JPH0331702A - Position sensor for cylinder rod - Google Patents

Abstract

PURPOSE:To optionally change the waveform of an output curve in accordance with a purpose and to easily execute signal processing by constituting a position sensor with a cylinder rod provided with an electromagnetic scale and a solenoid type head consisting of differential coils. CONSTITUTION:Reforming parts having respectively different electromagnetic characteristics are provided on the cylinder rod 1 with a fixed interval as a pattern and used as a scale. On the other hand, the solenoid type head 2 is constituted of detecting coils 2a, 2b whose winding directions are different from each other and an exciting coil 2c as a differential type. When the cylinder is differentially moved and the rod 1 is deformed in the axial direction, the difference of voltages generated by the coil 2c of the head 2 is detected by the coils 2a, 2b, so that an output is increased and the dispersion of a peak is reduced. Since an inflection point is set up on the center of a pattern in the electromagnetic scale, the dispersion of the pitch of the peak is also reduced. Thus, the waveform of a detected output curve can be optionally changed in accordance with a purpose and signal processing can easily be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cylinder rod position sensor, and more particularly to a cylinder rod position sensor using a solenoid type heald.

[Conventional technology]

The magnetic scale is known as a pattern formed by providing a base material with altered parts having different magnetic properties at regular intervals. For these magnetic scales, the detection side is a core-type magnetic head, M
Generally, a magnetic sensor element such as an R element or a Hall element or a solenoid type head is used. The present invention relates to the solenoid type head, and generally includes a bobbin made of a non-magnetic material such as synthetic resin and the like. It is known for its wrapped configuration. Although the above-mentioned core-type magnetic head and magnetic sensor element have the advantage of high detection output, they also have the disadvantage that gap management is difficult because they react sensitively to gap fluctuations. There is. Furthermore, as shown in FIG. 5, since the transformation point H of the magnetic scale 1 coincides with the output curve of the core-type magnetic head 3, the variation in the transformation point H of the magnetic scale 11 (which is a variation in the pitch of the magnetic pattern) ), there is an inconvenience that the width of the peak of the detection output also varies.

This problem arises from the fact that it is difficult to stably and clearly create a boundary between the magnetically altered part and the base material part in the magnetic pattern of the magnetic scale itself. On the other hand, the solenoid type head has a slightly lower detection output, but detects the electrical or magnetic characteristics by making them uniform in the circumferential direction of the scale, so gap management,
Another advantage is that it is easy to manage manufacturing variations in the electrical or magnetic transformation points of the electromagnetic scale itself.

(Problem to be Solved by the Invention) Although the solenoid type head has the above-mentioned advantages, the conventional single coil solenoid type head still has
As with other core-type magnetic heads and magnetic sensor elements, the deformation point of the scale coincides with the inflection point of the output curve of the solenoid-type head, thus avoiding a decrease in the detection density of the deformation point of the electromagnetic scale. The disadvantage is that it cannot be done.

The present invention focuses on the above-mentioned conventional problems, improves the detection accuracy and resolution of alteration points of an electromagnetic scale, and positions the cylinder rod so that an optimal output curve can be obtained for the detection purpose. The purpose is to share sensors.

[Means to solve the problem]

In order to achieve the above object, the cylinder rod position sensor according to the present invention will be described with reference to FIG. It has a structure consisting of. Further, in such a configuration, the pitch of the electromagnetic pattern of the electromagnetic scale and the width of the solenoid head may be different.

[Effect]

According to the above configuration, since the differential coil is used at the solenoid type node, the output characteristics are improved, and the inflection point of the output is at the center of the pattern of the electromagnetic scale, so the variation in peak width is reduced. Furthermore, since the pitch of the bangs of the electromagnetic scale provided on the cylinder rod and the width of the solenoid head are different, the waveform of the output curve to be detected can be freely changed depending on the purpose of detection.

[Embodiments] Examples of the cylinder rod position sensor according to the present invention will be described in detail below with reference to the drawings. FIG. 1 shows an embodiment according to claim 1.

Modified parts having different electromagnetic properties were provided at regular intervals on an oil cylinder rod (or pneumatic cylinder rod) l to form a pattern, and this was used as a scale.

On the other hand, the solenoid type head 2 is a differential type consisting of two (national detection coils 2a, 2b) and an excitation coil 2c with different winding directions.When the cylinder moves differentially and the cylinder rod 1 is displaced in the axial direction, , the throat 2 to the solenoid type
Since the detection coils 2a and 2b detect the voltage difference generated by the excitation coil 2C, as shown in Fig. 2, the detection output increases compared to the case where a single-coil solenoid head is used, and the output peak is reduced. Variations in height are reduced. Furthermore, since the inflection point is located at the center of the pattern of the electromagnetic scale, variations in the pitch of the peaks are also reduced.

FIG. 3 shows an embodiment of claim 2, and shows the width X of the solenoid head and the cylinder mouth.

In the relationship between the edge y and the reforming part provided in the door l, x<
The output curve is shown when y is set. In this case, the alteration point of the electromagnetic scale is output in a pulsed waveform. Furthermore, x
=y, the output curve is output in a waveform close to a sine curve, as shown in FIG. The dimensions of X and y can be arbitrarily selected depending on the pitch of the pattern of the electromagnetic scale provided on the cylinder rod, the mounting space of the solenoid head, etc. This makes it possible to obtain an optimal output curve for the purpose of detection. This width can be finely adjusted by adjusting the frequency. In other words, increasing the frequency is equivalent to decreasing the coil width, and decreasing the frequency is equivalent to increasing the coil width. Of course, it is also possible to finely adjust the magnetic flux distribution by using the magnetic material around the coil. In addition, a solenoid normally winds the conductor wire evenly around the length of the bobbin, but it is possible to intentionally make the winding uneven and change the magnetic flux distribution to adjust the output characteristics.

〔Effect of the invention〕

As explained above, according to the present invention, since the differential coil is used in the solenoid head, the width is adjusted to ga, and the output characteristics are improved compared to the conventional solenoid head. Furthermore, there are advantages in terms of management, such as ease of setting thresholds for detecting deformation points in cylinder rods, etc.

Furthermore, since the pitch of the pattern of the electromagnetic scale provided on the cylinder rod and the width of the solenoid head are different, the waveform of the output curve to be detected can be freely changed according to the detection purpose, increasing the capacity of signal processing. It is possible to improve the

[Brief explanation of drawings]

Figure 1: Conceptual diagram of a cylinder rod position sensor according to an embodiment of the solenoid head according to claim 1. Figures 2 and 4: Output curve detected by the solenoid head of Figure 1. Figure 3: An explanatory diagram of the output curve when the relationship between the solenoid head according to claim II and the pitch width of the electromagnetic scale pattern is changed. Figure 5: Conventional core Explanation of the output curve detected by the type magnetic head Figure 1... Cylinder rod 2... Solenoid type head Figure 1 Figure 2! ! i! ! Figure 3 Figure 4 Figure 5

Claims (2)

[Claims] (1) Cylinder rod 1 equipped with an electromagnetic scale
and a solenoid head 2 made of a differential coil. (2) The cylinder rod position sensor according to claim 1, wherein the pitch of the electromagnetic pattern of the electromagnetic scale and the width of the solenoid head are different.