Patent Publication Number: US-2022219652-A1

Title: Electro-hydraulic modulating valve pedal assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and all advantages of U.S. Provisional Patent Application No. 62/835,215 filed on Apr. 17, 2019, the content of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to an electro-hydraulic modulating valve pedal assembly to achieve a desired braking demand and for other applications. 
     BACKGROUND OF THE INVENTION 
     A variety of valves are designed for vehicles that are equipped with hydraulic power devices. For example, it is known to provide pedal-actuated hydraulic valves for forestry equipment, agricultural equipment, construction equipment, military equipment, and mining equipment. These hydraulic valves can be installed in conjunction with floor mounted pedals or suspended pedals to provide normal and emergency braking, and to operate industrial equipment. 
     Hydraulic circuits for pedal-actuated hydraulic valves typically include a pump or an accumulator and include a braking system or an industrial tool. If an accumulator is used, the accumulator can include a charging valve to provide a pressurized hydraulic fluid to the hydraulic brake valve. Known hydraulic brake modulation valves include a pressure port, a tank port, and a working port. These valves are mechanically actuated with a spool for controlling the flow of pressurized hydraulic fluid to the working port for use by the braking system or the industrial tool. 
     Despite the widespread acceptance of pedal-actuated hydraulic valves, there remains a continued need for an improved hydraulic pedal modulating valve assembly that can be better integrated into electronic control systems, including anti-lock braking (ABS) systems and autonomous driving systems. In particular, there remains a continued need for a hydraulic pedal assembly that can provide hydraulic pressure in response to both foot pedal actuation and electrical control inputs. 
     BRIEF SUMMARY 
     An improved electro-hydraulic modulating valve pedal assembly is provided. The electro-hydraulic pedal assembly is adapted to control the flow of hydraulic fluid both manually, through actuation of a pedal, and electrically, through activation of a solenoid. The pedal assembly is well suited for electronic control systems, including brake electronic control units (ECUs) for ABS braking, emergency braking, autonomous operation, and other applications. 
     In one embodiment, the electro-hydraulic pedal assembly includes a push rod that is mechanically coupled to a pedal, a solenoid that is magnetically coupled to the push rod (having a magnetic armature), and a spool valve that is configured to vary a hydraulic output in response to the force exerted by the push rod. The solenoid surrounds at least a portion of the magnetic armature for applying a magnetic force and driving the push rod in a first (downward) direction, the magnetic force being proportional to an electrical current supplied to the solenoid. The spool valve includes a spool that is concentrically arranged within a valve body, such that movement of the push rod in the first (downward) direction causes a corresponding movement of the spool in the first (downward) direction. In this position, the spool valve provides fluid communication between a pressure port and a work port. A return spring returns the spool valve to the neutral position. In the neutral position, the spool valve provides fluid communication between the working port and a tank port. 
     In the current embodiment, the electro-hydraulic pedal assembly includes a three-position hydraulic spool valve having two valve operators: a pedal and a solenoid. The hydraulic valve includes a working port coupled to a working unit, a pressure port coupled to a hydraulic pump, and a tank port coupled to a hydraulic reservoir. In the first valve position, the working port is coupled to the tank port to prevent unwanted pressure buildup from actuating the working unit. In the second valve position, all three ports are closed off from each other. In the third valve position, the pressure port is coupled to the working port. The valve operators function independently of each other and in parallel, such that the spool valve can respond to actuation by the pedal—independently of the energized state of the solenoid—and can respond to actuation by the solenoid—independently of the position of the pedal, to rapidly transition from one position to the next, optionally in response to electronic control signals from a brake ECU. 
     These and other features and advantages of the present invention will become apparent from the following description of the invention, when viewed in accordance with the accompanying drawings and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a first perspective view of an electro-hydraulic modulating valve pedal assembly in accordance with one embodiment of the present invention. 
         FIG. 2  is a second perspective view of an electro-hydraulic modulating valve pedal assembly in accordance with one embodiment of the present invention. 
         FIG. 3  is a cross-sectional view of the electro-hydraulic modulating valve pedal assembly of  FIGS. 1-2 . 
         FIG. 4  is a hydraulic circuit diagram of the electro-hydraulic modulating valve pedal assembly of  FIGS. 1-3 . 
         FIG. 5  is a perspective view of the electro-hydraulic modulating valve pedal assembly of  FIG. 1  modified to include a wall mounted foot pedal. 
         FIG. 6  is a cross-sectional view of the electro-hydraulic modulating valve pedal assembly of  FIG. 1  modified to include a tandem valve assembly. 
         FIG. 7  is a perspective view of the electro-hydraulic modulating valve pedal assembly of  FIG. 1  further including a Hall Effect sensor. 
     
    
    
     DETAILED DESCRIPTION OF THE CURRENT EMBODIMENT 
     Referring to  FIGS. 1-3 , an electro-hydraulic modulating valve pedal assembly in accordance with one embodiment is illustrated and generally designated  10 . The electro-hydraulic pedal assembly  10  generally includes a foot pedal  12  pivotably mounted to a base  14 , an internal push rod  16  (or armature) mechanically coupled to the foot pedal  12 , a three-position spool valve  18  that is configured to vary a hydraulic output in response to the force exerted on the push rod  16 , and a solenoid assembly  20  between the base  14  and the spool valve  18 , the solenoid assembly  20  being magnetically coupled to the push rod  16 . Each such feature of the electro-hydraulic pedal assembly  10  is separately discussed below. 
     The foot pedal  12  generally includes a pedal body  22  with an upward-facing contact surface  24 . As shown in  FIGS. 1 and 2 , the pedal body  22  is pivotably secured to the base  14  with an axle  26 . More specifically, the axle  26  is collared by left and right bearing journals  28  extending upwardly from the base  14 . The axle  26  therefore defines a primary pivot axis, about which the pedal body  22  can rotate. The foot pedal  12  also includes left and right connector flanges  30 ,  32  extending downwardly from the pedal body  22  and coupled to a piston  34 . The connector flanges  30 ,  32  are in alignment with each other and receive a pivot shaft  36  joined to the piston  34 , which is contained within a protective boot  38 . The pivot shaft  36  is parallel to the primary pivot axis, such that rotation of the pedal body  22  results in downward travel of the piston  34  into an internal chamber within the base  14  of the pedal assembly. 
     A cross-section of the foot pedal piston  34  in the neutral position is shown in  FIG. 3 . The foot pedal piston  34  defines a first seat  40  for a first spring S 1 , the first spring being in series with a second spring S 2 . The foot pedal piston  34  also defines a second seat  41  for a third spring S 3 , the third spring S 3  being in parallel with the first and second springs S 1 , S 2 . The uppermost portion of the push rod  16  is captured within an intermediate retainer  43 , such that downward movement of the retainer  43  results in downward movement of the push rod  16 . The lower portions of the second spring S 2  and the third spring S 3  are seated against an upward-facing shoulder  42 . The second spring S 2  is held captive between the retainer  43  and the upward-facing shoulder  42 , and the third spring S 3  is held captive between the second seat  41  and the upward-facing shoulder  42 . 
     In the neutral position shown in  FIG. 3 , the first and second springs S 1 , S 2  are not compressed. In addition, the first spring S 1  is slightly stronger than the second spring S 2 , with the difference in spring constants providing a downward force to the retainer  43 , the downward force being comparable to the force generated by the solenoid assembly  20 . The force from the solenoid assembly  20  and the foot pedal  12  is additive, such that applying both at the same time can result in a higher valve pressures if desired. 
     Referring again to  FIG. 3 , downward travel of the foot pedal piston  34  is opposed by each spring S 1 , S 2 , S 3  and causes downward travel of the push rod  16 . The push rod  16  extends through the solenoid assembly  20  and is surrounded by a magnetic armature  17 , the push rod  16  being joined to a spool  44  within a central bore  46  of the spool valve  18 . Activation of the solenoid coil  48  also causes downward travel of the push rod  16  (the push rod  16  being joined to the armature  17 ), which is opposed by the second spring S 2 . In this regard, the cumulative spring force that opposes downward travel of a solenoid-only-actuated push rod  16  is less than the cumulative spring force that opposes downward travel of a pedal-only-actuated push rod  16 , thereby accounting for the different forces generated by the solenoid assembly  20  and the foot pedal  12 . 
     Each spring S 1 , S 2 , S 3  is a compression coil spring in the illustrated embodiment, but can be a wave spring in other embodiments. The compression coil spring or the wave spring can be linear or progressive, optionally a dual-rate coil spring, further optionally a progressive coil spring. The armature  17  is formed of a ferromagnetic material, for example iron, and extends concentrically through a central bore of the pedal assembly  10 . The solenoid coil  48  surrounds at least a portion of the armature  17  for applying a magnetic force and driving the push rod  16  in a first (downward) direction, the magnetic force being proportional to the electrical current supplied to the solenoid coil  48 . The solenoid assembly  20  additionally includes a socket  50  for power cables, which provide the electrical current to the solenoid coil  48 . 
     As also shown in  FIG. 3 , the spool valve  18  includes a valve body  52  defining a pressure port  54 , a work port  56 , and a tank port  58 . The pressure port  54  provides a connection for a source of pressurized hydraulic fluid, for example a hydraulic pump or an accumulator. The work port  54  provides a connection for a working unit, for example a hydraulic cylinder or a brake. Lastly, the tank port  58  provides a connection for a tank or a hydraulic reservoir. In accordance with SAE standards, each port includes a conventional straight thread for connection to one or more conduits. The spool valve  18  further includes a bore  46  in alignment with the push rod  16  of the solenoid assembly  20 . The spool valve  18  also includes a return spring S 4  that biases the spool  44  in the de-energized direction (upwardly as shown in  FIG. 3 ). Consequently, the return spring S 4  acts to return the push rod  16  to the neutral position when the solenoid assembly  20  is de-energized. Further, the amount of force applied to the push rod  16  is proportional to the amount of brake pressure being applied. 
     More specifically, each of the ports  54 ,  56 , and  58  are in fluid communication with the bore  46 . The bore  46  includes a first annular surface  60  and a second annular surface  62  on either side of the work port  56 . These surfaces cooperate with the spool  44  to selectively direct fluid to the work port  56 . The spool  44  includes a first annular portion  64  and a second annular portion  66 . These annular portions are configured to coincide with the first annular surface  60  and the second annular surface  62  of the bore  46 . The spool  44  also includes a shoulder  68  proximate the upper end of the spool valve  18 . Also at the upper end of the spool valve  18 , a fifth spring S 5  is disposed in the bore  46 , the fifth spring S 5  optionally being a compression coil spring. A washer  72  is disposed between the shoulder  68  and the fifth spring S 5  to provide a mechanical stop to the spring compression. In addition, the washer  72  functions to define the neutral position of the spool  44 , which allows a faster release of work port pressure than would otherwise be possible. 
     In use, when pressurized fluid is desired at the working port  56 , the foot pedal  12  is manually compressed and/or the solenoid coil  48  is energized. The push rod  16  moves in the first (downward) direction, causing the spool  44  to likewise move in the first (downward) direction. The first, second, third, and fourth springs S 1 , S 2 , S 3 , S 4  provide the desired pedal feel during compression of the foot pedal  12 . If the solenoid coil  48  is energized without movement of the foot pedal  12 , only the second spring S 2  and the fourth spring S 4  oppose downward travel of the push rod  16 , and the piston  34  remains in the neutral position. In this position, pressurized fluid is permitted to flow from the pressure port  54  to work port  56  for operation of a working unit. At the same time, fluid flow to the tank port  58  is obstructed by a close fit between the lower annular surface  62  of the valve body and the lower annular portion  66  of the spool  44 . Upon the desired release of the pressurized fluid, the foot pedal  12  is depressed and/or the solenoid coil  48  is de-energized. The spool  44  moves in the second (upward) direction by the force from the second spring S 2  and the fourth spring S 4  and by the imbalance of fluid pressure forces acting on the spool  44 . The combination of the return spring force and the force resulting from residual work port pressure compresses the fifth spring S 5  and shifts the spool  44  in the second (upward) direction. In this neutral position, shown in  FIG. 3 , the necessary fluid flow need only accommodate leaking from the pressure port  54  into the bore  46  (exiting through the tank port  58 ) to prevent unwanted pressure buildup from actuating a working unit coupled to the working port  56 . 
     Referring now to  FIG. 4 , a hydraulic circuit diagram for the electro-hydraulic pedal assembly  10  is illustrated. The electro-hydraulic pedal assembly  10  is depicted as a three-position valve  100  having two valve operators: a pedal  102  and a solenoid  104 . The valve operators  102 ,  104  function independently of each other and in parallel, such that the valve  100  can respond to actuation by the pedal  102  independently of the energized state of the solenoid  100  and can respond to actuation by the solenoid  104  independently of the position of the pedal  102 . The working port  106  is coupled to a working unit  108 , the pressure port  110  is coupled to a hydraulic pump  112  and optional filter  114 , and the tank port  116  is coupled to a hydraulic reservoir  118 . In the first (neutral) position as shown in  FIG. 4 , the working port  106  is coupled to the tank port  116  to prevent unwanted pressure buildup from actuating the working unit  108 . In the second (intermediate) position, all three ports are closed off from each other. In the third (open) position, the pressure port  110  is coupled to the working port  106 . The solenoid  104  of the electro-hydraulic pedal assembly  10  is especially well suited for electronic control systems, including brake ECUs for ABS braking, emergency braking, semi-autonomous operation, and other applications. 
     As noted above in connection with  FIGS. 1-3 , the electro-hydraulic modulating valve pedal assembly  10  includes a floor-mounted foot pedal  12  for actuating a piston  34 . As alternatively shown in  FIG. 5 , the assembly  10  can include a wall-mounted foot pedal  12 . This embodiment is structurally and functionally similar to the embodiment of  FIGS. 1-3 , except that compression of the foot pedal  12  of  FIG. 5  causes a bracket assembly  70  to rotate clockwise (as viewed in  FIG. 5 ) about the axle  26 . The axle  26  is collared by the left and right bearing journals  28  extending upwardly from the base  14 . Consequently, compression of the foot pedal  12  results in downward travel of the piston  34  substantially in the manner set forth above in connection with the embodiment of  FIGS. 1-3 . Still other embodiments of the wall-mounted pedal  12  include an inverted-vertical configuration, such that the spool valve  18  is positioned vertically above the solenoid assembly  20 . 
     Referring now to  FIG. 6 , a further embodiment of the electro-hydraulic modulating valve pedal assembly  10  is illustrated. This embodiment is structurally and functionally similar to the embodiment of  FIGS. 1-3 , except that the spool valve  18  includes a tandem modulating valve. As a tandem modulating valve, the spool valve  18  of  FIG. 6  includes: a primary work port  56 , a secondary work port  57 , primary and secondary tank ports  58  in fluid communication with each other, and primary and secondary pressure ports (not visible). The primary work port  56 , the primary tank port  58 , and the primary pressure port are contained within an upper valve housing  72 . Similarly, the secondary work port  56 , the secondary tank port  58 , and the secondary pressure port are contained within a lower valve housing  74 . The push rod-actuated tandem spool valve  18  can be actuated substantially as set forth above in connection with the embodiment of  FIGS. 1-3 . In particular, the electro-hydraulic modulating valve pedal assembly  10  is adapted to control the flow of hydraulic fluid to the primary and secondary work ports  56 ,  57  manually through actuation of the foot pedal  12 , electrically through energization of the solenoid coil  48 , or cooperatively through actuation of the foot pedal  12  and energization of the solenoid coil  28  simultaneously. 
     Referring now to  FIG. 7 , a further embodiment of the electro-hydraulic modulating valve pedal assembly  10  is illustrated. The embodiment of  FIG. 7  is structurally and functionally similar to the embodiment of  FIGS. 1-3 , except that the embodiment of  FIG. 7  includes a sensor  80  for measuring the angular position of the foot pedal  12  directly or indirectly. The sensor  80  is a Hall Effect sensor (single or dual) in the current embodiment, but can include other contact or non-contact sensors in other embodiments. As also shown in  FIG. 7 , the Hall Effect sensor  80  is adapted to measure the position of the pivot shaft  36 , which also corresponds to the angular position of the pedal  12  and the linear position of the piston  34 . The Hall Effect sensor  80  provides an output, for example a pulse-width-modulated digital output that is indicative of the then-existing position of the pivot shaft  36 . The output of the Hall Effect sensor  80  is then provided to an electronic control unit, for example a brake ECU. The brake ECU (or other electronic control unit) can then control operation of ABS systems (or other systems) with improved accuracy over existing systems. While illustrated in connection with a single modulating valve  18 , the Hall Effect sensor  80  can also be used in combination with the tandem modulating valve  18  of  FIG. 6  in the same manner as set forth above. 
     The above description is that of current embodiments. Various alterations and changes can be made without departing from broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. This disclosure is presented for illustrative purposes and should not be interpreted as an exhaustive description of all embodiments or to limit the scope of the claims to the specific elements described in connection with these embodiments. The present invention is not limited to only those embodiments that include all of these features or that provide all of the stated benefits, except to the extent otherwise expressly set forth in the issued claims. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular.