QC/T 29096-2014Bench test methods for automotive steering gear assemblies (English PDF)

4.1 Test type

The test items of this Standard, from the main categories, are divided into the following three types:

- Performance test;

- Strength test;

- Durability test.

4.2 Accuracy of test instruments

The accuracy of the test instruments used in each test item must meet the following corresponding requirements:

- Accuracy requirement of angle sensor: 0.1°;

- Accuracy of displacement sensor: 0.01 mm;

- Accuracy of torque sensor: 1%;

- Accuracy of force sensor: 1%.

5.1 Performance

5.1.1 Full rotation angle of input shaft.

FIX the steering gear. There shall be no gap between the sensor and the input shaft. ROTATE the input shaft from one limit position to another limit position;

MEASURE the total rotation angle.

5.1.2 Rack travel.

FIX the steering gear. There shall be no gap between the sensor and the rack.

Install pull rods or substitutes on both ends of the rack; MEASURE the distance that the rack moves from one end to the other.

5.1.3 Transmission ratio.

5.1.3.1 Angular transmission ratio of recirculating-ball steering gear.

FIX the steering gear. Install the angle sensor close to the input shaft and the rocker arm shaft; the connection is required to be gap-free, see Figure 1.

ROTATE the input shaft from one-end limit position to the other-end limit position; DRIVE the input shaft at a speed of 10r/min ~ 15 r/min; MEASURE the instantaneous angle values of the input shaft and the rocker arm shaft. and reverse torque of the input shaft in the whole process. The input shaft speed is 15r/min.

REMOVE about 30° at both ends of the relationship curve, obtained by the test, between the rotation angle and the torque. Calculate the average torque of ± 180° in the middle and the average torque of the remaining rotation angles on both sides.

5.1.5 Rack moving force.

FIX the steering gear housing. Connect the force sensor and displacement sensor to the rack. The connection is required to be free of gaps. PUSH (PULL) the rack; MEASURE the moving force of the rack. The rack moving speed is 0.5m/min.

REMOVE the 3mm data at both ends of the displacement and force relationship curve obtained by the test; DRAW the displacement and force relationship curve.

5.1.6 Transmission clearance.

5.1.6.1 Transmission clearance of recirculating-ball steering gear.

Method 1: FIX the rocker arm shaft and the housing; LOAD a torque of ± 2N - m on the input shaft end; MEASURE the difference of the input shaft rotation angle, which is the clearance of this point (used for exit-factory test).

Method 2: Connect angle sensors to the input shaft and rocker arm shaft, respectively. The connection is required to be free of gaps. ADD a load of 10N - m to the rocker arm shaft; at a speed of 10r/min ~ 15r/min, drive the input shaft forward. MEASURE the instantaneous corresponding angle values of the input shaft and the rocker arm shaft. Then at the same speed, reversely drive the input shaft, to measure the same data (see Figure 3).

M1, M2 - Input and output torque of rocker arm shaft, N - m;

W1, W2 - Input and output torque of input shaft, N - m.

5.1.7.2 Transmission efficiency of pinion-and-rack steering gear.

FIX the steering gear. Connect the torque sensor and angle sensor to the input shaft. Connect the force sensor and displacement sensor to the rack. The connection is required to be free of gaps. At a speed of 15r/min, drive the input shaft; MEASURE the torque and rotation angle, force and displacement. In reverse efficiency, according to the transmission ratio and the input shaft speed, the drive speed is converted into rack displacement speed. The test load is loaded according to the load efficiency curve required by the manufacturer.

When not required, load according to the input shaft torque 4N - m ~ 5N - m, see Figure 6 (during the test, the steering gear has no pull rod and dust cover).

REMOVE about 30° at both ends of the input shaft rotation angle data obtained by the test and remove the corresponding torque and force. According to formula (5) and formula (6), calculate the efficiency of each point. DRAW the curve of input shaft rotation angle and efficiency. Calculate the average efficiency within the range of ± 180° in the middle and the average efficiency of the remaining rotation angles on both sides.

The efficiency is calculated according to formula (5) and formula (6):