the piston rod at the end of the piston' or the piston rod can be calculated from the ratio of the propagation time of the ultrasonic waves to Fluid pressure 7 cylinders. (2) In the ultrasonic transceiver, the transmitter and receiver are independent [-71. The fluid pressure cylinder according to claim 1 consisting of