JPH0345127Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a length detection sensor used for measuring the degree of expansion and contraction of a cylinder in a working machine used outdoors. A rod is inserted into and held in the cylindrical case so as to be slidable and telescopically movable in the axial direction of the cylindrical case, and a strip-shaped electrical resistor is attached to the inner surface of the cylindrical case, and The present invention relates to a length detection sensor for an outdoor working machine, which is provided with an electric contact for detecting the amount of expansion and contraction of the electric resistor as a voltage change by changing the sliding contact position of the electric resistor.

[Conventional technology]

This type of length detection sensor generally has a cylindrical case sealed tightly for waterproofing and dustproofing (see Utility Model Application No. 60-3406).

[Problem that the invention attempts to solve]

Therefore, when the rod tries to slide and extend, the negative pressure inside the cylindrical case increases, and the case reaches the very small gap that exists inside the coated insulator of the coated cord led out of the cylindrical case. Due to the internal negative pressure, moisture adhering to the exposed part of the core wire of the coated cord during rainy weather or car washing could seep into the gaps in the coated cord and be guided into the cylindrical case. Once inside, moisture does not come out due to the sealing properties of the case, and gradually accumulates during use, causing changes in the contact resistance of electrical contacts and metal materials. This caused deterioration and caused the sensor to malfunction.

In view of the above-mentioned circumstances, the present invention aims to prevent moisture from entering the cylindrical case and eliminate malfunctions of the sensor caused by this.

[Means for solving problems]

The characteristic configuration of the present invention to achieve the above object is that a ventilation path that communicates the internal space of the cylindrical case with the outside air is formed to open downward to the outside air, and the lower end opening area of this ventilation path is It is located at the length detection sensor point of the outdoor work equipment, which is set to a size that does not allow water to rise due to surface tension, and has the following functions and effects.

[Effect]

In other words, by providing a ventilation path to communicate the internal space of the cylindrical case with the outside air, even if the rod expands, the air pressure inside the cylindrical case and the outside air pressure are kept almost the same, and therefore negative pressure is maintained. This means that the influence of the wires no longer extends between the lines in the covering code. On top of that,
The ventilation path is formed downward, and the open area at the lower end is set to a size that prevents water droplets from rising at the same time as air intake due to surface tension, so water is prevented from entering through the ventilation path. be.
Furthermore, the formation of the ventilation passage allows water vapor from the outside air to enter the case, but this water vapor can conversely escape to the outside air, so there is no chance of condensation forming inside the case. , it is easily discharged out of the case due to heat generation of the resistor, etc.

[Effect of idea]

As a result, it has become possible to prevent water from entering and staying in the cylindrical case, and to eliminate malfunctions of the sensor caused by this.

〔Example〕

Hereinafter, embodiments of the configuration of the present invention will be described based on the drawings.

The riding-type tiller shown in FIG. The rotary cultivating device B is connected via the lower links 3, 3 and one top link 4 so as to be able to rise and fall freely, and the lift arms 2, 2 and the lower links 3, 3 are connected to the lift rod 5 and the double-acting hydraulic cylinder 6. By controlling the operation of the hydraulic cylinder 1.6, the tilling device B can be driven up and down and rolled with respect to the agricultural tractor A.

Further, a sensor 7 is attached to the rear of the agricultural tractor A to detect the left and right inclination angle of the tractor with respect to the horizontal plane as a fluctuation in the voltage signal, and the rolling hydraulic cylinder 6 is equipped with a sensor 7 that detects the horizontal tilt angle of the tractor with respect to the horizontal plane. A length detection sensor S is attached that detects the rolling attitude of the tillage device B with respect to the tractor A and outputs the detection result as a voltage signal fluctuation.

Then, based on the signal from the inclination angle detection sensor 7, a target expansion/contraction amount of the rolling hydraulic cylinder 6 suitable for maintaining the horizontal inclination angle of the tilling device B with respect to the horizontal plane within a set range is calculated, and the length is The cylinder 6 is configured to perform so-called rolling control in which the cylinder 6 is automatically operated to a target expansion/contraction amount while checking the expansion/contraction amount of the cylinder 6 based on a signal from the detection sensor S.

The length detection sensor S includes a first
As shown in FIGS. 8 to 8, a cylindrical case 8 consists of a case body 8A having a substantially U-shaped cross section and a plate-shaped lid 8B that is detachably attached to the opening side of the case body 8A.
The rod 9 is inserted and held in the cylindrical case 8 so that it can slide and expand in the axial direction, and the upper end of the case body 8A of the cylindrical case 8 is placed on the bottom 6A side of the rolling hydraulic cylinder 6. It is attached to a pin-shaped bracket 10 that is screwed and fixed, and the lower end of the rod 9 is attached to a bracket 11 that is fixed to the U-shaped connecting fitting 6B of the rolling hydraulic cylinder 6. It is configured to extend and contract integrally with the main body.

A hole 20 is bored in the upper part of the outer surface of the case body 8A, and an L-shaped holder 21 having an inner diameter of about 5 mm is screwed from the outside. A rubber pipe 22 having a length of approximately 15 cm is fitted into the opening at the lower end of the holder 21, thereby forming a ventilation passage 23 that communicates between the inside and outside of the cylindrical case 8.

The cylindrical case 8 is oriented parallel to the rolling hydraulic cylinder 6 with attachment points a and b to the brackets 10 and 11 located on the center line c of the cylindrical case 8. installed in condition.

On the inner surface of the lid 8B of the cylindrical case 8, a band-shaped electrical resistor 12 made of synthetic resin or sintered and a band-shaped conductor 13 made of metal are fixed and held in parallel positions with each other. A block body 16 has a non-conductive plate-like holder 14 made of synthetic resin or the like attached thereto, and a bifurcated electrical contact 15 that makes sliding contact with the electrical resistor 12 and the conductor 13 is fitted and fixed onto the upper end of the rod 9. Furthermore, cords 17A and 17B for inputting voltage are connected to both ends of the electric resistor 12, and a cord 17C for extracting the detected voltage is connected to the conductor 13, respectively.

At the lower end of the case body 8A of the cylindrical case 8,
The sliding contact guide portion 8a that guides the rod 9 in a telescopically movable manner via the bush 18 and the sealing material 19, and the electric resistor 12 and the conductor 13 are connected to the rod 9.
They are arranged so that they overlap in the direction of expansion and contraction.

The electrical resistor 12 is attached to a plate-shaped holder 14 via an adhesive such as a resin fixing agent, and the plate-shaped holder 14 is also attached to the lid 8 of the cylindrical case 8.
It is attached to B via adhesive.

[Another example]

To carry out the present invention, as shown in FIG. 5, a small-diameter pipe 24 is inserted into the lower end of the rubber pipe 22 leaving about 8 cm below, and the water droplets adhering to the surface of the rubber pipe 22 are removed into large particles on the pipe 24. surface tension near the opening at the lower end, which promotes it to fall quickly without sticking.

To carry out the present invention, as shown in Fig. 6, an L-shaped holder 21 has an inner diameter of about 2 mm and an outer diameter of about 10 mm, and a rubber pipe 22 has a length of about 15 cm and an inner diameter of about 10 mm. The suction pressure may be lowered to prevent dust from entering.

As the ventilation path 23 of the present invention, a metal pipe may be used instead of the rubber pipe 22, or it may be integrated with the holder 21. Further, they may be integrally molded with the cylindrical case 8, or the ventilation passage 23 may be formed using a vertical hole bored in the side wall of the cylindrical case 8 in the longitudinal direction.

[Brief explanation of the drawing]

The drawings show an embodiment of the length detection sensor for an outdoor working machine according to the present invention, in which Fig. 1 is a partially cutaway side view in an installed state, Fig. 2 is a longitudinal sectional view, and Fig. 3 is a horizontal sectional view. FIG. 4 is an overall perspective view of the outdoor working machine,
5 and 6 are enlarged views of main parts of another embodiment. 8... Cylindrical case, 9... Rod, 12... Electric resistor, 15... Electric contact.

Claims (1)

[Claims for Utility Model Registration] It has a cylindrical case 8 and a rod 9 that is inserted and held in the cylindrical case 8 so as to be slidable and telescopically movable in the axial direction of the cylindrical case 8. A strip-like electrical resistor 12 is attached to the rod 9, and an electrical contact 1 is provided on the rod 9 to detect the amount of expansion and contraction of both 8 and 9 as a voltage change by changing the sliding contact position of the electrical resistor 12.
5 is a length detection sensor for an outdoor working machine, in which a ventilation path 23 that communicates the internal space of the cylindrical case 8 with the outside air is formed to open downward to the outside air, The length detection sensor of an outdoor working machine has a lower end opening area of the ventilation passage 23 set to a size that does not allow water to rise due to surface tension. The length detection sensor for an outdoor working machine according to claim 1, wherein the ventilation path 23 is formed in a pipe 22 whose one end is connected to the cylindrical case 8 in communication.