QC/T 299.1-2014Automotive hydraulic power steering pumps - Part 1: Technical requirements (English PDF)

3.1 Displacement, q

The oil volume discharged by the steering pump per revolution, the unit is mL/r.

3.2 Minimum rotational speed, nmin

The minimum speed when the steering pump works stably, the unit is r/min.

3.3 Maximum rotational speed, nmax

The maximum rotational speed of the steering pump when it works stably, the unit is r/min.

3.4 Open rotational speed

Operating speed at which the steering pump's flow control valve is open.

3.4.1 No-load open rotational speed, n1k

Under no-load pressure, the working speed when the flow control valve of the steering pump is opened, the unit is r/min.

3.4.2 Load open rotational speed, n2k

Under the working pressure of 0.6Pmax, the working speed when the maximum control valve of the steering pump is opened, the unit is r/min.

3.5 Open flow

The output flow rate under the open rotational speed condition.

3.5.1 No-load open flow, Q1k

The output flow under the no-load open rotational speed condition, the unit is L/min.

3.5.2 Load open flow, Q2k

The output flow rate under the condition of 0.6Pmax working pressure and open rotational speed, the unit is L/min.

3.6 Limited flow, Qk

The output flow of the steering pump, within the specified speed range, the unit is L/min.

3.7 Maximum pressure, Pmax

The highest pressure that allows the steering pump to operate in a short time (i.e., the set pressure when the safety valve is opened), the unit is MPa.

3.8 No-load pressure, P0

The output pressure when the oil outlet pressure does not exceed 5% of the maximum pressure Pmax or 0.5 MPa, the unit is MPa.

3.9 Speed range

Under no-load pressure, the range from the lowest speed to the highest speed, when the steering pump works stably.

3.10 Driving power, N

The mechanical power that drives the steering pump, in kW.

3.11 Damage

The steering pump has leakage, abnormal noise, damaged parts, which cannot meet its performance requirements. conditions and requirements for etav' and etat' shall be determined through negotiation.

4.6 Air tightness

There shall be no leakage at all parts and assembly surfaces. When the medium (water or kerosene) immersion method is used for detection, there shall be no air bubbles; when the pressure drop method is used for detection, the pressure drop is allowed to be less than 1.8 x 10^-4 MPa.

4.7 Noise

Within the allowable speed and pressure range, the product must not have abnormal noise; its noise shall meet the requirements in Table 2.

Note: Commercial vehicles and passenger cars are defined according to GB/T 3730.1.

4.8 Cleanliness

The internal cleanliness of the product assembly shall meet the requirements in Table 3.

Note:

1 Please refer to 3.5 in GB/T 14039-2002 (ISO 4406) for details on the determination of microscope counting code; refer to 3.4 in GB/T 14039-2002 (ISO 4406) for details on the determination of automatic particle counter code.

2 For the cleanliness index of weighing method, refer to the acceptance criteria of JB/T 7858.

4.9 Drive power

The mechanical power, which drives the steering pump, shall meet the requirements of the manufacturer.

4.10 Pressure switch characteristics

The characteristics of the pressure switch shall meet the requirements of the manufacturer.

5.1 Constant rotational speed impact

After the constant rotational speed impact test, the maximum pressure is allowed to drop no more than 10%, compared to before the test; the flow rate is allowed to change no more than 10%; the volumetric efficiency and total efficiency meet the requirements after the reliability test in Table 1; damage is not allowed.

5.3 Durable to wear

After testing through the wear durability method, the maximum pressure is allowed to drop no more than 10%, compared to before the test; the flow rate is allowed to change no more than 10%; the volumetric efficiency and total efficiency meet the requirements after the reliability test in Table 1; damage is not allowed.

5.4 Low temperature

Low temperature start shall be normal.

5.5 Vibration

After the vibration test is completed, the maximum pressure is allowed to drop no more than 7%; the flow rate is allowed to change no more than 10%; no damage is allowed.

5.6 Flow cut-off

After the flow cut-off test, the components must not be damaged; the volumetric efficiency is allowed to drop by no more than 3%.

C.1 Calculation of steering resistance torque Mr

Steering resistance torque M is calculated according to formula C.1.

Where:

Mr - In-situ steering resistance moment on asphalt or concrete road, N · m; f - Sliding friction coefficient between the tire and the ground, which takes 0.7; G1 - Steering front axle load, N; P - Tire pressure, Pa.

C.2 Calculation of minimum working pressure Pmin required for steering

The minimum working pressure required for steering is calculated, according to the moment Mr which is calculated in formula C.1 and the cylinder diameter of the selected power steering gear, using formula C.2.

Where: Pmin - Minimum working pressure required for steering, MPa;

Mr - In-situ steering resistance moment on asphalt or concrete road, N · m; RF - Pitch circle radius of sector teeth, mm; S0 - Working area of power steering gear cylinder, mm2;

S1 - The area occupied by the outer diameter of the screw, mm2.

C.3 Calculation of theoretical flow Q0

The theoretical flow Q0 is calculated, according to formula C.3, using the maximum instantaneous speed of the steering wheel.

Where:

Q0 - Theoretical flow rate, L/min; n - The maximum instantaneous speed of the steering wheel of the car, 1.5 for cars and 1.25 for other vehicles, r/s; t - Power steering gear's screw pitch, mm; S - Actual working area of power steering cylinder, mm2.

C.4 Design of maximum pressure Pmax of steering pump

The result which is obtained from formula C.2 is the minimum working pressure required for steering. Since the steering pump has a safety protection function, it must be ensured that the working pressure shall not exceed the maximum design pressure of the steering pump; the designed working pressure shall not be greater than 0.85 pmax. Example 1:

The working pressure of the steering pump is 8 MPa, so the maximum pressure of the steering pump is designed to be 10 MPa.

C.5 Flow matching design of steering pump

According to the flow as calculated in formula C.3, system leakage must also be considered; the actually required flow is calculated according to formula C.4.

Where: Q1 - Actually required flow rate, L/min; Q0 - Theoretical flow rate, L/min; Q2 - Leakage in the steering gear, L/min.

C.6 Calculation of torque T

Where: T - Torque, N · m; […]