MXPA98007508A - Hydraulic system and bo - Google Patents

Abstract

The present invention relates to a hydraulic system for hydraulic fluid pressurized to a hydraulic actuator, characterized in that it comprises: a hydraulic fluid pump comprising a pump inlet and a pump outlet, a pressure accumulator, and a hydraulic fluid valve it comprises a hydraulic actuator port adapted for connection to the hydraulic actuator, said valve being movable between first and second positions, said valve when in the first position directs fluid from the outlet of the pump to the hydraulic actuator and directs fluid from the accumulator to the inlet of the pump, said valve when in the second position directs fluid from the outlet of the pump to the accumulator and directs fluid from the port of the hydraulic actuator to the inlet of the pump.

Description

HYDRAULIC SYSTEM AND PUMP BACKGROUND OF THE INVENTION The present invention relates to a high efficiency hydraulic system for supplying pressurized hydraulic fluid to a hydraulic actuator and to a pump suitable for use in said system. In a type of conventional hydraulic system, a gear pump is used to pressurize hydraulic fluid and to direct the pressurized hydraulic fluid to a hydraulic actuator such as a cylinder used to perform the work. Once the cylinder completes its cycle (either extension or retraction), the hydraulic fluid in the pump is diverted to the pump supply tank or the opposite side of the cylinder piston is directed to the return stroke. Because the supply tank is at low pressure, it is necessary for the pump to develop again its full working pressure required for the cylinder to perform its function during the next cycle.

BRIEF DESCRIPTION OF THE INVENTION The present invention is defined by the claims given below, and nothing in this section should be limited or limited by these claims. As an introduction, it can be established here that the preferred modality described below is a hydraulic system that operates with high efficiency. This hydraulic system includes a pressure accumulator and a control valve. In the first position of the control valve »the pressurized hydraulic fluid of the accumulator is supplied to the pump inlet» and the outlet of the pump is connected to the hydraulic actuator to cause the hydraulic actuator to extend or retract when the valve is moved to the second position »the hydraulic actuator is connected to the pump inlet and the salt of the pump is connected to the accumulator. As the hydraulic actuator ejects hydraulic fluid »the expelled fluid is passed through the pump and the valve to the accumulator» where it is stored under substantial pressure »ready for use in the next cycle. Since the stored pressurized hydraulic fluid from the accumulator is applied to the pump inlet in the next cycle, less pumping energy is required in the next cycle compared to the conventional hydraulic system described above. This invention also relates to an improved pump that is provided with high pressure seals between the pump body and both of the arrows extending outwardly from a central element such as the drive gear of a gear pump. By using high pressure seals on both arrows associated with the drive gear, the internal pressures are balanced and wear and friction are reduced.

BRIEF DESCRIPTION OF THE DRAWINGS Figures 1 and 2 are schematic views of a hydraulic system in first and second operating modes respectively. Figure 3 is a sectional cross-sectional view of the gear pump of Figures 1 and 2. Figure 4 is a cross-sectional view of the gear pump of Figure 3 taken in a transverse plane of that of Figure 3. Figures 5 and 6 are cross-sectional views corresponding to that of Figure 4 of modified forms of the gear pump of Figures 3 and 4.

DETAILED DESCRIPTION OF THE PREFERENTIAL MODALITIES CURRENTLY Turning now to the drawings »Figure 1 shows a schematic view of a hydraulic system 10 incorporating the currently preferred embodiment of this invention. The hydraulic system 10 includes a hydraulic actuator such as a cylinder 12 and a pressure accumulator 14. The hydraulic actuator can take any suitable form "including ndros cil acc double onadores or sinc Llos» acc rotating onadores "and other hydraulic actuators. Depending on the application »the hydraulic actuator can use a piston as illustrated in the drawing» or alternatively you can be formed using a diaphragm. The accumulator 14 may be any suitable pressure accumulator including those which utilize pistons »diaphragms» bladders or membranes. Typically »a contained volume of a suitable gas» a spring or a weight is provided in such a way that the pressure of the hydraulic fluid in the accumulator 14 increases as the quantity of hydraulic fluid stored in the accumulator increases. The hydraulic cylinder 12 and the accumulator 14 are connected in parallel to one side of a direction control valve 16. The port 26 in the valve 16 connected to the hydraulic cylinder 12 will be referred to as a hydraulic actuator or cylinder port in this specification. The other side of the steering control valve 16 includes two passages which are respectively connected to the inlet 20 and to the outlet 22 of a hydraulic fluid pump 18. In the embodiment of Figure 1 the pump 18 is illustrated as a gear pump »although other pumps such as vane pumps» piston pumps and rotary screw pumps can be used. As shown in Fig. 1, a bypass valve 24 operated by a pilot is provided. The bypass valve 24 provides free communication between the outlet of the pump 22 and the inlet 20 of the pump in the event that the pressure at the outlet of the pump 22 exceeds a predetermined value. The hydraulic system 10 includes two basic modes of operation as illustrated in FIGS. 1 and 2 respectively. In Figures 1 and 2 the hydraulic fluid of the higher pressure is indicated by a more densely dotted region 28 and the lower pressure hydraulic fluid is indicated by a less densely dotted region. In the first mode of operation (figure 1) »the valve 16 is placed in a first position» in which the pump outlet 22 is connected through the hydraulic cylinder port 26 to the hydraulic cylinder 12 »and in which the accumulator 14 is connected to inlet 20 of the pump. In this mode of operation the pressurized hydraulic fluid of the accumulator 14 is further pressurized by the pump 18 and taken to the hydraulic cylinder 12. As shown in Fig. 2 »in the second mode of operation the valve 16 is moved to the second position in which the outlet 22 of the pump 18 is connected to the accumulator 14 »and in which the hydraulic cylinder 12 is connected through the hydraulic cylinder port 26 and the valve 16 to the inlet 20 of the pump. In this mode of operation the pressurized hydraulic fluid of the cylinder 12 passes through the pump 18 and is stored in the accumulator 14. In this way »the need to discharge the hydraulic fluid from the hydraulic cylinder to the drain at atmospheric pressure is avoided» and the hydraulic fluid energy stored in the accumulator 14 is available for use when the valve 16 is returned to the first position in Figure 1 to ignite the hydraulic cylinder 12. Figures 3 and 4 provide further information regarding a pump 18 of suitable preference for use in the hydraulic system of Figures 1 and 2. As shown in Figures 3 and 4 »the pump 18 includes a body 40. In this embodiment the body includes upper and lower covers 64 (Figure 4)» and three basic components of the body 40 are joined by threaded fasteners (not shown). The body 40 supports a driving gear 44 and a tracking gear 46 for rotation "as well as a pressure relief valve 42 that is located between the inlet 20 and the outlet 22 (Figure 3). The pressure relief valve 42 ensures that pressures above a preset limit in the salt 22 are built back into the inlet 20, thus preventing the pressure at the outlet 22 from exceeding a predetermined threshold. As shown best in Figure 4 »the driving shaft 44 is connected to a motor 50 which can take any suitable shape. For example »electric motors» internal combustion engines »and turbines can be used for motor 50. Motor 50 rotates a pumping element 52 which in this mode includes first and second coaxial arrows 54» 56 which extend from any side of a central element 58. In this embodiment the central element 58 corresponds to the driving gear 44 of figure 3. As shown in figure 3 »the driving gear 44 defines the hydraulic fluid depressions 60 which cooperate with the recesses of hydraulic fluid 60 of tracking gear 46 to provide the conventional pump action of the gear pump. Returning to FIG. 4, bearings 62 are provided around the first and second arrows 54, 56 such that the arrows 54, 56 and thus the pumping element 52 are mounted for rotation in the body 40. A plate Use 68 is mounted around the arrow 54 adjacent the central element 58. As shown in Figure 4, two high pressure GG seals are provided. Each high pressure seal 66 is positioned around the respective arrow 54-56 adjacent an outer surface of the respective cover 64. Each high pressure GG seal substantially prevents the leakage of high pressure hydraulic fluid past seal 66. In this mode the high pressure GG seals are U-cup seals, although any suitable high pressure seal can be used. As used hereafter, the term "high pressure seal" is used to refer to a seal capable of sealing against the flow of pressurized hydraulic fluid at a pressure on a working scale that extends beyond the nearly 70 Kg / cm3. The high pressure seals 66 simultaneously perform two separate functions. First »they substantially eliminate leaks of hydraulic fluid out of the pump body 40 around the arrows 54» 56. Second »prevent the accumulation of high pressure hydraulic fluid at the end of the arrow 56. If such high pressure hydraulic fluid accumulated within the pump body 40 would result in an asymmetrical force tending to push the upper wear plate 68 (in the orientation of Figure 4) against the respective lid 64. thereby generating unwanted heat and friction. By properly sealing both arrows 54 »56 with the high pressure seals GG» this disadvantage is eliminated substantially in the pump 18. Figure 5 shows a first modification of the pump 18 »in which drains 70 are provided for the regions 72 adjacent to the high pressure seals 66. Such drains are useful for reasons of environment and home maintenance »but they are not required in all modalities. In the embodiment of Figure 5. Low pressure seals 74 prevent leakage of hydraulic fluid around the arrows 54-56 adjacent to the outer surfaces of the covers 64. The drains 70 are preferably connected to a pressure drain tank. atmospheric The two drains 70 can be joined to a common drain or can be connected indivdually to a containment tank. In the embodiment of FIG. 5 »low pressure seals 74 may be seals such as O-rings," cup seals "or labyrinth seals.

As used here, the term "low pressure seal" is used to cover seals that have a maximum sealing pressure of no more than about 7 kg / cm3. Figure 6 shows another modified version of the pump 18 »in which the low pressure seal adjacent the end of the arrow 56 is formed by a ring at 0 76 and a cover plate 78. Other suitable low pressure seals can be used. A wide variety of components can be adapted for use in this invention. Without attempting any limitation to the following claims, the following construction details are provided in order to define in greater detail the best form of the invention that is currently contemplated by the inventor.

Source Element Hydraulic Cylinder 12 Great Bend Ind. (Great Bend »KS)« 14830 Accumulator 14 Great Bend Ind. 1 * 14855 Seal 66 high pressure Amer can Varisea! Corp. (Denver »CO) 8567250-1135 cv Seal 74 low pressure Chicago Rawh of # CR12438 The pump 18 can be formed as a modified version of the pump sold by GearteK as part number GT 7300. The main modification is to provide the high pressure seals 66 and the low pressure seals 74 »76 as described above. The preferred embodiment described above can operate with the following pressures in the first and second operating modes illustrated above in Figures 1 and 2. These illustrative pressures are suitable for a 3-inch cylinder.

Location Hydraulic pressure Hydraulic pressure Mode 1 (Kg / cmz) Mode 2 (Kg / cmß) Hydraulic cylinder 12 112.48 7.03 Accumulator 14 70.3 112.48 Pump inlet 20 70.3 70.3 Pump outlet 22 112.48 112.48 The detailed description mentioned above has described only a few of the many forms that the present invention can take. For example, this invention can quickly be adapted for pneumatic systems in which the hydraulic fluid is a gas. For this reason, it is intended that the above detailed description be seen as an illustration of selected forms of this invention and not as a definition of the invention. They are only the following rei i dtions. including all equivalents »which attempt to define the scope of this invention.

Claims (8)

NOVELTY OF THE INVENTION CLAIMS

1. - A hydraulic system for supplying pressurized hydraulic fluid to a hydraulic actuator "said system consisting of: a hydraulic fluid pump comprising a pump inlet and a pump outlet» a pressure accumulator; and a hydraulic fluid valve comprising a hydraulic actuator port adapted for connection to a hydraulic actuator. said valve movable between first and second positions, said valve when in the first position directing fluid from the outlet of the pump to the hydraulic actuator and directing the fluid from the accumulator to the inlet of the pump »said valve when it is in the second position directing fluid from the pump outlet to the accumulator and directing the fluid from the port of the hydraulic actuator to the inlet of the pump.

2. The hydraulic system according to claim 1 »further characterized in that it comprises: a pump body» a rotating pump element mounted on the pump body »said pump element consisting of first and second arrows that extend towards out from opposite sides of a central element, said central element forming depressions of received hydraulic fluid, said first and second arrows joined in the body of the pump; and first and second high pressure seals. each seal interposed between the pump body and a respective arrow "said seals functioning to seal substantially against the flow of hydraulic fluid between the arrows and the pump body away from the central element.

3. A hydraulic fluid pump comprising: a pump body; a rotating pump element mounted on the body of the pump »said pump element consisting of first and second arrows extending outward from opposite sides of a central element» said central element forming hydraulic fluid receiving recesses said first and second arrows joined in the pump body; and first and second high pressure seals »each seal interposed between the pump body and one of the respective arrows» said seals operating to seal substantially against the flow of hydraulic fluid between the arrows and the pump body away from the central element. 4.- The hydraulic system »in accordance with the rei indication 1» or 2 or 3 »further characterized because the pump consists of a gear pump» and because the central element consists of a gear. 5. The hydraulic system according to the re-indication 2 or 3 further characterized in that it consists of at least one hydraulic fluid drain connected to the pump body to drain a respective region between one of the respective arrows and the body of the pump. pump, each region located on one side of the respective seal opposite the central element. 6. The hydraulic system according to claim 5. further characterized in that it consists of at least one low pressure seal, each low pressure seal located adjacent to the respective region to seal substantially against the flow of hydraulic fluid out of the body of the pump in the respective region. 7. The hydraulic system according to claim 6. further characterized in that said low pressure seals are each interposed between the pump body and each of the respective arrows. 8. The hydraulic system according to claim 2 or 3 »further characterized in that each high pressure seal consists of a respective annular cup seal.