Patent Application
20050211320
Not Applicable
Not Applicable
1. Field of the Invention
The present invention relates to hydraulic valves, and in particular to valve assemblies having a plurality of sections butted together to control several functions of a machine.
2. Description of the Related Art
Construction and agricultural machines employ a hydraulic system to operate different mechanical devices. For example a backhoe is a common earth moving machine that has a bucket attached to the end of an arm which in turn is coupled by a boom to a tractor. Separate hydraulic cylinders are connected between adjacent ones of those elements to produce movement of one with respect to the other, which operation is commonly referred to as a “function” of the machine. The machine operator controls a given function by operating a valve that governs the flow of pressurized fluid from a pump to the associated cylinder and back to a tank. Hydraulic motors and other types of actuators also are used to move machine elements.
Each valve is part of an assembly that controls the operation of several machine functions. In the case of a backhoe, an assembly of four valves may be provided in the assembly to swivel and tilt the boom, move the arm, and tilt the bucket. U.S. Pat. No. 4,693,272 describes a typical valve assembly having a plurality of individual sections butted side by side, with each section containing one of the control valves and associated components. Each valve section has a bore in which a control spool slides to meter fluid between a pair of workports and the supply and tank return lines.
The valve sections have through passages for the supply line, tank return line, and load sense circuit. When a plurality of these sections are butted side by side these passages align to convey fluid through the entire assembly. It is common in prior designs, the through passages intersect the spool bore so that the fluid flows around the control spool from one section to another. The high pressure and pressure changes in these fluid passages as compared to other regions of the valve section commonly produced physical distortion of the spool bore. Another common feature that contributed to bore distortion was a bridge galley used in the valve section to convey pressurized fluid between portions of the spool bore.
The valve sections are bolted between end sections that have ports to connect the supply and tank hoses to the assembly. Heretofore a relatively large contact area was machined on opposite side walls of each valve section to provide surfaces against which the adjacent assembly sections abutted. The through passages had openings in those surfaces which aligned with similar openings in the abutting section. Unless the large contact area was machined extremely flat and parallel to the area on the opposite side surface, proper contact with the abutting section was not achieved and the assembly fastening force distorted the valve section and its spool bore.
Therefore it is desirable to design a valve section in which the effects of these distortion producing characteristics are minimized.
A valve section for a multiple hydraulic valve assembly comprises a body with first and second side surfaces and an end surface. A bore extends into the body from the end surface. A plurality of primary mating surfaces are raised from locations on the first side surface that are remote from a region of the first side surface adjacent the bore. A plurality of secondary mating surfaces are raised from locations on the second side surface which are remote from a region of the second side surface adjacent the bore. The primary mating surfaces are adapted to mate with the secondary mating surface of another valve section, and the secondary mating surfaces are adapted to mate with a primary mating surface of yet another valve section.
The body includes a plurality of common passages that are spaced from the bore. For example, the common passages convey supply fluid from a pump, convey fluid back to a hydraulic system tank, and form part of a load sense circuit. Each common passage extends between one of the plurality of primary mating surfaces and one of the plurality of secondary mating surfaces. A plurality of passageways connect the bore and each of the plurality of common passages. A control spool is slidably received in the bore and meters fluid to and from a function of a machine.
With initial reference to
A plurality of common passages extend from one side of the body 12 to the opposite side. Specifically, a supply passage 26 runs from the first mating surface 18 to the opposite third mating surface 20. A first circular groove 24 surrounds the opening of the supply passage 26 through the first mating surface 18 and a first annular seal 25 is within that groove. A first tank passage 28 also extends between the first and third mating surfaces 18 and 20. A second circular groove 27 surrounds the opening of the first tank passage 28 through the first mating surface 18 and has a second annular seal 29 therein. A second tank passage 30 has openings in the second and fourth mating surfaces 19 and 21 on opposite sides of the body 12. A third circular groove 31 extends around the opening of the second tank passage 28 through the second mating surface 19 and receives a third annular seal 33. A load sense passage 32 runs between the fifth mating surface 22 and the sixth mating surface 23. A fourth circular groove 34 surrounds the opening of the first tank passage 28 through the first fifth surface 22 and has a fourth annular seal 35 therein.
Three fastener apertures also extend between the opposite sides of the valve body 12. A first fastener aperture 36 is between the first and third mating surfaces 18 and 20 and a second fastener aperture 37 runs from the second mating surface 19 to the fourth mating surface 21. The third fastener aperture 37 is between the fifth and sixth mating surface 22 and 23. As will be described, these fastener apertures receive bolts which secure a plurality of valve sections together in a side-by-side manner.
A pair of workports 39 and 40 open through the upper surface of the valve body 12 in the orientation of the valve section 10 illustrated in
Each of the supply passage 26, the first and second tank return tank return passages 28 and 30, and the load sense passage 32 are spaced from the bore 41. In previous spool valve designs, one or more of these passages crossed through the bore at a chamber that allowed fluid to flow around the spool from one side of the valve section to the other. Under some circumstances, the section to section fluid flow through these passages distorted the valve bore or spool, thereby adversely affecting the valve operation. In the present design, these passages 28, 30 and 32 are remote from the bore 41, thereby distancing the forces produced by the flow through the valve section 10.
As a result of that separation, the supply passage 26 is connected to the bore by a first passageway 46 formed by a portion of an aperture 48 beneath the bore and a supply conduit 50. A manually operated flow control regulator 52 is located within that aperture 48 and has a shaft projecting outwardly from the valve body 14 on which a knob 54 is attached. A second passageway 56 couples the first tank return passage 28 to the bore 41, and a third passageway 58 similarly couples the second tank return passage 30 to the bore 41. A pair of workport passageways 60 and 62 respectively connect the first and second workports 39 and 40 to the spool bore. A cross passage 64 extends between the two workport passageways 60 and 62 and has a first shuttle valve 66 therein which selectively applies the highest of the two workport pressures to a second shuttle valve 68 located in the load sense passage 32 (
Referring now to
An end cap 72 abuts the exposed third, fourth and sixth mating surfaces of the valve section at one end of the series of sections. The adjoining side of the end cap 72 is shown in
A ported end section 80 is located at the opposite end of the valve assembly 70. An inlet port 84 of the ported end section 80 is coupled to the supply passage 26 and enables a supply hose to be attached to the valve assembly 70. An outlet port 86 on the ported end section 80 leads to the first and second tank return lines 28 and 30 and receives a hose for the tank of the hydraulic system. An additional port (not shown) on the side of the ported end section 80 is provided for an external connection to the load sense passage 32. The ported end section 80 also has a plurality of apertures 88 to bolt the valve assembly 70 to the frame of the machine on which it is being used.
Three bolts 90 extend through apertures in the ported end section 80, the fastening apertures 36, 37 and 38 in each valve section 10, and the apertures 78 in the end section 72 at which a nut 92 is threaded onto each bolt and tightened to secure the valve assembly together. Because the fastening apertures 36, 37 and 38 of each valve section 10 extend through the mating surfaces 18, 19, 20, 21, 22 and 23, the force exerted by the bolts is applied to the those mating surfaces. The size of the mating surface areas also has been reduced from that of prior spool valve sections. These characteristics allow the amount of torque required to hold multiple valve sections together to be reduced, which minimizes distortion of the spool bore 41 from the fastening force.
Spool bore distortion also is minimized by spacing the common passages 26, 28, 30, and 32 from the spool bore area, reducing the size of the mating surface area between sections, and placing those mating surface areas outside the regions 94 and 96 of the first and second side surfaces 16 and 17, respectively, which are adjacent to the spool bore 41 within the valve body 12 (see
The foregoing description was primarily directed to a preferred embodiment of the invention. Although some attention was given to various alternatives within the scope of the invention, it is anticipated that one skilled in the art will likely realize additional alternatives that are now apparent from disclosure of embodiments of the invention. Accordingly, the scope of the invention should be determined from the following claims limited by the above disclosure.
