Patent Description:
Pressure supply units are used in conjunction with electro-hydraulic brake-by-wire systems for vehicles such as automobiles to provide brake pressure in place of a traditional booster, master cylinder and brake pedal arrangement. Pressure supply units are commanded by an Electronic Control Unit (ECU) which derives signals from a driver via sensors in a pedal feel emulator and/or from an auto pilot that can self-apply the brakes without driver intervention. Pressure supply units typically include a motor comprised of a stator and a rotatable rotor container within the stator, with the rotor housing a high efficiency screw assembly which is furthermore attached to a piston contained in a cylinder of a booster body. Rotation of the rotor effectuates translating movement of the spindle and piston, thereby causing the brake pressure change for effectuating the brakes.

There remains a continued need for improvements to such pressure supply units. Document <CIT> discloses an electric booster device and a booster device. In this electric booster device, a housing is provided with: a rear housing comprising a vehicle mounting plate; a front housing disposed between a master cylinder and the rear housing; and coupling members for coupling the master cylinder and the rear housing, with the front housing therebetween. When hydraulic pressure is generated in the master cylinder, the hydraulic reaction force from the master cylinder is thus transmitted to a first rear housing part via the coupling members, thereby making it possible to reduce the rigidity of the front housing. This makes it possible to make the electric booster device more compact and lightweight. Document <CIT> discloses an electric booster. Provided is an electric booster which can be downsized by enhancing space efficiency while reducing the effect of a magnetic field from outside on a magnetic sensor by means of a magnetic shield. The stroke amount of an input plunger <NUM> connected to a brake pedal <NUM> is detected by a stroke detection sensor. The operation of an electric motor is controlled by controller on the basis of the stroke amount of the input plunger to thrust a primary piston through a ball screw mechanism, and brake fluid pressure is thus generated by a master cylinder. The stroke detection device uses a Hall IC to detect magnetic flux densities from first and second magnet members mounted on the input plunger to obtain the stroke of the input plunger. The first and second magnet members and the Hall IC are disposed inside a linear-motion member formed of a cylindrical magnetic body of the ball screw mechanism to be magnetically shielded. Document <CIT> discloses a master cylinder for use in power trains of motor vehicles. A master cylinder for use in the power train of a motor vehicle to actuate the brakes or the friction clutch is designed to avoid the generation of screeching noise and/or the transmission of stray movements to the piston rod in response to shifting of the piston relative to the housing and relative to the sealing element(s) between the piston and the housing. This can be accomplished by causing the piston to turn relative to the housing and the sealing element(s) during axial movement in the housing and/or by installing one or more dampers between the piston and the housing and/or between the piston and the piston rod. The dampers can constitute separately produced parts and/or specially configured and/or finished surfaces provided on the piston and contacting the housing and/or the sealing element(s). The invention also relates to improvements in the configuration and/or the material(s) of the piston. Document <CIT> discloses a brake master cylinder arrangement with position transmitter element and coupling arrangement therefor. The invention relates to a brake master cylinder arrangement for a motor vehicle brake system, comprising at least one piston arrangement with: a pressure piston unit that can be moved along a movement axis and, together with a housing arrangement of the brake master cylinder arrangement, defines a pressure chamber; and a force input member that can be moved according to the actuation of the brake pedal and is coupled, or can be coupled, to the pressure piston unit so as to move therewith, the brake master cylinder also comprising: a position transmitter element that can be moved according to the actuation of the force input member; a detection unit designed to detect a movement of the position transmitter element; and a coupling arrangement designed to couple the position transmitter element to at least one element of the piston arrangement in a substantially rigid manner, along the movement axis, the coupling arrangement also being designed to allow a rotation of the at least one element of the piston arrangement in relation to the position transmitter element about the movement axis. Document <CIT> discloses a piston cylinder arrangement. This invention concerns a piston cylinder arrangement, comprising a housing-like cylinder in which a piston is axially movable, which can be operated by a piston rod moving through an external mechanical unit, whereby a spherical head of the piston rod is mechanically fixed on one end side of the piston. In the case of a piston cylinder arrangement, which can be mounted blindly, the spherical head of the piston rod is partially surrounded by a convex spherical shape, which, together with the spherical head, intervenes in a concave axial discharge in the front side of the piston. Document <CIT> discloses a transmitter hydraulic cylinder for hydraulic control device. The present invention relates to a transmitter hydraulic cylinder for a hydraulic control device, including: a piston configured to be slidable along an axis; and a control rod having one side installed in a joint connection manner in a driving element, such as a pedal, and the other side connected to the piston by a joint connection portion. One of the joint connection portions allows the transmitter hydraulic cylinder to operate, and the other allows the control rod to rotate according to two degrees of freedom facilitating the fastening of the control rod with respect to the driving element. All of the joint connection portions limit the relative rotation between the control rod and the piston about an axis.

According to an aspect of the invention, a pressure supply unit is provided for a brake system. The pressure supply unit comprises a booster body that defines a cylinder that extends along an axis. A piston is axially slideable within the cylinder. The piston defines a bore along the axis. A spindle extends along the axis and is received by the bore of the piston. The spindle is rotationally fixed and axially moveable for providing the axial movement of the piston. A motor is positioned about the spindle and is configured to axially translate the spindle for providing the axial movement of the piston. A ball and socket joint couples the spindle to the piston and is located within the bore defined by the piston. The ball and socket joint comprises a ball at a front end of the spindle and a socket in the bore of the piston and which receives the ball to accommodate pivoting movement of the spindle relative to the piston. The ball has a generally constant diameter but defines at least one scored segment for providing lateral movement of the ball relative to the socket while allowing the ball to inhibit axial movement of the ball outside of the socket, wherein the ball defines a plurality of scored segments in spaced relationship with one another.

The ball and socket joint provides a simple manner of accommodate pivoting movement of the spindle relative to the piston, thus providing reduced wear of the spindle and piston.

According to another aspect of the invention, a pressure supply unit is provided for a brake system. The pressure supply unit comprises a booster body that defines a cylinder extending along an axis. A piston is axially slideable within the cylinder. The piston defines a bore along the axis. A spindle extends along the axis and is received by the bore of the piston. The spindle is rotationally fixed and axially moveable for providing the axial movement of the piston. A motor is positioned about the spindle and configured to axially translate the spindle for providing the axial movement of the piston. The motor comprises an annular stator and an annular rotor rotatable within the stator in response to a current passing into the stator. At least one gear is rotatable in response to rotation of the rotor and is configured to rotate a magnet. A sensor is provided for detecting rotation of the magnet to determine a rotor angle of the rotor.

The arrangement of the at least one gear and sensor provide a simple, compact and reliable method for detecting a rotor angle of the rotor.

According to another aspect of the invention, a pressure supply unit is provided for a brake system. The pressure supply unit comprises a booster body that defines a cylinder extending along an axis. A motor cover is coupled to the booster body and defines a compartment. A piston is axially slideable within the cylinder. The piston defines a bore along the axis. A spindle extends along the axis and is received by the bore of the piston. The spindle is rotationally fixed and axially moveable for providing the axial movement of the piston. A motor is positioned about the spindle in the compartment of the motor cover and configured to axially translate the spindle for providing the axial movement of the piston. The motor comprises an annular stator and an annular rotor rotatable within the stator in response to a current passing into the stator. An anti-rotation sleeve is disposed about the spindle and fixed to the motor cover. The anti-rotation sleeve is configured to inhibit rotation of the spindle while permitting axial movement of the spindle. The motor cover presents an axially extending annular protrusion defining a pocket inside the compartment inside the motor cover. The anti-rotation sleeve is fixed to the motor cover inside the pocket.

The arrangement of the anti-rotation sleeve is fixed to the pocket of the motor cover provides a compact and simple arrangement for preventing rotation of the spindle. This arrangement further allows the motor cover to be constructed without a separate end cap on the motor housing.

Referring to the figures, wherein like numerals indicate corresponding parts throughout the several views, a pressure supply unit <NUM> is generally shown for a brake system of an automobile. More particularly, as best shown in <FIG> and <FIG>, the subject pressure supply unit <NUM> is used in conjunction with an electro-hydraulic brake-by-wire system where a motor <NUM>, spindle <NUM>, and piston <NUM> provide brake pressure in place of a traditional booster, master cylinder and brake pedal arrangement. The pressure supply unit <NUM> is commanded by an Electronic Control Unit (ECU) <NUM> (schematically shown) with derived signals from a traveler and/or forced sensor in a pedal feel emulator and/or from an auto pilot which can initiate braking independent of a driver. The pedal fee emulator provides brake pedal feel and feedback to a driver while a manual backup system is isolated from wheel brake circuits.

In more detail, the pressure supply unit <NUM> includes a booster body <NUM> that defines a cylinder <NUM> that extends along an axis. A motor cover <NUM> axially engages the booster body <NUM> and defines a compartment <NUM>. The piston <NUM> is axially received by the cylinder <NUM> and axially slideable within the cylinder <NUM> and the compartment <NUM> of the motor cover <NUM> for creating a brake pressure in the cylinder <NUM> in response to the sliding movement of the piston <NUM>. The piston <NUM> defines a bore <NUM> along the axis A, with the bore <NUM> terminating axially at an end <NUM>. The booster body <NUM> further includes a pair of recesses <NUM> that extend radially outwardly into the booster body <NUM> from the cylinder <NUM>, and extend annularly about the axis A. Each of the recesses <NUM> receives one of a pair of seals <NUM> that are configured to prevent the passage of fluid between the booster body <NUM> and piston <NUM> in the cylinder <NUM>.

The spindle <NUM> extends axially between a front end <NUM> received in the bore <NUM> of the piston <NUM>, and a rear end <NUM> located axially outside of the bore <NUM> in the compartment <NUM> of the motor cover <NUM>. The spindle <NUM> presents a threaded outer surface <NUM>. A ball and socket joint <NUM> (discussed in further detail below) connects the spindle <NUM> to the piston <NUM> in the bore <NUM>.

The motor <NUM> is positioned about the spindle <NUM> in the compartment <NUM> of the motor cover <NUM>. The motor <NUM> is configured to axially translate the spindle <NUM> for providing the axial movement of the piston <NUM>. More particularly, the motor <NUM> includes an annular stator <NUM> and an annular rotor <NUM>, each positioned about the axis A. The annular rotor <NUM> has a magnetic outer surface and is rotatable within the stator <NUM> about the axis A in response to a current being applied to the stator <NUM>. One or more bearings <NUM> are positioned radially between the rotor <NUM> and the motor cover <NUM> for accommodating rotation of the rotor <NUM> relative to the booster body <NUM>. As schematically shown, the motor <NUM> is connected to the ECU <NUM> to provide desired actuation of the motor <NUM>.

The rotor <NUM> presents an inner wall <NUM> that defines a channel <NUM> along the axis A. The channel <NUM> partially receives the piston <NUM> and receives the spindle <NUM>. As best shown in <FIG>, the inner wall <NUM> of the rotor <NUM> further defines a plurality of grooves <NUM> that extend axially and are arranged in circumferentially spaced relationship with one another.

A nut <NUM> is fixed to the inner wall <NUM> of the rotor <NUM> and is configured to convert rotational movement of the rotor <NUM> into axial translation of the spindle <NUM>. More particularly, the nut <NUM> presents a threaded inner surface <NUM> that is threadedly connected to the threaded outer surface <NUM> of the spindle <NUM> for providing axial movement of the spindle <NUM> in response to rotation of the rotor <NUM> and nut <NUM>. The threaded connection between the nut <NUM> and spindle <NUM> may include a plurality of ball bearings <NUM> for facilitating rotation between the components. A conventional threaded connection comprised exclusively inner threads and outer threads may also be employed. The nut <NUM> extends axially between a first nut end <NUM> and a second nut end <NUM>. A retainer plate <NUM> is fixed axially against the first nut end <NUM>. A plurality of fasteners <NUM>, such as bolts or the like, axially and rotationally fix the retainer plate <NUM> to the first nut end <NUM>. The retainer plate <NUM> presents a plurality of guides <NUM> that extend radially outwardly from an outer circumference of the retainer plate <NUM>. Each of the guides <NUM> are received by one of the grooves <NUM> of the rotor <NUM> to permit axially movement of the retainer plate <NUM> and nut <NUM> relative to the rotor <NUM> during assembly while inhibiting rotational movement of the retainer plate <NUM> and nut <NUM> relative to the rotor <NUM>.

As best shown in <FIG>, an anti-rotation sleeve <NUM> is disposed about the spindle <NUM> and fixed to the booster body <NUM>. The anti-rotation sleeve <NUM> is configured to inhibit rotation of the spindle <NUM> while permitting axial movement of the spindle <NUM>. The anti-rotation sleeve <NUM> extends axially between a proximal end <NUM> axially engaging the motor cover <NUM> and a distal end <NUM> axially engaging the second nut end <NUM> of the nut <NUM>. The anti-rotation sleeve <NUM> defines a radially inside wall <NUM>. The inside wall <NUM> of the anti-rotation sleeve <NUM> defines a plurality of grooves <NUM> that extend axially and spaced circumferentially from one another. A retainer <NUM> is located about the axis A inside the anti-rotation sleeve <NUM> and keyed to the rear end <NUM> of the spindle <NUM>. A generally rectangular-shaped protrusion <NUM> extends axially at the rear end <NUM> of the spindle <NUM>. The retainer <NUM> defines an opening <NUM> that has substantially the same shape as the protrusion <NUM>, and receives the protrusion <NUM> to key the retainer <NUM> to the spindle <NUM>. The retainer <NUM> presents a plurality of fingers <NUM> that extend radially outwardly from an outer circumference of the retainer <NUM>, with each finger <NUM> each received by one of the grooves <NUM> of the inside wall <NUM> of the anti-rotation sleeve <NUM> to inhibit rotational movement of the retainer <NUM> and spindle <NUM> while permitting axial movement of the retainer <NUM> and spindle <NUM> relative to the anti-rotation sleeve <NUM>. A bolt <NUM> or the like is threadedly received by the protrusion <NUM> along the axis A and axially secures the retainer <NUM> to the spindle <NUM>. As best shown in <FIG> and <FIG>, one or more wave washers <NUM> or other spring elements are positioned axially between the retainer <NUM> and the motor cover <NUM> for accommodating axial movement of the spindle <NUM> toward the motor cover <NUM>.

As best shown in <FIG> and <FIG>, the motor cover <NUM> presents an axially extending annular protrusion <NUM> that defines a pocket <NUM> inside the compartment <NUM> of the motor cover <NUM>. The anti-rotation sleeve <NUM> is rotationally fixed to the motor cover <NUM> inside the pocket <NUM>. More particularly, the anti-rotation sleeve <NUM> presents a flange <NUM> that extends radially outwardly at its proximal end <NUM>. The flange <NUM> presents at least one first planar surface <NUM> along a radially outer surface of the flange <NUM>. According to the example embodiment, a pair of first planar surfaces <NUM> are located on circumferentially opposite sides of the anti-rotation sleeve <NUM>, however any number of first planar surfaces <NUM> could be employed. As best shown in <FIG>, an outer surface of the protrusion <NUM> is compressed / punched radially inwardly in circumferential alignment with each of the first planar surfaces <NUM> of the anti-rotation sleeve <NUM> to define one or more staked portions <NUM> for axially and rotationally fixing the anti-rotation sleeve <NUM> to the motor cover <NUM>. The staked portions <NUM> may include one or more second planar surfaces <NUM> that overly the planar surfaces <NUM> to further aid in preventing rotation of the anti-rotation sleeve <NUM> relative to the motor cover <NUM>.

As best shown in <FIG> and <FIG>. the ball and socket joint <NUM> includes a ball <NUM> at the front end <NUM> of the spindle <NUM>, and a socket <NUM> adjacent to the end <NUM> of the bore <NUM> of the piston <NUM>. The socket <NUM> receives the ball <NUM> to accommodate pivoting movement of the spindle <NUM> relative to the piston <NUM>. The ball and socket joint <NUM> includes an insert <NUM> received in the bore <NUM> of the piston <NUM> and fixed to the piston <NUM> adjacent to the end <NUM> of the bore <NUM>. The insert <NUM> defines the socket <NUM>.

As best shown in <FIG>, the ball <NUM> defines at least one scored segment <NUM> for providing lateral movement of the ball <NUM> relative to the socket <NUM> while the ball <NUM> still inhibits pulling the spindle <NUM> axially free from the socket <NUM>. According to the example embodiment, the ball <NUM> defines a plurality of the scored segments <NUM> in spaced relationship with one another. Four scored segments <NUM> may be equally circumferentially spaced around the ball <NUM> to provide lateral movement in vertical and horizontal directions. Because of the scored segments <NUM>, the ball and socket joint <NUM> helps to compensate for any angular misalignment between the piston <NUM> and spindle <NUM> to minimize premature wear out of the ball screw by minimizing side loads. The arrangement of the ball and socket joint <NUM> and piston <NUM> also eliminates the need for a separate sleeve with an anti-rotation feature, thus significantly reducing cost and assembly complexity. Furthermore, with careful sizing and/or shaping of the ball <NUM>, small clearances can be maintained after insertion. This allows additional degrees of lateral freedom to assure elimination of binding of the spindle <NUM> at the ball <NUM>. Since the ball <NUM> is primarily unilaterally loaded by system brake pressure, small amount of travel at the start position of the ball <NUM> can be easily compensated for.

It should be appreciated that due to the locations and arrangements of the anti-rotation sleeve <NUM> and ball and socket joint <NUM>, side loads between piston <NUM> and spindle <NUM> are virtually non-existent.

As set forth in <FIG>, due to the aforementioned arrangement of the piston <NUM> and ball and socket joint <NUM>, two different assembly operations may be employed for installing the piston <NUM> and ball and socket joint <NUM>. More particularly, according to a first operation illustrated in <FIG>, the piston <NUM> may first be installed in the booster body <NUM>, and the ball and socket joint <NUM> may be snapped together after installation of the piston <NUM>. Alternatively, as illustrated in <FIG>, the ball and socket joint <NUM> and piston <NUM> may be assembled in advance, and the piston <NUM> may subsequently be inserted into the cylinder <NUM> of the booster body <NUM>. <FIG> shows an exploded assembly view of both of these arrangements.

As best shown in <FIG>, a capacitive rotor angle sensor assembly <NUM> may be positioned about the rotor <NUM> and located axially between the stator <NUM> and the booster body <NUM>. The capacitive rotor angle sensor assembly <NUM> includes a motor support plate <NUM> positioned axially against the booster body <NUM> in the compartment <NUM> of the motor cover <NUM> and positioned about the piston <NUM>. At least one sensor bearing <NUM> is located between the motor support plate <NUM> and the rotor <NUM> in order to allow relative rotation between the motor support plate <NUM> and rotor <NUM>. The capacitive rotor angle sensor assembly <NUM> includes a plurality of electrical connectors <NUM> electrically connecting the capacitive rotor angle sensor assembly <NUM> to the ECU <NUM> for transmitting rotor angle data <NUM>.

According to an alternate embodiment of a rotor angle sensor assembly <NUM> best presented in <FIG>, a first gear <NUM> is rotatable with the rotor <NUM>. A second gear <NUM> is meshed with the first gear <NUM>. An axially extending rod <NUM> is rotatable with the second gear <NUM> and is connected to a magnet <NUM>. A magnet sensor <NUM> is configured to detect the magnet <NUM> for determining rotor angle data and transmitting the rotor angle data to the ECU <NUM>. <FIG> illustrates that according to this arrangement, the first gear <NUM> may have a smaller diameter than the sensor bearing <NUM>. Accordingly, the sensor bearing <NUM> can be designed with the motor cover <NUM> as a "half-in / half-out" design and be used to pilot the motor <NUM> into the booster body <NUM>. <FIG> illustrates a connection of a first gear <NUM> to a rotor <NUM> according to this embodiment.

As demonstrated by <FIG>, a design advantage of the subject pressure supply unit <NUM> is that the motor <NUM> and piston <NUM> require no external feature in the cylinder <NUM> to restrain rotation of the piston <NUM>. Accordingly, even though the overall length of the motor <NUM> may be relatively long, savings in length of the cylinder <NUM> can compensate for this. To this point, three different embodiments for packaging the system are shown in <FIG>. More particularly, <FIG> show a first design in which a single master cylinder HCU block (anti-lock brake system controller) <NUM> has an extruded, transverse boss <NUM> which defines the cylinder <NUM>. The boss is integrally formed with the booster body <NUM>. Furthermore, <FIG> show a simplified sleeve <NUM> which defines the cylinder <NUM> (no rotational constraints necessary) that is coupled with a booster body <NUM> in which an extruded rectangular master cylinder / HCU block <NUM> is designed with a transverse motor <NUM>. Furthermore, <FIG> show a design in which a machined or cast and machined master cylinder block <NUM> is incorporated with a parallel motor <NUM> layout.

It should be appreciated that the simple assembly of the overall design of the subject pressure supply unit <NUM> provides cost savings advantages, elimination of critical build tolerance, and assembly processes geared to high volume production.

Claim 1:
A pressure supply unit (<NUM>) for a brake system, comprising:
a booster body (<NUM>) defining a cylinder (<NUM>) extending along an axis (A);
a piston (<NUM>) axially slideable within the cylinder (<NUM>);
the piston (<NUM>) defining a bore (<NUM>) along the axis (A);
a spindle (<NUM>) extending along the axis (A) and received by the bore (<NUM>) of the piston (<NUM>) and rotationally fixed and axially moveable for providing the axial movement of the piston (<NUM>); and
a motor positioned about the spindle (<NUM>) and configured to axially translate the spindle (<NUM>) for providing the axial movement of the piston (<NUM>);
wherein the pressure supply unit (<NUM>) further comprises a ball and socket joint (<NUM>) coupling the spindle (<NUM>) to the piston (<NUM>) and located within the bore (<NUM>) defined by the piston (<NUM>), the ball and socket joint (<NUM>) comprising a ball (<NUM>) at a front end of the spindle (<NUM>) and a socket (<NUM>) in the bore (<NUM>) of the piston (<NUM>) and receiving the ball (<NUM>) to accommodate pivoting movement of the spindle (<NUM>) relative to the piston (<NUM>),
characterized in that the ball (<NUM>) defines at least one scored segment (<NUM>) for providing lateral movement of the ball (<NUM>) relative to the socket (<NUM>) while allowing the ball (<NUM>) to inhibit axial movement of the ball (<NUM>) outside of the socket (<NUM>), wherein the ball (<NUM>) defines a plurality of scored segments (<NUM>) in spaced relationship with one another.