JP2008039621A - Device and method for measuring cam profile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measurement device capable of improving the measurement precision in the measurement of a cam profile and also capable of measuring the cam profile having no lift top. <P>SOLUTION: The master profile constituted of a design profile S to be used for working a cam, a profile X leading in the phase to the design value profile, and a profile Y lagged in the phase angle to the same. The actually measured profile Z obtained by actually measurement is compared with the master profiles S, X and Y over the full ranges of the cam profiles. The master profile is selected so as to minimize the difference of the comparison value, the selected angular variable of master profile is detected as the displacement of angle of the knock hole center being the reference of angular direction of the cam shaft and the center angle of the cam. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cam profile measuring device and a cam profile measuring method when processing a cam that opens and closes an engine valve of an internal combustion engine, for example.

  As is well known, for example, a cam provided on the outer periphery of a camshaft has been conventionally used as an operating part for opening and closing an intake valve and an exhaust valve in a valve operating device of an internal combustion engine for an automobile, for example.

  The characteristics of the intake and exhaust valves, such as the operating angle, valve lift, and opening / closing timing, have a significant effect on engine performance. However, the characteristics of the intake and exhaust valves, such as the operating angle, greatly depend on the cam profile performance. Therefore, the quality of the performance depends on how close it is to the design value when the cam profile is formed.

  For this reason, various methods for measuring a cam profile have been conventionally provided, and one of them is described in Patent Document 1 below.

  The measurement head unit measures the lift amount based on the cam profile of the cam piece, and the lift change rate conversion unit calculates the lift change rate for each predetermined unit rotation angle of the cam piece, based on the measured lift amount. Subsequently, the vertex position calculation unit calculates a reference phase position (vertex position) by extracting a switching point at which the positive change rate and the negative change rate of the lift change rate are switched, and the comparison unit calculates the above-described calculation. Based on the reference phase position, the design value of the cam piece and the shape before and after correction are compared and displayed on the display.

As a result, the apex position of the cam piece can be determined accurately and easily, and the profile of the measured cam piece can be easily compared before and after the design value and correction.
JP 2003-315031 A

  However, in the conventional cam profile measurement method, as described above, since the design value profile is compared with the measured profile, the apex position where the lift amount is maximum is set as the reference phase position and the design value is determined. The difference between the design value and the actual measurement value is calculated by superimposing the profiles of the actual measurement values. For this reason, the sensitivity of the lift amount with respect to the angle change in the vicinity of the vertex position of the cam piece is low, that is, the change in the lift amount with respect to the rotation angle is extremely low, and thus it is difficult to accurately identify the vertex position (angle). .

  Further, when the apex position is set as a reference position, for example, in the case of a cam shape in which the profile is terminated immediately after the apex position, such as a swing cam, or a cam shape having no apex portion, such a measuring method is used. I can't.

  The present invention has been devised in view of the above-described conventional problems. The invention of claim 1 includes a measuring unit that measures an actual value of a cam profile and an input unit that inputs a design value of the cam profile. A calculation unit that calculates a calculated value of at least one advanced or retarded phase profile based on the design value input to the input unit, the design value or the calculated value, and the actual measurement value, And a design value or a calculated value that minimizes these differences is determined, and a processing unit that calculates a difference between the specified design value or calculated value and the measured value is calculated by the processing unit. And an output unit for outputting the difference value.

  According to the present invention, in particular, in addition to the design value profile, a calculated value of a profile whose phase is advanced or retarded with respect to the design value is set, and the profile of the design value, the advance angle, or the delay is set. Since the profile with the least difference between the angled profile and the measured value profile is selected and specified, the angle direction of the camshaft can be determined even when the angle of the apex position (lift top position) cannot be specified. It is possible to calculate and display the difference between the design value and the actual measurement value regarding the angle between the center of the knock pin hole and the cam center angle, which is the standard of the above. As a result, the cam profile can be measured with high accuracy.

  Also, the position where the knock pin hole is formed is unclear and the apex position (angle) of the cam cannot be specified, or the lift top position (angle) cannot be specified from the measured value because the cam shape is missing at the apex position. However, it is possible to calculate and display the difference between the design value or the calculated value and the actually measured value.

  In the invention according to claim 2, the calculated value is an advanced angle calculated value of at least one profile of a phase advanced with respect to the designed value, or is delayed with respect to the designed value. It is a retardation calculation value of at least one profile of an angled phase.

  The invention according to claim 3 is a cam profile measuring method comprising a design value profile used for cam processing, and a profile whose phase is advanced and retarded with respect to the design value profile. The measured profile obtained by actually measuring the profile of the cam and the master profile are compared over the entire area of the profile, and the master profile that minimizes the difference between the comparison values is selected. The angle variable of the selected master profile is detected as an angular displacement between the center of the knock hole and the center angle of the cam, which is the reference in the angular direction of the camshaft.

  Therefore, this invention can achieve the same effects as those of the invention of the first aspect.

  Embodiments of a cam profile measuring apparatus and cam profile measuring method according to the present invention will be described below in detail with reference to the drawings. In this embodiment, the present invention is applied to a cam provided on a camshaft applied to an automobile internal combustion engine.

  First, a cam profile measuring device will be described. As shown in FIGS. 1 and 2, a camshaft 1 integrally having a plurality of cams 2 on an outer peripheral surface is provided on a bed 3 and both ends thereof are connected to spindles 4. Supported by the tail 5.

  The spindle 4 is rotationally driven by a drive mechanism unit 6. The drive mechanism unit 6 includes an electric motor, a reduction gear mechanism, a rotary encoder, and the like housed in a casing. The camshaft 1 is controlled to rotate at a predetermined speed via a spindle 4.

  Further, on the upper surface of the bed 3, a measuring unit 7 having a linear gauge 7 a that is a measuring element that contacts the outer peripheral cam surface 2 a of the cam 2 of the camshaft 1 and measures a cam profile is provided in the axial direction of the camshaft 1. It is arranged to be movable. The linear gauge 7a moves forward and backward in the vertical direction in FIG. 1 according to the shape of the cam surface 2a to be contacted, and measures the distance from the rotation center of the camshaft 1 to the cam surface 2a at every predetermined rotation angle. Thus, the advance / retreat amount of the linear gauge 7 a becomes the lift amount of the cam 2.

  Further, an integrated control unit 8 that performs overall control of the drive mechanism unit 6 and the measurement unit 7 and the like and various arithmetic processing described later is disposed at the side position of the bed 3, A printer 9 that outputs the measurement result of the cam profile detected by the integrated control unit 8 is disposed.

  As shown in FIG. 2, the integrated control unit 8 includes a control unit 10 that performs overall control such as rotation control of the electric motor of the drive mechanism unit 6, cam lift information from the measurement unit 7, and information on the drive mechanism unit 6. A profile unit 11 for obtaining a cam profile based on rotation angle information of the cam 2 accompanying the rotational drive of the electric motor from a rotary encode, a profile data value (actually measured value) obtained by the profile unit 11, and a master described later A comparison unit 12 that compares data values (design values, etc.) of a master profile set in advance from the profile output unit 15, and a combination that has the smallest difference ratio between the two profiles is selected from the comparison result by the comparison unit 12 And a display 14 for displaying a value selected by the selection unit 13. The The display 14 can also display instruction information from the control unit 10 to the drive mechanism unit 6.

  The contents displayed on the display 14 can be printed out by the printer 9.

  Hereinafter, an object and a method for specifically measuring the cam surface 2a (cam profile) of the cam 2 by the cam profile measuring device will be described with reference to the drawings.

  First, FIG. 3 shows a normal standard egg-shaped cam 2 provided on the camshaft 1, which is the same as that measured by the cam profile measuring device, and the cam 2 has a lift amount of 0. Base circle region 16 and cam mountain 17 having a predetermined lift amount. In addition, a knock pin hole 20 serving as a reference for the angle of the cam 2 is formed on one end face of the cam shaft 1, and a reference line 21 connecting the center 20 a of the knock pin hole 20 and the center 1 a of the cam shaft 1 is used as a reference. The rotation angle β of the cam 2 up to the position of the apex 17a of the cam crest 17 is set. As the angle reference point of the cam 2, a keyway formed on the outer peripheral surface of the camshaft 1 may be used.

  The basic cam lift curve (cam profile) of the cam 2 obtained from the relationship between the crank angle of the crankshaft (the rotation angle of the cam 2) and the valve lift has the characteristics shown in FIG. It is clear that the valve lift amount changes with the rotation of the valve, and the valve lift amount reaches the maximum value immediately before reaching the apex 17a of the cam crest 17, that is, in the vicinity of the apex 17a.

  FIG. 5 shows a cam profile of a cam such as a rocking cam in which the top (lift top) of the cam crest is not cut, instead of the egg-shaped cam 2. It is clear that the valve lift has reached its maximum value before reaching the apex. That is, a normal cam including an egg shape is formed so as to reach before reaching the apex regardless of the maximum lift value.

  Therefore, in this embodiment, the measured value of the cam profile of the egg-shaped cam 2 is measured by the measuring unit 7, and the measured value is imaged as a data waveform of the cam profile by the profile unit 11.

  As shown in FIG. 6, the master profile unit 15 has a design value profile S set in advance based on the specifications of the internal combustion engine and the like, and a phase position with respect to the design value profile S advanced by a plurality of stages. An angle value profile (S + nα °) (broken line portion X) and a retard angle profile (S-nα °) (broken line portion Y) in which the phase position is delayed by a plurality of stages with respect to the design value profile S Has been. It should be noted that the values of n and α can be arbitrarily set as required, and the number of the setting may be at least one.

  As shown in FIG. 7, the comparison unit 12 outputs a plurality of data waveform values shown in FIG. 6 output from the master profile unit 15, that is, a design value (thin line S), an advance value S + nα ° (dashed line X), The retardation value S-nα ° (broken line Y) and the actually measured data waveform value (thick line Z) obtained by the profile portion 11 are overlaid and compared.

  FIG. 8 is a graph showing a comparison result between the master profile (S, X, Y) and the actual value profile (Z). The difference from the reference line 0 on the upper side is a plus difference, and the lower minus direction is a difference. When the difference between the two is shown as an A waveform, the difference in the first half of the profile is small and large in the second half. In addition, when the waveform is shown as a C waveform, the difference in the first half is large and the difference in the second half is small. When the waveform is shown as a B waveform, the difference is small in both the first half and the second half. is there. Such a waveform display makes the magnitude of the difference and the position of the difference clear.

  Next, the processing in the selection unit 13 following the comparison processing by the comparison unit 12 will be described. In the comparison between the master profile (S, X, Y) and the actual value profile Z at the same rotation angle, FIG. 9, one of the master profiles (S, X, Y) is selected using the direction of the arrow and the length of the arrow with respect to the actual measurement value profile Z. That is, the direction of the arrow indicates the direction of the difference, the length of the arrow indicates the amount of the difference, and the one with the smallest difference between the two profiles is calculated by selecting one of the shortest master profiles of the arrow. Can be selected.

  As another method for obtaining the difference between the two profiles, as shown in FIG. 10, it is selected by calculating the sum of the valve lift amount differences between the master profile (S, X, Y) and the measured value profile Z. Is possible. That is, since the hatched area between both profiles shown in FIG. 10 is the difference in valve lift, the master profile with the smallest difference can be calculated and selected by comparing the areas.

  As another method for selecting the master profile having the smallest difference between the master profile (S, X, Y) and the actual value profile X, for example, the rotational speed or acceleration of the cam obtained from the valve lift amount is used. It is also possible to calculate using

  FIG. 11 is an example of a display screen of the display 14 after the measurement is completed, and numerical values of the rotation angle (deg) of the cam 2 and the lift amount (mm) of the cam 2 measured at a predetermined frequency are displayed on the upper part. At the same time, these values are imaged (graphed) on the lower part. The measurement frequency can be set arbitrarily.

  FIG. 12 is an example of a display screen of the display 14 that displays the difference between the measurement result and the master profile (S, X, Y). In the lower graph, the horizontal axis represents the rotation angle of the cam 2 and the vertical axis represents the rotation angle. It shows the difference in valve lift. The line P in the center of the graph shows that the difference between the two profiles is 0, and the upper and lower lines Q1 and Q2 of this P line show the upper and lower limit values such as the graphic specification of the difference between the two profiles. it's shown. The waveform line between Q1 and Q2 displays the difference between the measurement result of the actual measurement profile Z and the master profile (S, X, Y).

  By displaying the results on the display 14, the difference between the two profiles can be clearly recognized, and the measurement data of the repeated difference is accumulated while storing these data, thereby forming a cam profile with higher accuracy. It can be used as information.

  As described above, according to this embodiment, in particular, in addition to the design value profile S, the calculated value of the profile X whose phase is advanced or the profile Y whose phase is advanced with respect to the design value S is set. Since the profile with the smallest difference between the profile S of the design value, the advance angle, the retarded profile X, Y, and the profile Z of the actual measurement value is selected and specified, the apex position of the cam 2 (lift top position) ), The difference between the design value and the measured value regarding the angle between the center 20a of the knock pin hole 20 and the cam center angle, which is the reference for the angular direction of the camshaft 1, is calculated and displayed. It becomes possible. Thereby, a highly accurate profile of the cam 2 can be obtained.

  Also, the position where the knock pin hole is formed is unclear and the lift top position (angle) cannot be specified, or the lift top position (angle) cannot be specified from the measured value because the cam shape is missing at the lift top position. However, it is possible to calculate and display the difference between the design value or calculated value profiles S, X, and Y and the measured value profile Z.

  In FIG. 13, the basic configuration of the integrated control unit 8 is the same as that of the first embodiment, but the master profile generation method is changed. That is, first, a design value profile S is input in advance in the design value profile output unit 18, and the master in the integrated control unit 8 is based on the design value profile S information output from the design value profile output unit 18. The profile generator 19 generates the plurality of advance angle profiles X and retard angle profiles Y to generate the entire master profile (S, X, Y). The master profile (S, X, Y) information generated by the master profile generator 19 is input to the comparator 12.

  Therefore, according to this embodiment, since the final master profile (S, X, Y) is generated in the integrated control unit 8, it is possible to generate a more accurate profile.

  The present invention is not limited to the configuration of the above-described embodiment, and the cam can be applied to a cam used for general driving devices, in addition to the cam applied to the internal combustion engine. In addition, a device for actually measuring the cam profile can also be used.

The technical ideas other than the invention described in the claims, as grasped from the embodiment, will be described below.
(1) The output unit outputs data indicating a difference between an actual measurement value and a design value or a calculated value by a diagram, a table, or a graph representing a change in a valve lift amount with respect to a crank angle of the internal combustion engine. Item 2. The cam profile measuring device according to Item 1.
(2) The cam profile measuring device according to claim 1, wherein the output unit displays a difference between the measured value and a design value or a calculated value.
(3) By inputting a signal from the output unit, a difference between the measured value and a design value or a calculated value is displayed as at least one of a graph, a table, or a graph representing a change in the valve lift amount with respect to the crank angle of the internal combustion engine. The cam profile measuring device according to claim 1, further comprising a display unit configured to display the cam profile.
(4) The cam profile measurement method according to claim 3, wherein a comparison result between the selected master profile and the actually measured profile is detected as a difference between the design value and the actually measured value.

It is the schematic which shows embodiment of the measuring apparatus of the cam profile of this invention. It is a block diagram of the measuring device of the cam profile of this embodiment. It is a front view of the cam used for the cam profile measurement of this embodiment. It is a lift characteristic figure of this cam. It is a cam lift characteristic view of another different cam. It is the figure which imaged the master profile in this embodiment. It is the figure which imaged combining the master profile and measured value profile in this embodiment. It is the figure which imaged the several aspect of the difference of the master profile with which this embodiment is provided, and an actual value profile. It is the figure which imaged the method of calculating the minimum difference of the master profile and actual value profile in this embodiment. It is the figure which imaged other calculation methods about the minimum difference of a master profile and a measured value profile. It is the screen display figure which displayed the contents after measuring a cam profile by the relation between the rotation angle of a cam and the cam lift in this embodiment on a display. It is the screen display figure which displayed the contents of the difference between the actual measurement value profile and master profile in this embodiment on a display. FIG. 6 is a block diagram illustrating another method of generating a master profile.

Explanation of symbols

1 ... cam shaft 2 ... cam 2a ... cam surface (profile)
6 ... Drive mechanism 7 ... Measurement unit 8 ... Integral control unit S ... Design value profile X ... Advance value profile Y ... Delay angle profile Z ... Measured value profile

Claims (3)

A measurement unit for measuring the actual value of the profile of the cam;
An input unit for inputting the design value of the profile of the cam;
A calculating unit that calculates a calculated value of at least one advanced or retarded phase profile based on the design value input to the input unit;
The design value or calculation value is compared with the actual measurement value, the design value or calculation value that minimizes these differences is specified, and the difference between the specified design value or calculation value and the actual measurement value is calculated. A processing unit to
An output unit for outputting a difference value calculated by the processing unit;
An apparatus for measuring a cam profile, comprising: The calculated value is a calculated advance value of at least one profile having a phase advanced with respect to the design value, or a delayed calculation of at least one profile having a phase retarded with respect to the designed value. The cam profile measuring device according to claim 1, wherein the cam profile measuring device is a value. A master profile composed of a design value profile used for cam processing and a profile with an advanced phase and a retarded profile with respect to the design value profile;
Compare the measured value profile obtained by actually measuring the profile of the cam and the master profile over the entire profile,
Select the master profile that minimizes the difference in this comparison value,
A cam profile measurement method, wherein the angle variable of the selected master profile is detected as a displacement of an angle between a center of a knock hole and a center angle of a cam, which is a reference in an angular direction of the camshaft.