CN216111139U

CN216111139U - Crossing miniature water pump structure of purger

Info

Publication number: CN216111139U
Application number: CN202122783858.8U
Authority: CN
Inventors: 朱霄峰
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-11-11
Filing date: 2021-11-11
Publication date: 2022-03-22
Anticipated expiration: 2031-11-11

Abstract

The utility model discloses a crossed micro water pump structure of a cleaner, belonging to the field of water pumps of cleaners, and comprising two pressure assemblies which are crossed with each other; each pressure assembly comprises a plunger cavity, a water inlet pipeline and a water outlet pipeline, the axes of the plunger cavity, the water inlet pipeline and the water outlet pipeline are parallel, the same sides of the plunger cavity, the water inlet pipeline and the water outlet pipeline are communicated with one side cavity, a plunger is arranged in the plunger cavity, a first check valve component is arranged at the end part of the water inlet pipeline, and a second check valve component is arranged at the end part of the water outlet pipeline; the two plunger cavities are communicated with each other, the two water inlet pipelines are communicated with each other, the two water outlet pipelines are communicated with each other, the two water inlet pipelines are connected with the same water pipe, the two water outlet pipelines are connected with the same spray head, the plungers in the two plunger cavities are crossed, grooves are formed in the plungers, the positions of the two grooves are overlapped, one groove has a yielding space, an eccentric wheel assembly is arranged in the two grooves, and the eccentric wheel assembly is driven by a driving device. The utility model has high water pressure sprayed from the spray head and good cleaning effect.

Description

Crossing miniature water pump structure of purger

Technical Field

The utility model relates to the field of water pumps of cleaners, in particular to a crossed micro water pump structure of a cleaner.

Background

In daily life, people need to clear up articles such as outdoor table chair, barbecue, car, bicycle, pet, balcony, garage, in order to satisfy above-mentioned demand, the solution on the market is for providing a hand-held type purger, is equipped with the water pump that is used for pumping water and outside injection rivers in the purger.

Like the handheld high pressure cleaner of grant bulletin No. CN210218011U, the handheld high pressure cleaner adopts the direct current to supply power, can be through water piping connection outside water source, through the pump with water from the water inlet intake pump in, spout from the delivery port of pump again, but the space that holds water in this handheld high pressure cleaner's the pump is less, water can only be followed the intake antrum and extruded from the blowout of play water cavity again for the water pressure is not enough in the pump, and the flushing effect is relatively poor.

If the thin miniature water pump structure of the handheld cleaner with the publication number of CN212759222U is arranged, a plunger cavity, a water inlet pipeline and a water outlet pipeline are arranged in the water pump, the axes of the plunger cavity, the water inlet pipeline and the water outlet pipeline are parallel, the end parts of the plunger cavity, the water inlet pipeline and the water outlet pipeline in the same direction are communicated with the same side cavity, a plunger which is axially movable and used for changing the pressure in the side cavity is arranged in the plunger cavity, the water inlet pipeline is connected with a water pipe, the end part of the water inlet pipeline is provided with a first check valve component used for limiting water flow to flow from the water inlet pipeline to the side cavity, the water outlet pipeline is connected with a spray head, the end part of the water outlet pipeline is provided with a second check valve component used for limiting water flow to flow from the side cavity to the water outlet pipeline, and a driving component provided with the plunger is arranged. But this patent only sends water to outlet conduit in through two side chambeies continuously, send the water yield undersize for outlet conduit's delivery port water pressure is not enough, and the washing effect is relatively poor.

Disclosure of Invention

The utility model aims to provide a crossed micro water pump structure of a cleaner.

The technical scheme of the utility model is as follows: the crossed micro water pump structure of the cleaner is characterized by comprising two pressure assemblies which are crossed with each other;

each pressure assembly comprises a plunger cavity, a water inlet pipeline and a water outlet pipeline, the axes of the plunger cavity, the water inlet pipeline and the water outlet pipeline are parallel, the same sides of the plunger cavity, the water inlet pipeline and the water outlet pipeline are communicated with one side cavity, a plunger is arranged in the plunger cavity, the end part of the water inlet pipeline is provided with a first one-way valve component used for limiting water flow to the side cavity from the water inlet pipeline only, and the end part of the water outlet pipeline is provided with a second one-way valve component used for limiting water flow to the water outlet pipeline from the side cavity only;

plunger cavities of the two pressure assemblies are communicated with each other, water inlet pipelines of the two pressure assemblies are communicated with each other, water outlet pipelines of the two pressure assemblies are communicated with each other, the two water inlet pipelines are connected with the same water pipe, the two water outlet pipelines are connected with the same spray head, plungers in the two plunger cavities are crossed, grooves are formed in the plungers, the positions of the two grooves are overlapped, one groove is provided with a yielding space, an eccentric wheel assembly is arranged in the two grooves, and the eccentric wheel assembly is driven by a driving device.

The further optimization scheme of the utility model is as follows: the axial centers of a plunger cavity, a water inlet pipeline and a water outlet pipeline of a pressure assembly are positioned on the same plane, and the plunger moves axially to change the pressure in the side cavity.

The further optimization scheme of the utility model is as follows: the two water inlet pipelines are crossed, and the two water outlet pipelines are crossed.

The further optimization scheme of the utility model is as follows: the pipe diameter of the water inlet pipeline is larger than the water through hole diameter of the first one-way valve assembly, and the water through hole diameter of the first one-way valve assembly is larger than the water through hole diameter of the second one-way valve assembly.

The further optimization scheme of the utility model is as follows: the two sides of each pressure assembly are respectively provided with a left side cover and a right side cover, and the left side cover and the right side cover are internally provided with the side cavities.

The further optimization scheme of the utility model is as follows: the pressure assembly is provided with an upper cover which is covered above the plunger cavity.

The further optimization scheme of the utility model is as follows: the two pressure assemblies are integrally formed.

The further optimization scheme of the utility model is as follows: the eccentric wheel assembly comprises a primary wheel and a secondary wheel, an eccentric shaft is arranged on the primary wheel, the center of the secondary wheel is connected with the eccentric shaft, the axis of the primary wheel is positioned at the crossing center of the two pressure assemblies, and the primary wheel is driven by a driving device.

The further optimization scheme of the utility model is as follows: the eccentric wheel assembly comprises an eccentric wheel, and the axis of the eccentric wheel is connected with a driving device.

The further optimization scheme of the utility model is as follows: the width of the groove is greater than the diameter of the plunger.

Compared with the prior art, the utility model has the advantages that the plungers in the two plunger cavities are crossed, each plunger is provided with a groove, the positions of the two grooves are superposed, one groove has a yielding space, the eccentric wheel assembly is arranged in the two grooves, the driving device drives the eccentric wheel assembly to eccentrically rotate in the two grooves, the two plungers are respectively pushed to reciprocate in the two plunger cavities in the rotating process of the eccentric wheel assembly, water sucked into the four side cavities is continuously extruded into the water outlet pipeline and then sprayed out from the same spray head, the four side cavities enlarge the cavities for containing the water, and when the plungers move in the plunger cavities, the four side cavities continuously supply water to the water outlet pipeline, so that the water outlet pipeline has higher water pressure, the water flow sprayed out from the spray head has high strength, and the cleaning effect is better.

Drawings

The present invention will be described in further detail below with reference to the drawings and preferred embodiments, but those skilled in the art will appreciate that the drawings are only drawn for the purpose of illustrating the background art and explaining the preferred embodiments, and therefore should not be taken as limiting the scope of the present invention. Furthermore, unless specifically stated otherwise, the drawings are merely schematic representations based on conceptual representations of elements or structures depicted and may contain exaggerated displays and are not necessarily drawn to scale.

FIG. 1 is a schematic view of the structure of the present invention.

FIG. 2 is a schematic view of the structure of the present invention.

FIG. 3 is a schematic structural diagram of the present invention.

Fig. 4 is a partial cross-sectional view of the present invention.

Fig. 5 is an exploded view of the present invention.

FIG. 6 is a cross-sectional view of two pressure assemblies.

FIG. 7 is a cross-sectional view of two pressure assemblies.

Fig. 8 is a schematic diagram of the structure of two pressure assemblies.

FIG. 9 is a schematic diagram of two pressure assemblies.

Fig. 10 is a diagram showing the relationship between the plunger and the eccentric wheel assembly.

Fig. 11 is a cross-sectional view of the present invention.

Fig. 12 is a cross-sectional view of the present invention.

In the figure: 1. a pressure assembly; 2. a spray head; 3. a left side cover; 4. a right side cover; 5. a water pipe; 6. an upper cover; 7. connecting holes; 8. an eccentric wheel assembly; 9. a water outlet pipeline; 10. a lateral cavity; 11. a water inlet pipe; 12. a plunger cavity; 13. a plunger; 14. a groove; 15. a second one-way valve assembly; 16. a first one-way valve assembly; 17. a first-stage wheel; 18. an eccentric shaft; 19. a secondary wheel; 20. and sealing the rubber ring.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Those skilled in the art will appreciate that the description is illustrative only, and is not to be construed as limiting the scope of the utility model.

It should be noted that: like reference numerals refer to like items in the following figures, and thus, once an item is defined in one figure, it may not be further defined and explained in subsequent figures.

In the description of the present invention, it should be noted that the terms "inside" and "outside" are used for indicating the orientation or positional relationship based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship which is usually placed when the utility model is used, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the device or the element which is referred to must have a specific orientation, be constructed in a specific orientation and operation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.

As shown in fig. 1-12, the crossed micro water pump structure of the cleaning device includes two pressure assemblies 1 crossed with each other, preferably, two pressure assemblies 1 are integrally formed, two pressure assemblies 1 are combined into a whole, and two pressure assemblies 1 are crossed.

As shown in fig. 7-9, each of the pressure assemblies 1 includes a plunger cavity 12, an inlet pipe 11 and an outlet pipe 9 with parallel axes, and preferably, the axes of the plunger cavity 12, the inlet pipe 11 and the outlet pipe 9 of each of the pressure assemblies 1 are located on the same plane, so that the two pressure assemblies 1 crossing each other are more regularly distributed and more compact.

The plunger chambers 12 of the two pressure assemblies 1 are in communication with each other, preferably the two plunger chambers 12 are criss-crossed.

The inlet pipes 11 of the two pressure assemblies 1 are communicated with each other, wherein one inlet pipe 11 penetrates through the midpoint of the other inlet pipe 11 to be communicated with the other inlet pipe 11, and preferably, the two inlet pipes 11 are crossed.

The outlet conduits 9 of the two pressure assemblies 1 are in communication with each other, wherein one outlet conduit 9 extends through the midpoint of the other outlet conduit 9 to communicate with the other outlet conduit 9, preferably the two outlet conduits 9 cross.

Preferably, the intersection of the two plunger chambers 12, the intersection of the two inlet conduits 11 and the intersection of the two outlet conduits 9 fall on the same line.

The two water inlet pipelines 11 are connected with the same water pipe 5, the water pipe 5 and the pressure assembly 1 are integrally formed, the water pipe 5 is used for being externally connected with a water source, and the water pipe 5 conveys water flow into the water inlet pipelines 11; the two water outlet pipelines 9 are connected with the same spray head 2, the spray head 2 and the pressure assembly 1 are integrally formed, the spray head 2 is used for spraying water outwards, and the spray head 2 sprays water flow conveyed into the water outlet pipelines 9 outwards.

The same side end parts of the plunger cavity 12, the water inlet pipeline 11 and the water outlet pipeline 9 are communicated with the same side cavity 10, and four side cavities 10 are arranged around the whole combination of the two pressure assemblies 1.

Further, as shown in fig. 1-5, a left side cover 3 and a right side cover 4 are disposed on two sides of each pressure assembly 1, the side cavities 10 are disposed in the left side cover 3 and the right side cover 4, the same side cavity 10 is communicated with the same side end portion of the plunger cavity 12, the water inlet pipeline 11 and the water outlet pipeline 9, and two side cavities 10 are disposed on two sides of each pressure assembly 1. The left side cover 3 and the right side cover 4 are fixedly connected to the pressure assembly 1, and the left side cover 3 and the right side cover 4 are fixed to the pressure assembly 1 through screws. The side chamber 10 increases the amount of water contained within the present pump structure.

The end part of the water inlet pipeline 11 is provided with a first one-way valve assembly 16 for limiting water flow to only flow from the water inlet pipeline 11 to the side cavity 10, the end part of the water outlet pipeline 9 is provided with a second one-way valve assembly 15 for limiting water flow to only flow from the side cavity 10 to the water outlet pipeline 9, water sucked into the water inlet pipeline 11 by the water pipe 5 enters the side cavity 10 from the first one-way valve assembly 16, and water in the side cavity 10 can enter the water outlet pipeline 9 from the second one-way valve assembly 15 and then is sprayed out from the spray head 2.

Further, the pipe diameter of the water inlet pipe 11 is larger than the water through hole diameter of the first check valve assembly 16, the water through hole diameter of the first check valve assembly 16 is larger than the water through hole diameter of the second check valve assembly 15, and the pressure of water conveyed in the pressure assembly 1 is increased.

The first check valve assembly 16 and the second check valve assembly 15 are commercially available check valve structures, and the present invention is not explained in detail.

As shown in fig. 4, 5, 6, 10, every plunger 13 is arranged in the plunger cavity 12, axial movement of the plunger 13 in the plunger cavity 12 is used for changing the pressure in the side cavity 10, two the cross of the plunger 13 in the plunger cavity 12 is provided with a groove 14 on each plunger 13, one plunger 13 is located in the groove 14 of the other plunger 13, the positions of the grooves 14 of the two plungers 13 are overlapped, one groove 14 has an abdicating space, the plunger 13 can move left and right in the groove 14, preferably, the width of the groove 14 is greater than the diameter of the plunger 13, so that the two plungers 13 can move axially along the plunger cavity 12 in the two plunger cavities 12 respectively, and the problem of jamming due to mutual collision is avoided.

As shown in fig. 5 and 6, the whole formed by combining the two pressure assemblies 1 is provided with the upper cover 6, and the upper cover 6 is covered above the two plunger cavities 12 which are intersected with each other to limit the two plungers 13 to move in the plunger cavities 12. The upper cover 6 is fixedly connected to the pressure assembly 1, preferably, the upper cover 6 is fixedly connected to the pressure assembly 1 through screws, and other conventional connecting structures are also suitable for the patent.

An eccentric wheel assembly 8 penetrates through a connecting hole 7 on the upper cover 6 and extends into two grooves 14 to be linked with two plungers 13, the plungers 13 can be pushed by the eccentric wheel assembly 8 to move in the plunger cavity 12 along the axial direction of the plunger cavity 12, and the eccentric wheel assembly 8 is driven by a driving device.

Different structures of the eccentric wheel assembly 8 can extend into the two grooves 14 to be linked with the two plungers 13. For example:

first, as shown in fig. 10, the eccentric wheel assembly 8 includes a primary wheel 17 and a secondary wheel 19, the primary wheel 17 is provided with an eccentric shaft 18, the center of the secondary wheel 19 is connected with the eccentric shaft 18, the axle center of the first-stage wheel 17 is positioned at the crossing center of the two pressure assemblies 1, the first-stage wheel 17 is positioned in the connecting hole 7 and can rotate, the eccentric shaft 18 extends into the plunger cavity 12, so that the secondary wheel 19 is positioned in the two grooves 14 and linked with the two plungers 13, the primary wheel 17 is driven by a driving device, an output shaft of the driving device is connected with the axle center of the primary wheel 17, when the driving device drives the primary wheel 17 to rotate, the primary wheel 17 drives the secondary wheel 19 to eccentrically rotate, the secondary wheel 19 sequentially pushes the two side groove walls of the two grooves 14 in the two grooves 14, so that the two plungers 13 move in the plunger cavity 12 along the axial direction of the plunger cavity 12, and water pumping and water pressing are realized.

And in the second scheme, the eccentric wheel assembly 8 comprises an eccentric wheel, the eccentric wheel is positioned in the two grooves 14, the axis of the eccentric wheel is connected with a driving device, an output shaft of the driving device is connected with the axis of the eccentric wheel, the driving device drives the eccentric wheel to rotate in the two grooves 14, and the eccentric wheel sequentially pushes the two side groove walls of the two grooves 14 in the two grooves 14, so that the two plungers 13 move in the plunger cavity 12 along the axial direction of the plunger cavity 12, and water pumping and water pressing are realized.

The structure of the driving device has various types, for example, 1, the driving device comprises a body with a reduction gear set, and the eccentric wheel assembly 8 is driven to eccentrically rotate in two grooves 14 by connecting an output shaft on the reduction gear set with the eccentric wheel assembly 8, and the eccentric wheel assembly 8 pushes two plungers 13 to axially reciprocate in a plunger cavity 12; 2. the driving device comprises a driving motor, an output shaft of the driving motor is directly connected with the eccentric wheel assembly 8, and the driving motor drives the eccentric wheel assembly 8 to eccentrically rotate in the two grooves 14; 3. the drive means comprises a body with a linkage rod, such as a power tool of the type equivalent to a power drill, which drives the eccentric wheel assembly 8 to rotate eccentrically in the two recesses 14.

The drive arrangement of isostructure makes the water pump structure suitability of this patent stronger, can cooperate more diversified drive arrangement to be used for the equipment to form the purger and wash article.

As shown in fig. 11 and 12, when the water pump structure is connected with the driving device for use, the water pipe 5 is externally connected with a water source, the water pipe 5 can be connected with a water pumping hose, the water pumping hose is connected into a water source for pumping water, the driving device is started, the driving device drives the eccentric wheel assembly 8 to eccentrically rotate in the two grooves 14, one plunger 13 is firstly pushed to the left to the limit position in the rotating process of the eccentric wheel assembly 8, then the other plunger 13 is pushed upwards to the limit position, then the plunger 13 moving to the left to the extreme position is pushed to the right to the extreme position, finally the plunger 13 moving to the extreme position is pushed to the downward to the extreme position, one rotation process is completed, during the eccentric rotation process of the eccentric wheel assembly 8, the eccentric wheel assembly 8 repeats the actions, so that the two plungers 13 continuously pump the water in the water inlet pipeline 11 to the side cavity 10, and then extrude the water in the side cavity 10 to the water outlet channel and spray the water out of the spray head 2.

Specifically, the method comprises the following steps: the plunger 13 presses water in the side cavity 10 at the left side, the first check valve component 16 of the water inlet pipeline 11 at the left side end is in a closed state, the second check valve component 15 of the water outlet pipeline 9 at the left side end is pressed and opened by the water, the water enters the water outlet pipeline 9 and is sprayed out from the spray head 2, the plunger 13 sucks the water in the side cavity 10 at the right side, the water is sucked into the water inlet pipeline 11 from the water pipe 5, the first check valve component 16 of the right side end of the water inlet pipeline 11 is pressed and opened by the water, the water enters the side cavity 10 at the right side, the second check valve component 15 of the right side end of the water outlet pipeline 9 is in a closed state, then the eccentric wheel component 8 pushes the other plunger 13 upwards to a limit position, the plunger 13 presses the water in the side cavity 10 at the upper side, the first check valve component 16 of the water inlet pipeline 11 at the upper side end is in a closed state, the second check valve component 15 of the upper side end of the water outlet pipeline 9 is pressed and opened by the water, water enters the water outlet pipe 9 and is sprayed out of the spray head 2, the plunger 13 sucks the water in the side cavity 10 at the lower side, the water is sucked into the water inlet pipe 11 from the water pipe 5, the first check valve component 16 at the lower side end part of the water inlet pipe 11 is squeezed open by the water, the water enters the side cavity 10 at the lower side, the second check valve component 15 at the lower side end part of the water outlet pipe 9 is in a closed state, then the eccentric wheel component 8 pushes the plunger 13 moved to the left to the limit position to the right, the plunger 13 squeezes the water in the side cavity 10 at the right side, the first check valve component 16 at the right side end part of the water inlet pipe 11 is in a closed state, the second check valve component 15 at the right side end part of the water outlet pipe 9 is squeezed open by the water, the water enters the water outlet pipe 9 and is sprayed out of the spray head 2, the plunger 13 sucks the water in the side cavity 10 at the left side, and the water is sucked into the water inlet pipe 11 from the water pipe 5, the first check valve component 16 at the left end of the water inlet pipe 11 is pressed and opened by water, the water enters the side cavity 10 at the left side of the water pump, the second check valve component 15 at the left end of the water outlet pipe 9 is in a closed state, finally the eccentric wheel component 8 pushes the plunger 13 which moves downwards to a limit position, the plunger 13 presses the water in the side cavity 10 at the lower side, the first check valve component 16 at the lower end of the water inlet pipe 11 is in a closed state, the second check valve component 15 at the lower end of the water outlet pipe 9 is pressed and opened by water, the water enters the water outlet pipe 9 and is sprayed out from the spray head 2, the plunger 13 sucks the water in the side cavity 10 at the upper side, the water is sucked into the water inlet pipe 11 from the water pipe 5, the first one-way valve assembly 16 at the upper end of the inlet pipe 11 is pressed open by water, the water enters the upper side cavity 10, and the second one-way valve assembly 15 at the upper end of the outlet pipe 9 is in a closed state.

The eccentric wheel assembly 8 drives the two plungers 13 to continuously reciprocate in the two plunger cavities 12, so that the water pump structure is always in a water sucking and spraying state, the upper side cavity 10, the lower side cavity 10, the left side cavity 10 and the right side cavity 10 continuously convey water into the water outlet pipeline 9, the water is sprayed out from the same sprayer 2, the four side cavities 10 continuously convey water to improve the water pressure in the sprayer 2, the water pressure sprayed out of the sprayer 2 is large, and the cleaning effect is better.

Two ends of each plunger cavity 12 can be provided with a sealing rubber ring 20, the sealing rubber ring 20 can be sleeved on the plunger 13, the plunger 13 can move relative to the sealing rubber ring 20, and the sealing rubber ring 20 is used for oil sealing and water sealing to prevent oil lubricating the plunger 13 from entering the side cavity 10.

Or both ends of the plunger 13 are provided with sealing rubber rings 20, the sealing rubber rings 20 are fixed on the plunger 13 and move together with the plunger 13, and the sealing rubber rings 20 are used for oil sealing and water sealing to prevent oil lubricating the plunger 13 from entering the side cavity 10.

The cross-type micro-pump structure of the cleaner provided by the utility model is described in detail, and the principle and the implementation mode of the utility model are explained by applying specific examples, and the description of the examples is only used for helping to understand the utility model and the core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Claims

1. The crossed micro water pump structure of the cleaner is characterized by comprising two pressure assemblies which are crossed with each other;

2. The cross-type micro water pump structure of a cleaning device as claimed in claim 1, wherein the axial centers of the plunger chamber, the water inlet pipe and the water outlet pipe of a pressure assembly are located on the same plane, and the plunger is axially movable for changing the pressure in the side chamber.

3. The crossing micro pump structure for washer according to claim 1, wherein two inlet pipes cross and two outlet pipes cross.

4. The interdigitated micro-pump structure for a cleaning appliance according to claim 1, wherein the water inlet pipe has a pipe diameter greater than a water passage aperture of the first one-way valve assembly, the water passage aperture of the first one-way valve assembly being greater than a water passage aperture of the second one-way valve assembly.

5. The crossing type micro water pump structure of a washer according to claim 1, wherein each pressure assembly has left and right side covers on both sides, and the side cavities are formed in the left and right side covers.

6. The cross-type micro-pump structure for a cleaning device of claim 1, wherein the pressure assembly is provided with an upper cover, and the upper cover is arranged above the plunger cavity.

7. The crossing micro pump structure of washer according to claim 1 or 5 or 6, wherein two pressure assemblies are integrally formed.

8. The crossing type micro water pump structure of a washer according to claim 1, wherein the eccentric wheel assembly comprises a primary wheel and a secondary wheel, the primary wheel is provided with an eccentric shaft, the center of the secondary wheel is connected with the eccentric shaft, the axis of the primary wheel is located at the crossing center of the two pressure assemblies, and the primary wheel is driven by the driving device.

9. The crossing type micro water pump structure of a washer according to claim 1, wherein the eccentric wheel assembly comprises an eccentric wheel, and a driving device is coupled to a shaft center of the eccentric wheel.

10. The crossed micro water pump structure for a washer according to claim 1, wherein the width of the groove is larger than the diameter of the plunger.