GB2069700A

GB2069700A - Gap measuring device for piston rings

Info

Publication number: GB2069700A
Application number: GB8104077A
Authority: GB
Original assignee: Goetze GmbH
Current assignee: Goetze GmbH
Priority date: 1980-02-15
Filing date: 1981-02-10
Publication date: 1981-08-26
Also published as: CH648410A5; JPS56118601A; IT8119274A0; DE3005624C2; IT1135136B; DE3005624A1; GB2069700B

Abstract

A piston ring 1 is held in a gauge ring 2 so that the flat end surface 3 of the piston ring 1 and the corresponding surface 4 of the gauge ring 2 together form a measuring plane 5. A wedge probe 7 mounted for axial movement inside the sleeve 9 is biased towards the gap by a spring and is advanced into the gap as far as the gap will allow, the sleeve 9 is advanced until an abutment surface 10 abuts the piston ring 1 and the relative position of the wedge 7 and the sleeve 9 is converted by an electrical transducer 8 into an output signal indicating the width of the gap. <IMAGE>

Description

SPECIFICATION Gap measuring device for piston rings The invention relates to the measurement of the gap width in rings, such as piston rings, which are cut through at one circumferential position.

It is known for the testing of the gap width in piston rings, to place each piston ring exactly level in a gauge ring of the exact nominal diameter and to measure the gap width by means of a feeler gauge.

The gauge rings used for this measurement must be very accurate and dimensionally stable, since every deviation from the correct diameter is magnified by a factor of sir in the gap width. This method is also suitable for mass testing of piston rings, but has the disadvantage that the measurements obtained cannot be electronically processed.

In accordance with the invention there is provided an apparatus for measuring the width of a radial gap in rings, such as piston rings, which are cut through at one circumferential position, the apparatus having a gauge ring for holding the ring under test and having a measuring device consisting of a wedge mounted for axial movement inside a sleeve and an electrical transducer for measuring the relative position of the wedge and the sleeve, the output signal from the transducer indicating the width of the gap when the wedge protrudes from the sleeve to lodge in the gap and the sleeve is at a fixed distance from the ring under test.

The wedge may be inserted into the radial gap until an abutment on the sleeve comes into contact with the end surface of the gauge ring, which surface constitutes a measuring plane facing towards the sleeve. The wedge is preferably made in the form of a longitudinal displacement gauge pin. A known wedge geometry (k 1:10) at the tip of the gauge pin and the axially facing abutment enable the measuring base to be adjusted by placing the device on a flat surface which may be formed by a plate of hard stone or other hard mineral material. The axially facing surfaces of the ring to be measured and of the gauge ring on the side which abuts the sleeve form the measuring plane.

According to a preferred embodiment of the invention the end surface of the sleeve which faces towards the measuring plane is provided with a wear-resistant layer in order to ensure that the abutment surface remains flat and protected against severe wear for a long period of time. This is necessary in order to prevent the introduction of errors into the measurement results. Furthermore, the device for measuring the relative position of the wedge and the sleeve may be of an electrically inductive type, though clearly other kinds of device may be used.

The distance that the wedge penetrates into the gap in the ring being tested is converted in the transducer into electrical signals which are then fed to a counter in which they are evaluated. In the counter the incoming actual value is compared with a desired nominal value and thus the rejects or the rings which can be subjected to a refinishing operation may be sorted out rapidly. Care should be taken that the force exerted on the ring to be measured while the wedge is being pressed into the gap is less than the force required to displace the said ring in the gauge ring. If the force exerted by the wedge is too great the ring under test will be moved relative to the gauge ring and the measurement will be rendered false.Before using the device, the wedge which is interchangeable to suit various gap widths, and the distance moved by the wedge may be so adjusted electronically that the gap width is indicated as an absolute value. In this connection, any variation of the gauge rings from the correct internal diameters can also be taken account of, deviations from the nominal diameter being fed into a device which electronically scales the deviations by a factor of z and corrects the measured values of gap width.

An embodiment of the invention will now be described in detail by way of example with reference to the accompanying drawings, of which: Figures 1 and 2 are respectively a fragmentary sectional view and a fragmentary plan view, illustrating the principle of operation of a device embodying the invention, and Figure 3 is a vertical section of the whole of this device.

The measuring device shown in Figures 1 and 2 includes a gauge ring 2 which is dimensioned to suit the nominal size of a piston ring 1 to be measured.

The piston ring 1 is so arranged in the gauge ring 2 that a flat end surface 3 of the piston ring and a corresponding surface 4 of the gauge ring 2 together form a measuring plane 5. A measuring device 6, which is arranged above the measuring plane, consists mainly of a wedge 7 which can be thrust into the radial gap 11 of the piston ring 1 and a sleeve 9 containing an electrically inductive displacementtransducer8,thesleeve9 having an abutment surface 10 at that end which faces towards the measuring plane 5. In order to show the wedge 7 in greater detail, the measuring device 6 is shown in Figure 1 rotated through 90 .

Figure 3 is a sectional view showing the whole of the measuring device 6. The latter consists of the sleeve 9 which has an abutment 10 at its lower end and contains the wedge 7 which is interchangeably secured by means of a clamping screw 15 to the end of a rod fixed to a piston which is slidable in the sleeve 9. The wedge 7 is axially spring-loaded by means of a spring 14 acting against the abovementioned piston towards the measuring plane 5.

The abutment 10 of the sleeve 9 is provided on its end surface 12 facing the gauge ring with a wearresistant layer 13. The transducer 8, which is mounted in the upper end part of the sleeve 9 above the spring 14, converts the mechanical displacement X of the wedge 7 into electrical signals which are fed into a comparator. (not shown).

1. An apparatus for measuring the width of a radial gap in rings, such as piston rings, which are cut through at one circumferential position, the apparatus having a gauge ring for holding the ring under test and having a measuring device consisting

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Gap measuring device for piston rings The invention relates to the measurement of the gap width in rings, such as piston rings, which are cut through at one circumferential position. It is known for the testing of the gap width in piston rings, to place each piston ring exactly level in a gauge ring of the exact nominal diameter and to measure the gap width by means of a feeler gauge. The gauge rings used for this measurement must be very accurate and dimensionally stable, since every deviation from the correct diameter is magnified by a factor of sir in the gap width. This method is also suitable for mass testing of piston rings, but has the disadvantage that the measurements obtained cannot be electronically processed. In accordance with the invention there is provided an apparatus for measuring the width of a radial gap in rings, such as piston rings, which are cut through at one circumferential position, the apparatus having a gauge ring for holding the ring under test and having a measuring device consisting of a wedge mounted for axial movement inside a sleeve and an electrical transducer for measuring the relative position of the wedge and the sleeve, the output signal from the transducer indicating the width of the gap when the wedge protrudes from the sleeve to lodge in the gap and the sleeve is at a fixed distance from the ring under test. The wedge may be inserted into the radial gap until an abutment on the sleeve comes into contact with the end surface of the gauge ring, which surface constitutes a measuring plane facing towards the sleeve. The wedge is preferably made in the form of a longitudinal displacement gauge pin. A known wedge geometry (k 1:10) at the tip of the gauge pin and the axially facing abutment enable the measuring base to be adjusted by placing the device on a flat surface which may be formed by a plate of hard stone or other hard mineral material. The axially facing surfaces of the ring to be measured and of the gauge ring on the side which abuts the sleeve form the measuring plane. According to a preferred embodiment of the invention the end surface of the sleeve which faces towards the measuring plane is provided with a wear-resistant layer in order to ensure that the abutment surface remains flat and protected against severe wear for a long period of time. This is necessary in order to prevent the introduction of errors into the measurement results. Furthermore, the device for measuring the relative position of the wedge and the sleeve may be of an electrically inductive type, though clearly other kinds of device may be used. The distance that the wedge penetrates into the gap in the ring being tested is converted in the transducer into electrical signals which are then fed to a counter in which they are evaluated. In the counter the incoming actual value is compared with a desired nominal value and thus the rejects or the rings which can be subjected to a refinishing operation may be sorted out rapidly. Care should be taken that the force exerted on the ring to be measured while the wedge is being pressed into the gap is less than the force required to displace the said ring in the gauge ring. If the force exerted by the wedge is too great the ring under test will be moved relative to the gauge ring and the measurement will be rendered false.Before using the device, the wedge which is interchangeable to suit various gap widths, and the distance moved by the wedge may be so adjusted electronically that the gap width is indicated as an absolute value. In this connection, any variation of the gauge rings from the correct internal diameters can also be taken account of, deviations from the nominal diameter being fed into a device which electronically scales the deviations by a factor of z and corrects the measured values of gap width. An embodiment of the invention will now be described in detail by way of example with reference to the accompanying drawings, of which: Figures 1 and 2 are respectively a fragmentary sectional view and a fragmentary plan view, illustrating the principle of operation of a device embodying the invention, and Figure 3 is a vertical section of the whole of this device. The measuring device shown in Figures 1 and 2 includes a gauge ring 2 which is dimensioned to suit the nominal size of a piston ring 1 to be measured. The piston ring 1 is so arranged in the gauge ring 2 that a flat end surface 3 of the piston ring and a corresponding surface 4 of the gauge ring 2 together form a measuring plane 5. A measuring device 6, which is arranged above the measuring plane, consists mainly of a wedge 7 which can be thrust into the radial gap 11 of the piston ring 1 and a sleeve 9 containing an electrically inductive displacementtransducer8,thesleeve9 having an abutment surface 10 at that end which faces towards the measuring plane 5. In order to show the wedge 7 in greater detail, the measuring device 6 is shown in Figure 1 rotated through 90 . Figure 3 is a sectional view showing the whole of the measuring device 6. The latter consists of the sleeve 9 which has an abutment 10 at its lower end and contains the wedge 7 which is interchangeably secured by means of a clamping screw 15 to the end of a rod fixed to a piston which is slidable in the sleeve 9. The wedge 7 is axially spring-loaded by means of a spring 14 acting against the abovementioned piston towards the measuring plane 5. The abutment 10 of the sleeve 9 is provided on its end surface 12 facing the gauge ring with a wearresistant layer 13. The transducer 8, which is mounted in the upper end part of the sleeve 9 above the spring 14, converts the mechanical displacement X of the wedge 7 into electrical signals which are fed into a comparator. (not shown). CLAIMS

1. An apparatus for measuring the width of a radial gap in rings, such as piston rings, which are cut through at one circumferential position, the apparatus having a gauge ring for holding the ring under test and having a measuring device consisting of a wedge mounted for axial movement inside a sleeve and an electrical transducer for measuring the relative position of the wedge and the sleeve, the output signal from the transducer indicating the width of the gap when the wedge protrudes from the sleeve to lodge in the gap and the sleeve is at a fixed distance from the ring under test.

2. An apparatus according to claim 1, wherein a spring mounted inside the sleeve is arranged to axially bias the wedge towards that end of the sleeve from which the wedge protrudes.

3. An apparatus according to claim 1 or 2, wherein abutments are provided on that end of the sleeve from which the wedge protrudes.

4. An apparatus according to any of claims 1 to 3, wherein the end surface of the sleeve at the end from which the wedge protrudes is provided with a wear resistant layer.

5. An apparatus according to any of the claims 1 to 4, wherein the transducer operates by inductive means.

6. A method for measuring the width of a radial gap in rings, such as piston rings, which are cut through at one circumferential position wherein the ring under test is held in a gauge ring while a wedge protruding from the end of a sleeve is advanced into the gap as far as the gap will allow and with the said sleeve held at a fixed distance from the ring under test the width of the gap is indicated by an electrical transducer which converts the relative position of the wedge and the sleeve into an output signal.

7. A method according to claim 6, wherein a spring mounted inside the sleeve is arranged to axially bias the wedge towards that end of the sleeve from which the wedge protrudes.

8. A method according to claim 6 or 7, wherein the sleeve is positioned at a fixed distance from the ring under test by advancing the sleeve until it abuts the ring under test.

9. A method according to claim 6, wherein the sleeve and the wedge are advanced simultaneously towards the gap until the wedge penetrates the gap as far as the gap will allow whereupon the sleeve continues to advance against the bias of a spring until the sleeve abuts the ring under test, the output signal of the transducer then indicates the width of the gap.