Variable displacement pump

Abstract

Provided are apparatuses and methods for a variable displacement pump. An apparatus may include a motor having both a clockwise rotation and a counterclockwise rotation. An eccentric mechanism comprising a first eccentric and a second eccentric, the second eccentric being rotatable within the first eccentric. A stop mechanism including at least one stop plate configured to limit a rotational movement of the second eccentric within the first eccentric. A piston operably coupled to the eccentric mechanism, wherein a displacement of the piston is mechanically adjustable based on a relative rotational position of the first eccentric and the second eccentric. A housing configured to support the motor, the eccentric mechanism, the stop mechanism, and the piston.

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to U.S. Provisional Patent Application No. 63 / 754,030, which was filed on Feb. 5, 2025, which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates generally to liquid dispensing systems, and more specifically to a variable displacement pump that is true positive displacement and capable of precise dosage control.BACKGROUND

[0003] Traditional liquid pumps often face challenges in maintaining high accuracy across variable dosages, particularly in demanding commercial environments and with varying types of liquids. Existing solutions may lack flexibility in adjusting displacement during operation or require significant downtime to recalibrate or reconfigure the system. Moreover, many existing pumps fail to meet cost-effectiveness and reliability standards, especially when operating under stringent accuracy requirements of less than 0.25% tolerance. Therefore, there exists a need for a cost-effective, accurate, and versatile pump suitable for various applications, including syrup dispensing in the beverage industry.SUMMARY

[0004] According to an aspect of one or more examples, there is provided a variable displacement pump. The pump may include a motor configured with a clockwise rotation and a counterclockwise rotation, an eccentric mechanism including a first eccentric and a second eccentric, the second eccentric being rotatable within the first eccentric, a stop mechanism including at least one stop plate configured to limit rotational movement of the second eccentric within the first eccentric, a piston operably coupled to the eccentric mechanism, wherein a displacement of the piston is mechanically adjustable based on the relative rotational position of the first and second eccentrics, and a housing configured to support the motor, eccentric mechanism, stop mechanism, and piston. The stop mechanism may include two adjustable stop plates, each configured to set a maximum displacement of the piston. The stop mechanism may include a single stop plate configured to define two discrete dosages based on a direction of motor rotation. The dosages may be 0.1 ounces in a clockwise rotation and 0.01 ounces in a counterclockwise rotation. The pump may include a rotation sensor configured to count a number of motor rotations in either direction (clockwise or counterclockwise) and provide feedback for dosage accuracy. The housing may be constructed from plastic and include a replaceable cylinder sleeve for enhanced durability and ease of maintenance. The motor may be a compact gear motor selected for reduced cost and size. The pump may include ports for tubing, sensors, and motor wires, all exiting from a single side of the housing. The pump may achieve a dosage accuracy of less than 0.25% tolerance. The piston may be configured to perform multiple full rotations for compounded dosages.

[0005] According to an aspect of one or more examples, there is provided a method of dispensing a liquid using a variable displacement pump. The method may include operating a motor to rotate in a first direction (clockwise or counterclockwise) to achieve a first dosage, rotating an eccentric mechanism comprising a first eccentric and a second eccentric to adjust the displacement of a piston, limiting rotational movement of the second eccentric within the first eccentric using a stop mechanism, displacing the liquid using the piston to dispense the liquid through an outlet, and monitoring motor rotations with a rotation sensor to ensure accurate dosage. The first direction of motor rotation may achieve a dosage of 0.1 ounces. The method may include reversing the motor rotation to a second direction (opposite of the first direction) to achieve a second dosage. The second dosage may be 0.01 ounces. The method may include adjusting the stop mechanism to alter a maximum displacement of the piston. The eccentric mechanism may cancel displacement to a virtual zero by aligning the first eccentric and the second eccentric. The method may include replacing a cylinder sleeve within a housing for maintenance. The motor may be a compact gear motor selected for cost and size efficiency. The method may include streamlining ports to have all tubing, sensor, and motor wires exit from a single side. The liquid may dispensed with an accuracy of less than 0.25% tolerance.

[0006] These and other aspects, objects, features, and advantages of the example examples will become apparent to persons having ordinary skill in the art upon consideration of the following detailed description of example examples.BRIEF DESCRIPTION OF DRAWINGS

[0007] FIG. 1 shows an illustration of a variable displacement pump with a single stop plate according to one or more examples.

[0008] FIG. 2 shows an illustration of a variable displacement pump with two adjustable stop plates according to one or more examples.

[0009] FIG. 3 shows an exploded view of a variable displacement pump assembly according to one or more examples.

[0010] FIG. 4 shows a flow chart of a method of dispensing a liquid using a variable displacement pump according to one or more examples.DETAILED DESCRIPTION OF VARIOUS EXAMPLES

[0011] Reference will now be made in detail to the following various examples, which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The following examples may be embodied in various forms without being limited to the examples set forth herein.

[0012] FIG. 1 shows an illustration of a variable displacement pump 100 with a single stop plate according to one or more examples. The variable displacement pump 100 may enable dispensing of approximately 0.1 ounces of liquid when the motor rotates in the clockwise (CW) direction and approximately 0.01 ounces of liquid when the motor rotates in the counterclockwise (CCW) direction. For example, to dispense 0.31 ounces of liquid, the motor may rotate in the CW direction three times and rotate in the CCW direction one time. As shown in FIG. 1, the variable displacement pump 100 may include a single stop plate 110, an eccentric mechanism 120, and a piston 130. The eccentric mechanism 120 may include a first eccentric and a second eccentric, the second eccentric being rotatable within the first eccentric. The stop plate 110 may be configured to mechanically limit the rotational movement of the second eccentric within the first eccentric, defining two discrete dosages. The stop plate 110 may interact with a stop pin 140 mounted on the eccentric mechanism 120, ensuring precision and repeatability. The variable displacement pump 100 may allow for adjustable displacement of the piston 130 based on the relative positions of the eccentrics. The piston 130 may be operably coupled to the eccentric mechanism 120 and may be responsible for displacing the liquid for precise dosing. The displacement may be determined by the interaction between the stop plate 110 and the eccentric mechanism 120.

[0013] FIG. 2 shows an illustration of a variable displacement pump 200 with two adjustable stop plates according to one or more examples. The variable displacement pump 200 may allow the user to set dosages anywhere between approximately 0.00 ounces and 0.17 ounces. As shown in FIG. 2, the variable displacement pump 200 may include adjustable stop plates 210, an eccentric mechanism 220, and a piston 230. The two stop plates 210 may be used to define the maximum and minimum displacement of the piston 230. The adjustable stop plates 210 may be adjusted to customize the range of eccentric rotation, thereby allowing fine-tuned control over dosage volumes. Similar to the eccentric mechanism 120 in FIG. 1, the eccentric mechanism 220 may include a first eccentric and a second eccentric, enabling variable displacement of the piston 230. The adjustable stop plates 210 may allow for greater flexibility in configuring the variable displacement pump 200 for different applications. The stop pin 240 may interact with the adjustable stop plates 210 to restrict the rotation of the second eccentric. This mechanism may provide a mechanical limit to the piston's 230 movement, ensuring accuracy.

[0014] FIG. 3 shows an exploded view of a variable displacement pump assembly 300 according to one or more examples. As shown in FIG. 3, the variable displacement pump assembly 300 may include a motor 305, an eccentric mechanism 310, a piston 315, a stop mechanism 320, a replaceable cylinder sleeve 325, a rotation sensor 330, a rotating magnet and key 335, and valves 340. The motor 305 may be compact and reversible, and may drive the eccentric mechanism 310. The motor's 305 rotation direction (clockwise or counterclockwise) may determine the dosage dispensed. The eccentric mechanism 310 may include a first eccentric 345 (outer ring) and a second eccentric 350 (inner rotating element), allowing for adjustable displacement of the piston 315. The second eccentric 350 may rotate within the first eccentric 345, and their relative positioning may determine the piston's 315 movement. The piston 315 may be coupled to the eccentric mechanism 310. The piston 315 may move linearly to dispense liquid, converting rotational motion into displacement. The piston's 315 movement may be precisely controlled to ensure accurate dispensing. Depending on the configuration, the stop mechanism 320 may include one or two stop plates (e.g., single stop plate 110 in FIG. 1 or two adjustable stop plates 210 in FIG. 2) to limit the movement of the second eccentric. These stop plates may be adjustable in the two-plate configuration for customizable dosages. A stop pin 355 may be a protruding component in the eccentric mechanism 310. The stop pin 355 may interact with the stop plates, ensuring the range of motion is constrained. The cylinder sleeve 325 may simplify manufacturing and maintenance. The cylinder sleeve 325 may provide a durable surface for the piston 315 while allowing the pump housing to be constructed from plastic, reducing cost and weight.

[0015] The rotation sensor 330 may be mounted on the backside of the bore. The rotation sensor 330 may detect the number of rotations of the eccentric mechanism 310, enabling precise monitoring of dosages. The rotation sensor 330 may be tied to logic to calculate a prescribed dosage based on the rotation count. The rotation sensor 330 may be a Hall Effect sensor, or other type of magnetic sensor. The rotating magnet and key 335 may be centrally located on the eccentric shaft and move synchronously with it. A key may secure the magnet to the shaft, ensuring consistent alignment. As the magnet rotates, the rotation sensor 330 may detect magnetic field changes to count the number of rotations accurately. The valves 340 may be positioned at the top of the variable displacement pump 300. The valves 340 may regulate liquid flow into and out of the pump chamber. The valves 340 may prevent backflow and ensure smooth and controlled dispensing. Ball bearings may be used instead of traditional bronze bearings to enhance durability and reduce wear, ensuring smooth operation over extended periods. The variable displacement pump 300 may feature strategically positioned ports for tubing, sensor connections, and motor wiring. Connections may exit from a single side of the housing to streamline installation and minimize complexity.

[0016] The variable displacement pump assembly 300 may be designed to handle liquids of varying viscosities, making it suitable for a broad range of applications. The positive displacement mechanism may ensure consistent performance regardless of the fluid's thickness or flow characteristics. The modular design, including replaceable cylinder sleeves 325 and robust valve 340 structures, may support seamless operation with both low-viscosity liquids (e.g., water) and high-viscosity liquids (e.g., syrups, oils). Additionally, the motor 305 and eccentric mechanism 310 may be engineered to deliver precise dosages without being affected by changes in liquid viscosity.

[0017] FIG. 4 shows a flow chart of a method 400 of dispensing a liquid using a variable displacement pump according to one or more examples. At operation 410, the method 400 may include operating a motor to rotate in a first direction to achieve a first dosage. At operation 420, the method 400 may include rotating an eccentric mechanism comprising a first eccentric and a second eccentric to adjust a displacement of a piston. At operation 430, the method 400 may include limiting rotational movement of the second eccentric within the first eccentric using a stop mechanism. At operation 440, the method 400 may include displacing the liquid using the piston to dispense the liquid through an outlet. At operation 450, the method 400 may include monitoring motor rotations with a rotation sensor to ensure accurate dosage.

[0018] Various examples have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious to literally describe and illustrate every combination and subcombination of these examples. Accordingly, all examples can be combined in any way or combination, and the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the examples described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination.

[0019] It will be appreciated by persons skilled in the art that the examples described herein are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings.

Examples

Embodiment Construction

[0011]Reference will now be made in detail to the following various examples, which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The following examples may be embodied in various forms without being limited to the examples set forth herein.

[0012]FIG. 1 shows an illustration of a variable displacement pump 100 with a single stop plate according to one or more examples. The variable displacement pump 100 may enable dispensing of approximately 0.1 ounces of liquid when the motor rotates in the clockwise (CW) direction and approximately 0.01 ounces of liquid when the motor rotates in the counterclockwise (CCW) direction. For example, to dispense 0.31 ounces of liquid, the motor may rotate in the CW direction three times and rotate in the CCW direction one time. As shown in FIG. 1, the variable displacement pump 100 may include a single stop plate 110, an eccentric mechanism 120, and a piston 130. The eccentric mechanism...

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to U.S. Provisional Patent Application No. 63 / 754,030, which was filed on Feb. 5, 2025, which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates generally to liquid dispensing systems, and more specifically to a variable displacement pump that is true positive displacement and capable of precise dosage control.BACKGROUND

[0003] Traditional liquid pumps often face challenges in maintaining high accuracy across variable dosages, particularly in demanding commercial environments and with varying types of liquids. Existing solutions may lack flexibility in adjusting displacement during operation or require significant downtime to recalibrate or reconfigure the system. Moreover, many existing pumps fail to meet cost-effectiveness and reliability standards, especially when operating under stringent accuracy requirements of less than 0.25% tolerance. Therefore, there exists a need for a cost-effective, accurate, and versatile pump suitable for various applications, including syrup dispensing in the beverage industry.SUMMARY

[0004] According to an aspect of one or more examples, there is provided a variable displacement pump. The pump may include a motor configured with a clockwise rotation and a counterclockwise rotation, an eccentric mechanism including a first eccentric and a second eccentric, the second eccentric being rotatable within the first eccentric, a stop mechanism including at least one stop plate configured to limit rotational movement of the second eccentric within the first eccentric, a piston operably coupled to the eccentric mechanism, wherein a displacement of the piston is mechanically adjustable based on the relative rotational position of the first and second eccentrics, and a housing configured to support the motor, eccentric mechanism, stop mechanism, and piston. The stop mechanism may include two adjustable stop plates, each configured to set a maximum displacement of the piston. The stop mechanism may include a single stop plate configured to define two discrete dosages based on a direction of motor rotation. The dosages may be 0.1 ounces in a clockwise rotation and 0.01 ounces in a counterclockwise rotation. The pump may include a rotation sensor configured to count a number of motor rotations in either direction (clockwise or counterclockwise) and provide feedback for dosage accuracy. The housing may be constructed from plastic and include a replaceable cylinder sleeve for enhanced durability and ease of maintenance. The motor may be a compact gear motor selected for reduced cost and size. The pump may include ports for tubing, sensors, and motor wires, all exiting from a single side of the housing. The pump may achieve a dosage accuracy of less than 0.25% tolerance. The piston may be configured to perform multiple full rotations for compounded dosages.

[0005] According to an aspect of one or more examples, there is provided a method of dispensing a liquid using a variable displacement pump. The method may include operating a motor to rotate in a first direction (clockwise or counterclockwise) to achieve a first dosage, rotating an eccentric mechanism comprising a first eccentric and a second eccentric to adjust the displacement of a piston, limiting rotational movement of the second eccentric within the first eccentric using a stop mechanism, displacing the liquid using the piston to dispense the liquid through an outlet, and monitoring motor rotations with a rotation sensor to ensure accurate dosage. The first direction of motor rotation may achieve a dosage of 0.1 ounces. The method may include reversing the motor rotation to a second direction (opposite of the first direction) to achieve a second dosage. The second dosage may be 0.01 ounces. The method may include adjusting the stop mechanism to alter a maximum displacement of the piston. The eccentric mechanism may cancel displacement to a virtual zero by aligning the first eccentric and the second eccentric. The method may include replacing a cylinder sleeve within a housing for maintenance. The motor may be a compact gear motor selected for cost and size efficiency. The method may include streamlining ports to have all tubing, sensor, and motor wires exit from a single side. The liquid may dispensed with an accuracy of less than 0.25% tolerance.

[0006] These and other aspects, objects, features, and advantages of the example examples will become apparent to persons having ordinary skill in the art upon consideration of the following detailed description of example examples.BRIEF DESCRIPTION OF DRAWINGS

[0007] FIG. 1 shows an illustration of a variable displacement pump with a single stop plate according to one or more examples.

[0008] FIG. 2 shows an illustration of a variable displacement pump with two adjustable stop plates according to one or more examples.

[0009] FIG. 3 shows an exploded view of a variable displacement pump assembly according to one or more examples.

[0010] FIG. 4 shows a flow chart of a method of dispensing a liquid using a variable displacement pump according to one or more examples.DETAILED DESCRIPTION OF VARIOUS EXAMPLES

[0011] Reference will now be made in detail to the following various examples, which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The following examples may be embodied in various forms without being limited to the examples set forth herein.

[0012] FIG. 1 shows an illustration of a variable displacement pump 100 with a single stop plate according to one or more examples. The variable displacement pump 100 may enable dispensing of approximately 0.1 ounces of liquid when the motor rotates in the clockwise (CW) direction and approximately 0.01 ounces of liquid when the motor rotates in the counterclockwise (CCW) direction. For example, to dispense 0.31 ounces of liquid, the motor may rotate in the CW direction three times and rotate in the CCW direction one time. As shown in FIG. 1, the variable displacement pump 100 may include a single stop plate 110, an eccentric mechanism 120, and a piston 130. The eccentric mechanism 120 may include a first eccentric and a second eccentric, the second eccentric being rotatable within the first eccentric. The stop plate 110 may be configured to mechanically limit the rotational movement of the second eccentric within the first eccentric, defining two discrete dosages. The stop plate 110 may interact with a stop pin 140 mounted on the eccentric mechanism 120, ensuring precision and repeatability. The variable displacement pump 100 may allow for adjustable displacement of the piston 130 based on the relative positions of the eccentrics. The piston 130 may be operably coupled to the eccentric mechanism 120 and may be responsible for displacing the liquid for precise dosing. The displacement may be determined by the interaction between the stop plate 110 and the eccentric mechanism 120.

[0013] FIG. 2 shows an illustration of a variable displacement pump 200 with two adjustable stop plates according to one or more examples. The variable displacement pump 200 may allow the user to set dosages anywhere between approximately 0.00 ounces and 0.17 ounces. As shown in FIG. 2, the variable displacement pump 200 may include adjustable stop plates 210, an eccentric mechanism 220, and a piston 230. The two stop plates 210 may be used to define the maximum and minimum displacement of the piston 230. The adjustable stop plates 210 may be adjusted to customize the range of eccentric rotation, thereby allowing fine-tuned control over dosage volumes. Similar to the eccentric mechanism 120 in FIG. 1, the eccentric mechanism 220 may include a first eccentric and a second eccentric, enabling variable displacement of the piston 230. The adjustable stop plates 210 may allow for greater flexibility in configuring the variable displacement pump 200 for different applications. The stop pin 240 may interact with the adjustable stop plates 210 to restrict the rotation of the second eccentric. This mechanism may provide a mechanical limit to the piston's 230 movement, ensuring accuracy.

[0014] FIG. 3 shows an exploded view of a variable displacement pump assembly 300 according to one or more examples. As shown in FIG. 3, the variable displacement pump assembly 300 may include a motor 305, an eccentric mechanism 310, a piston 315, a stop mechanism 320, a replaceable cylinder sleeve 325, a rotation sensor 330, a rotating magnet and key 335, and valves 340. The motor 305 may be compact and reversible, and may drive the eccentric mechanism 310. The motor's 305 rotation direction (clockwise or counterclockwise) may determine the dosage dispensed. The eccentric mechanism 310 may include a first eccentric 345 (outer ring) and a second eccentric 350 (inner rotating element), allowing for adjustable displacement of the piston 315. The second eccentric 350 may rotate within the first eccentric 345, and their relative positioning may determine the piston's 315 movement. The piston 315 may be coupled to the eccentric mechanism 310. The piston 315 may move linearly to dispense liquid, converting rotational motion into displacement. The piston's 315 movement may be precisely controlled to ensure accurate dispensing. Depending on the configuration, the stop mechanism 320 may include one or two stop plates (e.g., single stop plate 110 in FIG. 1 or two adjustable stop plates 210 in FIG. 2) to limit the movement of the second eccentric. These stop plates may be adjustable in the two-plate configuration for customizable dosages. A stop pin 355 may be a protruding component in the eccentric mechanism 310. The stop pin 355 may interact with the stop plates, ensuring the range of motion is constrained. The cylinder sleeve 325 may simplify manufacturing and maintenance. The cylinder sleeve 325 may provide a durable surface for the piston 315 while allowing the pump housing to be constructed from plastic, reducing cost and weight.

[0015] The rotation sensor 330 may be mounted on the backside of the bore. The rotation sensor 330 may detect the number of rotations of the eccentric mechanism 310, enabling precise monitoring of dosages. The rotation sensor 330 may be tied to logic to calculate a prescribed dosage based on the rotation count. The rotation sensor 330 may be a Hall Effect sensor, or other type of magnetic sensor. The rotating magnet and key 335 may be centrally located on the eccentric shaft and move synchronously with it. A key may secure the magnet to the shaft, ensuring consistent alignment. As the magnet rotates, the rotation sensor 330 may detect magnetic field changes to count the number of rotations accurately. The valves 340 may be positioned at the top of the variable displacement pump 300. The valves 340 may regulate liquid flow into and out of the pump chamber. The valves 340 may prevent backflow and ensure smooth and controlled dispensing. Ball bearings may be used instead of traditional bronze bearings to enhance durability and reduce wear, ensuring smooth operation over extended periods. The variable displacement pump 300 may feature strategically positioned ports for tubing, sensor connections, and motor wiring. Connections may exit from a single side of the housing to streamline installation and minimize complexity.

[0016] The variable displacement pump assembly 300 may be designed to handle liquids of varying viscosities, making it suitable for a broad range of applications. The positive displacement mechanism may ensure consistent performance regardless of the fluid's thickness or flow characteristics. The modular design, including replaceable cylinder sleeves 325 and robust valve 340 structures, may support seamless operation with both low-viscosity liquids (e.g., water) and high-viscosity liquids (e.g., syrups, oils). Additionally, the motor 305 and eccentric mechanism 310 may be engineered to deliver precise dosages without being affected by changes in liquid viscosity.

[0017] FIG. 4 shows a flow chart of a method 400 of dispensing a liquid using a variable displacement pump according to one or more examples. At operation 410, the method 400 may include operating a motor to rotate in a first direction to achieve a first dosage. At operation 420, the method 400 may include rotating an eccentric mechanism comprising a first eccentric and a second eccentric to adjust a displacement of a piston. At operation 430, the method 400 may include limiting rotational movement of the second eccentric within the first eccentric using a stop mechanism. At operation 440, the method 400 may include displacing the liquid using the piston to dispense the liquid through an outlet. At operation 450, the method 400 may include monitoring motor rotations with a rotation sensor to ensure accurate dosage.

[0018] Various examples have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious to literally describe and illustrate every combination and subcombination of these examples. Accordingly, all examples can be combined in any way or combination, and the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the examples described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination.

[0019] It will be appreciated by persons skilled in the art that the examples described herein are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings.

Examples

Embodiment Construction

[0011]Reference will now be made in detail to the following various examples, which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The following examples may be embodied in various forms without being limited to the examples set forth herein.

[0012]FIG. 1 shows an illustration of a variable displacement pump 100 with a single stop plate according to one or more examples. The variable displacement pump 100 may enable dispensing of approximately 0.1 ounces of liquid when the motor rotates in the clockwise (CW) direction and approximately 0.01 ounces of liquid when the motor rotates in the counterclockwise (CCW) direction. For example, to dispense 0.31 ounces of liquid, the motor may rotate in the CW direction three times and rotate in the CCW direction one time. As shown in FIG. 1, the variable displacement pump 100 may include a single stop plate 110, an eccentric mechanism 120, and a piston 130. The eccentric mechanism...

Claims

1. A variable displacement pump, comprising:a motor having both a clockwise rotation and a counterclockwise rotation;an eccentric mechanism comprising a first eccentric and a second eccentric, the second eccentric being rotatable within the first eccentric;a stop mechanism including at least one stop plate configured to limit a rotational movement of the second eccentric within the first eccentric;a piston operably coupled to the eccentric mechanism, wherein a displacement of the piston is mechanically adjustable based on a relative rotational position of the first eccentric and the second eccentric; anda housing configured to support the motor, the eccentric mechanism, the stop mechanism, and the piston.

2. The pump of claim 1, wherein the stop mechanism comprises two adjustable stop plates, each stop plate configured to set a maximum displacement of the piston.

3. The pump of claim 1, wherein the stop mechanism comprises a single stop plate configured to define two discrete dosages based on a direction of motor rotation.

4. The pump of claim 3, wherein the dosages are 0.1 ounces in the clockwise rotation and 0.01 ounces in the counterclockwise rotation.

5. The pump of claim 1, further comprising a rotation sensor configured to count a number of motor rotations and provide a feedback for dosage accuracy.

6. The pump of claim 1, wherein the housing is constructed from plastic and includes a replaceable cylinder sleeve for enhanced durability and ease of maintenance.

7. The pump of claim 1, wherein the motor is a compact gear motor selected for reduced cost and size.

8. The pump of claim 1, further comprising ports for tubing, sensors, and motor wires, all exiting from a single side of the housing.

9. The pump of claim 1, wherein the pump achieves a dosage accuracy of less than 0.25% tolerance.

10. The pump of claim 1, wherein the piston is configured to perform multiple full rotations for compounded dosages.

11. A method of dispensing a liquid using a variable displacement pump, the method comprising:operating a motor to rotate in a first direction to achieve a first dosage;rotating an eccentric mechanism comprising a first eccentric and a second eccentric to adjust a displacement of a piston;limiting rotational movement of the second eccentric within the first eccentric using a stop mechanism;displacing the liquid using the piston to dispense the liquid through an outlet; andmonitoring motor rotations with a rotation sensor to ensure accurate dosage.

12. The method of claim 11, wherein the first direction of motor rotation achieves a dosage of 0.1 ounces.

13. The method of claim 11, further comprising reversing the motor rotation to a second direction to achieve a second dosage.

14. The method of claim 13, wherein the second dosage is 0.01 ounces.

15. The method of claim 11, further comprising adjusting the stop mechanism to alter a maximum displacement of the piston.

16. The method of claim 11, wherein the eccentric mechanism cancels displacement to a virtual zero by aligning the first eccentric and the second eccentric.

17. The method of claim 11, further comprising replacing a cylinder sleeve within a housing for maintenance.

18. The method of claim 11, wherein the motor is a compact gear motor selected for cost and size efficiency.

19. The method of claim 11, further comprising streamlining ports to have all tubing, sensor, and motor wires exit from a single side.

20. The method of claim 11, wherein the liquid is dispensed with an accuracy of less than 0.25% tolerance.

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