JPS5850256Y2 - position sensing device - Google Patents

Description

[Detailed description of the invention] This invention relates to a position detection device that detects the position of a moving member using a limit switch.
It can be applied to detecting the position of various link mechanisms, and is particularly suitable for the height detection device of this vehicle.

Position sensing devices using limit switches are widely used.

A commonly used method is shown in FIGS. 1 and 2.

In FIG. 1, a convex cam 2 is provided at the detection position of the moving link 3,
At the detection position, the convex portion pushes up the limit switch 1 attached to the base plate 4 to activate the contact and detect the position.

On the contrary, FIG. 2 shows a method in which a concave cam 5 is provided at the detection position of the movable link 3, the limit switch 1 is always pushed up, and the limit switch 1 is dropped into the recess at the detection position to activate the contact.

With these methods, it is unavoidable that the operating point of the limit switch differs depending on the direction of movement of the moving link due to the shape of the cam and the roller of the limit switch. There will be a large error.

In order to reduce the error in the operating point due to the direction of movement, it is necessary to make fine adjustments to the shapes of the cam and roller, as well as the precision of the relative position of the cam and limit switch. However, this method is not practical.

Therefore, when performing detection at one correct point or a point close to it, it is necessary to use two or more limit switches to detect the movement direction separately and process it electrically, or to use something other than a limit switch. method is used.

The present invention aims to reduce the error in the detection point due to the direction of movement when position detection is performed using one limit switch.

The present invention combines one limit switch and the rotatable cam combined with it on a common plywood board to maintain the relative position of the limit switch and cam with high accuracy, and the cam surface has a concave detection part. On the other hand, a part of the member whose position should be detected is slidably engaged with the fork part formed at one end of the cam, so that even when using one limit switch, the direction of movement of the member whose position should be detected is fixed. This reduces the error of the detection point due to

An embodiment of the present invention will be explained in detail with reference to FIGS. 3 and 4.

11 is a limit switch, 12 is a limit switch 11
A cam 14 is rotatably attached to a fixing pin 13 so as to be in contact with the roller 11a of the limit switch 11.
The limit switch 11 is fixed to this common base plate, and the cam 12 is attached via a fixing pin 13.

The cam 12 is provided with a recess 12b matching the shape of the roller 11a at one location on its circumference that contacts the roller 11a of the limit switch 11, and a bifurcated arm 12c on the opposite side.

15 is a movable link whose moved position is to be detected; 16 is a bifurcated arm 1 of the cam 12 fixed to the movable link 15;
2c is a movable pin that is slidably attached to the inside.

Note that the two-pronged arm 12c of the cam 12 has a length such that the movable pin 16 does not come off over the entire stroke of the movable link 15.

Now, when the movable link 15 is moving in either direction, the movable pin 16 coupled thereto rotates the cam 12 while sliding between the forked arms 12c of the cam 12.

At this time, since the recess 12b formed on the cam surface is also rotating and moving, the roller 11a of the limit switch 11 is pushed up along the cam surface.

When the movable link 15 moves in the direction of the arrow from the dashed line position 15' on the left side of the figure and reaches the detection point, the trifurcated arm 12c also moves by the movable pin 16 fixed to the movable link 15, and the cam 12 rotates, causing the cam surface to rotate. Since the recess 12b provided in D matches the roller 11a of the limit switch 11, the roller 1
1a falls into the recess 12b of the cam surface and becomes the state shown by the solid line, and at this position the contact of the limit switch 11 is activated.

When the moving link 15 further moves, the cam 12 rotates and the recess 12b on the cam surface comes off the roller again, causing the roller 1
1a is pushed up, and the limit switch 11 returns to its original state.

The two-pronged arm 12c of the cam 12 may be changed into a shape such as an elongated hole or a groove that has a similar effect.

Exactly the same effect occurs when the moving link 15 moves from the opposite side.

Therefore, the error in the operating point of the limit switch 11 due to the moving direction of the moving link 15 can be reduced.

In the above embodiment, a case has been described in which the movable pin 16 moves in an arc by the movable link 15, but a similar configuration can be used for linear motion of the movable pin.

As described above, the present invention mounts the relative positions of the limit switch and the cam with high precision through a common base plate, operates the limit switch by this cam, and connects a part of the member whose position is to be detected to the three-pronged part of the cam. Since the limit switch is slidably attached to the limit switch, it is not affected by rattling of the moving member, and position detection with less error depending on the direction of movement is possible with one limit switch.

Furthermore, since the cam is attached to a common base plate, it is smaller and more practical than when it is attached to a moving member.

Therefore, when applied to a vehicle height detection device, for example, the error in the detection position when the vehicle body is rising or falling is small, and the vehicle body can be supported at a substantially constant height in either case.

[Brief explanation of the drawing]

1 and 2 are front views showing an example of a general position detection device using a limit switch, FIG. 3 is a front view of the position detection device according to the present invention, and FIG. 4 is a side view thereof. 11... Limit switch, 12...
Cam, 13...Pin, 14...Common base plate, 15...Movement link, 16...Movement pin.

Claims (1)

[Scope of utility model registration request] A cam having a concave portion for activating the limit switch is rotatably mounted on the plywood board on which the limit switch is mounted, a forked portion is formed on this cam, and a part of the moving member whose position is to be detected is formed on the cam. A position detection device characterized in that the device is slidably engaged with a forked portion.