GB1584618A - Combination of an internal combustion engine and an inductive scanning device - Google Patents

Description

(54) THE COMBINATION OF AN INTERNAL COMBUSTION ENGINEw AND AN INDUCTIVE SCANNING DEVICE (71) We, VDO ADOLF SCHINDLING AG, of 103 Graftstrasse, FrankfurtlMain, Germany, a body corporate organized 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 particularly described in and by the following statement: The present invention relates to the combination of an internal combustion engine and an inductive scanning device for controlling the timing of the ignition system, said inductive scanning device having a transmitting element formed with a slot through which the element to be scanned is passed and, located on both sides of the slot, oscillation frequency determining elements of an oscillator which is a part of the electronic system of the scanning device.

Some known combinations of internal combustion engines and inductive scanning devices of this type, which are generally known as slot initiators, possess a transmitter element having a slot on both sides of which there is in each particular instance arranged a coil having a ferromagnetic or ferrite core. One of the two coils is the oscillation coil and the other the feedback coil of an oscillator the output signals of which are rectified before being fed to a threshold value switch. If there is a metallic object between the two coils, the oscillator is damped and there appears at the threshold value switch either no output signal or an output signal having a predetermined first amplitude. When the metallic object is removed out of the zone between the coils, the oscillator begins to oscillate and there appears at the output of the threshold value switch a signal having a predetermined second amplitude.

These known combinations of internal combustion engines and scanning devices which are used in conjunction with a serrated disc travelling through the slot, for the measurement of speed, have the disadvantage that their structural volume is relatively large and that as a rule a three-wire or three-core line is required for connection thereto to the oscillator.

Additionally, they have the disadvantage that variations in the clear coil spacing which may already be based on manufacturing tolerance may produce variations in the sensitivity of the arrangements. Finally, since their coils are sealed with resin for fixing the spacing and achieving the smallest possible structural volume, they can be employed only within a limited temperature range of approximately -15 OC to approximately +80 OC.

According to the present invention, there is provided the combination of an internal combustion engine and an inductive scanning device for controlling the timing of the ignition system, said inductive scanning device including a ferrite core having a pair of limbs extending to define a slot through which an element to be scanned is passed, a coil carried by said core, and an oscillator, the oscillation frequency determining elements of which are said limbs.

The transmitter element can thus be designed to be as small as desired. The limits are determined solely by the thickness of the object to be scanned, in accordance with which the slot dimensioning must be determined. The need for fixing the spacing of the core elements is dispensed with since there is only a single core, and this dispenses also with the abovementioned disadvantages connected therewith.

A special advantage of the invention resides in that the transmitter element is substantially less sensitive to jarring than are the known ones.

In a preferred form, the core may be of approximate U-shape. In an alternative form, the core may be of approximate C-shape. Such design has, by comparison with the previously described design, the advantage that the magnetic field is focused more strongly with the result that variations in the depth of dipping of the article to be scanned into the slot have no or at most only negligible influence on the measurement. This influence can be further reduced by the arrangement whereby in the case of a core designed to be of C-shape the effective cross section end faces extend parallel to each other. This arrangement achieves further focusing of the magnetic field.

The present invention will now be described in greater detail by way of example with reference to the accompanying drawing wherein: Figure 1 shows a block circuit diagram of one preferred form of an inductive scanning device hacing a transmitter element provided with a U-shaped core; and Figure 2 shows a transmitter element having a C-shaped core.

Referring first to Figure 1, the inductive scanning device comprises a transmitter element 1 having a slot 2 into which projects a rotating disc 3 having teeth 4. The transmitter element 1 comprises a U-shaped ferrite core 5 having two limbs 6 and 7, forming the slot 2, and a coil 8.

The coil 8 together with the core 5, is the oscillation frequency determining element of an oscillator 9. The oscillator 9 feeds a rectifier stage 10. The output from the rectifier stage 10 feeds a threshold value switch 11 which in turn feeds a power stage 12. The power stage 12 supplies a pulse signal, the frequency of which is proportional to the speed of the disc 3. The said pulse signal may be used to trigger an ignition system such as that of an internal combustion engine.

Referring now to the modified arrangement shown in Figure 2, the transmitter element 1' comprises a C-shaped ferrite core 13 the effective cross sectional end faces 14 and 15 of which extend parallel to each other.

WHAT WE CLAIM IS: 1. In combination an internal combustion engine and an inductive scanning device for controlling the timing of the ignition system, said inductive scanning device including a ferrite core having a pair of limbs extending to define a slot through which an element to be scanned is passed, a coil carried by said core, and an oscillator, the oscillation frequency determining elements of which are said limbs.

2. The combination according to claim 1, wherein the core is designed to be approximately U-shaped.

3. The combination according to claim 1, wherein the core is designed to be approximately Shaped.

4. The combination according to claim 3, wherein the effective cross sectional end faces extend parallel to each other.

5. The combination of an internal combustion engine and an inductive scanning device for controlling the timing of the ignition system, said inductive scanning device being constructed substantially as herein described with reference to and as illustrated in Figure 1 or Figure 2 of the accompanying drawing.

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

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. device hacing a transmitter element provided with a U-shaped core; and Figure 2 shows a transmitter element having a C-shaped core. Referring first to Figure 1, the inductive scanning device comprises a transmitter element 1 having a slot 2 into which projects a rotating disc 3 having teeth 4. The transmitter element 1 comprises a U-shaped ferrite core 5 having two limbs 6 and 7, forming the slot 2, and a coil 8. The coil 8 together with the core 5, is the oscillation frequency determining element of an oscillator 9. The oscillator 9 feeds a rectifier stage 10. The output from the rectifier stage 10 feeds a threshold value switch 11 which in turn feeds a power stage 12. The power stage 12 supplies a pulse signal, the frequency of which is proportional to the speed of the disc 3. The said pulse signal may be used to trigger an ignition system such as that of an internal combustion engine. Referring now to the modified arrangement shown in Figure 2, the transmitter element 1' comprises a C-shaped ferrite core 13 the effective cross sectional end faces 14 and 15 of which extend parallel to each other. WHAT WE CLAIM IS:

1. In combination an internal combustion engine and an inductive scanning device for controlling the timing of the ignition system, said inductive scanning device including a ferrite core having a pair of limbs extending to define a slot through which an element to be scanned is passed, a coil carried by said core, and an oscillator, the oscillation frequency determining elements of which are said limbs.

2. The combination according to claim 1, wherein the core is designed to be approximately U-shaped.

3. The combination according to claim 1, wherein the core is designed to be approximately Shaped.

4. The combination according to claim 3, wherein the effective cross sectional end faces extend parallel to each other.

5. The combination of an internal combustion engine and an inductive scanning device for controlling the timing of the ignition system, said inductive scanning device being constructed substantially as herein described with reference to and as illustrated in Figure 1 or Figure 2 of the accompanying drawing.