RECIPROCATING PUMP

Abstract: A suction hole (91a) and a discharge hole (91b) are formed at the center and on the outer periphery of a valve seat (91) mounted at the end of a cylinder (5) in a reciprocating pump. A suction valve (92) and a discharge valve (93) are provided at the inner and outer surfaces of the valve seat (91) at a cylinder chamber (5a) side to be urged toward the valve seat (91) by first and second valve springs (94) and (95). Futher, a spring retainer (11) is provided midway along the cylinder (5) through which a plunger (7) is telescoped to allow passage of the plunger (7) for supporting the first valve spring (94) so that the position for the plunger (7) to complete its reciprocating motion is provided in the vicinity of the valve (93) to thereby reduce the excessive volume and accordingly the residual air amount so as to improve the rise at restarting time.

Description: SPECIFICATION Reciprocating Pump FIELD OF THE ART This invention relates to a reciprocating pump, and more particularly to a reciprocating pump which is provided, at the foremost end of a cylinder supporting a plunger in a relation of being freely reciprocating, with a suction passage, a discharge passage, and a valve device comprising a suction valve and a discharge valve, so that the plunger reciprocates to actuate the suction valve and discharge valve, thereby discharging pressure fluid. BACKGROUND OF THE ART Conventionally, a well-known valve device used for the reciprocating pump has one valve seat provided with a suction bore and a discharge bore and supports a suction valve and a discharge valve. The conventional valve device is provided at the center thereof with the suction bore and at the outer pe ripheral portion with the discharge bore and is mounted on the foremost end of a cylinder housing therein a plunger. The suction valve is provided at the inside of valve seat facing within the cylinder chamber, and a discharge valve is provided at the outside of valve seat. A first coiled valve spring biasing the suction valve to the valve seat is housed within the cylinder chamber and a second coiled valve spring biasing the discharge valve to the valve seat is supported to a cylinder head provided outside the cylinder. The first valve spring is supported at its one end to a spring holder provided within the cylinder chamber. The first valve spring is coiled in uniform diameters. The spring seat has a smaller inner diameter than a coil diameter of the spring and is disposed within te cylinder chamber in which the plunger reciprocates. Hence, the spring holder causes interference with the reciprocation of plunger, whereby termination of the forward movement of plunger conventionally is set before the spring holder. Such construction, however, leads to formation of a large unoccupied space or surplus volume within the cylinder chamber. In ¯ detail , the surplus volume is excessively large enough to accomodate the first valve spring and spring holder within the cylinder chamber. Hence, in a case that the pump is operated to open the suction bore to the atmosphere: after a stop of the pump's running1 a large amount of residual air in the cylinder chamber creates a problem of poor starting characteristics when restarting the pump's running. In other words, when air remains in the cylinder chamber, an amount of liquid taken in through the suction bore at a suction stroke by the backward movement of plunger becomes smaller in proportion to the amount of residual air. While, the liquid taken in at the suction stroke is discharged together with the air at a discharge stroke by the forward movement of plunger. Hence, a large quantity of air, if residual in the cylinder chamber, takes a relatively long time to be thoroughly exhausted out of the cylinder chamber. As a result, starting characteristics of the pump for running in suction and discharge becomes poor, thereby creating the problem in that a pressure rise until the rating pressure for running is delayed. In the light of the aforesaid problems, this invention has been designed. An object of the invention is to provide a reciprocating pump capable of preventing surplus volume within the cylinder chamber from being enlarged even when a valve device bearing at one valve seat the suction and discharge valves is incorporated with the foremost end of the cylinder. DISCLOSURE OF THE INVENTION The reciprocating pump of the invention is so constructed that; on the foremost end of the cylinder is mounted a valve seat having atthe center thereof a suction bore and at the outer peripheral portion a discharge bore; the valve seat is provided on the inside at the cylinder chamber side with a suction valve and at the outside with a discharge valve so that the suction valve and discharge valve are biased to the valve seat by means of a first and a second valve spring; within the cylinder and on the way of reciprocation of the plunger is provided a spring holder through which the plunger is passable and which supports the first valve spring biasing the suction valve; and the forward movement of plunger within the cylinder is adapted to terminate in proximity to the suction valve. Hence, the- surplus volume within the cylinder chamber is reduced so that ,even when the pump is operated to open the suction bore to the atmosphere in a cessation of the pump's running, the starting characteristics of pump, when it restarts for running, can be improved. Consequently, the reciprocating pump of the invention is suitable for a sprinkler for the crops or a washing device injecting high pressure water on a hull. BRIEF DESCRIPTION OF THE DRAWINGS Fig.1 is a schematic longitudinal sectional side view of an embodiment of the inveniton, Fig.2 is an enlarged sectional side view of the principal portion of the embcdiment in Fig.1, and Fig.3 is an enlarged sectional plan view of the principal portion of the same. THE BEST FORM FOR PRACTICE OF THE INVENTION The best form to put the inveniton into practice will be detailed in accordance with the drawings. Referring to Figs.1 and 2, a triplex type reciprocating pump of three plungers disposed in parallel is shown. The pump mainly comprises a housing 1, a drive shaft 2 supported rotatably thereto through bearings 3, three cylindrical cam bodies 4 having eccentric bores )4a and mounted on the drive shaft 2 respectively, three cylinders 5 mounted on the housing 1, three plungers supported within cylinder chambers 5a of cylinders 5 in a relation of being freely reciprocating and connected with the cam bodies 4 through rods 6 respectively, a cylinder head 8 having a suction passage 8 and provided at the foremost ends of cylinders 5, and three valve devices 9 provided at the foremost ends of cylinders 5 respectively. Between the outer periphery of each plunger 7 and the inner periphery of each cylinder chamber 5a are provided a sealing member 51, a seal holder 52 for the sealing member 51, and a spring 53 to bias the sealing member 51 to the seal holder 52. Each cylinder 5 is interposed between the housing 1 and the cylinder head 8, and the cylinder head 8 is fixed to the housing 1 through mounting bolts (not shown). The valve devices 9 each comprise a valve seat 91 having at the center thereof a suction bore 91a and at the outer peripheral portion a discharge bore 91h,a suction valve 92 for opening-and closing the suction bore 91a, a discharge valve 93 for opening and closing the discharge bore9lb, and a first and a second valve spring/for bias /94 - ing the suction valve 92 and discharge valve 93 to thé valve seat 91. The valve seat 91 comprises a main body 91c of a round-plate-like shape and a cylindrical portion 9d extending axially outwardly from the center of one side of the main body 91c,so that a through bore formed at the center of main body 91c and an inner space of the cylinder cal portion 91d form the suction bore 91 a. The discharge bore 91b is formed at the outer peripheral portion of main body 91c. The outer peripheral edge of main body 91c is interposed between the foremost end of each cylinder 5 and the cylinder head 8 so that the main body 91c together with the cylinder 5 is fixed to the housing 1 through the cylinder head 8 fixed thereto. In addition, the main body 91c and cylindrical portion 91d may be integral or separakL When separated, they are easy to produce The suction valve 92 is disposed at the outlet side of suction bore 91a and within the cylinder chamber Sa. The discharge valve 93 is disposed at the outlet side of discharge bore 91b and within the discharge passage 8. The first and second valve springs 94 and 95 bias the suction valve 92 and discharge valve 93 to the valve seat 91. Between the suction passage 8a at the cylinder head 8 and the discharge passage 8b thereof are provided three through bores 8c into which the cylindrical portion 91d at each valve seat 91 is inserted at one axial end, so that the suction bore 91a is allowed to communicate with the suction passage 8a. Within the cylinder chamber 5a and on the way of reciprocation of the plunger 7 is provided a ring-like shaped spring holder 11 through'which the plunger 7 is passable, the spring holder 11 supporting the first valve spring 94 which biases the suction valve 92, and the spring 53 which biases the sealing member 51. The first valve spring 94 is coiled in a frustoconical shape and its base of larger coil diameter is positioned at the plunger side so that the foremost end of plunger 7 may be insertable into the valve spring 94, the first valve spring 94 and spring holder 11 being housed within the cylinder chamber 5a. Also,the forward movement of plunger 7 is terminated a in proximity to the suction valve 92. The second valve spring 95 is supported on an inner surface 8b of discharge passage 8. In addition, in the drawings, reference numeral 12 designates a housing cover, 7a designates a plunger guide, 7b desigantes a plunger pin, and 96 designates a guide tube for the second valve spring 95. In the reciprocating pump of the invention constructed as foregoing, the drive shaft 2 rotates to reciprocate the plunger 7, so that the discharge valve 93 closes and the suction valve 92 opens when the plunger 7 moves backward, whereby liquid stored in a tank or water in a pond or river is taken into the cylinder chamber 5a from the inlet of suction passage 8a by way of the suction passage 8a and suction bore 91a. While, the suction valve 92 closes and the discharge valve 93 opens when the plunger 7 moves forward, whereby the liquid within the cylinder chamber 5a is subjected to pressure so as to be discharged into the discharge passage 8b through the discharge bore 91b. The pump in working as foregoing, stops the rotation of drive shaft 2 upon a finish of,for example, water sprinkling on the crops or washing the hull or the like. When the above works are over, the suction passage 8a opens in- the atmo-sphere at the same time as input to the drive shaft 2 is stopped. At this time, if the drive shaft 2 is rotating under inertia , the liquid within the cylinder chamber 5a is substituted for air, so that the liquid, in certain circumstances, may be discharged thoroughly. In a case that a large quantity of air flows into the cylinder chamber 5a upon a stop of the pump's running, the residual air within the chamber 5a, when restarting the pump's running, should be discharged through the discharge bore 91b by reciprocation of the plunger 7 to thereby raise degree of vacuum within the cylinder chamber 5a. The reciprocating pump of the invention can reduce to a minimum the surplus volume in the cylinder chamber 5a due to the fact that the valve spring 94 biasing the suction valve 92 and the spring holder 11 supporting the valve spring 94, can be housed within the cylinder chamber 5a and that termination a of the forward movement of plunger 7 can approach the suction valve 92. Consequently, a suction amount of liquid, when the pump restarts to run, increases to exhaust the residual air relatively for a short time, thereby enabling pressure to rise quickly in initial running of the pump. Besides the triplex type reciprocating pump shown in Figs.1 and 2, a single, double or four or more multi-plunger type reciprocating pump may have the same construction as the invention. As seen from the above, the reciprocating pump of the inveniton, in spite of bearing the suction valve and discharge valve by one valve seat, is capable of housing within the cylinder chamber the valve spring biasing the suction valve and the spring holder supporting the valve spring, and of positioning the terminate of forward movoment of the plunger in proximity to the suction valve, thereby making it possible to minimize the surplus volume within the cylinder chamber. As a result, the residual air within the cylinder chamber can be exhausted in a short time, thereby quickly raising pressure in the initial running. POSSIBILITY OF UTILIZATION FQR INDUSTRY Accordingly, the reciprocating pump of the inveniton is suitable for a hydraulic pump used for ma-i! chine tools, a pump for sprinkling over the crops liquid medicine or water in a pond or river, a washing pump for injecting high pressure water on a hull, or a fire pump loaded on a motor fire engine, especially for a pump, in a cessation of its running, opening the suction passage in the atmosphere.

Claims: CLAIMS 1. A reciprocating pump which is provided with a valve device at the foremost end of a cylinder supporting therein a plunger in a relation of being freely reciprcating so that said plunger reciprocates to actuate a suction valve and a discharge valve at said valve device, said pump being characterized in that; on the foremost end of said cylinder is mounted a valve seat provided at the center with a suction bore and at the peripheral portion with a discharge bore, said valve seat being provided at its inner surface at the cylinder chamber side with a suction valve and at the outer surface with a discharge valve so that said suction valve and discharge valve are biased to said valve seat through a first and a second valve spring; within said cylinder and on the way of reciprocation of said plunger is provided a spring holder through which said plunger is allowed to pass, said spring holder supporting said first valve spring which biases said suction valve; and the position of termination of forward movement of said plunger within said cylinder is adapted to be brought in proximity to said suction valve. 2. A reciprocating pump according to claim 1, being characterized in that said first valve spring comprises a frustocoilical-shaped coil spring and is supported at the larger coil-diameter side to a spring holder provided at said cylinder,so that, when said plunger moves forward, the foremost end of said plunger enters said first valve spring to thereby bring the position of termination of forward movement of said plunger in proximity to said suction valve.

Inventors: NAMEKATA, YORIAKI
Applicants: ARIMITSU INDUSTRY CO., LTD.
Application year: 1981
Main classification: F04B21
IPC codes: F04B53