JP4045861B2 - Valve lifter processing method and valve lifter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a valve lifter processing method and a valve lifter.
[0002]
[Prior art]
Generally, the valve lifter includes a shim-equipped valve lifter in which a shim is disposed and a shimless valve lifter in which no shim is disposed. Whichever type of valve lifter is used, in order to improve engine performance and reduce noise, it is necessary to adjust the valve clearance, which is the gap between the valve lifter and the cam, to an appropriate value.
[0003]
If a shim-equipped valve lifter is used, the valve clearance is adjusted by selective assembly of shims. Specifically, several tens of kinds of shims having different thicknesses in predetermined increments (10 to 20 μm increments) are prepared in advance. And the shim selected from dozens of kinds of shims is assembled. If a shimless valve lifter is used, the valve clearance is adjusted by selective assembly of the valve lifter. Specifically, several tens of types of valve lifters having different thicknesses in predetermined increments are prepared in advance. Then, a valve lifter selected from several tens of types of valve lifters is assembled to the cylinder head.
[0004]
For example, Japanese Patent Application Laid-Open No. 11-2000820 discloses a technique using plastic processing (press processing) as rough processing of a valve lifter. However, even in the technique described in the above publication, dozens of types of valve lifters having different thicknesses are prepared by finishing after roughing, and the valve lifter selected from these dozens of types of valve lifters is used as a cylinder head. Adjust the valve clearance by assembling. This is the same as the above technique.
[0005]
However, according to the conventional techniques as described above, since the thickness of the prepared valve lifter is limited to several tens of ways, it is not possible to select a valve lifter having an appropriate thickness that can truly achieve a desired valve clearance. There is a case. In other words, not only an error in processing the valve lifter but also an error in selecting the valve lifter occurs. As a result, the valve clearance varies, and as a result, the valve opening / closing timing may vary. This point may cause a problem when the engine is further improved in performance and noise. In addition, managing dozens of types of valve lifters as inventory causes an increase in management costs.
[0006]
On the other hand, as shown in Japanese Patent Application Laid-Open No. 2000-145413, the surface of the protruding portion (boss portion) with which the shaft end of the valve contacts in the shimless valve lifter has a hardness higher than a predetermined value by heat treatment, and wear resistance Performance and friction reduction. Therefore, it is necessary that the surface hardness of the boss after processing does not become a predetermined value or less.
[0007]
[Problems to be solved by the invention]
The present invention has been made to solve the above problems. Accordingly, an object of the present invention is to provide a method for processing a valve lifter that can realize further high performance and low noise of an engine by reducing variation in valve clearance, and in addition, is managed as inventory. This is to reduce the number of valve lifters.
[0008]
Moreover, the objective of this invention is providing the processing method of the valve lifter which the surface hardness of the boss | hub part after a process does not become below a predetermined value in addition to the said objective.
[0009]
[Means for Solving the Problems]
The above object of the present invention is achieved by the following means.
[0010]
(1) The valve lifter processing method of the present invention is a valve lifter processing method including a protrusion that contacts the shaft end of the valve, and a position related to the position of the shaft end of the valve in a state where the valve is assembled to the cylinder head. An acquisition step of acquiring data, and a processing step of adjusting the processing allowance of the protrusion of the valve lifter using the position data acquired in the acquisition step, and processing the protrusion. .
[0011]
(2) In the above machining step, the distance between the base circle surface when the cam is attached and the shaft end of the valve is calculated in a state where the cam is not assembled, and the desired valve is calculated from the calculated distance. The protrusion is processed until the value obtained by subtracting the clearance matches the thickness of the valve lifter.
[0012]
(3) Furthermore, it has the heat processing process which forms the hardened layer thicker than the largest machining allowance of the said protrusion part on the surface of the said protrusion part before the process by the said process process.
[0013]
(4) The valve lifter according to the present invention uses the position data relating to the position of the protruding portion protruding in the direction opposite to the surface with which the cam contacts and the shaft end of the valve in a state where the valve is assembled to the cylinder head. And a hardened layer formed on the surface of the protrusion, which is thicker than the maximum processing allowance within a range in which the processing allowance of the protrusion is adjusted.
[0014]
【The invention's effect】
According to the first aspect of the present invention, the position data relating to the shaft end position of the valve in a state where the valve is assembled to the cylinder head is obtained, and the machining allowance for the protrusion of the valve lifter is obtained using the obtained position data. Since the protrusion is processed, a valve lifter having an appropriate thickness that can truly achieve a desired valve clearance can be manufactured at any time, and variations in valve clearance can be reduced. As a result, further enhancement of performance and noise reduction of the engine can be realized. In addition, since the types of valve lifters managed as inventory can be reduced, the management cost can be reduced.
[0015]
According to the second aspect of the present invention, the distance between the base circle surface when the cam is attached and the shaft end position of the valve is calculated in a state where the cam is not assembled. Adjustment processing of the valve lifter can be realized in a form adapted to the process sequence with the head assembly line.
[0016]
According to the invention described in claim 3, since the hardened layer thicker than the maximum machining allowance of the protrusion is formed on the surface of the protrusion before processing by the processing step, the surface hardness of the protrusion after processing is predetermined. The adjustment process of the valve lifter can be applied without lowering the value.
[0017]
According to the invention described in claim 4, since the valve lifter has a hardened layer thicker than the maximum machining allowance within the range in which the machining allowance of the protrusion is adjusted, the adjustment work is applied to the valve lifter. Even so, it is possible to prevent the surface hardness of the projecting portion after processing from becoming a predetermined value or less.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0019]
FIG. 1 is a block diagram showing an example of a cylinder head manufacturing system to which a valve lifter processing method according to an embodiment of the present invention is applied.
[0020]
This manufacturing system includes a valve lifter processing facility (valve lifter processing line) 100 and a cylinder head assembly facility (cylinder head assembly line) 200. The valve lifter processing facility 100 is a facility mainly for processing the valve lifter, and the cylinder head assembly facility 200 is a facility for assembling the valve, the valve lifter, and the cam to the cylinder head.
[0021]
The cylinder head assembly facility 200 measures the position of the shaft end (end of the valve stem) of each valve in a state where the valve is assembled to the cylinder head, and acquires position data. The valve processing facility 100 adjusts the processing allowance (processing amount) of the valve lifter using the acquired position data. Therefore, the processing cost of the valve lifter can be adjusted for each valve. The valve lifter that has been processed in the valve lifter processing facility 100 is supplied to the cylinder head assembly facility 200 by the transfer device 700 and assembled to the corresponding cylinder head.
[0022]
As described above, the valve lifter processing line and the cylinder head assembly line are organically related, and the position data regarding the position of the shaft end of each valve at the time of cylinder head assembly is sequentially reflected in the adjustment of the valve lifter processing allowance. This is one of the features of the present invention.
[0023]
The valve lifter processing facility 100 includes a bubble lifter processing unit 110, a data input unit 120, a storage unit 130, an interface 140, and a processor 150.
[0024]
The bubble lifter processing unit 110 includes a processing machine that processes the bubble lifter and a jig that holds the valve lifter. The data input unit 120 is a touch panel, a mouse, a keyboard, and the like, and is used for inputting various data and commands. The storage unit 130 is a memory or a hard disk, and stores data and commands. The interface 140 is used to communicate with other equipment such as the cylinder head assembly equipment 200. The processor 140 executes various operations and control of the above-described units.
[0025]
On the other hand, the cylinder head assembly facility 200 includes a cylinder head assembly unit 210, a data input unit 220, a storage unit 230, an interface 240, a processor 250, and a measurement unit 260.
[0026]
The cylinder head assembly unit 210 assembles the valve, the cam, and the valve lifter processed by the valve lifter processing unit 110 to the cylinder head. The measurement unit 260 preferably includes a linear gauge capable of micron order measurement. The measurement unit 260 measures the position of the shaft end of the valve in a state where the valve is assembled to the cylinder head. The measuring unit 260 can also measure various dimensions of the cam and the cylinder head. The measurement unit 260 is preferably an automatic measurement device. However, the measurement unit 260 may be a manual measurement device. Furthermore, the measurement unit 260 may be a plurality of measurement devices. In other words, various dimensions do not need to be measured by one measuring device, and may be measured by a plurality of measuring devices.
[0027]
The processor 250 performs various calculations and controls. In particular, arithmetic processing is executed based on data obtained by measurement by the measurement unit 260 or other measuring device. The calculation result is stored in the storage unit 230. A machining command obtained from the calculation result is given to the bubble lifter machining facility 100. The machining command is preferably transmitted to the valve lifter machining facility 100 through the interface 240, but the present invention is not limited to this case.
[0028]
Next, the processing part of the valve lifter will be described.
[0029]
2A and 2B are views showing the valve lifter processing portion shown in FIG.
[0030]
The bubble lifter processing section 110 includes a spindle 112 provided with a grindstone 111 for grinding the bubble lifter 300, rollers 114 and 116 for holding the valve lifter 300 and rotating it in the direction opposite to the spindle rotation direction, and the valve lifter 300. And a shoe 118 for holding down.
[0031]
The valve lifter 300 to be processed is a shimless valve lifter, and includes a boss portion 310 (protruding portion) that protrudes in a direction opposite to a surface that contacts the cam (hereinafter referred to as a “crown surface”). The boss portion 310 is ground by the grindstone 111 described above.
[0032]
3A is a cross-sectional view of the valve lifter before grinding of the boss portion 310, and FIG. 3B is a cross-sectional view of the valve lifter after grinding of the boss portion 310. The valve lifter 300 includes a crown surface 301 that contacts the cam, an outer peripheral portion 302, and a boss portion 310. The thickness W of the valve lifter 300 is defined as the distance between the crown surface 301 and the end surface of the boss portion 310.
[0033]
According to the processing method of the present embodiment, the length (hereinafter referred to as “grinding allowance”) d of the portion removed by grinding and the thickness W of the valve lifter 300 are as described below when the valve is assembled to the cylinder head. It changes individually according to the valve position data etc. This is different from the conventional processing method in which the grinding allowance and the thickness W of the valve lifter 300 are substantially constant (for example, 0.2 mm) in one batch. For example, according to the present embodiment, the grinding allowance (processing allowance) d varies in the range of 0.2 to 0.6 mm. In addition, the grinding allowance d of the present embodiment is longer than the grinding allowance set in the conventional machining method for the convenience of adjusting the valve clearance by adjustment processing, not by adjusting the valve clearance by selective assembly. There are many.
[0034]
As shown by hatching in FIG. 3, the end surface of the boss portion 310 is subjected to a curing process by a heat treatment such as quenching. In the present specification, a portion having a hardness equal to or greater than the required surface hardness determined by the engine specifications is defined as a hardened layer. The machining layer of the present embodiment has a maximum grinding allowance within a range in which the grinding allowance (machining allowance) of the protruding portion can be adjusted using the position data of the shaft of the valve in a state where the valve is assembled to the cylinder head. Also thick. For example, when the grinding allowance is adjusted between 0.2 and 0.6 mm, the hardened layer has a layer thickness greater than the maximum grinding allowance of 0.6 mm. Therefore, quenching is deeper than that of a normal valve lifter.
[0035]
FIG. 4 is a diagram showing the relationship between the depth from the surface of the valve lifter before grinding of the boss portion and the hardness (HRC: Rockwell hardness C scale). The measurement value in the case of the valve lifter of the present embodiment is indicated by a double circle. As a comparative example, a black circle indicates a measurement example in the case of a valve lifter that is processed with a grinding allowance fixed at 0.2 mm.
[0036]
In the comparative example, since the grinding allowance is 0.2 mm (constant), the hardened layer has a layer thickness of 0.2 mm or more. On the other hand, in the case of the present embodiment shown in FIG. 4, the grinding allowance is adjusted in the range of 0.2 to 0.6 mm, so the hardened layer is 0.6 mm which is the maximum grinding allowance within this range. It is formed thicker. In order to form a hardened layer that is thicker than the hardened layer of the comparative example, in this embodiment, the time for the heat treatment process such as carburizing and quenching is set longer than that of the comparative example.
[0037]
Next, processing steps when the valve lifter processing method in the present embodiment is applied will be described.
[0038]
FIG. 5 is a flowchart showing a valve lifter processing step (comparative example) used for selective assembly, and FIG. 6 is a flowchart showing a valve lifter adjustment processing step in the present embodiment.
[0039]
First, the process of the comparative example will be briefly described.
[0040]
First, a grinding process is performed on the outer peripheral surface and the crown surface of the valve lifter 300 (step S100, step S110). This process is usually called roughing. Next, a coating and heat treatment process is performed (step S120). As a result, a hardened layer is formed on the end surface of the boss portion 310. Next, the outer peripheral surface is distorted by finishing the outer peripheral surface distorted in the heat treatment in step S120.
[0041]
Next, the boss part 310 is ground (step S140). In this comparative example, in one batch, the grinding allowance d of the boss portion 310 and the thickness W of the valve lifter 300 are constant. After grinding in step S140, the thickness W of the valve lifter 300 is measured, and the measured thickness W and other data contents are imprinted on a predetermined surface of the valve lifter 300 (step S150, step S160). In addition, you may add outer peripheral part grinding between step S140 and step S150, In that case, the quality of an outer peripheral surface can be improved more. Finally, the valve lifter 300 is stored for each type of thickness W (step S170).
[0042]
On the other hand, the valve lifter processing step of the present embodiment will be described.
[0043]
Steps S200 and S210 in FIG. 6 are the same as in the comparative example. Next, in step S220, a heat treatment and a surface treatment process are performed. In this step, a hardened layer is formed on the end surface of the boss portion 310. As described above, by controlling the heat treatment time, a hardened layer thicker than the maximum grinding allowance within the adjustment range of the grinding allowance is formed. The adjustment range of the grinding allowance is appropriately determined based on, for example, the thickness tolerance of the valve lifter 300 after crown surface grinding in step S210 and the dimensional tolerance of each part of the valve, cam, and cylinder head. Since step S230 is the same as the process of step S130, description thereof is omitted.
[0044]
In step S240, the shaft end position of the valve in a state where the valve is assembled to the cylinder head is acquired. Further, in step S250, the distance between the base circle surface and the valve shaft end position when the cam is attached is calculated. This calculation process is executed in a state where the cam is not actually assembled. In step S260, an appropriate thickness W of the valve lifter 300 adapted to the dimensional relationship in each cylinder is determined by subtracting a desired valve clearance value from the calculated distance.
[0045]
The contents of step S240 to step S260 will be described with reference to FIG. FIG. 7 is a diagram schematically showing a state in which the valve is assembled to the cylinder head.
[0046]
First, the valve 500 is assembled to the cylinder head 400. Specifically, a spring retainer is attached to the top of the shaft (valve stem) of the valve 500 via a pair of valve cotters. A spring 510 is mounted between the spring retainer and the cylinder head 400. As a result, the valve 500 is in a state where the port is closed. Various measurements are performed with the valve 500 assembled to the cylinder head 400. On the other hand, in the present embodiment, the valve lifter 300 and the cam 600 indicated by chain lines in the drawing are not assembled to the cylinder head 400. Therefore, preferably, various measurements are performed in a state where the cam 600 is not assembled to the cylinder head 400. Therefore, even before the cam 600 is assembled in the valve lifter processing line, measurement is possible, and the measurement result can be reflected in the valve lifter processing line. As a result, the adjustment processing of the valve lifter can be realized in a form adapted to the process sequence between the valve lifter processing line and the cylinder head assembly line.
[0047]
A distance AC from the reference point A to the shaft end C of the valve 500 is measured with an intersection point of a reference surface 410, which is a joint surface between the cylinder head 400 and the cylinder block, and a line obtained by extending the axis of the valve 500 as a reference point A. The Further, the distance from the reference point A to the bearing (cam journal) 420 of the camshaft and the diameter of the bearing 420 are measured. Further, the diameter of the cam shaft 610 of the cam 600 paired with the bearing 420 is measured. Based on the distance to the bearing 420, the diameter of the bearing 420, and the diameter of the camshaft 610, the distance AS from the reference point A to the center point S of the camshaft is calculated. Further, the diameter (radius) SB of the base circle (reference circle) of the cam 600 is measured. Based on these measurement results, a value (AS-AC-SB) obtained by subtracting the distance AC and the diameter SB from the distance AS is calculated. As a result, the distance SC between the base circle surface when the cam 600 is attached and the shaft end position of the valve 300 is calculated. By subtracting a desired valve clearance value T from this distance SC, an appropriate thickness W of the valve lifter adapted to the dimensional relationship in each cylinder is determined. The desired valve clearance T is, for example, 0.2 mm, but is appropriately set depending on the engine specifications.
[0048]
Next, in step S270 of FIG. 6, a processing command including information on the thickness W determined in step S260 and other information is notified to the valve lifter processing equipment 100. And the boss | hub part 310 is ground until the thickness of the valve lifter 300 corresponds with the thickness W determined by step S260. In addition, you may add outer peripheral part grinding between step S270 and step S280, and an outer peripheral surface quality can be improved more in that case.
[0049]
Then, after the boss portion 310 is ground, the thickness of the valve lifter 300 is measured, and the measured thickness and other data are imprinted on a predetermined surface of the valve lifter 300 (steps S280 and S290).
[0050]
According to the above-described method, the valve lifter 300 that is strictly adapted to the dimensional relationship in each cylinder is processed each time. Therefore, an appropriate valve clearance can be obtained without preparing dozens of valve lifters in advance. Can be realized.
[0051]
Finally, the relationship between the cylinder head assembly line (cylinder head assembly facility 200) and the valve lifter processing line (valve lifter processing facility 100) in this embodiment will be described using the sequence chart shown in FIG.
[0052]
First, in the cylinder head assembly facility 200, the valve 500 is assembled to the cylinder head 400 (step S1), and various measurements (see FIG. 7) in a state where the valve is assembled are executed (step S2). As a result, an appropriate thickness W of the valve lifter 300 is determined.
[0053]
On the other hand, while the above steps S1 and S2 are executed, the valve lifter processing facility 100 creates a cured film on the surface of the boss portion 310 of the valve lifter 300 by heat treatment (step S3). In the valve lifter processing facility 100, the thickness of the valve lifter before grinding of the boss portion 310 is measured (step S4).
[0054]
A processing command including information on the appropriate thickness W is given from the cylinder head assembly facility 200 to the valve lifter processing facility 100 (step S5). Preferably, the processing command includes information on the correspondence between the thickness W and the valve (information on which valve the calculated thickness W corresponds to) as well as information on the appropriate thickness W. ing.
[0055]
The valve lifter processing facility 100 that has received the processing command determines a grinding allowance for the boss portion 310 (step S6) and grinds the boss portion 310 (step S7). As a result, the boss portion 310 is adjusted. Thereafter, the thickness of the valve lifter 300 after the grinding of the boss portion 310 is measured (step S8) and stamped (step S9). Thereafter, the valve lifter 300 that has been processed is placed on a pallet and supplied from the valve lifter processing facility 100 to the cylinder head assembly facility 200 (step S10). At this time, the valve lifter 300 is preferably arranged on the pallet so that the correspondence relationship between the processed valve lifter 300 and the cylinder to which the valve lifter 300 should be attached can be understood.
[0056]
Then, the cylinder head assembly facility 200 takes out the valve lifter 300 from the pallet and assembles it to the corresponding cylinder (step S11). The empty pallet is returned to the valve lifter processing equipment 100 side (step S12).
[0057]
According to the valve lifter processing method configured as described above, the shaft end position C of the valve 500 in a state where the valve 500 is assembled to the cylinder head 400 is acquired, and the acquired shaft end position C of the valve 500 and the cam The machining allowance of the boss part 310 of the valve lifter 300 is adjusted based on the dimension SB of 600, and the boss part 310 is machined. Therefore, variation in valve clearance can be reduced to improve engine performance and reduce engine noise, and the number of types of valve lifters that need to be managed as inventory can be reduced.
[0058]
As described above, the valve lifter processing method and the valve lifter according to the present invention have been described, but it goes without saying that the present invention can be appropriately added, modified, and omitted by those skilled in the art within the scope of the technical idea thereof.
[0059]
For example, in the above description, the distance AC from the reference point A to the shaft end C of the valve 500, the distance from the reference point A to the camshaft bearing 420, the diameter of the bearing 420, the diameter of the camshaft 610, the base of the cam 600 The diameter of the circle (reference circle) and the like have been actually measured, but the present invention is not limited to this case. A point other than the reference point A may be used as the reference point. For example, the position of the shaft end C of the valve 500 may be used as the reference point. Unlike the above description, the reference point may not be on the axis of the valve 500. Even in this case, since the angle of the valve 500 with respect to the reference surface is constant, a desired dimension can be appropriately obtained using a trigonometric function or the like. Further, instead of directly measuring the distance from the reference point to the shaft end C of the valve 500, the distance to the valve shaft end is measured by measuring the distance to the point where the relationship with the valve shaft end is established. Can also be measured indirectly. Needless to say, the order of measurement can be changed as appropriate.
[0060]
In the above description, the machining command is calculated by calculation in the processor on the cylinder head assembly facility side, but the present invention is not limited to this case. For example, the valve lifter processing facility may receive measurement data from the cylinder head assembly facility, and the processor on the valve lifter processing facility side may calculate a processing command based on the measurement data.
[0061]
In the above description, the case where the selective assembly of the valve lifter is not used at all and only the adjustment process of the valve lifter is used has been described. However, the present invention is not limited to this case. That is, the selective assembly of the valve lifter and the adjustment process of the valve lifter can be used in combination. In other words, instead of preparing several dozen types of valve lifters with different thicknesses, only three types of valve lifters with different thicknesses (thin, medium, and thickness) are prepared. Then, the most suitable valve lifter is selected from these three types of valve lifters, and the adjustment process as described above is applied to the selected valve lifter. Even in this case, the number of types of valve lifters to be managed as inventory can be reduced from several tens to about three, and variation in valve clearance can be reduced to further improve engine performance and noise. be able to.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of a manufacturing system to which a valve lifter processing method according to an embodiment of the present invention is applied.
FIG. 2 is a view showing a valve lifter processing portion.
FIG. 3 is a cross-sectional view of a valve lifter according to an embodiment of the present invention.
FIG. 4 is a diagram showing the relationship between the depth from the surface of the valve lifter and the hardness.
FIG. 5 is a flowchart showing a valve lifter processing step used for selective assembly as a comparative example.
FIG. 6 is a flow chart showing a valve lifter adjusting process in the present embodiment.
FIG. 7 is a diagram schematically showing a state in which a valve is assembled to a cylinder head.
FIG. 8 is a sequence chart showing a relationship between a cylinder head assembly line and a valve lifter processing line.
[Explanation of symbols]
100 ... Valve lifter processing equipment,
200 ... cylinder head assembly equipment,
300 ... Valve lifter,
310 ... Boss part,
400 ... Cylinder head,
500 ... valve,
600 ... cam,
C: Valve shaft end position.

Claims (4)

A method for processing a valve lifter having a protrusion that contacts a shaft end of the valve,
An acquisition step of acquiring position data relating to the position of the shaft end of the valve in a state where the valve is assembled to the cylinder head;
A processing step of adjusting the processing allowance of the protruding portion of the valve lifter using the position data acquired in the acquiring step, and processing the protruding portion. In the machining step, the distance between the base circle surface when the cam is attached and the shaft end of the valve is calculated in a state where the cam is not assembled, and a desired valve clearance is subtracted from the calculated distance. The valve lifter processing method according to claim 1, wherein the protrusion is processed until an obtained value and a thickness of the valve lifter coincide with each other. The valve lifter processing method according to claim 1, further comprising a heat treatment step of forming a hardened layer thicker than a maximum machining allowance of the protrusion on the surface of the protrusion before processing by the processing step. A protrusion protruding in a direction opposite to the surface with which the cam contacts;
It is thicker than the maximum machining allowance within the range in which the machining allowance of the protrusion is adjusted using position data regarding the position of the shaft end of the valve in the state where the valve is assembled to the cylinder head, And a hardened layer formed on the surface.

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