JP2006090239A - Device and method for adjusting valve clearance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately adjust a valve clearance with a cylinder head assembled to a cylinder block, in regard to a device for adjusting the valve clearance. <P>SOLUTION: This valve clearance adjusting device adjusts the valve clearance between a rocker arm R having an adjust screw A and a valve stem end part, and is provided with a driver 2 for rotating the adjust screw A, a drive source 5 for rotating and driving the driver 2, a measuring means 7 for measuring displacement of the adjust screw A by measuring displacement of the driver 2, and a claw part 9 arranged in the lower part of the rocker arm R so as to move back-and-force and up-and-down and capable of being engaged with the rocker arm R. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus and method for adjusting the valve clearance between an engine rocker arm and a valve stem.

Conventionally, in engine assembly, the valve clearance between the rocker arm and the valve stem has been manually adjusted using a thickness gauge for each valve. On the other hand, in recent years, a system has been proposed in which the valve clearance is automatically adjusted in an engine assembly line (see, for example, Patent Document 1).
The valve clearance adjustment method disclosed in Patent Document 1 will be briefly described below. In FIG. 3, C is a cam formed on the camshaft, R is a rocker arm that is pivotally supported by the cam C, V is a valve that is driven to open when the rocker arm R abuts, B is a valve spring that urges the valve V in the closing direction, S is a valve seat that the valve V abuts when the valve is closed, and A is screwed to the rocker arm R. An adjustment screw N that can be brought into contact with the upper end of the stem of the valve V is a lock nut for fixing the position of the adjustment screw A.

As shown in the figure, the socket 1 is engaged with the lock nut N, and the socket 1 is connected to the AC nut runner 3. When the nut runner 3 is driven, the socket 1 is rotated and the lock nut N is rotationally driven. Reference numeral 4 denotes a torque converter.
A driver 2 is engaged with the adjustment screw A, and the driver 2 is connected to an AC servo motor 5 via a speed reduction mechanism 6. Therefore, the position of the adjustment screw A is adjusted by driving the servo motor 5, and the valve clearance T between the adjustment screw A and the stem end of the valve V can be adjusted. The driving of the nut runner 3 and the servo motor 5 is controlled by a microcomputer. An electronic micrometer 7 for measuring the displacement of the valve V is installed on the tip side (combustion chamber side) of each valve V, and the measured value is stored and calculated by the microcomputer.

Next, the procedure for adjusting the valve clearance will be described. First, the value of the electronic micrometer 7 is read with the cam C as the reference position and the valve V is seated against the valve seat S, and at this time, the lift amount T _1. = 0 (# 1).
Then, the lock nut N is loosened and the adjustment screw A is screwed to the set value T ₂ (# 2). Next, the camshaft is rotated once and the lift amount X of the valve V is measured by the electronic micrometer 7 (# 3). This lift amount X takes into account that the rocker arm R and the like bend due to the influence of the load of the valve spring B, and the lift amount X is smaller than the lift amount S by the camshaft by the bend amount ΔS.

Thereafter, the adjusting screw A is reversely rotated, and the screw is unscrewed from T ₂ to T ₃ by restricting the rotation angle (# 4). Thereby, the backlash of the drive system of the adjustment screw A is canceled. Further, the angle θ of the adjusting screw A at T ₃ is set to the reference angle (θ = 0 °).
Next, the adjustment screw A is unscrewed by an angle corresponding to the amount obtained by adding T ₃ to the specified valve clearance T (here, 0.15 mm on the intake side and 0.25 mm on the exhaust side), and the lock nut N is tightened. The adjustment is finished (# 5).

Next, the adjusted valve clearance is checked as follows.
The camshaft is rotated, and the displacement amount T ₄ of the valve V from the lift amount T ₁ = 0 in # 1 is measured by the electronic micrometer 7 (# 6). This T4 is smaller than the lift amount S by the camshaft by the amount obtained by adding the deflection amount ΔS to the valve clearance T.
T ₄ = S− (T + ΔS)
Next, T ₄ is subtracted from the lift amount X in # 3. This value c is
c = XT ₄
= (S-ΔS)-{S- (T + ΔS)}
= T.

Therefore, the value c is the valve clearance T set by correcting the deflection amount ΔS of the rocker arm or the like. Therefore, the value c is adjusted depending on whether the value c is within the specified accuracy (± 0.03 mm or less) of the valve clearance. Pass / fail can be determined.
Japanese Patent No. 2712681

However, the technique disclosed in Patent Document 1 has the following problems.
In general, when the cylinder head and the cylinder block are assembled, deformation due to bolt tightening occurs in both of them. Therefore, it is preferable to adjust the valve clearance after the cylinder head and the cylinder block are assembled. However, with the technique of Patent Document 1, the valve clearance cannot be measured in a state where the cylinder head and the cylinder block are assembled. For this reason, in the technique of Patent Document 1, the amount of deformation at the time of assembling the cylinder head and the cylinder block affects the valve clearance, and the error increases.

  In order to avoid such a problem, it is conceivable to measure the upper surface of the spring retainer RT, but the retainer rotates due to the friction of the adjusting screw A when the valve V and the adjusting screw A come into contact with each other, resulting in a measurement error. Therefore, the reference position with zero lift cannot be correctly captured. Further, since the lift amount before and after adjustment is used for the determination, an error in lift amount measurement and the like is added to the adjustment error.

In addition, accurate adjustment is not possible due to the backlash of the screw when the nut is tightened due to the gap between the screw groove of the adjustment screw and the driver tip, and the backlash between the rocker arm and the adjustment screw when the screw is tightened. There is a problem.
The present invention has been devised in view of such problems, and provides a valve clearance adjusting device and an adjusting method that can accurately adjust the valve clearance in a state where the cylinder head and the cylinder block are assembled. Objective.

  A valve clearance adjusting device according to the present invention is a valve clearance adjusting device for adjusting a valve clearance between a rocker arm having an adjusting screw and a valve stem end, a driver for rotating the adjusting screw, and a rotation of the driver. A driving source for driving, a measuring means for measuring the displacement of the adjusting screw by measuring the displacement of the driver, and a claw that is disposed in the lower part of the rocker arm so as to be capable of moving forward and backward and vertically and engageable with the rocker arm (Claim 1).

Preferably, the driver includes an urging means for urging the tip of the driver so as to abut against a driver groove formed in the adjustment screw.
Preferably, the measuring means is provided above the driver, and the measuring means measures the displacement of the upper end position of the driver.
In addition, it is preferable that a lock nut for fixing the position of the adjustment screw, a socket engageable with the lock nut, and a nut runner for driving the socket are provided.

  Further, the measurement gauge is reset in a state where the rocker arm is in contact with the end of the valve stem, and the displacement of the driver and the pitch of the adjustment screw from this state until the rocker arm contacts the base circle of the cam. Based on the above, it is preferable to include control means for feedback-controlling the operation of the drive source so that the valve clearance becomes a target value.

  A valve clearance adjusting method according to the present invention is a valve clearance adjusting method for adjusting a valve clearance between a rocker arm having an adjusting screw and a valve stem end, and a screwdriver for rotating the adjusting screw is screwed to the adjusting screw. The displacement of the driver is measured from the state where the rocker arm is brought into contact with the end of the valve stem until the rocker arm comes into contact with the base circle of the cam, and the displacement and the pitch of the adjusting screw The driver is rotated on the basis of the above (claim 6).

  Preferably, the adjustment screw is preliminarily tightened so that the valve clearance is within a predetermined initial range, and a preparatory step for temporarily tightening a lock nut for fixing the adjustment screw is set in the preparatory step. Temporary adjustment step of rotating the adjustment screw based on the valve clearance and the pitch of the adjustment screw so that the valve clearance is close to a target value, the valve clearance set in the temporary adjustment step and the pitch of the adjustment screw And a main adjustment step of rotating the adjustment screw so that the valve clearance becomes a target value (claim 7).

Further, by rotating the driver to the tightening side and then rotating the driver to the loose side, the backlash between the screw groove of the adjustment screw and the driver tip when the lock nut is tightened is canceled. You may comprise (Claim 8).
Further, after the lock nut is tightened, the displacement measurement value of the driver is reset to zero while the rocker arm is in contact with the valve stem end again, and the locker arm is pulled up until the rocker arm comes into contact with the base circle of the cam. It may be configured to have a step of measuring the displacement in the state and finally measuring the created clearance to determine pass / fail (claim 9).

  According to the valve clearance adjusting device and the adjusting method of the present invention, the valve clearance is measured at the upper end portion of the driver engaged with the adjustment screw. Therefore, the valve clearance can be measured and adjusted after the cylinder head and the cylinder block are assembled. It becomes possible. For this reason, the amount of deformation after assembling the cylinder head and the cylinder block does not affect the valve clearance, and the valve clearance can be adjusted with high accuracy. In addition, the valve clearance can be adjusted by feedback control, and the measurement result is very close to the actual clearance and the evaluation is excellent.

  Hereinafter, a valve clearance adjusting device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the overall configuration thereof. In the figure, C is a cam formed on the camshaft, R is a rocker arm pivotally supported by the cam C, V is a valve that is driven to open when the rocker arm R abuts, and B is a valve V. A valve spring that urges in the closing direction, S is a valve seat with which the valve V abuts when the valve is closed, A is an adjustment screw that is screwed to the rocker arm R and can abut on the stem upper end of the valve V, and N is an adjustment screw A A lock nut for fixing the position of the engine, and these members constitute an engine valve system to which the present invention is applied.

Further, as shown in the figure, the apparatus is provided with a socket 1 that can be engaged with a lock nut N. The socket 1 is connected to an AC nut runner 3, and when the nut runner 3 is driven, the socket 1 is rotated and the lock nut N is rotated. Reference numeral 4 denotes a torque converter.
A screw rotation driver (hereinafter simply referred to as a driver) 2 that can be engaged with the adjustment screw A is provided above the adjustment screw A. The driver 2 is connected to an AC servomotor (drive source) 5 via a speed reduction mechanism 6, and the position of the adjustment screw A is adjusted by driving the servomotor 5, and the stem of the adjustment screw A and the valve V is adjusted. The valve clearance T between the ends is adjusted. The position and angle of the driver 2 are set so as to coincide with the center position and angle of the adjusting screw A when the rocker arm R contacts the cam C.

The nut runner 3 and the servo motor 5 are connected to a control means (controller) (not shown), and their operations are controlled based on a control signal from the controller.
A claw portion 9 as shown is provided in the vicinity of the rocker arm R. The claw portion 9 is connected to a forward / reverse actuator and a vertical movement actuator (both not shown) for moving the claw portion 9 in the horizontal direction and the vertical direction in the figure, and controls the operation of these actuators. Thus, the claw portion 9 can lift the rocker arm R. In the present embodiment, the lifting force of the claw portion 9 is set constant, but the lifting force is monitored (monitored) by the controller.

  A measurement gauge 7 as a measuring means is attached to the upper end portion of the driver 2, and the valve clearance is measured or detected by the measurement gauge 7. Here, when the rocker arm R is brought into contact with the base circle portion of the cam C from the state in which the rocker arm R is brought into contact with the valve stem end (that is, the tip of the adjusting screw A is brought into contact with the valve stem end). If the clearance is small and the rotation angle of the rocker arm R is small, the adjusting screw A and the driver 2 are displaced by the same dimension as the valve clearance. Therefore, in this device, the valve clearance is measured by measuring the displacement of the driver 2 engaged with the tip of the adjustment screw A by the measurement gauge 7.

  Specifically, the value of the measurement gauge 7 is set to zero in a state where the rocker arm R is in contact with the end of the valve stem (that is, the end of the adjusting screw A is in contact with the end of the valve stem) The measurement gauge 7 measures the displacement of the driver 2 when the rocker arm R is brought into contact with the base circle portion of the cam C from this state. In this case, since the adjusting screw A and the driver 2 are displaced by the same dimension as the valve clearance, the measured displacement amount of the driver 2 = valve clearance.

As shown in the figure, a spring 8 is provided above the driver 2 to urge the driver 2 downward. The urging force of the spring 8 is configured so that the driver 2 is always in close contact with the adjustment screw A. ing.
Next, a valve clearance adjustment method using the present apparatus will be described with reference to the time chart of FIG. 2. This adjustment method mainly includes a preparation stage (preparation step), a temporary adjustment stage (temporary adjustment step), and a main adjustment stage (main book). Adjustment step) and a determination step (determination step).

The preparation stage will be described first. First, the cylinder head portion of the engine is installed in the state shown in FIG. In this case, it is preferable that the engine cylinder block and the cylinder head be assembled.
Then, as shown in FIG. 2 (f), the measurement gauge is once reset to zero, and thereafter, as shown in FIGS. 2 (d) and 2 (e), the forward / reverse actuator is actuated to move the claw portion 9 to the rocker arm R. When the claw portion 9 reaches the lower side of the rocker arm R by being advanced downward, the advancement of the claw portion 9 is stopped, and the vertical movement actuator is operated to raise the claw portion 9 upward. As a result, the rocker arm R is brought into contact with the base circle portion of the cam C.

Next, the driver 2 and the adjustment screw A are engaged. That is, as shown in FIG. 2A, the driver 2 is slightly rotated to the tightening side and the loosening side, respectively, and then rotated only to the tightening side. The reason why the driver 2 is slightly rotated to the tightening side and the loosening side is to ensure that the driver 2 is engaged with the groove (cross groove) of the adjusting screw A.
The reason why the predetermined number of rotations is tightened thereafter is to bring the tip of the adjustment screw A closer to the upper end of the valve stem so that the gap between the two is within a predetermined initial range. That is, when adjusting the valve clearance, the adjustment screw A is rotated so that the clearance is already within a predetermined initial range (so that the error is reduced) before the start of the adjustment.

Next, as shown in FIG. 2 (e), an actuator (not shown) is actuated to temporarily lower the claw 9 to bring the rocker arm R into contact with the upper end of the stem of the valve V (adjustment screw A). After resetting the gauge 7 to zero, the claw portion 9 is pulled up again to bring the rocker arm R into contact with the base circle of the cam C.
At this time, as shown in FIG. 2F, the value measured by the measurement gauge 7, that is, the valve clearance at this time is read and stored in a controller (not shown). This completes the preparation stage.

Next, the process proceeds to the temporary adjustment stage. First, the adjustment screw A is rotated until the measurement value reaches the target value while monitoring the measurement value of the measurement gauge 7. As shown in FIG. 2A, after the driver 2 rotates to the tightening side, the driver is slightly rotated to the loose side for the purpose of canceling backlash between the screw groove and the driver tip.
Then, temporary tightening before this adjustment is performed. That is, as shown in FIG. 2B, the nut runner 3 is operated to temporarily tighten the lock nut N. This temporary tightening is completed by once tightening the lock nut N with a predetermined torque for a predetermined number of rotations, then loosening the lock nut N by a predetermined angle and then tightening the lock nut N again at a predetermined angle.

  The reason for this temporary tightening will be described. Since there is a minute backlash between the rocker arm R and the adjustment screw A, if the adjustment screw A is adjusted with the lock nut N loosened, the valve This is because when the lock nut N after the clearance adjustment is tightened, the adjustment screw A is lifted upward by this amount of play, and the valve clearance is displaced. Since this deviation varies from part to part, a program that estimates this deviation cannot be incorporated. Therefore, here, the lock nut N is lightly tightened in advance so that the adjustment screw A can be adjusted.

Then, as shown in FIGS. 2 (e) and 2 (f), after temporary tightening, the claw portion 9 is temporarily lowered to bring the rocker arm R into contact with the upper end of the stem of the valve V (with the adjustment screw A). Reset measurement gauge 7 to zero. Thereafter, the claw portion 9 is pulled up to bring the rocker arm R into contact with the base circle of the cam C, and the value measured by the measurement gauge 7 is read.
Next, the process proceeds to the final adjustment stage, and the clearance is adjusted in the same manner as in the temporary adjustment stage. Here, since the valve clearance is adjusted once in the preliminary adjustment stage of the previous stage, the difference from the target value should be very small in this adjustment stage. However, since it is considered that the valve clearance does not fall within a predetermined range (for example, within the target value ± 0.03 mm) only at the temporary adjustment stage, final adjustment is performed at this final adjustment stage. Yes.

Now, in this final adjustment stage, the adjustment screw A is rotated until the measurement value reaches the target value while monitoring the measurement value of the measurement gauge 7 as in the temporary adjustment stage.
Then, as shown in FIG. 2B, the nut runner 3 is driven, the lock nut N is tightened under a predetermined condition, and the lock nut N is finally tightened. Thereafter, as shown in FIGS. 2 (e) and 2 (f), the claw portion 9 is once lowered to bring the rocker arm R into contact with the upper end of the stem of the valve V, the measurement gauge 7 is reset to zero, and the claw portion 9 is pulled up. Measure the valve clearance. This is the end of this adjustment step.

  Next, the process proceeds to the determination step. In this determination step, it is determined whether or not the valve clearance is within a predetermined range in the valve clearance measurement in the main adjustment step. If the valve clearance is not within the predetermined range, the operator is within the predetermined range. Adjust manually (or manually). When the valve clearance is not within the predetermined range, the above-described main adjustment stage and determination stage may be repeatedly executed until the valve clearance falls within the predetermined range.

On the other hand, if the valve clearance is within a predetermined range, the actuator of the claw portion 9 is operated to lower and retract the claw portion 9 to complete a series of valve clearance adjustments.
By adjusting the valve clearance as described above, the valve clearance is measured by the displacement of the driver 2 engaged with the adjustment screw A. Therefore, the valve clearance can be measured and adjusted after the cylinder head and the cylinder block are assembled. It becomes possible. For this reason, there is an advantage that the amount of deformation after the cylinder head and the cylinder block are assembled does not affect the valve clearance, and the valve clearance can be adjusted with high accuracy.

Further, since the driver 2 is configured to always contact the adjustment screw A by the spring 4, it is possible to reliably prevent the vertical play between the driver 2 and the adjustment screw A.
Moreover, since the displacement of the upper end position of the driver 2 is measured by the measurement gauge 7, the accuracy of the valve clearance can be further increased. That is, there is a problem that if the measurement is performed on the lower surface of the valve as in the prior art, the valve clearance cannot be measured and adjusted after the above-described cylinder head and cylinder block are assembled.

  Also, when measuring the upper surface of the retainer, it can be adjusted after the cylinder head and cylinder block are assembled. However, it is impossible to measure the actual clearance, and the screw contacts the valve during the adjustment and measurement process. Since the displacement is measured while rotating the screw in the state, a rotation and a tilting motion are generated in the valve by a gap of the valve guide by a moment caused by friction between the valve and the screw. In this state, since the point at which the retainer (which moves in the same manner as the valve) starts to be displaced (ie, the clearance zero point) is stored, the error is large.

On the other hand, since the upper end portion of the driver 2 does not rotate when the valve clearance is measured, the valve clearance can be measured with high accuracy.
In addition, after adjusting the adjustment screw A, the nut runner 3 operates and the lock nut N is tightened while the driver is fixed, whereby the adjustment screw A is automatically locked, so that the valve clearance is maintained with high accuracy. can do. Moreover, the dispersion | variation in the clearance by co-rotation of an adjustment screw can be suppressed. Further, after the driver 2 is rotated to the tightening side, the driver 2 is rotated to the loose side to obtain a target value. Therefore, the screw groove of the adjustment screw A and the tip of the driver 2 when the lock nut N is tightened are used. Since the backlash is canceled, the accuracy of the valve clearance can be further increased.

  Next, a modified example of this embodiment will be described. In this modified example, only the operation control method of the servo motor 5 in the temporary adjustment stage or the final adjustment stage is different. That is, in this modification, the servo motor 5 (driver 2) is rotated until the measurement value reaches the target value while the above-described embodiment monitors the measurement value of the measurement gauge 7, whereas the following method is used. Then, the adjustment screw A is rotated.

  That is, the controller calculates the difference between the value measured by the measurement gauge 7 and the valve clearance target value, and determines the adjustment screw A from the calculated result and the pitch of the adjustment screw A to set the valve clearance to the target value. It is calculated whether to rotate. Then, the controller outputs an instruction signal to the servo motor 5 based on the calculation result, whereby the driver 2 rotates and the valve clearance is set near the target value. Further, the measurement result at this time is input to the controller, and the operation of the servo motor 5 is feedback-controlled based on the measurement value, so that the valve clearance is adjusted to the target value.

  According to such a modified example, the measurement gauge is reset in a state where the rocker arm R is in contact with the end of the valve stem, and the displacement of the driver is measured from this state until the rocker arm contacts the base circle of the cam. In addition, since the operation of the servomotor 5 is feedback controlled so that the valve clearance becomes a target value based on the displacement and the pitch of the adjusting screw, there is an advantage that the accuracy of the valve clearance can be further improved.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, only one temporary adjustment stage is provided, but the temporary adjustment stage may be provided a plurality of times.

It is a schematic diagram which shows the principal part structure of the valve clearance adjustment apparatus concerning one Embodiment of this invention. It is a figure explaining the effect | action of the valve clearance adjustment apparatus concerning one Embodiment of this invention. It is a figure for demonstrating the prior art.

Explanation of symbols

1 socket 2 driver 3 nutrunner 5 AC servo motor (drive source)
6 Deceleration mechanism 7 Measuring gauge (measuring means)
8 Spring (biasing means)
9 Claw A Adjust screw B Valve spring C Cam N Lock nut R Rocker arm S Valve seat V Valve

Claims (9)

A valve clearance adjusting device for adjusting a valve clearance between a rocker arm having an adjusting screw and a valve stem end,
A driver for rotating the adjusting screw;
A drive source for rotationally driving the driver;
Measuring means for measuring the displacement of the adjusting screw by measuring the displacement of the driver;
A valve clearance adjusting device comprising: a claw portion which is disposed at a lower portion of the rocker arm so as to be movable forward and backward and vertically and engageable with the rocker arm. Biasing means for biasing the tip of the driver so as to abut against a driver groove formed in the adjustment screw;
The valve clearance adjusting device according to claim 1, wherein: 3. The valve clearance adjusting device according to claim 1, wherein the measuring means is provided above the driver, and the displacement of the upper end position of the driver is measured by the measuring means. A lock nut for fixing the position of the adjustment screw;
A socket engageable with the lock nut;
The valve clearance adjustment device according to any one of claims 1 to 3, further comprising a nut runner for driving the socket. The measurement gauge is reset while the rocker arm is in contact with the valve stem end, and based on the displacement of the driver and the pitch of the adjustment screw until the rocker arm comes into contact with the base circle of the cam from this state. 5. The valve clearance adjusting device according to claim 1, further comprising control means for performing feedback control of the operation of the drive source so that the valve clearance becomes a target value. A valve clearance adjustment method for adjusting a valve clearance between a rocker arm having an adjusting screw and a valve stem end,
A driver for rotating the adjusting screw is brought into contact with a thread groove of the adjusting screw;
The displacement of the driver is measured from the state in which the rocker arm is in contact with the valve stem end until the rocker arm contacts the base circle of the cam, and the driver is rotated based on the displacement and the pitch of the adjustment screw. A valve clearance adjustment method, characterized by: A preliminary step of tightening the adjustment screw in advance so that the valve clearance falls within a predetermined initial range, and temporarily tightening a lock nut for fixing the adjustment screw;
A temporary adjustment step of rotating the adjustment screw so that the valve clearance is close to a target value based on the valve clearance set in the preparation step and the pitch of the adjustment screw;
The main adjustment step of rotating the adjustment screw so that the valve clearance becomes a target value based on the valve clearance set in the temporary adjustment step and the pitch of the adjustment screw. 6. The valve clearance adjusting method according to 6. By rotating the driver to the tightening side and then rotating the driver to the loose side, the backlash between the screw groove of the adjustment screw and the driver tip when the lock nut is tightened is cancelled. The valve clearance adjusting method according to claim 7. After the lock nut is tightened, the displacement measurement value of the driver is reset to zero with the rocker arm abutting against the valve stem end again, and the rocker arm is pulled up until it abuts against the base circle of the cam. 9. The valve clearance adjustment method according to claim 7 or 8, further comprising a step of finally measuring the displacement created by measuring the displacement of the above and determining pass / fail.

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