Plunger pump

Abstract

The utility model discloses a plunger pump which comprises an outer spring, a pump cylinder, a spring cap and a plunger rod, the plunger rod divides the inner space of the pump cylinder into an upper oil cavity and a lower oil cavity, the plunger rod is provided with a second oil hole and a valve rod, the valve rod is elastically installed in the plunger rod, and the outer spring is arranged in the pump cylinder. The plunger rod moves between an opening position and a closing position relative to the plunger rod; when the oil pressure of the lower oil cavity is smaller than a preset value P, the valve rod is located at a closed position, and the upper oil cavity and the lower oil cavity are relatively sealed; and when the oil pressure of the lower oil cavity is not smaller than a preset value P, the valve rod is jacked to the opening position by the oil pressure, and the upper oil cavity is communicated with the lower oil cavity. According to the plunger pump, dynamic communication and sealing control of the upper oil cavity and the lower oil cavity are achieved through the movable valve rod, and the defect that a hydraulic working cylinder only has one jacking value due to a traditional single-displacement pump is overcome.

Description

Technical Field

[0001] The utility model relates to the technical field of non-power hydraulic systems, and more specifically, to a plunger pump, such as a manual hydraulic jack, a manual hydraulic stacker, a manual hydraulic pallet truck, a manual hydraulic platform truck, etc., and also to similar machines that are stepped on by foot, wherein the key technology is the hydraulic source pump. Background Art

[0002] Generally, similar non-powered hydraulic machinery has a single-displacement plunger pump as its pump source, such as common hydraulic jacks, manual hydraulic pallet trucks, manual hydraulic stackers, etc. The problem with these single-pump hydraulic mechanisms is that each time the pump pressure makes a stroke, its fluid flow is a fixed displacement, and its matching hydraulic working cylinder also has only one jacking value. This traditional technology has been used to this day.

[0003] Of course, there is also a horizontal jack, which is also a double-displacement technology, and its two-pillar piston pumps are arranged in a side-by-side double row, which takes up a large space and is not compact enough.

[0004] With reference to the above, the prior art is still unable to achieve a plunger pump with a compact structure. Summary of the invention

[0005] The utility model aims to solve one of the technical problems in the related art to a certain extent. To this end, the utility model proposes a plunger pump, which realizes the dynamic connection and sealing control of the upper oil chamber and the lower oil chamber through a movable valve stem, overcoming the limitation that the hydraulic working cylinder has only one lifting value brought by the traditional single displacement pump.

[0006] The technical solution adopted by the utility model is: to provide a plunger pump, including an outer spring, a pump cylinder, a spring cap and a plunger rod, wherein the plunger rod divides the internal space of the pump cylinder into an upper oil chamber and a lower oil chamber, the plunger rod is provided with a second oil hole and a valve stem, the valve stem is elastically installed in the plunger rod and moves between an open position and a closed position relative to the plunger rod;

[0007] When the oil pressure in the lower oil chamber is less than a preset value P, the valve stem is in a closed position, and the upper oil chamber and the lower oil chamber are relatively sealed;

[0008] When the oil pressure in the lower oil chamber is not less than a preset value P, the oil pressure pushes the valve stem to an open position, and the upper oil chamber is connected to the lower oil chamber.

[0009] After adopting the above structure, the upper and lower oil chambers are dynamically connected and sealed with the help of a movable valve stem. That is, when the oil pressure in the lower oil chamber is less than the preset value P, the plunger rod is in a low-load state, the load pressure is insufficient to overcome the elastic force of the elastic installation of the valve stem, and the valve stem is in a closed position. When the oil pressure in the lower oil chamber is not less than the preset value P, the plunger rod is in a high-load state, the load pressure is sufficient to overcome the elastic force of the elastic installation of the valve stem, the valve stem is in an open position, and the manual plunger pump is more labor-saving. The above setting overcomes the limitation that the hydraulic working cylinder has only one jacking value brought by the traditional single-displacement pump, and significantly improves its applicability and flexibility.

[0010] According to one embodiment of the utility model, a variable spring is provided between the valve stem and the plunger rod, and the variable spring has an elastic tendency to keep the valve stem in a closed position; the variable spring normally pushes the valve stem so that its lower end face is tightly fitted with the upper end face of the valve seat, and when the pressure in the lower oil chamber is greater than that in the upper oil chamber, the liquid pressure overcomes the action force of the variable spring, thereby pushing the valve stem away and separating it from the end face of the valve seat.

[0011] According to one embodiment of the utility model, the valve stem is provided with a first oil hole, and a valve seat is fixedly installed at one end of the plunger rod located in the lower oil chamber. A steel ball is elastically installed on the valve seat, and the steel ball is used to seal the first oil hole. The valve seat, plunger rod, steel ball and valve stem are combined to form a one-way valve structure.

[0012] According to one embodiment of the utility model, a valve spring is provided between the steel ball and the valve seat, and the valve spring has an elastic tendency to enable the steel ball to maintain sealing of the first oil hole; the valve spring is used to pre-tighten the steel ball to fit the opening at one end of the first oil hole.

[0013] According to an embodiment of the utility model, the valve seat has a stepped through hole, and the valve spring is installed in the larger hole of the stepped through hole; when the one-way valve structure is opened, the oil in the upper oil chamber flows into the lower oil chamber through the stepped through hole.

[0014] According to an embodiment of the utility model, the valve stem is in a closed position, and the first oil hole is connected to the second oil hole; the plunger rod returns upward to perform an oil suction stroke, and the pressure in the upper oil chamber is greater than the pressure in the lower oil chamber. The medium temporarily stored in the upper oil chamber passes through the second oil hole and the first oil hole of the plunger rod, and then opens the one-way valve structure and flows into the lower oil chamber. The insufficient part of the lower oil chamber is supplemented from the oil tank.

[0015] According to an embodiment of the present utility model, the valve stem is located in a closed position, and the end of the valve stem abuts against the valve seat.

[0016] According to an embodiment of the utility model, a third sealing ring is provided between the valve seat and the valve stem.

[0017] According to an embodiment of the utility model, when the plunger rod moves upward to perform an oil suction stroke, the one-way valve structure opens, and the upper oil chamber is connected to the lower oil chamber through the one-way valve structure.

[0018] According to an embodiment of the present invention, the second oil hole is a T-shaped or Y-shaped three-way channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A cross-sectional view of a plunger pump in an embodiment of the utility model;

[0021] Figure 2 It is a partial enlarged view of the plunger pump in the embodiment of the utility model.

[0022] Description of the numbers in the figure:

[0023] 1. Outer spring; 2. First sealing ring; 3. Pump cylinder; 4. Second sealing ring; 5. Dust seal; 6. Spring cap; 7. Bowl-shaped washer; 8. Cylindrical pin; 9. Plunger rod; 10. Variable spring; 11. Valve stem; 12. Steel ball; 13. Valve seat; 14. Valve spring; 15. Third sealing ring; 16. Sealing washer;

[0024] A. Upper oil chamber; B. Lower oil chamber; c. First oil hole; d. Second oil hole; G. Resistance. DETAILED DESCRIPTION

[0025] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention. Embodiment 1

[0026] like Figure 1-2 As shown, in this embodiment, a plunger pump is disclosed, comprising an outer spring 1, a pump cylinder 3, a spring cap 6 and a plunger rod 9, wherein the plunger rod 9 divides the inner space of the pump cylinder 3 into an upper oil chamber A and a lower oil chamber B, and the plunger rod 9 is provided with a second oil hole d and a valve stem 11, wherein the valve stem 11 is elastically installed in the plunger rod 9 and moves between an open position and a closed position relative to the plunger rod 9;

[0027] When the oil pressure in the lower oil chamber B is less than the preset value P, the valve stem 11 is in the closed position, and the upper oil chamber A and the lower oil chamber B are relatively sealed;

[0028] When the oil pressure in the lower oil chamber B is not less than a preset value P, the oil pressure pushes the valve stem 11 to an open position, and the upper oil chamber A is connected to the lower oil chamber B.

[0029] Furthermore, in this embodiment, the pump cylinder 3 is installed at a predetermined station, such as a hydraulic jack, a hand hydraulic pallet truck or a manual hydraulic stacker. A groove for an external oil circuit is opened at the predetermined station, and the pump cylinder 3 is threadedly connected to the inner wall of the groove, and a sealing gasket 16 is arranged between the two. The sealing gasket 16 is made of soft metal and plays a sealing role with the outside after being pressed by the pump cylinder 3. An outer spring 1 is arranged on the outer periphery of the pump cylinder 3, and the piston part of the plunger rod 9 is located in the pump cylinder 3 and slides with the inner wall of the pump cylinder 3. The rod body of the plunger rod 9 passes through the hole at the upper end of the pump cylinder 3 and extends out of the pump cylinder 3. The upper end of the plunger rod 9 is connected to a spring cap 6 and a bowl-shaped gasket 7, and is fixed by a cylindrical pin 8. The upper end of the outer spring 1 is against the lower end of the spring cap 6, and a second sealing ring 4 and a dust ring 5 are arranged between the rod body of the plunger rod 9 and the hole at the upper end of the pump cylinder 3. A first sealing ring 2 is arranged between the piston part of the plunger rod 9 and the inner wall of the pump cylinder 3.

[0030] Furthermore, the functions of the various components in this embodiment are as follows: the outer spring 1 is used for rebounding, and it can push the plunger rod 9 to reset through the spring cap 6, the bowl-shaped gasket and the cylindrical pin 8. The first sealing ring 2 is used to separate the upper oil chamber A and the lower oil chamber B. The pump cylinder 3 is a double-shoulder type, divided into upper and lower sections, the upper end has a smaller diameter, and is provided with a second sealing ring 4 and a dust ring 5; the lower end has a larger diameter and is a smooth cylindrical shape. The second sealing ring 4 is the main seal, used to prevent the oil in the pump cylinder 3 from leaking out. The spring cap 6 is used for the outer spring 1 to resist and transmit force. The bowl-shaped gasket 7 limits the cylindrical pin 8 from slipping off the plunger rod 9. The plunger rod 9 is a double-shoulder type, the upper main section has a smaller diameter and is longer, a cylindrical pin 8 is provided near the upper end, and the lower end has a larger diameter and is shorter, and the first sealing ring 2 is provided on it. The variable spring 10 is used to push the valve stem 11 so that its lower end face is in close contact with the upper end face of the valve seat 13. When the pressure in the lower oil chamber B is greater than that in the upper oil chamber A, the hydraulic pressure overcomes the force of the variable spring 10, thereby pushing the valve stem 11 away from the end face of the valve seat 13. The valve stem 11 and the valve seat 13 form a pressure valve. When the pressure valve is closed, the displacement is large, and when the pressure valve is opened, the displacement is small.

[0031] Specifically, a variable spring 10 is provided between the valve stem 11 and the plunger rod 9, and the variable spring 10 has an elastic tendency to keep the valve stem 11 in a closed position; the variable spring 10 normally pushes the valve stem 11 so that its lower end face is tightly fitted with the upper end face of the valve seat 13. When the pressure in the lower oil chamber B is greater than that in the upper oil chamber A, the liquid pressure overcomes the action force of the variable spring 10, thereby pushing the valve stem 11 away from the end face of the valve seat 13.

[0032] Specifically, combined Figure 2 As shown, in this embodiment, the valve stem 11 is provided with a first oil hole c, and the plunger rod 9 is fixedly mounted with a valve seat 13 at one end of the lower oil chamber B, and the valve seat 13 is elastically mounted with a steel ball 12, and the steel ball 12 is used to seal the first oil hole c, and the valve seat 13, the plunger rod 9, the steel ball 12 and the valve stem 11 are combined to form a one-way valve structure. A valve spring 14 is provided between the steel ball 12 and the valve seat 13, and the valve spring 14 has an elastic tendency to keep the steel ball 12 sealing the first oil hole c; the valve spring 14 is used to pre-tighten the steel ball 12 to fit the opening at one end of the first oil hole c.

[0033] Furthermore, in this embodiment, the steel ball 12, the valve seat 13, the valve stem 11, and the valve spring 14 form a one-way valve, allowing the oil in the upper oil chamber A to flow to the lower oil chamber B, and preventing the oil in the lower oil chamber B from flowing to the upper oil chamber A. A third sealing ring 15 is provided between the valve seat 13 and the plunger rod 9, and the third sealing ring 15 is used for sealing the threaded connection between the plunger rod 9 and the valve seat 13, thereby blocking the oil flow between the upper oil chamber A and the lower oil chamber B through the thread gap.

[0034] Specifically, the valve seat 13 has a stepped through hole, and the valve spring 14 is installed in the larger hole of the stepped through hole; when the one-way valve structure is opened, the oil in the upper oil chamber A flows into the lower oil chamber B through the stepped through hole. The valve stem 11 is in a closed position, and the first oil hole c is connected with the second oil hole d; the plunger rod 9 returns upward to perform an oil suction stroke, and the pressure in the upper oil chamber A is greater than the pressure in the lower oil chamber B. The medium temporarily stored in the upper oil chamber A flows into the lower oil chamber B after passing through the second oil hole d and the first oil hole c of the plunger rod 9, and the insufficient part of the lower oil chamber B is supplemented from the oil tank. The valve stem 11 is in a closed position, and the end of the valve stem 11 abuts against the valve seat 13. A third sealing ring 15 is provided between the valve seat 13 and the valve stem 11. When the plunger rod 9 moves upward to perform an oil suction stroke, the one-way valve structure is opened, and the upper oil chamber A is connected with the lower oil chamber B through the one-way valve structure. The second oil hole d is a T-shaped three-way hole, and in other embodiments, the second oil hole d is a Y-shaped three-way hole. That is, the second oil hole d has three openings, two of which are located on the outside of the plunger rod 9 and are arranged opposite to each other, and the remaining opening is located at the lower end of the plunger rod 9, and the steel ball is used to seal the opening.

[0035] Furthermore, in this embodiment, the working principle of the plunger pump is as follows:

[0036] 1. The pump cylinder 3 and the plunger rod 9 form two groups of working chambers, the upper oil chamber A and the lower oil chamber B. The upper oil chamber A is a plunger type, and the effective cylinder diameter is the small diameter of the plunger rod 9. The lower oil chamber B is a piston type, and the effective cylinder diameter is the large diameter of the pump cylinder 3.

[0037] 2. When the plunger rod 9 is working with a small diameter, it is currently a small-displacement pump, and when the pump cylinder 3 is working with a large diameter, it is currently a large-displacement pump.

[0038] 3. The valve stem 11, valve seat 13 and variable spring 10 form a pressure valve, which is closed when the pressure in the lower oil chamber B is low, and opened when the pressure in the lower oil chamber B is high. When this valve is closed, the displacement is large, and when this valve is opened, the displacement is small.

[0039] 4. The steel ball 12, valve stem 11 and valve spring 14 form a one-way valve, which only allows the liquid medium to flow from the upper oil chamber A to the lower oil chamber B, and prevents the lower oil chamber B from flowing to the upper oil chamber A.

[0040] 5. The plunger rod 9 relies on the rebound force of the external spring 1 to drive the spring cap 6, the bowl-shaped washer and the cylindrical pin 8 to move upward. When it moves upward, it is the oil suction working stroke. When the plunger rod 9 moves downward under the action of external force, it is the oil discharge working stroke.

[0041] 6. The pressure valve composed of the valve stem 11, the valve seat 13 and the variable spring 10 will open and close according to the size of the external resistance G. When it is closed, it will output a large displacement, and when it is opened, it will output a small displacement. Since the opening and closing of the pressure valve is related to the current working pressure, the automatic switching can achieve the purpose of automatic displacement change without additional operation.

[0042] 7. The plunger rod 9 performs a downward oil discharge stroke under the action of external force. If the external resistance G is small, the pressure fed back to the lower oil chamber B is also small, which is insufficient to overcome the force of the variable spring 10. The valve stem 11 is still attached to the valve seat 13, and the pressure valve is in a closed state. At this time, the one-way valve structure is also closed. This is the large-diameter working state of the pump cylinder 3, so a large-displacement output cycle is completed, and the upper oil chamber A is in the current negative pressure or vacuum state;

[0043] 8. The plunger rod 9 performs a downward oil discharge stroke under the action of external force. If the external resistance G is large, the pressure fed back to the lower oil chamber B is also large. When this force balances the force of the variable spring 10, the valve stem 11 is pushed away from the valve seat 13, and the pressure valve opens. Part of the oil in the lower oil chamber B flows to the upper oil chamber A through the pressure valve and the second oil hole d, making the large cylinder inoperative and the small pump working instead, presenting a small displacement output cycle. The one-way valve structure is still in a closed state. At this time, the upper oil chamber A only serves to temporarily store the excess medium in the lower oil chamber B.

[0044] 9. Then the plunger rod 9 returns upward to perform an oil suction stroke. The pressure in the upper oil chamber A is greater than the pressure in the lower oil chamber B. The medium temporarily stored in the upper oil chamber A flows back to the lower oil chamber B through the second oil hole d of the plunger rod 9, the first oil hole c of the valve stem 11, and the one-way valve structure is opened. The insufficient part is supplemented from the oil tank, and then an oil suction cycle is completed.

[0045] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0046] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0047] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A plunger pump, comprising an outer spring, a pump cylinder, a spring cap and a plunger rod, wherein the plunger rod divides the inner space of the pump cylinder into an upper oil chamber and a lower oil chamber, characterized in that: The plunger rod is provided with a second oil hole and a valve stem, and the valve stem is elastically installed in the plunger rod and moves between an open position and a closed position relative to the plunger rod; When the oil pressure in the lower oil chamber is less than a preset value P, the valve stem is in a closed position, and the upper oil chamber and the lower oil chamber are relatively sealed; When the oil pressure in the lower oil chamber is not less than a preset value P, the oil pressure pushes the valve stem to an open position, and the upper oil chamber is connected to the lower oil chamber.

2. The plunger pump according to claim 1, characterized in that: A variable spring is arranged between the valve stem and the plunger rod, and the variable spring has an elastic tendency to keep the valve stem in a closed position.

3. The plunger pump according to claim 1, characterized in that: The valve stem is provided with a first oil hole, and a valve seat is fixedly installed at one end of the plunger rod located in the lower oil chamber. A steel ball is elastically installed on the valve seat, and the steel ball is used to seal the first oil hole. The valve seat, plunger rod, steel ball and valve stem are combined to form a one-way valve structure.

4. The plunger pump according to claim 3, characterized in that: A valve spring is provided between the steel ball and the valve seat, and the valve spring has an elastic tendency to enable the steel ball to keep sealing the first oil hole.

5. The plunger pump according to claim 4, characterized in that: The valve seat has a stepped through hole, and the valve spring is installed in a larger hole of the stepped through hole.

6. The plunger pump according to claim 3, characterized in that: The valve stem is located at a closed position, and the first oil hole is communicated with the second oil hole.

7. The plunger pump according to claim 3, characterized in that: The valve stem is in a closed position, and the end of the valve stem abuts against the valve seat.

8. The plunger pump according to claim 3, characterized in that: A third sealing ring is provided between the valve seat and the valve stem.

9. The plunger pump according to claim 3, characterized in that: When the plunger rod moves upward to perform an oil suction stroke, the one-way valve structure opens, and the upper oil chamber is communicated with the lower oil chamber through the one-way valve structure.

10. The plunger pump according to any one of claims 1 to 9, characterized in that: The second oil hole is a T-shaped or Y-shaped three-way channel.

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