Patent Description:
For an electrical power steering system (EPS), an input shaft is connected to a steering wheel in a drivetrain. Accordingly, in the case that the steering wheel is turned (e.g., by a driver), the input shaft drives a torsion bar to turn at an angle relative to an output shaft. A torque sensor senses the angle and sends a signal to an electronic control unit (ECU). Based on this steering wheel torque signal and an overall vehicle signal, the ECU sends a corresponding control signal to a power amplifier module such that the power module and three-phase circuits provide power to a motor in a certain mode for driving the motor. Motor torque is amplified by a worm and worm wheel and transmitted to the output shaft such that the motor provides power assistance in a desired manner (e.g., as intended by the driver).

Conventionally, the ECU is arranged separately from the motor, i.e., the motor and the ECU are assembled separately to a servo housing, and then the motor is connected to the ECU with resistance welding or screws, etc..

However, there are problems in this arrangement of motor and ECU. This brings inconvenience to fault detection and/or after-sales replacement. The reason is that for this conventional arrangement of the module, if an individual part of the module is to be substituted, the whole system needs replacement. The cost of such an operation is very high.

Further, a separate RPS sensor module is required to be installed on the motor to detect angles of rotor rotation of the motor. However, the total space occupied by the ECU, the RPS sensor module, and the motor is relatively large and the cost of parts is high. This heavier arrangement is not in the trend of a lightweight requirement for automobiles and hard to meet the need of customers seeking light-weight.

Document <CIT> shows an example of a prior art electric power steering drive module according to the preamble of claim <NUM>.

Therefore, it is desired to provide an improved electric power steering drive module to solve at least one of the above problems.

An objective of this application is to solve the above-mentioned problem of separate arrangement of ECU and motor, and resulting problems of higher weight, larger space occupation and higher cost.

Accordingly, at one aspect of the present application, provided is an electric power steering drive module comprising: a motor comprising a housing, stator coils disposed inside the housing, a motor shaft disposed at the center of the stator coils, and motor three-phase terminals leading from the stator coils towards a side of the motor and being exposed outside the housing,.

In one possible embodiment, the electric power steering drive module further comprises: an electronic control unit top-cover fixed to the electronic control unit circuit board assembly.

In one possible embodiment, the electric power steering drive module further comprising: an electronic control unit top-cover fixed to the electronic control unit base.

In one possible embodiment, the electronic control unit circuit board assembly is fixed to the electronic control unit base by the electronic control unit connector being closely fitted to the electronic control unit connector slot.

In one possible embodiment, the magnet is configured to be aligned with the Rotor Position Sensor chip, wherein the Rotor Position Sensor chip obtains the angular error of the motor rotor angle by controlling the distance between the magnet and the Rotor Position Sensor chip.

In one possible embodiment, the electronic control unit circuit board comprises three motor pinholes and the guide comprises three pilot holes, and wherein the three motor pinholes are configured to be respectively aligned with each of the three pilot holes.

In one possible embodiment, the three ends of the terminals are configured to pass through the guiding recess, the pilot holes and the motor pinholes respectively, for being exposed outside the electronic control unit circuit board assembly.

In one possible embodiment, the guide comprises: fixing tabs disposed at two ends of the backside of the guide respectively; and mounting support surfaces disposed on the backside of the guide and positioned between the fixing tabs, wherein the guide is fixed with its backside to the electronic control unit circuit using the fixing tabs and the mounting support surfaces.

Further, at another aspect of the present application, provided is an electrical power steering system comprising an electric power steering drive module as above.

Further, at yet another aspect of the present application, provided is a vehicle comprising an electrical power steering system as above.

The electric power steering drive module according to the present application has at least the following advantages: simplifying motor structure by integrating constructing, efficient usage of space, and cost-saving. This facilitates the layout of the whole vehicle.

Some embodiments of the present application are described below with reference to the accompanying drawings. It should be noted that the figures are not drawn to scale. Certain details may have been enlarged for clarity, and others that are not necessary to be shown are omitted.

As shown in <FIG>, the present application discloses an improved electric power steering drive module comprising a motor <NUM>, an electronic control unit (ECU) base <NUM>, an ECU circuit board assembly <NUM>, an ECU top-cover <NUM>, and a magnet <NUM>.

The motor <NUM> includes stator coils located therein. The stator coils may be connected with any suitable way (e.g., delta connection). The stator coils may lead to terminals <NUM> for motor's three-phase windings, as shown in <FIG>.

The ECU base <NUM> is secured to the motor <NUM> at the side of the motor <NUM> wherefrom the terminals <NUM> leading out of the motor <NUM>.

The ECU base <NUM> includes a guiding recess <NUM> located therein, a magnet mounting through-hole <NUM>, a capacitor mounting hole <NUM>, an inductor mounting hole <NUM>, and an ECU connector slot <NUM>.

As shown in <FIG>, the ECU circuit board assembly <NUM> includes an ECU circuit board, a guide <NUM> fixed to the lower surface of the ECU circuit board, a Rotor Position Sensor (RPS) chip <NUM>, a capacitor <NUM>, an inductor <NUM>, and an ECU connector <NUM>.

The guiding recess <NUM> may be configured to be able to be fitted tightly with the guide <NUM>.

The motor <NUM> further comprises a motor shaft <NUM> positioned at the center of the stator coils. The motor shaft <NUM> is configured to be able to pass through the magnet mounting through-hole <NUM> and able to have a magnet <NUM> thereon. The magnet <NUM> is positioned to be aligned with the RPS chip <NUM>.

The capacitor <NUM> may be configured to be tightly mounted in the capacitor mounting hole <NUM>. The inductor <NUM> may be configured to be fitted tightly in the inductor mounting hole <NUM>.

The ECU connector <NUM> may be configured to be fitted tightly into the ECU connector mounting slot <NUM> such that the ECU circuit board assembly <NUM> is able to be mounted tightly on the ECU base <NUM>.

The ECU connector <NUM> further is integrated with connection ports for whole vehicle Controller Area Network (CAN) signals, power supply, torque signals, etc. In this way, the overall structure is compact and easy to assemble.

As shown in <FIG> and <FIG>, the ECU circuit board includes three motor pinholes (also called ECU current output interfaces) <NUM> provided thereon.

The guide <NUM> includes three pilot holes <NUM>. The three motor pinholes <NUM> are respectively configured to be able to be connected to each of the three pilot holes <NUM> of the guide <NUM>.

Ends of terminals <NUM> may be exposed from the ECU board assembly <NUM> by passing through the guiding recess <NUM>, the pilot holes <NUM>, and the motor pinholes <NUM> in sequence and respectively.

The terminals <NUM> are soldered to the motor pinholes <NUM> with solder joints (e.g. by tin soldering). In this manner, ECU-controlled three-phase power is able to be delivered from the motor pinholes <NUM>, the solder joints, and the terminals <NUM> to the motor <NUM>.

In the case that the motor's three-phase power is profiled as sine waves with time, a magnetic field with a certain rotation speed is formed inside the motor <NUM>. This magnetic field will drive the motor shaft <NUM> to rotate for achieving motor power assistance.

The ECU top-cover <NUM> may be fixed to the ECU circuit board assembly <NUM> to protect the ECU circuit board assembly <NUM> and the terminals <NUM>. Alternatively, the ECU top-cover <NUM> may be tightly secured to the ECU base <NUM> such that the ECU circuit board assembly <NUM> is protected between them.

Generally, for ensuring reliable soldering, the gaps around the oval holes for the terminals and the ECU current output interfaces need to be controlled to be within small ranges.

However, in practice, for ensuring a reliable assembly, an automatic production line is adopted for installing the ECU circuit board assembly. In this case, it is difficult for the terminals to pass through the motor pinholes since the gaps between the motor pinholes and the terminals are very small. One solution of the prior art is using controlled position tolerance and assembly process tolerance for the terminals to facilitate the terminals to pass through the ECU current output interfaces. However, this approach requires an additional process for motor pin position adjustment increasing scrap rates of parts and results in a significant cost increase.

As shown in <FIG>, the guide <NUM> according to an embodiment of the present application is illustrated for solving the above problem.

The guide <NUM> may have the same shape as that of the guiding recess <NUM>, in the shape of an arc.

The guide <NUM> includes fixing tabs <NUM> disposed at two ends of the backside thereof respectively.

The guide <NUM> also includes mounting support surfaces <NUM> located at the backside thereof and between the fixing tabs <NUM>.

The guide <NUM> may be fixed to the ECU board with its backside using the fixing tabs <NUM> and the mounting support surfaces <NUM>.

The guide <NUM> also includes three pilot holes <NUM> provided thereon. the pilot holes are spaced apart by the mounting support surfaces <NUM>. The pilot holes <NUM> are through holes. The pilot holes <NUM> may have the same dimensions, sizes, and/or shapes as those of the ECU current output interfaces <NUM>.

According to an embodiment of the present application, the pilot holes <NUM> are funnel-shaped. Optionally, the upper and/or lower openings of the funnel have oval cross-sections.

Due to the relatively large position tolerances and assembly tolerances of the terminals <NUM>, the guide <NUM> shown in this application, in particular each pilot hole <NUM> of the guide <NUM> with funnel-shaped, may be adjusted for the terminals <NUM> such that in the case that there are deviations in the relative positions between the terminals <NUM> and the ECU current output interfaces <NUM>, the terminals <NUM> follow the funnels of the guide <NUM> and pass through the ECU current output interfaces <NUM>. In this way, a more advantageous soldering process for the terminals <NUM> and the ECU current output interfaces <NUM> is obtained.

In an embodiment of the present application, the ECU base <NUM> may be fixed to the ECU circuit board assembly <NUM>; as an alternative, the ECU base <NUM> may be fixed to the bearings <NUM> of the motor.

In this way, the structure of the motor <NUM> is simplified and the device that would otherwise be required to install the motor bearing <NUM> can be omitted such that costs may be saved. Further, the overall size of the ECU and the motor <NUM> combined is reduced, which is advantageous to the layout of the whole vehicle.

As shown in <FIG>, in an embodiment of the present application, the magnet <NUM> is assembled at the end of the motor shaft <NUM>; the RPS chip <NUM> is integrated on the ECU circuit board assembly <NUM>.

The reading of angular error of the motor rotor angle by the RPS chip <NUM> is ensured by controlling the spacing between the magnet <NUM> and the RPS chip <NUM>.

This arrangement saves the assembly space required for separate placement of the RPS sensor compared to the prior art and eliminates the need for parts to mount the RPS sensor in conventional ways, which in turn effectively reduces the cost for parts.

Claim 1:
An electric power steering drive module comprising:
a motor (<NUM>) comprising a housing, stator coils disposed inside the housing, a motor shaft (<NUM>) disposed at the center of the stator coils, and motor three-phase terminals (<NUM>) leading from the stator coils towards a side of the motor (<NUM>) and being exposed outside the housing,
an electronic control unit base (<NUM>) fixed to the motor (<NUM>) at the side of the exposed terminals (<NUM>), wherein the electronic control unit base (<NUM>) includes a guiding recess (<NUM>), a magnet mounting through-hole (<NUM>), a capacitor mounting hole (<NUM>), an inductor mounting hole (<NUM>), and an electronic control unit connector slot (<NUM>) disposed therein,
an electronic control unit circuit board assembly (<NUM>) fixed to the electronic control unit base (<NUM>) at the opposite side of the motor (<NUM>) and includes an electronic control unit circuit board, and a guide (<NUM>), a Rotor Position Sensor chip (<NUM>), a capacitor (<NUM>), an inductor (<NUM>), and an electronic control unit connector (<NUM>) fixed to the lower surface of the electronic control unit circuit board; and
a magnet (<NUM>),
wherein the motor shaft (<NUM>) is configured to pass through the magnet mounting through-hole (<NUM>) characterised in that the magnet (<NUM>) is snapped onto the end of the motor shaft (<NUM>), and
wherein the capacitor (<NUM>) is configured to be tightly mounted in the capacitor mounting hole (<NUM>), the inductor (<NUM>) is configured to be tightly mounted in the inductor mounting hole (<NUM>), and the electronic control unit connector (<NUM>) is configured to be fitted tightly in the electronic control unit connector slot (<NUM>).