PATENT DOCUMENT

Publication Number: US-10814690-B1
Application Number: US-201815935293-A
Country: US
Kind Code: B1

Title: Active suspension system with energy storage device

Abstract:
An active suspension system for a vehicle having a wheel that is subject to an external force includes an actuator having an output structure that is connected to the wheel, an energy storage device having a compressible chamber, a valve assembly that is operable to control flow of a working fluid between the actuator and the energy storage device, and a controller that determines whether to permit or resist motion of the output structure in response to the external force. The controller permits motion of the output structure by allowing fluid to flow from the actuator to the energy storage device using the valve assembly, thereby compressing the compressible chamber. The controller resists motion of the output structure by allowing fluid to flow from the energy storage device to the actuator using the valve assembly, thereby expanding the compressible chamber.

Claims:
What is claimed is: 
     
       1. An active suspension system for a vehicle having a wheel that is subject to an external force, comprising:
 an actuator having an output structure that is connected to the wheel such that the external force acts on the output structure; 
 an energy storage device having a compressible chamber; 
 a valve assembly that is positioned in fluid communication between the actuator and the energy storage device and is operable to control flow of a working fluid between the actuator and the energy storage device; and 
 a controller that makes a determination to permit motion of the output structure in response to the external force or to resist motion of the output structure in response to the external force, and controls the valve assembly according to the determination. 
 
     
     
       2. The active suspension system of  claim 1 , wherein:
 the controller permits motion of the output structure when a desired travel direction for the output structure matches an external force direction, and the controller resists motion of the output structure when a desired travel direction for the output structure is opposite the external force direction, 
 the controller permits motion of the output structure by controlling the valve assembly to allow fluid to flow from the actuator to the energy storage device using the valve assembly, thereby compressing the compressible chamber, and 
 the controller resists motion of the output structure by controlling the valve assembly to allow fluid to flow from the energy storage device to the actuator using the valve assembly, thereby expanding the compressible chamber. 
 
     
     
       3. The active suspension system of  claim 1 , wherein a compressible medium is disposed in the compressible chamber. 
     
     
       4. The active suspension system of  claim 3 , wherein the compressible medium is a gas. 
     
     
       5. The active suspension system of  claim 4 , further comprising:
 a pressure regulator for increasing and decreasing a gas pressure within the compressible chamber. 
 
     
     
       6. The system of  claim 1 , wherein an elastic structure is disposed within the compressible chamber. 
     
     
       7. The system of  claim 1 , wherein an energy storage actuator is disposed within the compressible chamber. 
     
     
       8. The system of  claim 1 , wherein the working fluid is a magnetorheological hydraulic fluid and the valve assembly includes electromagnetic coils. 
     
     
       9. The system of  claim 1 , further comprising:
 a low-pressure reservoir that stores a portion of the working fluid; and 
 a pump that is connected to the low-pressure reservoir to supply the working fluid from the low-pressure reservoir to the valve assembly. 
 
     
     
       10. The system of  claim 1 , wherein the energy storage device is connected to the valve assembly by a two-directional flow line. 
     
     
       11. A system, comprising:
 a hydraulic actuator having a body, a piston rod that extends out of the body, a piston head disposed in the body, a first volume defined inside the body on a first side of the piston head, and a second volume defined inside the body on a second side of the piston head; 
 an energy storage device having a housing, a first chamber defined inside the housing, a second chamber defined inside the housing, and a compressible chamber defined inside the housing; 
 a first valve assembly that is operable to control flow of a working fluid between the first volume of the hydraulic actuator and the first chamber of the energy storage device; 
 a second valve assembly that is operable to control flow of the working fluid between the second volume of the hydraulic actuator and the second chamber of the energy storage device; and 
 a controller that controls operation of at least one of the first valve assembly or the second valve assembly to store energy in the energy storage device by compressing the compressible chamber by flow of the working fluid into the energy storage device from the hydraulic actuator when a desired travel direction for the piston rod matches an external force direction, and controls operation of at least one of the first valve assembly or the second valve assembly to release energy from the energy storage device by expanding the compressible chamber by flow of the working fluid into the hydraulic actuator from the energy storage device when the desired travel direction for the piston rod is opposite the external force direction. 
 
     
     
       12. The system of  claim 11 , wherein the energy storage device is configured such that the compressible chamber is located between the first chamber and the second chamber. 
     
     
       13. The system of  claim 12 , wherein flow of the working fluid into the first chamber is operable to compress the compressible chamber and flow of the working fluid into the second chamber is operable to compress the compressible chamber. 
     
     
       14. The system of  claim 11 , wherein a compressible gas is located in the compressible chamber. 
     
     
       15. The system of  claim 14 , further comprising:
 a pressure regulator that is operable to increase and decrease an amount of the compressible gas that is located in the compressible chamber. 
 
     
     
       16. The system of  claim 11 , wherein a compression spring is located in the compressible chamber. 
     
     
       17. The system of  claim 11 , wherein the first valve assembly is connected to the first chamber of the energy storage device by a first two-directional flow line and the second valve assembly is connected to the second chamber of the energy storage device by a second two-directional flow line. 
     
     
       18. A method, comprising:
 determining a desired direction of travel for an actuator; 
 determining an external force direction of an external force that is applied to the actuator; 
 determining whether the external force direction matches the desired direction of travel for the actuator; 
 in response to determining that the external force direction matches the desired direction of travel for the actuator, controlling a valve assembly to cause storage of energy from the actuator in an energy storage device by compressing a compressible chamber of the energy storage device by flow of a working fluid into the energy storage device from the actuator, wherein the valve assembly is positioned in fluid communication between the actuator and the energy storage device and is configured to control flow of the working fluid between the actuator and the energy storage device along a two-directional flow line; and 
 in response to determining that the external force direction does not match the desired direction of travel for the actuator, controlling the valve assembly to cause release of energy from the energy storage device to the actuator by expanding a compressible chamber of the energy storage device by flow of the working fluid from the energy storage device to the actuator. 
 
     
     
       19. The method of  claim 18 , wherein the valve assembly is configured to establish flow of the working fluid between the actuator and the energy storage device along the two-directional flow line and to block flow of the working fluid between the actuator and the energy storage device along the two-directional flow line. 
     
     
       20. The method of  claim 18 , wherein a compressible medium is located in the compressible chamber.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/486,584, entitled “Active Suspension System with Energy Storage Device,” filed on Apr. 18, 2017, the content of which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The application relates generally to active suspension systems. 
     BACKGROUND 
     Active suspension systems incorporate actuators that are controlled by an external controller to change the ride characteristics of a vehicle in response to sensed conditions. Functions performed by active suspension systems can include, for example, controlling the vertical movement of the wheels of the vehicle relative to a vehicle body of the vehicle, controlling damping firmness at each of the wheels, and self-levelling. 
     SUMMARY 
     One aspect of the disclosed embodiments is an active suspension system for a vehicle having a wheel that is subject to an external force. The active suspension system includes an actuator having an output structure that is connected to the wheel, an energy storage device having a compressible chamber, a valve assembly that is operable to control flow of a working fluid between the actuator and the energy storage device, and a controller that determines whether to permit or resist motion of the output structure in response to the external force. The controller permits motion of the output structure by allowing fluid to flow from the actuator to the energy storage device using the valve assembly, thereby compressing the compressible chamber. The controller resists motion of the output structure by allowing fluid to flow from the energy storage device to the actuator using the valve assembly, thereby expanding the compressible chamber. 
     Another aspect of the disclosed embodiments is a system that includes a hydraulic actuator having a body, a piston rod that extends out of the body, a piston head disposed in the body, an upper volume defined inside the body on a first side of the piston head, and a lower volume defined inside the body on a second side of the piston head. The system also includes an energy storage device having a housing, an upper chamber defined inside the housing, a lower chamber defined inside the housing, and a compressible chamber defined inside the housing. The system also includes an upper valve assembly that is operable to control flow of a working fluid between the upper volume of the hydraulic actuator and the upper chamber of the energy storage device. The system also includes a lower valve assembly that is operable to control flow of the working fluid between the lower volume of the hydraulic actuator and the lower chamber of the energy storage device. The system also includes a controller that controls of operation at least one of the upper valve assembly or the lower valve assembly to store energy in the energy storage device by compressing the compressible chamber by flow of the working fluid into the energy storage device from the hydraulic actuator when a desired travel direction for the piston rod matches an external force direction. The controller controls operation of at least one of the upper valve assembly or the lower valve assembly to release energy from the energy storage device by expanding the compressible chamber by flow of the working fluid into the hydraulic actuator from the energy storage device when the desired travel direction for the piston rod is opposite the external force direction. 
     Another aspect of the disclosed embodiments is a method that includes determining a desired direction of travel for an actuator, determining an external force direction of an external force that is applied to the actuator, and determining whether the external force direction matches the desired direction of travel for the actuator. In response to determining that the external force direction matches the desired direction of travel for the actuator, the method includes controlling a valve assembly to cause storage of energy from the actuator in an energy storage device by compressing a compressible chamber of the energy storage device by flow of a working fluid into the energy storage device from the actuator. In response to determining that the external force direction does not match the desired direction of travel for the actuator, the method includes controlling the valve assembly to cause release of energy from the energy storage device to the actuator by expanding a compressible chamber of the energy storage device by flow of the working fluid from the energy storage device to the actuator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustration that shows a portion of a vehicle that has a hydraulic actuator, an actuation system, and a suspension system controller. 
         FIG. 2  is a block diagram that shows the actuation system. 
         FIG. 3A  is a diagram that shows an upper valve assembly of the actuation system. 
         FIG. 3B  is a diagram that shows a lower valve assembly of the actuation system. 
         FIG. 4  is a diagram that shows an energy storage device of the actuation system according to a first example. 
         FIG. 5  is a diagram that shows an energy storage device of the actuation system according to a second example. 
         FIG. 6  is a diagram that shows an energy storage device of the actuation system according to a third example. 
         FIG. 7  is a diagram that shows an energy storage device of the actuation system according to a fourth example. 
         FIG. 8  is a flowchart that shows an example of a control process for an active suspension system with an energy storage device. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure herein relates to an active suspension that includes a hydraulic actuator and an energy storage device. The energy storage device includes a compressible medium or an elastic structure that is compressed by fluid flow resulting from external forces that are applied to the hydraulic actuator. Valves control fluid flow to and from the energy storage device so that stored energy can be retained and later released when needed to supply fluid pressure to the hydraulic actuator. 
       FIG. 1  shows a portion of a vehicle  100  that has a vehicle body  102 . The vehicle body  102  may include internal structural portions and external portions that are aesthetic and/or structural in nature. As examples, the vehicle body  102  may include one or more of a unibody, a frame, a subframe, a monocoque, and body panels. 
     The vehicle  100  includes a road wheel  104 . The road wheel  104  is one of multiple (e.g., four) wheels that can be included as part of the vehicle  100  to contact the surface on which the vehicle  100  is travelling. The characteristics of the road wheel  104  are responsible, in part, for the amount of friction available, and the road wheel  104  therefore includes a friction enhancing structure such as a conventional pneumatic tire that is formed in part from synthetic rubber. 
     The road wheel  104  is mechanically connected to the vehicle body  102  in a manner that allows motion of the road wheel  104  relative to the vehicle body  102 . This connection includes a hydraulic actuator  106  that is operable to dampen motion of the road wheel  104  relative to the vehicle body  102 . The hydraulic actuator  106  is an actively controlled component having one or more adjustable characteristics, as will be described herein. During operation of the vehicle  100 , the road wheel  104  is subjected to external forces F_ext, and the hydraulic actuator  106  can be controlled to react to the external forces F_ext in a desired manner. 
     The hydraulic actuator  106  includes a cylinder body  108 , a moveable output structure such as a piston rod  110  that extends out of the cylinder body  108 , and a piston head  112  that is located inside the cylinder body  108 . An internal space of the cylinder body  108  is divided by the piston head  112  into an upper volume  114  and a lower volume  116 . The upper volume  114  is located inside the cylinder body  108  on a first side of the piston head  112 . The lower volume  116  is located inside the cylinder body  108  on a second side of the piston head  112 . An upper hydraulic feed line  118  is connected to the cylinder body  108  to supply fluid to and receive fluid from the upper volume  114 . A lower hydraulic feed line  120  is connected to the cylinder body  108  to supply fluid to and receive fluid from the lower volume  116 . 
     The upper hydraulic feed line  118  and the lower hydraulic feed line  120  of the hydraulic actuator  106  are connected to an actuation system  122 . The actuation system  122  is operable to regulate transmission of fluid to and from the hydraulic actuator  106  in order to control the operating characteristics of the hydraulic actuator  106 . As will be explained herein, the actuation system  122  includes hydraulic components that facilitate fluid flow and electrical components that can be controlled by commands in the form of signals and/or data to allow operation of the actuation system  122  by an external controller. In the illustrated example, the actuation system  122  receives commands from a suspension system controller  124  over an electrical connection, for example, a data network that complies with the Controller Area Network standard. 
     The suspension system controller  124  is operable to control operation of the actuation system  122  and other active suspension components. The suspension system controller  124  can include a memory and a processor that is operable to execute instructions that are stored in the memory in order to perform suspension control operations. The suspension system controller  124  determines and outputs commands that are transmitted to the actuation system  122 . The commands, when executed by the suspension system controller  124 , modify one or more operating characteristics of the actuation system  122 . The suspension system controller  124  can receive information from sensors, such as sensors associated with the hydraulic actuator  106 , and determine the commands based on the information received from the sensors. 
       FIG. 2  is block diagram that shows the actuation system  122 . The actuation system  122  includes a low-pressure accumulator  226 , a pump  228 , an upper valve assembly  230 , a lower valve assembly  232 , and an energy storage device  234 . 
     The low-pressure accumulator  226  serves as a reservoir for excess quantities of a working fluid that is used by the hydraulic actuator  106 . The working fluid is a hydraulic fluid, such as an oil (or other liquid), and is incompressible. 
     The low-pressure accumulator  226  is connected to the pump  228  by a pump supply line  236 . The pump supply line  236  allows transmission of the working fluid from the low-pressure accumulator  226  to the pump  228 . A one-way flow valve  238  can be included along the pump supply line  236  so that fluid flows only from the low-pressure accumulator  226  to the pump  228 , and backflow from the pump  228  to the low-pressure accumulator  226  is prevented. 
     The pump  228  provides the working fluid to the upper valve assembly  230  and the lower valve assembly  232 . The pump  228  is connected to the upper valve assembly  230  by an upper valve supply line  240 . The pump  228  is connected to the lower valve assembly  232  by a lower valve supply line  242 . 
     The upper valve assembly  230  is connected to multiple components of the actuation system  122 , and regulates flow of the working fluid to and from these components by controlling the states of multiple valves, which will be discussed further herein. The upper valve assembly  230  is connected to the upper hydraulic feed line  118  to allow the upper valve assembly  230  to supply the working fluid to the upper volume  114  of the hydraulic actuator  106  and to receive the working fluid from the upper volume  114  of the hydraulic actuator  106 . The upper valve assembly  230  is connected to the low-pressure accumulator  226  by an upper return line  244  to return an excess volume of the working fluid from the upper valve assembly  230  to the low-pressure accumulator  226 . The upper valve assembly  230  is connected to the energy storage device  234  by an upper energy storage line  246  to supply the working fluid to the energy storage device  234  and to receive the working fluid from the energy storage device  234 . 
     The lower valve assembly  232  is connected to multiple components of the actuation system  122 , and regulates flow of the working fluid to and from these components by controlling the states of multiple valves, which will be discussed further herein. The lower valve assembly  232  is connected to the hydraulic feed line  120  to allow the lower valve assembly  232  to supply the working fluid to the lower volume  116  of the hydraulic actuator  106  and to receive the working fluid from the lower volume  116  of the hydraulic actuator  106 . The lower valve assembly  232  is connected to the low-pressure accumulator  226  by a lower return line  248  to return an excess volume of the working fluid from the lower valve assembly  232  to the low-pressure accumulator  226 . The lower valve assembly  232  is connected to the energy storage device  234  by a lower energy storage line  250  to supply the working fluid to the energy storage device  234  and to receive the working fluid from the energy storage device  234 . 
     As will be explained further herein, the energy storage device  234  includes a compressible medium that is compressed elastically by flow of the working fluid to the energy storage device  234  through the upper energy storage line  246  and the lower energy storage line  250 . The flow of the working fluid to the energy storage device  234  can result from the external forces F_ext that are applied to the hydraulic actuator  106 . The pressures generated by the external forces F_ext are sufficient to allow the working fluid to flow into the energy storage device  234  from the hydraulic actuator  106  and compress the compressible medium without additional pumping. Conversely, the pressures generated by compressing the compressible medium are sufficient to allow the working fluid to flow into the hydraulic actuator  106  from the energy storage device  234  and cause motion of the piston rod  110  without additional pumping. By controlling the upper valve assembly  230  and the lower valve assembly  232 , this energy can be retained in the energy storage device  234  and subsequently released to assist operation of the hydraulic actuator  106 . Use of the energy stored by the energy storage device  234  to operate the hydraulic actuator  106  can allow the actuation system  122  to respond more rapidly to changing magnitudes of the external forces F_ext, and can allow use of less energy by the pump  228 , and/or can allow the pump  228  to be smaller in size than what would otherwise be required for the actuation system  122  if the energy storage device  234  was not present. 
       FIG. 3A  is a diagram that shows the upper valve assembly  230  of the actuation system  122 . The upper valve assembly  230  includes an upper valve body  331 , an upper feed valve  319 , an upper supply valve  341 , an upper return valve  345 , and an upper storage valve  347 . The upper valve body  331  interconnects the upper feed valve  319 , the upper supply valve  341 , the upper return valve  345 , and the upper storage valve  347  such that when two of these valves are open simultaneously, fluid communication is established between them. An upper valve controller  352  can be incorporated in the upper valve assembly  230  and is electrically connected to actuate movement of each of the upper feed valve  319 , the upper supply valve  341 , the upper return valve  345 , and the upper storage valve  347  between respective open and closed positions, or to control a respective degree of opening of each valve. The upper valve controller  352  is operated by commands that are received from the suspension system controller  124 . 
     The upper feed valve  319  regulates a fluid flow Q 1 _T along the upper hydraulic feed line  118  with respect to the upper valve assembly  230 . The fluid flow Q 1 _T is a two-directional flow that is operable to supply fluid to the upper volume  114  of the hydraulic actuator  106  from the upper valve assembly  230  along the upper hydraulic feed line  118 , and receive fluid that is returned to the upper valve assembly  230  from the upper volume  114  of the hydraulic actuator  106  along the upper hydraulic feed line  118 . 
     The upper supply valve  341  regulates a fluid flow Q 2 _T along the upper valve supply line  240  with respect to the upper valve assembly  230 . The fluid flow Q 2 _T is a one-directional flow that is operable to supply fluid to the upper valve assembly  230  from the pump  228  along the upper valve supply line  240 . 
     The upper return valve  345  regulates a fluid flow Q 3 _T along the upper return line  244  with respect to the upper valve assembly  230 . The fluid flow Q 3 _T is a one-directional flow that is operable to return fluid to the low-pressure accumulator  226  from the upper valve assembly  230  along the upper return line  244 . 
     The upper storage valve  347  regulates a fluid flow Q 4 _T along the upper energy storage line  246  with respect to the upper valve assembly  230 . The fluid flow Q 4 _T is a two-directional flow that is operable to supply fluid to the energy storage device  234  from the upper valve assembly  230  along the upper energy storage line  246  and receive fluid that is returned to the upper valve assembly  230  from the energy storage device  234  to the upper valve assembly  230  along the upper energy storage line  246 . 
     The upper valve assembly  230  allows control of fluid flow between the upper volume  114  of the hydraulic actuator  106  and the energy storage device  234 . For example, the suspension system controller  124  can transmit a command to the upper valve controller  352  that causes the upper feed valve  319  and the upper storage valve  347  to move to open positions, which allows flow between the upper volume  114  of the hydraulic actuator  106  and the energy storage device  234  through the upper valve assembly  230 , the upper feed valve  319 , and the upper storage valve  347  directly, without use of the low-pressure accumulator  226  or the pump  228 . 
       FIG. 3B  is a diagram that shows the lower valve assembly  232  of the actuation system  122 . The lower valve assembly  232  includes a lower valve body  333 , a lower feed valve  321 , a lower supply valve  343 , a lower return valve  349 , and a lower storage valve  351 . The lower valve body  333  interconnects the lower feed valve  321 , the lower supply valve  343 , the lower return valve  349 , and the lower storage valve  351  such that when two of these valves are open simultaneously, fluid communication is established between them. A lower valve controller  354  can be incorporated in the lower valve assembly  232  and is electrically connected to actuate movement of each of the lower feed valve  321 , the lower supply valve  343 , the lower return valve  349 , and the lower storage valve  351  between respective open and closed positions, or to control a respective degree of opening of each valve. The lower valve controller  354  is operated by commands that are received from the suspension system controller  124 . 
     The lower feed valve  321  regulates a fluid flow Q 1 _B along the lower hydraulic feed line  120  with respect to the lower valve assembly  232 . The fluid flow Q 1 _B is a two-directional flow that is operable to supply fluid to the lower volume  116  of the hydraulic actuator  106  from the lower valve assembly  232  along the lower hydraulic feed line  120 , and receive fluid that is returned to the lower valve assembly  232  from the lower volume  116  of the hydraulic actuator  106  along the lower hydraulic feed line  120 . 
     The lower supply valve  343  regulates a fluid flow Q 2 _B along the lower valve supply line  242  with respect to the lower valve assembly  232 . The fluid flow Q 2 _B is a one-directional flow that is operable to supply fluid to the lower valve assembly  232  from the pump  228  along the lower valve supply line  242 . 
     The return valve  349  regulates a fluid flow Q 3 _B along the return line  248  with respect to the lower valve assembly  232 . The fluid flow Q 3 _B is a one-directional flow that is operable to return fluid to the low-pressure accumulator  226  from the lower valve assembly  232  along the return line  248 . 
     The lower storage valve  351  regulates a fluid flow Q 4 _B along the lower energy storage line  250  with respect to the lower valve assembly  232 . The fluid flow Q 4 _B is a two-directional flow that is operable to supply fluid to the energy storage device  234  from the lower valve assembly  232  along the lower energy storage line  250  and receive fluid that is returned to the lower valve assembly  232  from the energy storage device  234  along the lower energy storage line  250 . 
     The lower valve assembly  232  allows control of fluid flow between the lower volume  116  of the hydraulic actuator  106  and the energy storage device  234 . For example, the suspension system controller  124  can transmit a command to the lower valve controller  354  that causes the lower feed valve  321  and the lower storage valve  351  to move to open positions, which allows flow between the lower volume  116  of the hydraulic actuator  106  and the energy storage device  234  through the lower valve assembly  232 , the upper feed valve  319 , and the upper storage valve  347  directly, without use of the low-pressure accumulator  226  or the pump  228 . 
     In one implementation, the working fluid can be a magnetorheological (MR) hydraulic fluid. The MR hydraulic fluid can be, for example, an oil with ferromagnetic particles suspended in the oil. The MR hydraulic fluid reacts to magnetic fields by changing viscosity, as a result of the ferromagnetic particles moving from a first state in which the ferromagnetic particles are distributed randomly in the oil absent a significant magnetic field, to a second state in which the ferromagnetic particles form chains along the flux lines of the magnetic field. 
     To control flow of the MR hydraulic fluid, the valves that are incorporated in the upper valve assembly  230  and the lower valve assembly  232  are electromagnetic coils in implementations that utilize the MR hydraulic fluid. When the coils are fully energized, flow of the MR hydraulic fluid stops. When the coils are fully deenergized, the MR hydraulic fluid flows normally. The current applied to the coils can be controlled between fully energized and fully deenergized states to control flow of the MR hydraulic fluid, and this type of control can be utilized to apply damping to the hydraulic actuator  106 . 
       FIG. 4  is a diagram that shows the energy storage device  234  of the actuation system  122 . The energy storage device  234  includes a cylindrical housing  456  that is connected to the upper energy storage line  246  and the lower energy storage line  250 . An upper piston head  458  and a lower piston head  460  are disposed inside the cylindrical housing  456 . The upper piston head  458  and the lower piston head  460  are rigid structures that can move longitudinally within the cylindrical housing  456 . To guide motion of the upper piston head  458  and the lower piston head  460 , guide structures  462  can be formed inside the cylindrical housing  456  to engage and constrain motion of the upper piston head  458  and the lower piston head  460 . The guide structures  462  can be, for example, longitudinally extending tracks or grooves that are engaged by corresponding projections that are formed on the upper piston head  458  and the lower piston head  460 . 
     The upper piston head  458  and the lower piston head  460  divide the interior of the cylindrical housing  456  into several spaces that are substantially sealed against fluid flow between them. In the illustrated example, the cylindrical housing  456  is divided into three spaces including an upper chamber  464 , a lower chamber  466 , and a compressible chamber  468 . 
     The upper chamber  464  is located adjacent to the upper piston head  458  and may, for example, be located between the upper piston head  458  and an end portion of the cylindrical housing  456 . The upper chamber  464  is in fluid communication with the upper energy storage line  246  such that the working fluid flows into and out of the upper chamber  464  through the upper energy storage line  246 . The volume of the upper chamber  464  is dependent upon the position of the upper piston head  458 . In some implementations, the upper piston head  458  can be the only movable structure that forms part of the extents of the upper chamber  464 , with the remainder of the upper chamber  464  being bounded by the cylindrical housing  456  or other fixed/incompressible structures. The upper piston head  458  is shown in an uncompressed position, resulting in a minimum volume for the upper chamber  464 . An example of a compressed position  459  of the upper piston head  458  is illustrated in broken lines. The compressed position  459  of the upper piston head  458  is defined when the working fluid flows into the upper chamber  464  and applies force to the upper piston head  458  to move it toward the compressed position  459 . When the upper piston head  458  is in the compressed position  459 , a maximum volume can be defined for the upper chamber  464 . 
     The lower chamber  466  is located adjacent to the lower piston head  460  and may, for example, be located between the lower piston head  460  and an end portion of the cylindrical housing  456 . The lower chamber  466  is in fluid communication with the lower energy storage line  250  such that the working fluid flows into and out of the lower chamber  466  through the lower energy storage line  250 . The volume of the lower chamber  466  is dependent upon the position of the lower piston head  460 . In some implementations, the lower piston head  460  can be the only movable structure that forms part of the extents of the lower chamber  466 , with the remainder of the lower chamber  466  being bounded by the cylindrical housing  456  or other fixed/incompressible structures. The lower piston head  460  is shown in an uncompressed position, resulting in a minimum volume for the lower chamber  466 . An example of a compressed position  461  of the lower piston head  460  is illustrated in broken lines. The compressed position  461  of the lower piston head  460  is defined when the working fluid flows into the lower chamber  466  and applies force to the lower piston head  460  to move it toward the compressed position  461 . When the lower piston head  460  is in the compressed position  461 , a maximum volume can be defined for the lower chamber  466 . 
     The compressible chamber  468  is defined between the upper piston head  458  and the lower piston head  460 . The volume of the compressible chamber  468  is dependent upon the position of the upper piston head  458  and the position of the lower piston head  460 . 
     The compressible chamber  468  stores energy by allowing the working fluid that is present in the upper chamber  464  and the lower chamber  466  to compress a compressible medium that is present inside the compressible chamber  468 . As one example, the compressible medium is a compressible gas, such as air. The compressible medium is elastic, such that the compressible medium returns to its original state when the force applied by the working fluid is removed. 
     When the upper piston head  458  and/or the lower piston head  460  move toward the compressed positions  459 ,  461 , thereby compressing the compressible chamber  468 , energy is stored in the compressible medium that is located in the compressible chamber  468  as a result of the working fluid being forced into the upper chamber  464  and/or the lower chamber  466 . When the upper piston head  458  and/or the lower piston head  460  move toward the uncompressed positions, thereby expanding the compressible chamber  468 , energy is removed from the compressible medium, and is utilized to force the working fluid out of the upper chamber  464  and/or the lower chamber  466 . 
       FIG. 5  is a diagram that shows an energy storage device  534  that can be utilized in the actuation system  122  in place of the energy storage device  234 . The energy storage device  534  includes a cylindrical housing  556  that is connected to the upper energy storage line  246  and the lower energy storage line  250 . An upper piston head  558  and a lower piston head  560  are disposed inside the cylindrical housing  556 . The upper piston head  558  and the lower piston head  560  are rigid structures that can move longitudinally within the cylindrical housing  556 . To guide motion of the upper piston head  558  and the lower piston head  560 , guide structures  562  can be formed inside the cylindrical housing  556  to engage and constrain motion of the upper piston head  558  and the lower piston head  560 . The upper piston head  558  and the lower piston head  560  divide the interior of the cylindrical housing  556  into several spaces that are substantially sealed against fluid flow between them. In the illustrated example, the cylindrical housing  556  is divided into three spaces including an upper chamber  564 , a lower chamber  566 , and a compressible chamber  568 . These components of the energy storage device  534  are all as described with respect to similarly named components of the energy storage device  234 . 
     The compressible chamber  568  stores energy by allowing the working fluid that is present in the upper chamber  564  and the lower chamber  566  to compress the volume displaced by the compressible chamber  568  within the cylindrical housing  556  and thereby compress a compressible medium that is present inside the compressible chamber  568 . As one example, the compressible medium is a compressible gas, such as air. 
     When the upper piston head  558  and/or the lower piston head  560  move toward compressed positions  559 ,  561 , thereby compressing the compressible chamber  568 , energy is stored in the compressible medium that is located in the compressible chamber  568  as a result of the working fluid being forced into the upper chamber  564  and/or the lower chamber  566 . When the upper piston head  558  and/or the lower piston head  560  move toward the uncompressed positions, thereby expanding the compressible chamber  568 , energy is removed from the compressible medium, and is utilized to force the working fluid out of the upper chamber  564  and/or the lower chamber  566 . 
     In order to vary the amount of energy stored in the compressible medium, the energy storage device  534  incorporates a pressure regulator  570 . The pressure regulator  570  is operable to increase and decrease a gas pressure within the compressible chamber  568 . 
     The pressure regulator  570  is connected to the energy storage device  534  by a pressure regulation line  572  and is in fluid communication with the compressible chamber  568  through the pressure regulation line  572 . The pressure regulator  570  can include a supply of high pressure gas, such as from a compressor, and can be operable to remove gas from the compressible chamber  568 , such by venting using a venting valve. The pressure regulator  570  can be an electromechanical system that receives commands from the suspension system controller  124 , wherein the commands cause the pressure regulator  570  to supply and/or remove gas from the compressible chamber  568  of the energy storage device  534 . 
     The pressure regulator  570  can increase the pressure within the compressible chamber  568  by supplying pressurized gas to the compressible chamber  568  through the pressure regulation line  572 . During supply of pressurized gas to the compressible chamber  568 , the upper piston head  558  and the lower piston head  560  can remain fixed in place, by holding the amount of working fluid within the energy storage device  534  constant using the upper valve assembly  230  and the lower valve assembly  232 . By increasing the pressure within the compressible chamber  568 , the pressure regulator  570  adds energy to the energy storage device  534 . The pressure regulator  570  can decrease the pressure within the compressible chamber  568 , such as by venting or pumping gas from the compressible chamber  568  to atmosphere or to a tank. During removal of gas from the compressible chamber  568 , the upper piston head  558  and the lower piston head  560  can remain fixed in place, by holding the amount of working fluid within the energy storage device  534  constant using the upper valve assembly  230  and the lower valve assembly  232 . By decreasing the pressure within the compressible chamber  568 , the pressure regulator  570  removes energy from the energy storage device  534 . 
       FIG. 6  is a diagram that shows an energy storage device  634  that can be utilized in the actuation system  122  in place of the energy storage device  234 . The energy storage device  634  includes a cylindrical housing  656  that is connected to the upper energy storage line  246  and the lower energy storage line  250 . An upper piston head  658  and a lower piston head  660  are disposed inside the cylindrical housing  656 . The upper piston head  658  and the lower piston head  660  are rigid structures that can move longitudinally within the cylindrical housing  656 . To guide motion of the upper piston head  658  and the lower piston head  660 , guide structures  662  can be formed inside the cylindrical housing  656  to engage and constrain motion of the upper piston head  658  and the lower piston head  660 . The upper piston head  658  and the lower piston head  660  divide the interior of the cylindrical housing  656  into several spaces that are substantially sealed against fluid flow between them. In the illustrated example, the cylindrical housing  656  is divided into three spaces including an upper chamber  664 , a lower chamber  666 , and a compressible chamber  668 . These components of the energy storage device  634  are all as described with respect to similarly named components of the energy storage device  234 . 
     The compressible chamber  668  stores energy by allowing the working fluid that is present in the upper chamber  664  and the lower chamber  666  to compress the volume displaced by the compressible chamber  668  within the cylindrical housing  656  in opposition to a force exerted upon the upper piston head  658  and the lower piston head  660  by an elastic structure that is located inside the compressible chamber  668  and is in engagement with the upper piston head  658  and the lower piston head  660 . In the illustrated example, the elastic structure includes a compression spring  674 . In alternative implementations, the elastic structure includes multiple springs, includes structures that behave like springs, or include other elastic structures that are able to resist compression in response to application of an external force and subsequently return to their original states when the external force is removed. 
     When the upper piston head  658  and/or the lower piston head  660  move toward compressed positions  659 ,  661 , thereby compressing the compressible chamber  668 , energy is stored in the compression spring  674  as the length of the compression spring  674  decreases as a result of the working fluid being forced into the upper chamber  664  and/or the lower chamber  666 . When the upper piston head  658  and/or the lower piston head  660  move toward the uncompressed positions in response to the force applied to them by the compression spring  674 , thereby expanding the compressible chamber  668 , energy is removed from the compressible medium, and is utilized to force the working fluid out of the upper chamber  664  and/or the lower chamber  666 . 
       FIG. 7  is a diagram that shows an energy storage device  734  that can be utilized in the actuation system  122  in place of the energy storage device  234 . The energy storage device  734  includes a cylindrical housing  756  that is connected to the upper energy storage line  246  and the lower energy storage line  250 . An upper piston head  758  and a lower piston head  760  are disposed inside the cylindrical housing  756 . The upper piston head  758  and the lower piston head  760  are rigid structures that can move longitudinally within the cylindrical housing  756 . To guide motion of the upper piston head  758  and the lower piston head  760 , guide structures  762  can be formed inside the cylindrical housing  756  to engage and constrain motion of the upper piston head  758  and the lower piston head  760 . The upper piston head  758  and the lower piston head  760  divide the interior of the cylindrical housing  756  into several spaces that are substantially sealed against fluid flow between them. In the illustrated example, the cylindrical housing  756  is divided into three spaces including an upper chamber  764 , a lower chamber  766 , and a compressible chamber  768 . These components of the energy storage device  734  are all as described with respect to similarly named components of the energy storage device  234 . 
     The compressible chamber  768  stores energy by allowing the working fluid that is present in the upper chamber  764  and the lower chamber  766  to compress the volume displaced by the compressible chamber  768  within the cylindrical housing  756  in opposition to a force exerted upon the upper piston head  758  and the lower piston head  760  by an energy storage actuator  776  that is located inside the compressible chamber  768  and is connected to and/or in engagement with the upper piston head  758  and the lower piston head  760 . The force exerted by the energy storage actuator  776  is controlled the by the suspension system controller  124 . As one example, the energy storage actuator  776  can be an electric motor and can also include a gear train or linkage that connects the electric motor to the upper piston head  758  and the lower piston head  760 . As another example, the energy storage actuator  776  can be a hydraulic actuator that is connected to the upper piston head  758  and the lower piston head  760  by piston rods. As another example, the energy storage actuator  776  can be an electromagnetic actuator that generates a magnetic field that attracts or repels the upper piston head  758  and the lower piston head  760 . 
     When the upper piston head  758  and/or the lower piston head  760  move toward compressed positions  759 ,  761 , thereby compressing the compressible chamber  768 , energy is stored in the energy storage device  734  as a function of the volume of the working fluid that is present within the upper chamber  764  and the lower chamber  766  and available to be forced out of the energy storage device  734  by movement of the upper piston head  758  and the lower piston head  760  toward the uncompressed positions, thereby expanding the compressible chamber  768 . 
     The energy storage device  234 , the energy storage device  534 , the energy storage device  634 , and the energy storage device  734  can be utilized in combination with one another for the purpose of storing energy using a compressible chamber. As an example, the compressible gas discussed in connection with the energy storage device  234  can be utilized in combination with the compression spring  674  of the energy storage device  634 . 
       FIG. 8  is a flowchart that shows an example of a process  800  for controlling an active suspension system with an energy storage device. The process  800  may be implemented using the hydraulic actuator  106 , the actuation system  122 , and may be implemented in part by software executed by some or all of the components of the vehicle  100 , such as the suspension system controller  124 . Although the process  800  is described in the context of active suspension control, it should be understood that the process  800  is applicable to actuator control generally. 
     Operation  801  includes determining a desired position and a desired direction of travel for an actuator. As an example, operation  801  can include determining a desired position for the piston rod  110  of the hydraulic actuator  106  relative to the cylinder body  108 . The desired position for the piston rod  110  is determined, for example, by the suspension system controller  124 , in order to achieve certain handling or ride quality characteristics. The desired direction of travel is determined based on a current position of the piston rod  110  of the hydraulic actuator  106 . The current position of the piston rod  110  may be determined, for example, by sensors that are incorporated in the hydraulic actuator  106  and provide output signals to the suspension system controller  124 . Such a sensor could be, for example, a linear variable differential transformer (LVDT). The desired direction of travel is then determined by comparison of the current position of the piston rod  110  and the desired position of the piston rod  110 . As an example, a first direction of travel can correspond to retraction of the piston rod  110  into the cylinder body  108 , and a second direction of travel can correspond to extension of the piston rod  110  from the cylinder body  108 . 
     Operation  802  includes determining an external force, such as F_ext, and an external force direction. The external force that is acting upon the piston rod  110  of the hydraulic actuator  106  can be measured by a sensor. As one example, the external force can be measured by a force sensor, such as a hydraulic force transducer. As another example, the external force can be determined based on motion of the piston rod  110 , as measured with a position sensor as previously described. The magnitude of the external force has a magnitude that corresponds to the direction of the external force. The direction of the external force may correspond to the first direction of travel of the piston rod  110  or the second direction of travel of the piston rod  110 . 
     In operation  803 , a determination is made as to whether to permit or resist motion of the piston rod  110  in response to the external force. This determination is made by comparing the desired direction of travel and the external force direction. If the desired direction of travel of the piston rod  110  matches the external force direction, the process proceeds to operation  804 . If the desired direction of travel of the piston rod  110  is opposite the external force direction, the process proceeds to operation  805 . 
     Operation  804  and operation  805  are performed using an energy storage device, such as the energy storage device  234 , the energy storage device  534 , the energy storage device  634 , or the energy storage device  734 , and will be explained with reference to the energy storage device  234 . In some implementations, use of the energy storage device  234  to store or release energy in operation  804  and operation  805  is only performed when additional criteria are satisfied. These criteria may be related to, as examples, the magnitude of the external force, the velocity of the piston rod  110 , and fluid pressures at one location or multiple locations in the hydraulic actuator  106  and/or the actuation system  122 . 
     In operation  804 , it has been determined that the direction of the external force is acting in the same direction as the desired direction of travel of the piston rod  110 . In response, the suspension system controller  124  operates at least one of the upper valve assembly  230  or the lower valve assembly  232  to permit motion of the piston rod  110  by allowing fluid to flow from the hydraulic actuator  106  to the energy storage device  234 , thereby compressing the compressible chamber  468  of the energy storage device  234 . 
     In operation  804 , since the actuation system  122  is able to allow the piston rod  110  to change position in correspondence with application of the external force, excess energy may be present in the actuation system  122 , and this energy can be stored by compressing the compressible medium or elastic structure in an energy storage device, such as the energy storage device  234 . To do so, fluid communication is established between the hydraulic actuator  106  and the energy storage device  234 , for example, such as by operation of valves as described in connection with the upper valve assembly  230  and the valve assembly  232 . Fluid is allowed to flow into the energy storage device  234 . Energy storage can continue, for example, until there is no longer enough excess energy in the actuation system  122  to compress the compressible medium of the energy storage device  234 , or until the direction of the external force is no longer acting in the same direction as the desired direction of travel of the piston rod  110 . When energy storage is completed, fluid communication between the hydraulic actuator  106  and the energy storage device  234  is blocked, such as by operation of valves as described in connection with the upper valve assembly  230  and the lower valve assembly  232 . 
     During operation  804 , damping can be applied to the motion of the piston rod  110 , such as by controlling the rate at which the working fluid is permitted to flow to the energy storage device  234 . 
     In operation  805 , it has been determined that the direction of the external force is acting opposite the desired direction of travel of the piston rod  110 . In response, the suspension system controller  124  operates at least one of the upper valve assembly  230  or the lower valve assembly  232  to resist motion of the piston rod  110  by allowing fluid to flow from the energy storage device  234  to the hydraulic actuator  106 , thereby expanding the compressible chamber  468  of the energy storage device  234 . 
     In operation  805 , to achieve motion of the piston rod  110  in the desired direction of travel, the actuation system  122  applies a force in opposition to the external force. To supplement fluid pressure that is otherwise available in the actuation system  122 , such as from the pump  228 , additional energy can be added to the actuation system  122 . This additional energy can be released by expansion of the compressible medium or elastic structure in an energy storage device, such as the energy storage device  234 . To do so, fluid communication is established between the hydraulic actuator  106  and the energy storage device  234 , such as by operation of valves as described in connection with the upper valve assembly  230  and the valve assembly  232 . Fluid is allowed to flow from the energy storage device  234  to the hydraulic actuator  106 . Energy release can continue, for example, until there is no longer enough excess energy in the energy storage device  234  to cause movement of the piston rod  110 , or until the direction of the external force is no longer acting in opposition to the desired direction of travel of the piston rod  110 . When energy storage is completed, fluid communication between the hydraulic actuator  106  and the energy storage device  234  is blocked, such as by operation of valves as described in connection with the upper valve assembly  230  and the lower valve assembly  232 . 
     Subsequent to operation  804  or  805 , the process  800  can return to operation  801 .

Metadata:
Filing Date: 20180326
Publication Date: 20201027
Grant Date: 20201027
Priority Date: 20170418
Inventors: KATZOURAKIS, Diomidis
PORRITT, CHRISTOPHER L.
HUENNEKENS, JOHANNES A.
MEES, HUIBERT
KEAS, PAUL J.
Assignee: APPLE INC
CPC Classifications: [{"code": "B60G2600/182", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2500/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2400/64", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2204/62", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/44", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/416", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/414", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/413", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/412", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/0165", "inventive": true, "first": true, "tree": "[]"}, {"code": "B60G17/0155", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G2202/413", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2400/64", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/412", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/414", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2600/182", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2204/62", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/0155", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G2202/416", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/0165", "inventive": true, "first": true, "tree": "[]"}, {"code": "B60G2500/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/44", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2204/62", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/412", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2500/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2600/182", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/0165", "inventive": true, "first": true, "tree": "[]"}, {"code": "B60G2202/416", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G17/0155", "inventive": true, "first": false, "tree": "[]"}, {"code": "B60G2202/414", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/413", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2202/44", "inventive": false, "first": false, "tree": "[]"}, {"code": "B60G2400/64", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 72944630