EP4719791A1 - Hydraulic control apparatus for first and second piston actuators of an active suspension system of a vehicle - Google Patents

Abstract

Aspects and embodiments of the invention relate to a hydraulic control apparatus (17), an actuator system (16), and a vehicle (1). The hydraulic control apparatus (17) is for first and second piston actuators (502L, 502R) of an active suspension system (104) of a vehicle (1). The hydraulic control apparatus (17) comprises: a first hydraulic gallery (G1L) hydraulically couplable to a first fluid chamber (C1) of the first piston actuator (502L); a second hydraulic gallery (G2L) hydraulically couplable to a second fluid chamber (C2) of the first piston actuator (502L); a third hydraulic gallery (G1R) hydraulically couplable to a first fluid chamber (C1) of the second piston actuator (502R); a fourth hydraulic gallery (G2R) hydraulically couplable to a second fluid chamber (C2) of the second piston actuator (502R); and a fifth hydraulic gallery (G3) to hydraulically interconnect the first, second, third, and fourth hydraulic galleries (G1L, G2L, G1R, G2R).

Description

HYDRAULIC CONTROL APPARATUS FOR FIRST AND SECOND PISTON ACTUATORS OF AN ACTIVE SUSPENSION SYSTEM OF A VEHICLE

TECHNICAL FIELD

The present disclosure relates to a hydraulic control apparatus for a piston actuator of an active suspension system of a vehicle. Aspects of the invention relate to a hydraulic control apparatus, an actuator system, and a vehicle.

BACKGROUND

An active suspension system of a vehicle can be hydraulically-actuated. The active suspension system can comprise a hydraulically-controlled piston actuator. The piston actuator is controlled by a hydraulic control apparatus comprising hydraulic circuits. One of the hydraulic circuits is hydraulically coupled to a first fluid chamber of the piston actuator, while another of the hydraulic circuits is hydraulically coupled to a second fluid chamber of the piston actuator. The hydraulic pressure in each hydraulic circuit is actively controlled by a pump and/or valve arrangement, to control the force-displacement characteristics of the piston actuator, or even to actively extend or retract the piston actuator.

It is an aim of the present invention to address one or more of the disadvantages associated with the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a hydraulic control apparatus, an actuator system, and a vehicle as claimed in the appended claims.

According to an aspect of the present invention there is provided a hydraulic control apparatus for first and second piston actuators of an active suspension system of a vehicle, such as left and right piston actuators of the vehicle. The hydraulic control apparatus comprises: a first hydraulic gallery hydraulically couplable to a first fluid chamber of the first piston actuator; a second hydraulic gallery hydraulically couplable to a second fluid chamber of the first piston actuator; a third hydraulic gallery hydraulically couplable to a first fluid chamber of the second piston actuator; a fourth hydraulic gallery hydraulically couplable to a second fluid chamber of the second piston actuator; and a fifth hydraulic gallery to hydraulically interconnect the first, second, third, and fourth hydraulic galleries.

According to another aspect of the present invention there is provided a hydraulic control apparatus for first and second piston actuators of an active suspension system of a vehicle, such as left and right piston actuators of the vehicle. The hydraulic control apparatus comprises: a first hydraulic gallery hydraulically couplable to a first fluid chamber of the first piston actuator; a second hydraulic gallery hydraulically couplable to a second fluid chamber of the first piston actuator; a third hydraulic gallery hydraulically couplable to a first fluid chamber of the second piston actuator; a fourth hydraulic gallery hydraulically couplable to a second fluid chamber of the second piston actuator; and a fifth hydraulic gallery to hydraulically interconnect the first, second, third, and fourth hydraulic galleries concurrently via respective valves.

In other words, the fifth hydraulic gallery is a shared hydraulic gallery, shared by the first and second piston actuators. There are at least three advantages to having the shared hydraulic gallery. Firstly, it enables sharing of certain other components as will be described. This reduces part count. Secondly, the shared hydraulic gallery enables equalisation of hydraulic fluid temperatures for both piston actuators. Unequal temperatures may be encountered in situations where more work is done by one piston actuator than the other piston actuator, such as driving over road surfaces of asymmetric roughness. Thirdly, the shared hydraulic gallery enables a greater rate of thermal dissipation due to the larger heat exchange area.

The respective valves may be configured to lower hydraulic fluid pressure such that the fifth hydraulic gallery is a low-pressure hydraulic gallery relative to the first, second, third, and fourth hydraulic galleries. Therefore, the fifth hydraulic gallery can be regarded as a shared low-pressure hydraulic gallery. The first, second, third, and fourth hydraulic galleries can be regarded as high-pressure hydraulic galleries.

The hydraulic control apparatus may comprise a first pump operable to control hydraulic pressure across the first piston actuator, and a second pump operable to control hydraulic pressure across the second piston actuator. The first pump may be operable to pump hydraulic fluid between the first and second hydraulic galleries. The first pump may be bidirectional. The second pump may be operable to pump hydraulic fluid between the third and fourth hydraulic galleries. The second pump may be bidirectional.

An advantage is that the pumps can provide a Fully Active Suspension (FAS) function, because each pump can control the force-displacement characteristics of each piston actuator independently of each other. The use of bidirectional pumps minimises part count.

The first and second pumps may be controllable to apply an extending force to the first piston actuator while concurrently applying a retracting force to the second piston actuator. The first and second pumps may be controllable to apply a retracting force to the first piston actuator while concurrently applying an extending force to the second piston actuator.

An advantage is providing an active roll control function, in examples where the first and second piston actuators are left and right piston actuators. During this time, the fifth hydraulic gallery hydraulically interconnects the first, second, third, and fourth hydraulic galleries via the respective valves, as described earlier. The first and second pumps may be controllable to apply extending forces to the first and second piston actuators concurrently. The first and second pumps may be controllable to apply retracting forces to the first and second piston actuators concurrently.

An advantage is providing an active pitch control function, in examples where the first and second piston actuators are left and right piston actuators. During this time, the fifth hydraulic gallery hydraulically interconnects the first, second, third, and fourth hydraulic galleries via the respective valves, as described earlier.

The ability to provide both active roll control and active pitch control, sometimes simultaneously, means that the hydraulic control apparatus can be described as a ‘FAS’ apparatus. Although the FAS apparatus involves duplication of some components for each piston actuator, such as separate pumps, valves and galleries, some components can be shared as will be described below.

The hydraulic control apparatus may comprise at least one hydraulic component connected to the fifth hydraulic gallery, and hydraulically couplable to the first, second, third and fourth hydraulic galleries via the respective valves. This component can be regarded as a shared hydraulic component.

The at least one hydraulic component may comprise a hydraulic accumulator. The hydraulic accumulator may be a low-pressure hydraulic accumulator, for example where the fifth hydraulic gallery is a low-pressure hydraulic gallery relative to the first, second, third, and fourth hydraulic galleries. The hydraulic accumulator may be connected to low-pressure sides of the respective valves.

The hydraulic accumulator may be configured to compensate for system volume changes of the hydraulic control apparatus. For example, the hydraulic accumulator may be sized to compensate for thermal expansion of hydraulic fluid. Additionally, or alternatively, the hydraulic accumulator may be sized to compensate for system volume changes caused by portions of piston rods entering or leaving fluid chambers of the piston actuators. As a piston actuator retracts, a portion of a corresponding piston rod will enter a fluid chamber of the piston actuator, forcing some hydraulic fluid into the hydraulic accumulator.

An advantage of having a shared hydraulic accumulator is a reduction in vehicle weight due to a reduction in the number of hydraulic accumulators, where each low-pressure hydraulic accumulator has a mass in the order of magnitude of kilograms. In an implementation where the vehicle comprises four piston actuators, one for each corner of the vehicle, two shared low-pressure hydraulic accumulators can be used instead of four independent low-pressure hydraulic accumulators.

The hydraulic accumulator may have a volume sized to accommodate at least double a peak piston rod-based hydraulic volume reduction of one of the piston actuators. The peak reduction may be encountered at maximum actuator retraction. Therefore, where the hydraulic accumulator is shared, it can accommodate the fluid displaced by simultaneous retraction of both piston actuators. The volume may be even greater than this value, to further accommodate thermal expansion of hydraulic fluid. The hydraulic control apparatus may comprise the shared hydraulic accumulator as well as independent hydraulic accumulators. The hydraulic control apparatus may comprise a first hydraulic accumulator connected to the first hydraulic gallery, a second hydraulic accumulator connected to the second hydraulic gallery, a third hydraulic accumulator connected to the third hydraulic gallery, and a fourth hydraulic accumulator connected to the fourth hydraulic gallery, wherein the shared hydraulic accumulator is a fifth hydraulic accumulator.

The first, second, third, and fourth hydraulic accumulators may be high-pressure hydraulic accumulators, for example where the first, second, third, and fourth hydraulic galleries are high-pressure hydraulic galleries relative to the fifth hydraulic gallery. The first, second, third, and fourth hydraulic accumulators may be connected to high-pressure sides of the respective valves. The first, second, third, and fourth hydraulic accumulators may be configured to operate at a relatively high pressure compared to the fifth, shared, low- pressure hydraulic accumulator.

Where the fifth hydraulic accumulator is shared, a volume of the fifth hydraulic accumulator may be greater than a volume of at least one of the first, second, third, or fourth hydraulic accumulators.

The above examples refer to the at least one hydraulic component being a hydraulic accumulator. Additionally, or alternatively, the at least one hydraulic component may comprise a bleed port to enable bleeding of air from the first, second, third, fourth, and fifth hydraulic galleries concurrently.

An advantage is that the hydraulic control apparatus is easier to service, in production or during vehicle maintenance, as fewer overall bleed ports are needed. In an implementation where the vehicle comprises four piston actuators, one for each corner of the vehicle, two bleed ports can be used instead of four independent bleed ports.

The respective valves may comprise a plurality of first valves, each connected to a different one of the first, second, third, and fourth hydraulic galleries, and arranged to permit one-way hydraulic fluid flow into the fifth hydraulic gallery. The plurality of first valves may be configured to lower the hydraulic fluid pressure as described earlier. The plurality of first valves may each comprise pressure control valves operable to apply a force counteracting fluid flow in proportion to applied electrical current. The plurality of first valves may each have a high-pressure side (inlet side) connected to a respective one of the first, second, third, and fourth hydraulic galleries, and a low-pressure side (outlet side) connected to the fifth hydraulic gallery. The plurality of first valves may define a first interface between the fifth hydraulic gallery and the first, second, third, and fourth hydraulic galleries.

As an alternative to the first valves, the hydraulic control apparatus may comprise a plurality of fixed inlets collectively arranged to permit one-way hydraulic fluid flow into the fifth hydraulic gallery from the first, second, third, and fourth hydraulic galleries. The respective valves may additionally comprise a plurality of second valves each connected to a different one of the first, second, third, and fourth hydraulic galleries and arranged to permit one-way hydraulic fluid flow out of the fifth hydraulic gallery. The plurality of second valves may comprise check valves. The second valves may be in parallel hydraulic fluid branches to the first valves. The plurality of second valves may define a second interface between the fifth hydraulic gallery and the first, second, third, and fourth hydraulic galleries.

The hydraulic control apparatus may comprise a plurality of damper valves each connected to a different one of the first, second, third, and fourth hydraulic galleries and arranged to control hydraulic fluid flow towards the respective valves. Each damper valve may comprise a controllable valve to variably control hydraulic fluid flow away from the respective piston actuator and towards the plurality of first valves. The hydraulic control apparatus may comprise a check valve in parallel to each damper valve, arranged to permit one-way hydraulic fluid flow towards the respective piston actuator.

In some examples, the fifth hydraulic gallery may be shared by additional piston actuators. In examples where the first and second piston actuators are at a first end or side of the vehicle, the fifth hydraulic gallery may be further shared by third and fourth piston actuators at a second opposite end or side of the vehicle. Therefore, the hydraulic control apparatus may comprise: a sixth hydraulic gallery hydraulically couplable to a first fluid chamber of a third piston actuator; a seventh hydraulic gallery hydraulically couplable to a second fluid chamber of the third piston actuator; an eighth hydraulic gallery hydraulically couplable to a first fluid chamber of a fourth piston actuator; and a ninth hydraulic gallery hydraulically couplable to a second fluid chamber of the fourth piston actuator; wherein the fifth hydraulic gallery is arranged to hydraulically interconnect the first, second, third, fourth, sixth, seventh, eighth, and ninth hydraulic galleries concurrently via respective valves.

The sixth, seventh, eighth, and ninth hydraulic galleries may have the same features as the first, second, third, and fourth hydraulic galleries, respectively. The respective valves for the sixth, seventh, eighth, and ninth hydraulic galleries may have the same features as the respective valves for the first, second, third, and fourth hydraulic galleries.

According to another aspect of the invention, there is provided an actuator system comprising a first piston actuator, a second piston actuator, and a hydraulic control apparatus comprising: a first hydraulic gallery coupled to a first fluid chamber of the first piston actuator; a second hydraulic gallery coupled to a second fluid chamber of the first piston actuator; a third hydraulic gallery coupled to a first fluid chamber of the second piston actuator; a fourth hydraulic gallery coupled to a second fluid chamber of the second piston actuator; and a fifth hydraulic gallery to hydraulically interconnect the first, second, third, and fourth hydraulic galleries concurrently via respective valves. According to a further aspect of the invention, there is provided a vehicle comprising the actuator system. The first piston actuator may be a left piston actuator for controlling displacement of a left wheel of the vehicle. The second piston actuator may be a right piston actuator for controlling displacement of a right wheel of the vehicle. The first and second piston actuators may be at a first end of the vehicle, such that the left and right wheels may be front wheels or rear wheels. In some examples, the vehicle comprises a second one of the actuator system, for a second end of the vehicle. The two actuator systems may be hydraulically independent. Alternatively, as described earlier, the fifth hydraulic gallery of each actuator system may be the same, shared gallery.

According to a further aspect of the present invention there is provided a hydraulic control apparatus for first and second piston actuators of an active suspension system of a vehicle, the hydraulic control apparatus comprising no more than one shared hydraulic accumulator and/or no more than one shared bleed port, shared by the first and second piston actuators.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination that falls within the scope of the appended claims. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination that falls within the scope of the appended claims, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 illustrates an example of a vehicle;

FIG. 2 illustrates an example of an active suspension system of a vehicle;

FIG. 3A illustrates a first example of an actuator system of an active suspension system;

FIG. 3B illustrates a detail view of respective valves and pumps of the actuator system of FIG. 3A;

FIG. 3C illustrates a detail view of damper valves and check valves of the actuator system of FIG. 3A; and

FIG. 4 illustrates a second example of an actuator system of an active suspension system.

DETAILED DESCRIPTION

A vehicle 1 in accordance with an embodiment of the present invention is described herein with reference to the accompanying FIG. 1. In some, but not necessarily all examples, the vehicle 1 is a passenger vehicle, also referred to as a passenger car or as an automobile. In other examples, embodiments of the invention can be implemented for other applications, such as commercial vehicles. FIG. 1 is a front perspective view and illustrates a longitudinal x-axis between the front and rear of the vehicle 1 representing a centreline, an orthogonal lateral y-axis between left and right lateral sides of the vehicle 1 , and a vertical z-axis. A forward/fore direction typically faced by a driver’s seat is in the negative x-direction; rearward/aft is +x. A rightward direction as seen from the driver’s seat is in the positive y-direction; leftward is -y. These are a first lateral direction and a second lateral direction.

In summary, FIGS. 2 and 3C illustrate an example of a hydraulic control apparatus 17 for first and second piston actuators 502L, 502R of an active suspension system 104 of a vehicle 1 , such as left and right piston actuators of the vehicle. The hydraulic control apparatus 17 comprises: a first hydraulic gallery G1 L hydraulically couplable to a first fluid chamber C1 L of the first piston actuator 502L; a second hydraulic gallery G2L hydraulically couplable to a second fluid chamber C2L of the first piston actuator 502L; a third hydraulic gallery G1 R hydraulically couplable to a first fluid chamber C1 R of the second piston actuator 502R; a fourth hydraulic gallery G2R hydraulically couplable to a second fluid chamber C2R of the second piston actuator 502R; and a fifth hydraulic gallery G3 to hydraulically interconnect the first, second, third, and fourth hydraulic galleries G1 L, G2L, G1 R, G2R concurrently via respective valves X1 L, X1 R, X2L, X2R, V2L, V2R, V4L, V4R.

The term ‘hydraulically couplable’ means ‘coupled’ when the hydraulic control apparatus 17 is connected to the first and second piston actuators 502L, 502R. If the system is filled with hydraulic fluid, then ‘coupled’ means ‘hydraulically coupled’.

First, an active suspension system is described with reference to FIG. 2. FIG. 2 illustrates an example active suspension system 104 of the vehicle 1 , connecting a vehicle body 102 to vehicle wheels 12.

The active suspension system 104 comprises front left active suspension 106 for a front left wheel FL, front right active suspension 116 for a front right wheel FR, rear left active suspension 108 for a rear left wheel RL, and rear right active suspension 1 18 for a rear right wheel RR. The active suspension for each wheel (e.g. quarter/corner) of the vehicle 1 may be individually controllable by a control system 200.

FIG. 2 also shows a torque source 103 such as an internal combustion engine or electric machine, for driving at least some of the vehicle wheels 12.

The active suspension 106, 116, 108, 118 for each corner of the vehicle 1 comprises an actuator 502.

As will be described, the actuator 502 is a hydraulic actuator such as a hydraulic fluid-filled chamber containing a piston 24L/24R (FIGS. 3A-3C). The actuator 502 is therefore a piston actuator of a hydraulic system. The fluid may comprise hydraulic oil. One end of the actuator 502 is coupled to a vehicle wheel 12 and the other end is coupled to the vehicle body 102. A spring 504 (e.g. coil or pneumatic) may be in equilibrium and acting in parallel with the actuator 502.

When the active suspension system 104 is undisturbed, the piston 24L/24R of the hydraulic actuator 502 sits at a neutral position in the chamber.

The piston 24L/24R can move in either direction inside the chamber, e.g. due to a road disturbance or body accelerations compressing or extending the actuator 502. As will be described, the piston 24L/24R can displace fluid out of the chamber into hydraulic circuits (described further below). The fluid imparts a restoring force against movement of the piston 24L/24R. Energy can be added to and/or extracted from the actuator 502 by pumping fluid and/or controlling valves to regulate fluid pressure to either side of the piston 24L/24R.

The damping of the actuator 502 can be modified by controlling a damper valve at a constriction, which regulates the force realized by the fluid transferred in and out of the actuator 502 by movement of the piston 24L/24R. Bump and rebound damping rates could be controlled independently in some examples.

Further, energy can be added to or removed from the actuator 502 in order to control various suspension characteristics including, but not limited to the damping curve (force-velocity relationship) of the actuator 502.

In FIG. 2 but not necessarily all examples, the spring 504 comprises an active spring such as a pneumatic spring, enabling control of ride height. The control system 200 may be configured to pump gas (e.g. air) in or out of the pneumatic spring 504 to control ride height.

Energy can be added to or removed from the pneumatic spring 504 in order to increase or decrease the volume of the pneumatic spring 504. Increasing the volume can lift the vehicle body 102 in the z-axis. In the example of FIG. 2 this enables the wheel-to-body distance to be changed independently at different ends and/or at different corners of the vehicle 1 .

Additionally or alternatively, the spring 504 comprises a passive spring (e.g. coil) or is omitted entirely.

Control of the active suspension system 104 relies on one or more sensors. Wheel travel may be sensed by a wheel-to-body displacement sensor 514 (suspension displacement-based sensor), for example. The wheel- to-body displacement sensor 514 is placed somewhere on the active suspension 106, 116, 108, 118 and can sense the position of the wheel 12 along an arc defined by suspension geometry. An example of a wheel-to- body displacement sensor 514 is a rotary potentiometer attached to a lever, wherein one end of the lever is coupled to the vehicle body 102, and the other end is coupled to a suspension link.

In some examples, the control system 200 more accurately determines the wheel travel and/or its associated derivatives by fusing information from the wheel-to-body displacement sensor 514 with information from hub accelerometers 516. In at least some examples the control system 200 is configured to control the active suspension system 104 by transmitting a force request to the active suspension 106, 116, 108, 118 or to a low-level controller thereof. The force request may be an arbitrated force request based on requests from various requestors and information from various sensors.

FIG. 2 illustrates additional optional features that may interact with the control system 200 to influence force request calculation. These include any one or more of:

- a hub-mounted accelerometer 516 for each wheel 12, coupled to the unsprung mass of the vehicle 1 .

- at least one vehicle body accelerometer 522 coupled to the vehicle body 102 (sprung mass). A particular example includes a 3DOF or 6DOF inertial measurement unit (IMU). A unit may comprise an accelerometer or a multi-axis set of accelerometers.

FIG. 3A illustrates an example actuator system 16 comprising left and right actuators 502L, 502R and a hydraulic control apparatus 17 for each actuator 502L, 502R. A topology of the hydraulic control apparatus 17 is shown. FIGS. 3B and 3C are detail views of parts of the hydraulic control apparatus 17.

The hydraulic control apparatus 17 comprises hydraulic circuits 28L, 28R, 29L, 29R. The hydraulic control apparatus 17 is hydraulically coupled or couplable to each actuator 502L, 502R by galleries 30L, 30R, 32L, 32R.

In an implementation, the active suspension system 104 comprises an independent hydraulic control apparatus 17 for each end of the vehicle 1 (each pair of actuators 502L, 502R), wherein the control system 200 is configured to determine independent control signals for controlling each of the actuators 502L, 502R substantially independently of each other to provide a Fully Active Suspension (FAS) function.

However, the hydraulic control apparatus 17 is not limited to that shown in FIGS. 3A-3C, which is for illustrative purposes only. Aspects of the invention are applicable to other suspension hydraulic circuit arrangements.

First, the left side of the actuator system 16 is described, for the left actuator 502L.

The actuator 502L includes a cylinder 22L containing piston 24L. The cylinder 22L is secured to a left wheel FL or RL (FIG. 2) and the piston 24L is secured to the vehicle body 102 (FIG. 2) via a rod 26L. The piston 24L defines a first fluid chamber C1 L and a second fluid chamber C2L. The piston 24L fluidly isolates the first fluid chamber C1 L from the second fluid chamber C2L. In the illustrated example, the first fluid chamber C1 L is an annulus chamber and the second fluid chamber C2L is a piston chamber. The rod 26L is immersed in the annulus chamber (C1 L). In another example, the direction of the actuator 502L is reversed so that the cylinder 22L is secured to the vehicle body 102 via rod 26L, and the piston 24L is secured to the wheel FL or RL.

The hydraulic control apparatus 17 includes a hydraulic pump PL having a first port PP1 and a second port PP2 (FIG. 3B). In the illustrated example, the pump PL is bidirectional so as to selectively generate flow out of the first port PP1 or second port PP2. In other examples, separate single-direction pumps are provided, or a single-direction pump is connected to a direction-controlling valve.

The hydraulic control apparatus 17 of FIG. 3A includes valves V1 L, V2L, V3L, and V4L. The valves V1 L, V2L, V3L, and V4L may be electromagnetically controlled. The valves V1 L, V2L, V3L, and V4L may be electromagnetically controlled by the control system 200 by varying electrical current.

Valve arrangement V1 L includes a damper valve V1A and a check valve V1 B. Similarly valve arrangement V3L includes a damper valve V3A and a check valve V3B.

Valves V2L and V4L are both variable pressure control valves (PCVs). The PCVs are operable to apply a force counteracting fluid flow in proportion to applied electrical current. PCV valves V2L and V4L may have a pilot stage and a main stage. Valves V2L and V4L have controllable orifice sizes to control pressure. The pilot stage may have a small, magnetically actuated poppet valve, to generate a pressure in a chamber that then acts on the larger main stage. The main stage may be closed by a spring and forced open by fluid flow from the actuator 502L, opposed by the spring and pressure force generated by the pilot stage (or a magnetic force if there is no pilot stage). The valves V2L and V4L may be normally closed and may allow one-way flow. In other examples, the valves V2L and V4L comprise a different type of hydraulic valve.

The illustrated hydraulic control apparatus 17 also includes first and second hydraulic accumulators A1 L, A2L, and first and second hydraulic galleries G1 L, G2L. The hydraulic control apparatus 17 also includes check valves X1 L, X2L.

Gallery G1 L connects port PP1 of pump PL, outlet X10 of check valve X1 L, inlet V2I of valve V2L, hydraulic accumulator A1 L, and port V1 C of valve arrangement V1 L. The valves V2L, X1 L are shown in parallel fluid passages. The respective valves V2L, X1 L are configured to control fluid flow through their respective fluid passages.

Gallery G2L connects port PP2 of pump PL with outlet X2O of checkvalve X2L, inlet V4I of valve V4L, hydraulic accumulator A2L, and port V3C of valve arrangement V3L. The valves V4L and X2L are shown in parallel fluid passages respectively. The respective valves V4L, X2L are configured to control fluid flow through their respective fluid passages.

Gallery 30L connects the first fluid chamber C1 L of the actuator 502L with port V1 D of valve arrangement V1 L. Similarly, gallery 32L connects the second fluid chamber C2L of the actuator 502L with port V3D of valve arrangement V3L.

As can be seen from FIG. 3A, a first hydraulic circuit 28L defined at least by gallery G1 L and gallery 30L connect the first port PP1 of the hydraulic pump PL to the first chamber C1 L of the actuator 502L. Where the first chamber C1 L is an annulus chamber, the first hydraulic circuit 28L can be described as an annulus circuit. Similarly, a second hydraulic circuit 29L defined at least by gallery G2L and gallery 32L connect the second port PP2 of the hydraulic pump PL with the second chamber C2L of the actuator 502L. Where the second chamber C2L is a piston chamber, the second hydraulic circuit 29L can be described as a piston circuit. The hydraulic circuits 28L, 29L collectively define a compression circuit and a rebound circuit.

The first and second galleries G1 L, G2L are high-pressure galleries, and the first and second accumulators A1 L and A2L are high-pressure accumulators, because they are connected to the high-pressure side (inlet V2I) of the valves V2L and V4L respectively. (Optionally, they may also have stiffer diaphragms (reactors) than a low-pressure accumulator A3 discussed further below.).

The right side of the actuator system 16 may be substantially identical to that of the left side and reference numerals terminating L in the description above are simply replaced with reference numerals terminating R. The only point of note is that the first and second accumulators A1 L, A2L and galleries G1 L, G2L on the left side are herein referred to as third and fourth hydraulic accumulators A1 R, A2R, and third and fourth hydraulic galleries G1 R, G2R on the right side.

In accordance with aspects and embodiments, a shared low-pressure hydraulic gallery G3 is provided to interconnect the left and right galleries G1 L, G2L, G1 R, G2R. The low-pressure gallery G3 connects a single, fifth hydraulic accumulator A3, and a single bleed port B, with outlet V2O of valve V2L, outlet V4O of valve V4L, inlet X1 1 of check valve X1 L, inlet X2I of check valve X2L, outlet V2O of valve V2R, outlet V4O of valve V4R, inlet X1 I of check valve X1 R, inlet X2I of check valve X2R. The gallery G3 may continuously and uninterruptably connect all of the aforementioned points. Uninterruptable means, for example, free from any intervening blockable valves. This includes intervening check valves, such that the flow is uninterruptable in a first flow direction and uninterruptable in a second opposite flow direction.

The accumulator A3 and bleed port B are therefore concurrently shared by the chambers C1 L, C2L, C1 R, C2R of the actuators 502L, 502R and any intervening hydraulic components. Therefore, only one of each (A3, B) are needed. The accumulator A3 can be regarded as a low-pressure accumulator because it is to the outlet side (low-pressure side) of the valves V2L, V2R, V4L, and V4R.

In operation, the control system 200 is configured to determine an appropriate setpoint indicative of required hydraulic pressure in one or both of the chambers C1 L, C2L of the actuator 502L. The control system 200 is configured to separately and concurrently determine an appropriate setpoint indicative of required hydraulic pressure in one or both of the chambers C1 R, C2R of the actuator 502R. The setpoint obtained (received or calculated) by the control system 200 may be a pressure setpoint or an actuator force setpoint, for example.

In an example, the control system 200 may increase the setpoint for the second fluid chamber C2L of the actuator 502L when it is desired to cause an extension force to be generated by the actuator 502L, for example to counter vehicle body roll in a leftwards direction as the vehicle turns right. This extension force at least partially counters the retracting force caused by the vehicle body roll. When it is determined that the actual pressure in second fluid chamber C2L of the actuator 502L is below the setpoint, then the pump PL is operated so as to pump fluid from the first gallery G1 L through the pump PL into the second gallery G2L. As the pressure in gallery G2L rises, hydraulic fluid may flow past check valve V3B of valve arrangement V3L causing the hydraulic pressure in gallery 32L and hence in the second fluid chamber C2L of the actuator 502L to also rise. Hydraulic pressure in hydraulic accumulator A2L will similarly rise. The pressure in gallery G2L relative to the setpoint is controlled by the valve V4L by restricting the flow back to the low-pressure gallery G3.

As the pressure in gallery G2L increases, so the pressure in gallery G1 L may fall. Check valve X2L will prevent fluid flow through the valve X2L from gallery G2L to gallery G3 when the pressure in gallery G2L is greater than the pressure in gallery G3. As the pressure in gallery G1 L drops to a pressure below the pressure in gallery G3, then check valve X1 L will open, thereby equalising the pressure in galleries G1 L and G3.

As the pressure in the second fluid chamber C2L of the actuator 502L increases, the piston 24L may rise (when viewing FIG. 3A) causing hydraulic fluid to be expelled from the first fluid chamber C1 L of the actuator 502L. The expelled fluid will flow into gallery G1 L dependent upon the flow characteristics of damper valve V1A, thus replacing some of the fluid lost from gallery G1 L to gallery G2L via pump PL. Hydraulic fluid from hydraulic accumulator A1 L may pass into gallery G1 L.

After a period of time a steady equilibrium will be reached wherein the pressure in gallery G2L, accumulator A2L, gallery 32L and in the second fluid chamber C2L of the actuator 502L are all equal. The magnitude of this steady state pressure, equal to the setpoint, will determine the appropriate pump speed and setting of valve V4L.

Consider the scenario where there is a disturbance input in the form of the wheel FL/RL hitting a bump. Whilst the target pressure in the second fluid chamber C2L of the actuator 502L is tending to extend the actuator 502L, the bump in the road will cause the actuator 502L to contract therefore causing hydraulic fluid to flow out of the contracting second fluid chamber C2L of the actuator 502L and consequently into the expanding first fluid chamber C1 L of the actuator 502L. Fluid flow into the expanding first fluid chamber C1 L is provided primarily by hydraulic fluid from accumulator A1 L flowing through check valve V1 B. However, hydraulic fluid flowing out of the contracting second fluid chamber C2L of the actuator 502L is damped by valve V3A. Thus valve V3A acts as a damper valve under these circumstances. Hydraulic fluid passing through damper valve V3A will primarily cause fluid to flow into accumulator A2L. Once the bump has been negotiated the piston 24L will return to its steady state position. The bump will create a high frequency road induced input which is accommodated primarily by accumulator A2L which is close to the second fluid chamber C2L of the actuator 502L when compared with accumulator A3.

However, as a rate/magnitude of bump travel increases, movement of the piston 24L within the cylinder 22L may cause the pressure in chamber C2L of the actuator 502L and gallery G2L to increase above the valve pressure setting of valve V4L in which case the opening of the valve V4L will be momentarily increased so as to limit the pressure in gallery G2L. Simultaneously, the large bump will cause the volume of chamber C1 L of the actuator 502L to increase in size. Therefore, hydraulic fluid flows out of accumulator A1 L into gallery G1 L and on to gallery 30L via check valve V1 B. Hydraulic fluid also flows out of accumulator A3, through gallery G3, into gallery G1 L via check valve X1 L and on to gallery 30L via check valve V1 B.

If the disturbance input is in the opposite direction, such as a rebound, the fluid flow will be in the opposite direction. The rebound will cause the actuator 502L to extend thereby causing hydraulic fluid to flow out of the contracting first fluid chamber C1 L of the actuator 502L and consequently into the expanding second fluid chamber C2L of the actuator 502L. Fluid flow into the expanding second fluid chamber C2L is provided primarily by hydraulic fluid from accumulator A2L flowing through check valve V3B. However, hydraulic fluid flowing out of the contracting first fluid chamber C1 L of the actuator 502L is damped by valve V1 A. Thus valve V1A acts as a damper valve under these circumstances. Hydraulic fluid passing through valve V1A will primarily cause fluid to flow into accumulator A1 L. Once the rebound has been negotiated the piston 24L will return to its steady state position. The rebound will create a high frequency road induced input which is accommodated primarily by accumulator A1 L which is close to the first fluid chamber C1 L of the actuator 502L when compared with accumulator A3.

However, as a rate/magnitude of rebound travel increases, movement of the piston 24L within the cylinder 22L may cause the pressure in contracting chamber C1 L of the actuator 502L and gallery G1 L to increase above the valve pressure setting of valve V2L in which case the opening of the valve V2L will be momentarily increased so as to limit the pressure in gallery G1 L. Concurrently, the large rebound will cause the volume of chamber C2L of the actuator 502L to increase in size. Therefore, hydraulic fluid flows out of accumulator A2L into gallery G2L and on to gallery 32L via check valve V3B. Hydraulic fluid also flows out of accumulator A3, through gallery G3, into gallery G2L via check valve X2L and on to gallery 32L via check valve V3B.

Consider the scenario where the bump is concurrently encountered at the right wheel FR/RR. The bump in the road will cause the actuator 502R to contract therefore causing hydraulic fluid to flow out of the contracting second fluid chamber C2R of the actuator 502R and consequently into the expanding first fluid chamber C1 R of the actuator 502R. Fluid flow into the expanding first fluid chamber C1 R is provided primarily by hydraulic fluid from accumulator A1 R flowing through check valve V1 B of valve arrangement V1 R. However, hydraulic fluid flowing out of the contracting second fluid chamber C2R of the actuator 502R is damped by damper valve V3A of valve arrangement V3R. Hydraulic fluid passing through damper valve V3A of valve arrangement V3R will primarily cause fluid to flow into accumulator A2R. Once the bump has been negotiated the piston 24R will return to its steady state position. The bump will create a high frequency road induced input which is accommodated primarily by accumulator A2R which is close to the second fluid chamber C2R of the actuator 502R when compared with accumulator A3.

However, as a rate/magnitude of bump travel increases, movement of the piston 24R within the cylinder 22R may cause the pressure in chamber C2R of the actuator 502R and gallery G2R to increase above the valve pressure setting of valve V4R in which case the opening of the valve V4R will be momentarily increased so as to limit the pressure in gallery G2R. Concurrently, the large bump will cause the volume of chamber C1 R of the actuator 502R to increase in size. Therefore, hydraulic fluid flows out of accumulator A1 R into gallery G1 R and on to gallery 30R via check valve V1 B of valve arrangement V1 R. As the bump is encountered by both actuators 502L, 502R concurrently, hydraulic fluid concurrently flows out of low-pressure accumulator A3, through gallery G3, into galleries G1 L and G1 R, via check valves X1 L and X1 R, and on to galleries 30L and 30R, via check valves V1 B of valve arrangements V1 L and V1 R. When both wheels then rebound concurrently, hydraulic fluid then flows into the low-pressure accumulator A3 from both the actuators 502L, 502R concurrently. If the temperature of the hydraulic fluid changes anywhere in the actuator system 16, the hydraulic fluid is able to flow into and out of the accumulator A3 in dependence on the change in temperature.

The volume of the low-pressure accumulator A3 may be greater than the volumes of accumulators A1 L, A1 R, A2L, and A2R.

Overall, the first fluid chamber C1 L of the actuator 502L can vent fluid to both hydraulic accumulators A1 L and A3. The second fluid chamber C2L of the actuator 502L can vent fluid to both hydraulic accumulators A2L and A3. The first fluid chamber C1 R of the actuator 502R can vent fluid to both hydraulic accumulators A1 R and A3. The second fluid chamber C2R of the actuator 502R can vent fluid to both hydraulic accumulators A2R and A3.

The hydraulic accumulators A1 L, A1 R, A2L, and A2R are relatively close both physically and hydraulically to the fluid chambers C1 L, C1 R, C2L, and C2R of the respective actuator 502L, 502R, so these accumulators A1 L, A1 R, A2L, and A2R can accommodate high frequency road induced inputs which tend to require relatively low amounts of hydraulic fluid to accommodate. If the control system’s setpoint is moving, the accumulators A1 L, A1 R, A2L, or A2R may need to be filled more. Conversely the low-pressure accumulator A3, being larger, is better able to compensate for system volume changes due the fluid temperature changes, system volume changes (e.g., due to rod insertion and retraction), and larger relative movements of the pistons 24L, 24R often associated with low frequency driver induced inputs.

The valves V2L, V2R are variable PCV valves, and the valve pressure setting of a valve V2L, V2R can be electronically varied to suit the particular circumstances. The valve V2L, V2R may comprise a variable restriction (variable orifice). Specifically, the valve pressure setting of valve V2L, V2R may be dependent upon the setpoint for the first chamber C1 L, C1 R of the respective actuator 502L, 502R. The valve pressure setting of valve V2L, V2R may further be dependent upon the operating point of the respective pump PL, PR. The more electrical current is applied to the PCV V2L, V2R, the more counteracting force restricts the flow. The PCV V2L, V2R needs continuous electrical current to counteract that pressure.

Similarly, the valves V4L, V4R are variable PCV valves, and the valve pressure setting of a valve V4L, V4R can be electronically varied to suit the particular circumstances. The valve V4L, V4R may comprise a variable restriction (variable orifice). In particular, the valve pressure setting of valve V4L, V4R may be dependent upon the setpoint in the second chamber C2L, C2R of the respective actuator 502L, 502R. The valve pressure setting of valve V4L, V4R may further be dependent upon the operating point of the respective pump PL, PR. The more electrical current is applied to the PCV V4L, V4R, the more counteracting force restricts the flow. The PCV V4L, V4R needs continuous electrical current to counteract that pressure.

In steady state conditions, hydraulic fluid pumped in a first direction from the first port PP1 of pump PL/PR flows through the PCV V2L/V2R, past the check valve X2L/X2R, and back to the second port PP2 of the pump PL/PR. Hydraulic fluid pumped in the opposite direction from the second port PP2 of the pump PL/PR flows through the PCV V4L/V4R, past the check valve X1 L/X1 R, and back to the first port PP1 of the pump PL/PR. The hydraulic pressure in each circuit 28L, 28R, 29L, 29R is determined predominantly or entirely by the controllable pressure through the PCVs V2L, V2R, V4L, V4R.

In some examples, the low-pressure hydraulic gallery G3 may be shared by all of the piston actuators 502 of the vehicle 1 , such as front-left, front-right, rear-left, and rear-right actuators 502. This enables just one low- pressure accumulator A3 and bleed port B to be used for the whole active suspension system 104 of the vehicle 1 . Where a first hydraulic control apparatus 17 of FIGS. 3A-3C is for a first end of the vehicle (front or rear), a second hydraulic control apparatus 17 of FIGS. 3A-3C may be provided for the second opposite end of the vehicle. Therefore: the hydraulic gallery G1 L of the second apparatus 17 would be a sixth hydraulic gallery of the actuator system 16; the hydraulic gallery G2L of the second apparatus 17 would be a seventh hydraulic gallery of the actuator system 16; the hydraulic gallery G1 R of the second apparatus 17 would be an eighth hydraulic gallery of the actuator system 16; the hydraulic gallery G2R of the second apparatus 17 would be a ninth hydraulic gallery of the actuator system 16; the hydraulic gallery G3 would be common to the first and second apparatus 17, such that the same gallery G3 hydraulically interconnects all of the first, second, third, fourth, sixth, seventh, eighth, and ninth hydraulic galleries concurrently, via the respective valves described herein.

The term ‘concurrently’ in this document refers to events happening at the same time. The term ‘simultaneously’ can be used instead, without implying a greater degree of synchronisation.

Features described in the preceding description may be used in combinations other than the combinations explicitly described. Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not. Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

FIG. 4 illustrates another example of an actuator system 16 and hydraulic control apparatus 17. The outboard parts of the actuator system 16 are unchanged, so have been cropped out to simplify the Figure. In this implementation, the low-pressure hydraulic gallery G3 is replaced by a pair of individual low-pressure galleries G3L, G3R and a shared low-pressure gallery G4. The shared gallery G4 is the fifth gallery referred to earlier, and the individual galleries G3L, G3R are sixth and seventh galleries.

The shared low-pressure gallery G4 fulfils the function of the shared gallery G3 of FIGS. 3A-3C, but is not connected to the individual low-pressure galleries G3L, G3R. Instead, the gallery G4 is connected to:

- the housing of pump PL by a fixed inlet FIL, to receive hydraulic fluid from the left galleries G1 L, G2L;

- the housing of pump PR by a fixed inlet FIR, to receive hydraulic fluid from the right galleries G1 R, G2R;

- the left gallery G1 L by check valve X3L, to supply hydraulic fluid to gallery G1 L;

- the left gallery G2L by check valve X4L, to supply hydraulic fluid to gallery G2L;

- the right gallery G1 R by check valve X3R, to supply hydraulic fluid to gallery G1 R;

- the right gallery G2R by check valve X4R, to supply hydraulic fluid to gallery G2R; and

- the accumulator A3.

The individual low-pressure galleries G3L, G3R have the same features and functions as described previously, the difference being that they are not directly interconnected with each other. The interconnection is instead achieved by the gallery G4. Therefore, the galleries G3L, G3R are left-side and right-side galleries, respectively.

The gallery G4 concurrently hydraulically interconnects the respective valves X3L, X4L, X3R, X4R of the first, second, third and fourth hydraulic galleries G1 L, G2L, G1 R, G2R.

The gallery G4 comprises two inlets and four outlets, wherein the first and second inlets comprise the fixed inlets FIL or FIR, and wherein the first, second, third, and fourth outlets comprise the check valves X3L, X4L, X3R, X4R respectively.

The fixed inlets FIL, FIR to gallery G4 are fixed as opposed to variable inlets, meaning that they lack a valve. In other examples, the inlets FIL, FIR may be variable inlets controlled by PCVs similar to the earlier-described valves V2L, V4L, V2R, V4R.

In some, but not necessarily all examples, the pump housings of the pumps PL, PR, collectively comprise the inlets and outlets to/from gallery G4. The fixed inlet FIL, FIR may be connected to an impeller chamber of the respective pump PL or PR. The outlet comprising the respective check valve X3L or X3R may be connected to the pump housing to the side of port PP1 (FIG. 3B) of the respective pump PL or PR. The outlet comprising the respective check valve X4L or X4R may be connected to the pump housing to the side of port PP2 (FIG. 3B) of the respective pump PL, PR.

The fixed inlets FIL, FIR are two-way passages, so theoretically the low-pressure gallery G4 can provide hydraulic fluid to the pump PL, PR. However, the positioning of the fixed inlets FIL FIR in the impeller chamber of the pump PL, PR means that this can only happen when the pump is not turning or when cavitation occurs, because otherwise the pressure at FIL, FIR is higher than in G4 which would prevent backflow into the pump PL, PR via FIL, FIR and only allow flow from gallery G4 to galleries G1 L, G2L, G1 R, G1 L via the check valves X3L, X4L, X3R, X4R.

Claims

1 . A hydraulic control apparatus for first and second piston actuators of an active suspension system of a vehicle, the hydraulic control apparatus comprising: a first hydraulic gallery hydraulically couplable to a first fluid chamber of the first piston actuator; a second hydraulic gallery hydraulically couplable to a second fluid chamber of the first piston actuator; a third hydraulic gallery hydraulically couplable to a first fluid chamber of the second piston actuator; a fourth hydraulic gallery hydraulically couplable to a second fluid chamber of the second piston actuator; and a fifth hydraulic gallery to hydraulically interconnect the first, second, third, and fourth hydraulic galleries.

2. The hydraulic control apparatus of claim 1 , wherein the fifth hydraulic gallery hydraulically interconnects the first, second, third, and fourth hydraulic galleries via respective valves.

3. The hydraulic control apparatus of claim 2, wherein the fifth hydraulic gallery hydraulically interconnects the first, second, third, and fourth hydraulic galleries concurrently via the respective valves.

4. The hydraulic control apparatus of claim 2 or 3, comprising a plurality of fixed inlets collectively arranged to permit one-way hydraulic fluid flow into the fifth hydraulic gallery from the first, second, third, and fourth hydraulic galleries.

5. The hydraulic control apparatus of any one of claims 2 or 4, wherein the respective valves comprise a plurality of second valves each connected to a different one of the first, second, third, and fourth hydraulic galleries and arranged to permit one-way hydraulic fluid flow out of the fifth hydraulic gallery.

6. The hydraulic control apparatus of any one of claims 2 to 5, comprising a plurality of damper valves each connected to a different one of the first, second, third, and fourth hydraulic galleries and arranged to control hydraulic fluid flow towards the respective valves.

7. The hydraulic control apparatus of any one of claims 2 to 6, comprising at least one hydraulic component connected to the fifth hydraulic gallery, and hydraulically couplable to the first, second, third and fourth hydraulic galleries via the respective valves.

8. The hydraulic control apparatus of claim 7, wherein the at least one hydraulic component comprises a hydraulic accumulator and/or a bleed port to enable bleeding of air from the first, second, third, fourth, and fifth hydraulic galleries concurrently.

9. The hydraulic control apparatus of claim 8, comprising a first hydraulic accumulator connected to the first hydraulic gallery, a second hydraulic accumulator connected to the second hydraulic gallery, a third hydraulic accumulator connected to the third hydraulic gallery, and a fourth hydraulic accumulator connected to the fourth hydraulic gallery, wherein the hydraulic accumulator is a fifth hydraulic accumulator, and wherein the first, second, third, and fourth hydraulic accumulators are configured to operate at a relatively high pressure compared to the fifth hydraulic accumulator.

10. The hydraulic control apparatus of claim 9, wherein a volume of the fifth hydraulic accumulator is greater than a volume of at least one of the first, second, third, or fourth hydraulic accumulators.

11 . The hydraulic control apparatus of any preceding claim, comprising a first pump operable to control hydraulic pressure across the first piston actuator, and a second pump operable to control hydraulic pressure across the second piston actuator.

12. The hydraulic control apparatus of claim 11 , wherein the first and second pumps are controllable to apply extending forces to the first and second piston actuators concurrently or apply retracting forces to the first and second piston actuators concurrently, while the fifth hydraulic gallery hydraulically interconnects the first, second, third, and fourth hydraulic galleries.

13. An actuator system comprising the hydraulic control apparatus and the first and second piston actuators, of any one of the preceding claims.

14. A vehicle comprising the actuator system of claim 13.

15. The vehicle of claim 14, wherein the first piston actuator is a left piston actuator for controlling displacement of a left wheel of the vehicle, and wherein the second piston actuator is a right piston actuator for controlling displacement of a right wheel of the vehicle.