JPH0518406A - Oil-hydraulic apparatus with stroke sensor - Google Patents

Abstract

PURPOSE:To construct a device concerned in a compact size by installing a built-in stroke sensor in a hydraulic apparatus. CONSTITUTION:A rod sensor 7 with a solenoid A fitted internally is fixed to the bottom surface of a cylinder 1 in such a way as stretching in the cylinder axial direction, and a piston rod 3 is made from a non-magnetic or a feeble magnetic substance. A measuring hole 6 opening to the piston 2 side is provided in the axis of the piston rod 3, and in this hole the rod sensor 7 is inserted with possibility of relative movement. The stroke amount of the piston 2 is sensed from the overlapping length of the rod sensor 7 and hole 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic device incorporating a stroke sensor.

2. Description of the Related Art An outboard motor attached to the stern of a hull can change the inclination (boat angle) of the bow with respect to the water surface by operating the inclination angle, and the fuel consumption rate can be controlled by controlling the boat angle. It is possible to carry out an efficient sailing with less. In general, such tilting operation of the outboard motor is performed by a hydraulic device composed of a cylinder and a piston, and the hydraulic device has a stroke sensor for knowing the stroke amount of the piston in order to automatically control the boat angle. There is one that is built in. And this stroke sensor has a rod sensor made of a non-magnetic material protruding from the tip on the piston side, and an electromagnetic coil attached to the bottom surface on the cylinder side.
The rod sensor is inserted therein, and the stroke amount is detected by the change in the overlap length between the rod sensor and the electromagnetic coil when the piston strokes.

However, since the above-mentioned stroke sensor is provided so as to extend the rod sensor in the axial direction from the end face of the piston, the rod sensor is connected between the end face of the piston and the bottom face of the cylinder so that the rod sensor is not damaged by the lowering of the piston. It was necessary to secure enough space between them. Therefore, the cylinder inevitably becomes long in the axial direction, and as a result, the size of the device is inevitably increased.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hydraulic device with a stroke sensor, which has a built-in stroke sensor and enables the device to be made compact.

[0004]

SUMMARY OF THE INVENTION To achieve the above object, the present invention relates to a hydraulic device in which a piston is slidably inserted in a cylinder, and a rod sensor in which an electromagnetic coil is installed is provided on the bottom surface of the cylinder. While fixed so as to extend in the direction, the piston rod is made of a non-magnetic material or a weak magnetic material, and a measurement hole that opens to the piston side is provided at the axial center of the piston rod, and the rod sensor is provided in the measurement hole. It is characterized in that it is inserted so as to be relatively movable, and the stroke amount of the piston is detected by the overlap length of the rod sensor and the measuring hole.

As described above, since the rod sensor is composed of the electromagnetic coil and is fixed to the bottom surface of the cylinder, and the rod sensor is inserted into the measuring hole provided at the axial center of the piston rod, the piston is mounted on the bottom surface of the cylinder. It becomes possible to make the stroke as close as possible, and it becomes possible to shorten the cylinder length while providing the stroke sensor.

[0006]

1 shows a hydraulic device with a stroke sensor according to an embodiment of the present invention, in which 1 is a cylinder, 2 is a piston, and 3 is a piston rod. Supply holes 4 and 5 for supplying hydraulic oil are provided at the bottom of the cylinder 1, and the piston 2 is axially driven by the supplied hydraulic oil.

The piston rod 3 is made of a weak magnetic material or non-magnetic material such as copper, brass and stainless steel. More preferably, the piston 2 is also preferably made of a weak magnetic material or a non-magnetic material. A measuring hole 6 is provided at the axial center of the piston rod 3 so as to extend in the axial direction, and is opened at the end surface of the piston 2.

On the other hand, a sensor portion 9 composed of a rod sensor 7 and a support portion 8 is provided on the bottom surface of the cylinder 1, and the rod sensor 7 serves as a measuring hole 6 for the piston rod 3.
Is inserted to have an overlap length L. This overlap length L changes by the same length corresponding to the stroke amount of the piston 2, and therefore, by detecting the overlap length L as a change in the voltage V, as described below, The stroke amount of 2 is detected.

As shown in FIG. 2, an electromagnetic coil A is internally provided in the rod sensor 7 of the sensor section 9, and a supporting section 8 is also provided.
Another electromagnetic coil B is installed inside. The electromagnetic coil A forms a rod by being inserted into a resin pipe or embedded in a resin. As shown in FIG. 3, the two electromagnetic coils A and B are connected to the three lead wires a, b, and c together with the secondary electromagnetic coil 12 to form a bridge circuit. The primary electromagnetic coil 11 to which the oscillator 10 is connected is arranged in parallel with the secondary electromagnetic coil 12 of this bridge circuit, and thereby a constant AC voltage is generated. The output voltage V from this bridge circuit is output via the rectifier circuit 13 and is detected by a detector (not shown).

When the piston 2 strokes in the axial direction in the hydraulic device having the above structure, the overlap length L of the rod sensor 7 with respect to the measuring hole 6 changes, and the change causes the current flowing through the electromagnetic coil A to change. The output voltage V from the circuit changes. That is, as shown in FIG. 4, since the output voltage V changes in proportion to the change in the overlap length L, the stroke amount of the piston 2 can be known by detecting the output voltage V.

In the above-described hydraulic equipment, the rod sensor 7 is constituted by the electromagnetic coil A as a built-in stroke sensor, and the rod sensor 7 is inserted into the measuring hole 6 provided at the axial center of the piston rod 3. Therefore, the rod sensor 7 is not damaged even if the piston 2 is lowered to the bottom surface of the cylinder 1. That is, since it is not necessary to secure a large space between the piston end surface and the cylinder bottom surface, the length in the cylinder axial direction can be shortened. As a result, the device can be made compact.
INDUSTRIAL APPLICABILITY The present invention can be used not only as a hydraulic device for tilting an outboard motor, but also in various applications such as a hydraulic device for suspending a vehicle body.

[0012]

As described above, in the hydraulic equipment of the present invention, the rod sensor is constructed from the electromagnetic coil, is fixed to the bottom surface of the cylinder, and is inserted into the measurement hole provided at the axial center of the piston rod. Therefore, it is not necessary to secure a large space between the piston end surface and the cylinder bottom surface to protect the rod sensor, and the device can be made compact.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a hydraulic device with a stroke sensor according to an embodiment of the present invention.

FIG. 2 is a side view showing a main part of a sensor unit used in the present invention.

FIG. 3 is an electric circuit diagram of a stroke sensor according to the present invention.

FIG. 4 is a relationship diagram between an overlap length L and an output voltage V.

[Explanation of symbols]

1 cylinder 2 piston 3
Piston rod 6 Measuring hole 7 Rod sensor
A, B electromagnetic coil

Claims (1)

Claim: What is claimed is: 1. In a hydraulic device in which a piston is slidably inserted in a cylinder, a rod sensor in which an electromagnetic coil is installed is fixed to the bottom surface of the cylinder so as to extend in the cylinder axial direction. On the other hand, the piston rod is composed of a non-magnetic material or a weak magnetic material, a measurement hole opening to the piston side is provided in the axial center of the piston rod, and the rod sensor is inserted into the measurement hole so as to be relatively movable, A hydraulic device with a stroke sensor configured to detect the stroke amount of the piston by the overlap length between the rod sensor and the measurement hole.