Multi-boost synchronized hydraulic pump

Abstract: The disclosed multi-boost synchronized hydraulic pump comprises a plurality of piston-type pumping means installed in series, a common connecting shaft (4) connecting these pumping means and a driving means for synchronously driving a plurality of pistons (3) through this connecting shaft (4), and is configurated in a manner capable of supplying pressurized liquid of equal pressure and equal flow rate from a plurality of pumping means.

Description: The present invention relates to a multi-boost synchronized hydraulic pump, and specifically relates to a multi-boost synchronized hydraulic pump which is optimum to deliver synchronously a plurality of hydraulic flows. Conventionally, in the case of driving, for example, a plurality of hydraulic cylinders in a synchronized manner by hydraulic fluid supplied from a single hydraulic supply source, generally a hydraulic supply piping is branched and a flow control valve or a variable throttle valve is inserted in each branch piping and a hydraulic cylinder is connected to each branch piping, and thereby the flow rate of hydraulic fluid supplied to each cylinder is adjusted to become equal. In the known hydraulic pump using variable throttle valves or the like, adjustment of the degree of opening one throttle valve affects the control of flow rate of the other throttle valves, and therefore it is very difficult to adjust a variable throttle valve inserted in each branch piping, and problems exist that consideration is required on setting the length and the bent part of the branch piping to each hydraulic cylinder equal whenever possible, no stable operation is obtainable because of variation in flow rate due to variation in open air temperature and the number of parts such as pipes and valves of the piping system is increased. One object of the present invention is to provide a multi-boost synchronized hydraulic pump which can be manufactured easily at a low cost and wherein the number of the hydraulic operation chambers can be varied as required. Another object of the present invention is to provide a multi-boost synchronized hydraulic pump wherein the discharging pressure and discharging rate can be set freely only by partly replacing parts. GB-A-1,128,962 discloses a coaxial array of cylinders having as a driving means a common pressurised hydraulic fluid supply means, the entire assembly of pistons in the cylinders being mechanically ganged to ensure synchronized operation of two or more identical rains. US-A-3,783,620 discloses a synchronizer in the form of a set of cylinders mechanically interconnected for synchronous operation, and simultaneously supplied to move with hydraulic pressure from a common source, whereby the single hydraulic pressure source can then feed the piston in each cylinder and thus respective discharges from the cylinders to other working cylinders will be synchronised by virtue of the mechanical interconnection of the cylinders. FR-A-1 575 806 likewise discloses a synchronizer for providing a plurality of discharge flows generated by a single supply flow by way of a set of mechanically interconnected cylinders. GB-A-1,128,962 forms the basis of the preamble of claim 1, and claim 1 indicates the scope of the invention. In some embodiments each cylinder chamber is defined by an integral component having the sidewall and the endwall, and in others a separate endwall and sidewall are provided for each cylinder chamber. Preferably the components making up the assembly of cylinder chambers are capable of being dismantled for ready replacement of some of the components and for changing the number of cylinder chambers in the assembly. Seals may be provided at the junction of the sidewall to the topwall. The preferred form of the invention using these formats in which the cylinders can be readily assembled one behind another allows the number of cylinders to be changed and also allows the geometry of individual cylinders to differ, for example by having a different internal diameter for one of the cylinders as compared with another, and a correspondingly different piston. Another way of changing the geometries of the cylinders is to provide some of the pistons with greater diameter spacer extensions than others. The important consideration is that the swept area of the piston in the cylinder chamber will have the desired value which may be different from one cylinder to the next. Mechanically linking the pistons together will mean that some of the cylinders will have higher delivery pressures than others in the case where the swept area is different from one cylinder to the next. Where the swept area is the same for all cylinders, the discharge hydraulic flows are equal in speed and volume flow rate and may drive synchronised actuating rams. Providing a different swept area will allow a degree of synchronisation but the flow rates of the various discharge flows will not all be the same. Where the swept areas of the cylinder chambers differ, the various delivery hydraulic flows may be combined to drive a common hydraulic cylinder, by way of respective pressure relief valves which thereby allow the flows to occur sequentially, to give a stepped operation of the common hydraulic cylinder. The pistons may be individually fixed integrally to the connecting shaft, or they may be sequentially fitted coaxially around the shaft and then fastened in place, for example by means of a nut. Apart from the return-spring-loaded type single-acting pneumatic cylinder illustrated as driving means it is possible to use a return-spring-loaded single-acting hydraulic cylinder, a double-acting type pneumatic cylinder or hydraulic cylinder, a solenoid type actuator, a motor and a cam driven by such motor, or a motor and a crank mechanism driven by such motor. The invention will be further described by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a cross-sectional view of a multi-boost synchronized hydraulic pump which is not in accordance with the invention but is useful for describing it. Fig. 2 is a plan view of the hydraulic pump as shown in Fig. 1. Fig. 3 through Fig. 5 are cross-sectional views of major parts of modifications of the hydraulic pump as shown in Fig. 1, respectively which modifications are also applicable to pumps of the invention. Fig. 6 is a side view of a lubricant supply pump of a first embodiment of the present invention. Fig. 7 is a cross-sectional view of a major part of a modification of the lubricant supply pump as shown in Fig. 6. Description is now made on a plurality of specific embodiments in accordance with the present invention with reference to drawings and other pumps. Fig. 1 shows a multi-boost synchronized booster which is not in accordance with the present invention, but assists in describing it, and this booster is suitable for applications to the hydraulic apparatuses, for example, for a carrying cart having a lifting function, a metal mould fixing apparatus of a press machine, injection moulding machine or the like, a positioning apparatus of a metal mould of a press machines or work to be machined, and press shearing apparatus. This multi-boost booster comprises a casing 1, four cylindrical cylinder chambers 2 formed in series inside this casing 1, a piston 3 installed slidably in each cylinder chamber 2, a connecting shaft 4 integrally connecting the four pistons 3, and a driving means 5 for synchronously driving the four pistons 3 reciprocatively through the connecting shaft 4. The casing 1 is formed with four divided units 1A of casing 1 corresponding to the respective cylinder chambers 2, and each divided unit 1A of casing 1 is configurated integrally with a partition wall part 1a configurating the top end wall of the cylinder chamber 2 and a peripheral wall part 1b configurating the peripheral wall of the cylinder chamber 2. These four divided units 1A of casing 1 are stacked upward, and as shown in Fig. 2, being tightened to a casing 10 of the driving means 5 with four through bolts 22. In addition, an inner diameter D₁ of four cylinder chambers 2 is formed equally, and the length thereof is formed also equally. A hydraulic operation chamber 6 is sectioned on the upper side of the piston 3 in each cylinder chamber 2, and each hydraulic operation chamber 6, a hydraulic path 7 connected thereto and a pressure receiving chamber 23a of a cylinder 23 at the end of the hydraulic path 7 are all filled with oil. An intake/discharge port 8 making the hydraulic path 7 communicate with the hydraulic operation chamber 6 penetrates through the peripheral wall part 1b of each cylinder chamber 2, and opens to the top end of the inner peripheral surface of the hydraulic operation chamber 6. Also, the portion sectioned on the lower side of the piston 3 in each cylinder chamber 2 communicates with the open air through an air passage hole 9 formed on the partition wall part 1a of the cylinder chamber 2 to prevent the inner pressure from decreasing when the piston 3 ascends. In addition, a top end wall 10a of the casing 10 of the driving means 5 is used also as a bottom end wall of the casing 1, and the air passage hole 9 of the lowermost cylinder chamber 2 is formed on this top end wall 10a. On the top surface of each piston 3, a spacer 11 defining the interval between pistons 3 is formed integrally with each piston 3. The thickness and the outer diameter D₁ of the four pistons 3 and the length (height) and the outer diameter D₂ of the spacers 11 are formed equal respectively. The top end of each spacer 11 penetrates through the partition wall 1a of the cylinder chamber 2 and is fitted into a recess formed on the bottom surface of the piston 3 above. Shaft holes 4A are formed in the center parts of four pistons 3 and spacers 11 along the whole length, and the connecting shaft 4 consisting of a long through bolt is inserted into the shaft holes 4A, and the bottom part of this connecting shaft 4 is inserted into a piston 12 of the pneumatic cylinder 5 and a spacer 13 defining the interval between the piston 12 and the piston 3 in the lowermost cylinder chamber 2, and is tightened together with a nut 14, and thereby the four pistons 3 and spacers 11, the spacer 13 and the piston 12 are connected integrally and coaxially. The driving means 5 comprises a cylindrical casing 10 the top and bottom ends of which are closed and which configurates a single-type pneumatic cylinder provided with a compressed spring 17 for restoration, a cylinder chamber 15 formed inside this, a piston 12 installed slidably in this cylinder chamber 15, a pressure receiving chamber 16 sectioned on the lower side of this piston 12 in the cylinder chamber 15, and the compressed spring 17 installed on the upper side of the piston 12. The portion sectioned on the upper side of the piston 12 in the cylinder chamber 15 communicates with the open air through an air passage hole 18 penetrating the peripheral wall of the casing 10, and a compressed air supply/exhaust apparatus 19 is connected to the pressure receiving chamber 16 through an intake/discharge port 19a. This compressed air supply/exhaust apparatus 19 is configurated in a manner that when the control sequence is started manually or automatically, it supplies compressed air of a predetermined pressure to the pressure receiving chamber 16, drives the piston 12 upward, drives four pistons 3 upward through the piston 12 and the connecting shaft 4, and lifts them to the position where a limit switch 20 is turned to ON through the connecting shaft 4 and stops them at that position, and when the control sequence is ended manually or automatically, the pressure of the pressure receiving chamber 16 is released. In addition, the position of the limit switch 20 can be adjusted by an adjust screw 21. In accordance with the multi-boost synchronized booster configurated as described above, when the operation of the compressed air supply/exhaust apparatus 19 is started manually or automatically, compressed air is supplied to the pressure receiving chamber 16 of the pneumatic cylinder 5, and the piston 12 is lifted, and the four pistons 3 are synchronously driven upward through the connecting shaft 4. Then the oil filling each hydraulic chamber 6, the hydraulic path 7 and the hydraulic cylinder 23 is pressurized, being supplied to the pressure receiving chamber 23a of each cylinder 23. Here, the inner diameter D₁ of four cylinder chambers 2 and the outer diameter D₂ of spacers 11 of four pistons 3 are formed equal respectively, and the four pistons 3 are connected integrally through the connecting shaft 4, and resultingly the stroke L thereof becomes the same, and therefore hydraulic fluid of equal pressure and equal flow rate is supplied to the hydraulic path 7 from the four hydraulic operation chambers 6 respectively in a synchronized manner, and is supplied to the pressure receiving chamber 23a of the cylinder 23, and the protruding speeds and the amounts of protrusion of the piston rods become accurately the same. When the protruding operation of the piston rod of the cylinder 23 is stopped, by releasing the pressure of the pressure receiving chamber 16 of the driving means 5, the four pistons 3 are synchronously lowered by elastic force of the spring 17 through the piston 12 and the connecting shaft 4, and each cylinder 23 is synchronously restored while hydraulic fluid of equal amount is returned from the pressure receiving chamber 23a of the cylinder 23 to each hydraulic operation chamber 6 with the same pressure. A load applied from the outside through each cylinder 23 acts on each piston 3, and the load exerted on each piston 3 acts in the direction of the axial center thereof, generating no moment to the other pistons 3. Accordingly, an external load exerts on each cylinder 23 as a deviated load, and even if the loads shared by the respective pistons 3 become uneven, there is no fear of causing a poor operation or disabled operation, and a smooth operation can be performed. In this case, by increasing or decreasing the numbers of the divided units 1A of casing 1 and the pistons 3 with the spacer 11 in the interior thereof and replacing the connecting shaft 4 and the bolt 22, the number of hydraulic operation chambers 6 of the multi-boost booster can be set freely. In addition, the divided unit 1A of casing 1 and the piston 3 with the spacer 11 of the same kinds can be mass-produced at low costs, and therefore the manufacturing cost of the multi-boost booster can be reduced to a great extent. The casing 1 is formed in such a manner that the divided unit 1A of casing 1, corresponding to each cylinder chamber 2 are connected in series, and therefore by increasing or decreasing the number of the divided units 1A of casing 1 and the number of the pistons 3 and the spacers 11, this is applicable also to the case where the number of cylinders 23 of the driven side differs. The casing 1 is formed in a divided manner corresponding to the cylinder chambers 2, but is also possible to form the casing 1 integrally. In this case, a plurality of cylinder chambers 2 are formed in the casing 1, and therefore, for example, as shown in Fig. 3, a cylindrical hole 1c is formed in the casing 1, and the partition wall parts 1a sectioning each cylinder chamber 2 and sleeves 31 configurating the inner peripheral wall of each cylinder chamber 2 between the partition wall parts 1a have only to be inserted alternately into the casing through this hole 1c. In addition, here, the pressing area of each hydraulic operation chamber 6 is made to differ by means of different inner diameters of the sleeves 31, and thereby the discharging pressure of hydraulic fluid from each hydraulic operation chamber 6 is made to differ. Also, as shown in Fig. 4, the above-mentioned divided unit 1A of casing 1 can be further divided into a partition wall portion 1a configurating the end wall of the cylinder chamber 2 and a peripheral wall portion 1b configurating the peripheral wall of the cylinder chamber 2. Also, as shown in Fig. 4, it is also possible to form the piston 3 and the spacer 11 in a separate manner. Furthermore, as shown in Fig. 5, the connecting shaft 4 and each piston 3 may be configurated in a manner that each piston 3 is clamped by the stepped surface 4a formed on the connecting shaft 4 and a nut 32 screwed to the connecting shaft 4. In this case, the position of the piston 3 is defined by the stepped surface 4a, and therefore the spacer 11 may be omitted. Also, in this case, by forming the connecting shaft 4 in a stepped manner to have different diameters, the hydraulic force of each piston 3 differs on a hydraulic operation chamber 6 basis. In this case, to make the discharging pressure of the hydraulic operation chamber 6 equal, although not illustrated, the cross-sectional area of each hydraulic operation chamber 6 is required to be made equal by fitting the sleeves having the same outer diameter to the connecting shaft 4 for the respective pistons 3. Fig. 6 shows a lubricating oil supply pump suitable for a rolling apparatus in accordance with the present invention. In the casing 1 of this lubricating oil supply pump, the cylinder chambers 2 having the same diameter and the same length are formed in series, and the pistons 3 having the same thickness and the same outer diameter are slidable in the respective cylinder chambers 2. The four pistons 3 are connected integrally to the piston 12 of the driving means 5 through the connecting shaft 4 consisting of a through bolt as in the case of Fig. 1. The above-mentioned driving means 5 is similar to the one in the above described pumps. The hydraulic operation chamber 6 on one side of the piston 3 in each cylinder chamber 2 is connected to an external lubricating oil supply source 34 through an intake port 8a, and each discharge port 8b installed independently from this intake port 8a is connected respectively to places to be lubricated in the rolling apparatus. Here, to obtain a pumping function, each intake port 8a is connected to the lubricating oil supply source 34 through an intake branch piping 36 wherein a check valve 35 is installed individually, and a check valve 38 is also installed in a discharge piping 37 connected to the discharge port 8b. Also, in this lubricating oil supply pump, the outer diameter of the spacer 11 in the hydraulic pump 6 nearest to the driving means 5 is formed larger than the outer diameters of the spacers of the other hydraulic operation chamber 6, and the pressing area of that hydraulic operation chamber 6 is narrowed to generate a discharging pressure higher than those of the other hydraulic operation chambers 6. Also, the amount of hydraulic discharge from each hydraulic operation chamber 6 is controlled by controlling the stroke of the connecting shaft 4 likewise the pump as shown in Fig. 1. However, in this embodiment, when the connecting shaft 4 is brought in contact with the limit switch 20, the pressure of the pressure receiving chamber 16 of the driving means 5 is released, and the piston 12 and the connecting shaft 4 are pushed back in the direction of increasing the volume of the hydraulic operation chamber 6 by the spring 17. Also, the position of the limit switch 20 is adjusted by automatically rotating the adjust screw 21 by a required amount by a motor 38. In the lubricating oil supply pump configured as described above, when compressed air is supplied from the compressed air supply/exhaust apparatus 19 to the pressure receiving chamber 16 of the driving means 5, the piston 12 moves towards the casing 1, and each piston 3 is driven in the direction of reducing the volume of the hydraulic operation chamber 6. Then, the pressure lubricating oil is discharged from each hydraulic operation chamber 6 to the discharge piping 37. At this time, the discharged pressures from the three upper hydraulic operation chambers 6 are the same, and the amount of hydraulic discharge thereof are also the same. The discharging pressure of lubricating oil discharged from the hydraulic operation chamber 6 nearest to the driving means 5 is higher than those of lubricating oil discharged from the other hydraulic operation chambers 6, and the amount of discharge thereof is smaller than the amounts of discharge of the other hydraulic chambers 6. To simplify the description, here, only the discharging pressure of one hydraulic operation chamber 6 differs from the discharging pressures of the other hydraulic operation chambers 6, but in the actual lubricating oil supplying apparatus, it is also possible to make the discharging pressure differ on a hydraulic operation chamber 6 basis. In this embodiment, the hydraulic operation chamber 6 is installed on one side of the piston 3, but, for example, as shown in Fig. 7, it is also possible to form the hydraulic operation chamber 6 on the both sides of the piston 3. In this case, the driving means 5 is desirably configurated with a double-type pneumatic cylinder or hydraulic cylinder. The multi-boost synchronized hydraulic pump in accordance with the present invention is applied to a booster supplying pressurized liquid to a plurality of hydraulic actuators or a pump or distributor supplying pressurized liquid intermittently, and for a booster, it is applied, for example, to a carrying cart having a lifting function, a stationary lifting apparatus, a positioning apparatus of metal mold of press machine or work to be machined, a metal mold fixing apparatus of press machine or injection molding machine and a hydraulic apparatus such as a press machine and a shearing apparatus. Also, for a pump or distributor, it is applied, for example, to a lubricating oil supply pump of a rolling mill.

Claims: A multi-boost synchronized hydraulic pump comprising: a casing (1), comprising a plurality of cylindrical units (1b) each with an associated end wall (1a), a plurality of cylinder chambers (2) formed in series in said casing (1), a piston (3) slidable in each cylinder chamber (2), and having an associated spacer extension (11) by which it engages the piston in the next chamber, on at least one side of the piston (3) of each cylinder chamber (2) an intake port (8, 8a) for admitting liquid to a hydraulic operating chamber (6) and on at least one side of the piston a discharge port (8, 8b) for discharging pressurized liquid from each hydraulic operation chamber (6), a connecting shaft (4) passing through said pistons (3) and holding them in a coaxial array and engageable with said pistons for driving them in their respective cylinder chambers (2); characterised in that the pump is a supply pump for supplying a liquid from a supply to a point of use; in that in each cylinder chamber (2) there is a said intake port (8a) and discharge port (8b) on the same side of the piston (3); in that each said intake port is connected to a source (34) a check valve (35) and each said discharge port is connected to a point of use via a check valve (38); and by a single common driving means (5) connected to and synchronously driving said connecting shaft (4) to displace said array of said pistons (3) along their respective cylinder chambers (2). A multi-boost synchronized hydraulic pump according to claim 1, wherein the swept areas of a plurality of said pistons (3) are equal. A multi-boost synchronized hydraulic pump according to claim 1, wherein the pistons have different swept areas. A multi-boost synchronized hydraulic pump according to any one of claims 1 to 3, wherein a casing portion forming each cylinder chamber (2) of some of said cylinder chambers (2) is configurated with a cylinder member (1b) and a partition wall member (1a) separate therefrom. A multi-boost synchronized hydraulic pump according to claim 1 or 2, wherein said casing (1) is configurated with a common outer cylinder member covering a plurality of said cylinder chambers (2), partition wall members (1a) partitioning between said cylinder chambers and sleeves (31) which form respectively the peripheral wall portion of each cylinder chamber (2) and define the positions of said partition wall members (1a). A multi-boost synchronized hydraulic pump according to any one of claims 1 to 5, wherein said cylindrical spacer extensions (11) are cylindrical and formed integrally on each said piston (3), and said connecting shaft (4) passes through said pistons (3) and said spacer extensions (11). A multi-boost synchronized hydraulic pump according to any preceding claim which is double acting, with intake and discharge ports (8a, 8b) on both sides of each piston.

Inventors: TAKESHIMA SHOJIRO C O AIOI SEI, TAKESHIMA, SHOJIRO C/O AIOI SEIKI INC.
Applicants: AIOI SEIKI KK, AIOI SEIKI INC.
Application year: 1988
Main classification: F15B11
IPC codes: F15B11