GB1578419A

GB1578419A - Pointers for display instruments

Info

Publication number: GB1578419A
Application number: GB2261378A
Authority: GB
Original assignee: Mannesmann VDO AG
Current assignee: Mannesmann VDO AG
Priority date: 1977-05-26
Filing date: 1978-05-25
Publication date: 1980-11-05
Also published as: AU3629278A; DE2723783A1; FR2393400A2; JPS541652A; FR2393400B2

Description

(54) IMPROVEMENTS IN POINTERS FOR DISPLAY INSTRUMENTS (71) We, VDO ADOLF SCHIND LING AG, of 103 Grafstrasse, Frankfurt/ Main, Germany, a body corporate organised according to the laws of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be par ticularly described in and by the following statement: The present invention relates in general to pointers for display instruments, and more particularly to pointers for display instruments having a pointer arm, a socket, a balancing weight and, if necessary, a covering cap arranged betwen the pointer arm, and the socket and the balancing weight. The covering cap is secured to the pointer arm by rivets formed on the pointer arm, the socket and the balancing weight being combined as an integral unit.The integral unit is a sintered or die-cast element made from a metallic material of medium to high specific gravity.

This known method of construction of pointers makes it possible to achieve a pointer residual imbalance two to three times smaller than that of a previously known pointer. There are two main reasons for this.

Firstly, the manufacturing tolerances of the pointer arm and the sintered or die-cast unit comprising a socket and a balancing weight can be kept extremely small. Secondly, at worst the tolerances of only three (instead of four) elements are combined. The socket, the balancing weight, and the receiving bores for the rivet pins and the pointer shaft, can be manufactured economically in a single working step by a sintering or die-casting process. Assembly of the sintered or die-cast element, the pointer arm and the cover cap if appropriate, is extremely simple and can be carried out by an automatic machine.

In order to satisfactorily secure the pointer to the pointer shaft, it is known for both the receiving bore provided for the pointer shaft in the socket contact and the free end of the pointer shaft to be slightly conical.

However, despite this measure, the pointer does not remain securely fixed to the pointer shaft for a sufficiently long time, especially when using die-cast elements of zinc. This is mainly due to the materials used for the pointer, which are either too hard or too soft for a secure fixing to be achieved.

An object of the present invention is to obviate this disadvantage.

According to the present invention there is provided a pointer for a display instrument having a pointer arm, and an integral unit comprising a socket and a balancing weight, said unit being secured to the pointer arm, wherein said socket is provided with a sleeve for engaging with the shaft of the pointer when located therein.

The material from which the sleeve is made depends on the method used to connect the pointer to the pointer shaft. If the pointer is hammered on to the pointer shaft (for example in a mechanical velocity meter) then it is desirable to manufacture the sleeve from brass. If, however, the pointer is screwed onto the pointer shaft (for example in a moving coil metering instrument), then aluminium is the most suitable material for the sleeve.

Preferably, the sleeve is knurled on its outer surface so that it engages snugly with the socket.

The present invention will now be des cribed in greater detail by way of example with reference to the accompanying drawing, in which: Figure 1 shows a partially sectioned lateral elevation of a pointer; and Figure 2 shows a plan view of the pointer shown in Figure 1.

Referring to the drawing, the pointer comprises a pointer arm 1 made from plastics material, and a single integral unit 4 designed as a zinc die-cast component. The unit 4 is secured to the pointer arm 1 by means of two rivets 2 and 3 attached at one end thereof.

The integral unit 4 includes a circular disc 5 having two faces 6 and 7. The end face 6 which faces the pointer arm 1 is plane; the other end face 7 has formed upon it a projection 8, in the shape of a sector of a circle, which acts as a balancing weight, and a central socket 9. The socket 9 is formed with a receiving bore 10 into which is pressed a brass sleeve 17. The sleeve 17 then receives the pointer shaft (not shown) which is a push fit thereinto.

In a preferred form, the sleeve 17 is knurled on its outer surface.

WHAT WE CLAIM IS:- 1. A pointer for a display instrument having a pointer arm, and an integral unit comprising a socket, and a balancing weight, said unit being secured to the pointer arm, wherein said socket is provided with a sleeve for engaging with the shaft of the pointer when located therein.

2. A pointer according to claim 1, wherein the sleeve is adapted to receive the shaft of the pointer as a push fit thereinto.

3. A pointer according to claim 1, in which the sleeve is knurled on its outer surface.

4. A pointer according to any one of the preceding claims, in which the sleeve is made of brass.

5. A pointer according to claim 1, wherein the sleeve is internally threaded so as to be screwed onto a threaded pointer shaft.

6. A pointer according to claim 5, in which the sleeve is made of aluminium.

7. A pointer for a display instrument substantially as herein described with reference to the accompanying drawing.

Reference has been directed in pursuance of section 9, subsection (1) of the Patents Act, 1949, to Patent No. 1395695.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

5 having two faces 6 and 7. The end face 6 which faces the pointer arm 1 is plane; the other end face 7 has formed upon it a projection 8, in the shape of a sector of a circle, which acts as a balancing weight, and a central socket 9. The socket 9 is formed with a receiving bore 10 into which is pressed a brass sleeve 17. The sleeve 17 then receives the pointer shaft (not shown) which is a push fit thereinto.

In a preferred form, the sleeve 17 is knurled on its outer surface.

WHAT WE CLAIM IS:- 1. A pointer for a display instrument having a pointer arm, and an integral unit comprising a socket, and a balancing weight, said unit being secured to the pointer arm, wherein said socket is provided with a sleeve for engaging with the shaft of the pointer when located therein.
2. A pointer according to claim 1, wherein the sleeve is adapted to receive the shaft of the pointer as a push fit thereinto.
3. A pointer according to claim 1, in which the sleeve is knurled on its outer surface.
4. A pointer according to any one of the preceding claims, in which the sleeve is made of brass.
5. A pointer according to claim 1, wherein the sleeve is internally threaded so as to be screwed onto a threaded pointer shaft.
6. A pointer according to claim 5, in which the sleeve is made of aluminium.
7. A pointer for a display instrument substantially as herein described with reference to the accompanying drawing.

Reference has been directed in pursuance of section 9, subsection (1) of the Patents Act, 1949, to Patent No. 1395695.