Valve Timing Measurement 气门正时测量.doc

Valve Timing Measurement 气门正时测量
2010-05-06 22:39:42 View:85
Purpose
目的
The performance and emissions behaviour of any internal combustion engine is heavily dependant upon timing, lift and duration of the inlet and exhaust valves
任何内燃机的性能和排放指标主要依
Purpose
目的
The performance and emissions behaviour of any internal combustion engine is heavily dependant upon timing, lift and duration of the inlet and exhaust valves
任何内燃机的性能和排放指标主要依赖于进排气门打开时间, 升程, 打开持续时间

Equipment
测量设备

- Crankshaft angle gauge 曲轴角度测量仪
- Dial test indicator   杠杆千分表 (DTI)
- DTI mounting bracket DTI安装支架
- Suitable stylus extension bar (to reach the piston) 合适的延伸杆（以延伸到活塞）

Measurement of Valve Maximum Opening Point (also known as Valve Peak or MOP)
气门最大打开点测量(气门最大升程)

In addition to the equipment listed above, a smaller probe will be required for measuring the valve position. 
除了以上设备，还需要一个很小的探针以测量气门位置

Step 步骤 1
Rotate the engine crankshaft, so that the piston in cylinder number one is at Top Dead Center, this should be measured using the crankshaft angle gauge.
转动发动机曲轴，因此通过测量曲轴角度测量仪让第一缸的活塞到达上止点

Step 步骤 2
Rotate the engine crankshaft further until the valve is opened to its maximum opening point.  Judge the maximum opening visually.
继续转动发动机曲轴直到气门达到最大打开点。目视确认最大开启量

Step 步骤 3
Install the DTI on the first valve to be measured, ensuring that the gauge is mounted parallel to the axis of the valve and around 75% loaded. The DTI probe should be in contact with a flat area of either the tappet or the spring retainer. Zero the gauge.
将DTI安装于首个待测气门上，取保量规平行于气门的中心轴并加载约75％。DTI的探针应置于挺柱或锁夹的平面上。清零。

Step 步骤 4
Slowly rotate the crankshaft in the clockwise direction (normal rotation) until the valve lift is 0.5mm before the highest point. Note the reading from the crankshaft angle gauge.
缓慢顺时针方向（通常转动方向）转动曲轴直到气门升程达到最高点前0.5mm，记录曲轴角度测量仪读数

Step 步骤 5
Slowly rotate the crankshaft further in the forward direction, until the gauge moves over the maximum valve lift position and falls to 0.5mm after the maximum lift position. Again, note the crankshaft angle gauge reading.
继续缓慢转动曲轴直到气门越过最大位置并回落0.5mm，再次记录曲轴角度测量仪读数

Step 步骤 6
The maximum valve lift will be the mean (average) of the two timing readings. Calculate the average of the two readings by adding them together and dividing the result by two. Record this value.
最大气门升程将取两次读数的平均值。将两次读数相加，再除以2。记录这个数值。

Step 步骤 7
Repeat Steps 5, 6 & 7, to confirm the result.
重复步骤5，6&7，以确认测量结果。

Notes
提示

Ensure that the DTI probe is positioned on a flat part of the valve retainer, or follower in the case of direct attack arrangements, i.e. such that the probe does not move across the face of the retainer as the measurement is completed.
确保DTI探针是安置于气门锁夹或摇臂（直接驱动布置）的平面上，也就是在测量完成前DTI探针不能在锁夹平面上移动

Following determination of piston Top Dead Center, there should be no alterations to the crankshaft angle gauge.  If this is knocked in any way during the remaining procedure, the TDC timing should be rechecked.
在确定活塞上止点时，曲轴角度测量仪读数不应该有任何改变。如果在过程中读数有任何滞留，应该再次检查上止点。

Valve Opening and Closing Points
气门开启和关闭点

Measuring accurately the opening point is extremely difficult.  This is more often achieved by calculation, based upon measured maximum lift values and known cam duration.
精确测量气门打开点非常困难，一般是通过基于测量所得最大升程和已知的凸轮持续角进行计算

Step 步骤 1
Rotate the crankshaft until the valve is towards the middle of the b ase circle of the cam.
转动曲轴直到凸轮型线基准圆的中间点

Step 步骤 2
Install a DTI on the valve in the same way as detailed above.  Zero the gauge.
装一个DTI，方式如上描述。清零。

Step 步骤 3
If possible, set tappet clearance to –0.1mm (i.e. 0.1mm valve lift), and re-zero the gauge.  If this is not possible by means of setting an adjustment, a solid tappet should be made and installed such that the valve lift is greater than or equal to 0.1mm, but not more than 0.2mm.
可能的话，设置气门顶住到-0.1mm（例如0.1mm气门升程），重新清零DTI，如果不能通过调节器调节，可以使用一个无弹性气门顶柱替换原有的，大于0.1mm，少于0.2mm。此举目的是放大气门升程，方便在仪器精度范围内测量。

Step 步骤 4
Rotate the crankshaft in the direction of normal operation until the lobe is approximately opposite the maximum lift condition (center of base circle).  Judgment can be used as to the exact starting point.  If the starting point proves to be too close to the valve event being measured, rotate the engine forward through one and three quarters revolutions and begin again.
旋转曲轴到约为与气门升程最大相反的位置（基准圆中点），此时可以作为开始测量点，如果觉得不太对，可以旋转发动机1和3/4圈，重新开始

Step 步骤 5
Rotate the crankshaft in 5°CA increments, recording valve lift at each point.
以5度曲轴转角步长测量，记录每步长气门升程

Step 步骤 6
Continue to record valve lift versus crank angle until the DTI reading moves off zero.  At this point continue to record data at 2° CA increments.  Continue this until the DTI reads 1.0mm.
持续记录直到DTI回复读数0.在这个情况下继续旋转2度曲轴转角，读取数据。继续直至DTI读数为1.0mm

Step 步骤 7
Plot the data of lift versus timing on a graph, and plot a best fit curve through the points.  If the data is too variable review the positioning and condition of the DTI and take further data.
基于升程和曲轴转角画图，连成一条合适曲线，如果数据不是一条平滑曲线，重新检查位置和DTI情况，测量更多数据

Step 步骤 8
All data should be recorded and compared with the designed cam profile so that true top-of-ramp timings can be determined.
所得数据应和设计值相比较，以得到真实的正时

Step 步骤 9
Recheck the zero of the base circle within 10° of the reading of the DTI becoming constant