Piezo-Actuated Syringe Pump Drive for Precise Low-Wear Dosing
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Solution Overview
Problem
Existing medical syringe pumps with piezoelectric spindle drives suffer from high wear, increased installation space, energy consumption, noise, and limited accuracy due to numerous moving parts, which affect their durability, precision, and suitability for portable infusion pumps.
Innovation Solution
A piezoelectric drive unit with a push rod oscillating in the longitudinal direction, utilizing piezo actuators for precise movement and clamping mechanisms to minimize moving parts, ensuring accurate and stable fluid dispensing with reduced wear and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a drive unit with a motor, gear, and belt is used to drive a syringe plunger, then the device can achieve controlled fluid delivery, but the device complexity increases and the achievable acceleration is limited to less than 100 μm/s²
Solution Approach 1:
The patent replaces the traditional motor-gear-belt mechanical transmission system with a piezoelectric actuator that directly drives the plunger. This substitution eliminates complex mechanical components while enabling precise control of fluid delivery and achieving accelerations greater than 100 μm/s² through direct electromagnetic-to-mechanical energy conversion.
Solution Approach 2:
The drive unit is segmented into distinct functional modules: the piezoelectric actuator module, the syringe mounting module, and the control module. This segmentation allows each component to be optimized independently and facilitates easier assembly, maintenance, and replacement of individual components without affecting the entire system.
2Ease of operation
If a motor with gear and belt is used, then controlled fluid delivery is achieved, but the plunger acceleration is limited to less than 100 μm/s²
Solution Approach 1:
The patent replaces the traditional motor-gear-belt mechanical transmission system with a piezoelectric actuator that directly drives the plunger. This substitution eliminates complex mechanical components while enabling precise control of fluid delivery and achieving accelerations greater than 100 μm/s² through direct electromagnetic-to-mechanical energy conversion.
Solution Approach 2:
The piezoelectric actuator provides dynamic control of the plunger motion, enabling rapid acceleration and deceleration cycles. The actuator can quickly respond to control signals and adjust the plunger position, achieving accelerations greater than 100 μm/s² while maintaining precise control over fluid delivery rates.
3Measurement precision
If motors are positioned close to the plunger for direct drive, then control precision improves, but heat generation from motors becomes a harmful factor
Solution Approach 1:
The patent replaces the motor-driven system with a piezoelectric actuator that generates mechanical motion through piezoelectric expansion and contraction. This substitution eliminates the heat generation problem associated with motors while maintaining precise control of the plunger position and fluid delivery, as piezoelectric materials can be positioned immediately adjacent to the plunger without thermal interference.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The piezoelectric drive unit provides quiet, precise, and robust fluid dispensing with reduced wear, lower energy consumption, and a compact design, suitable for extended use in medical pumps, including portable infusion pumps.
Implementation Method 1
a piezoelectric element having a piezoelectric stack including a stack base, a stack top, and a piezoelectric element body extending between the stack base and the stack top
Data Source
Figure 1~2
Figure 3a~3b
Figure 4a~4d
AI summary
A piezo-electric drive unit (100) for a medical syringe pump with: a drive frame (70), a control unit (110), a push rod (10) which can be moved in an oscillating manner on the drive frame (70) in the longitudinal direction (x) by a longitudinal stroke by means of a longitudinal stroke device with a first piezo-actuator, a linear guide (60) which is parallel to the push rod (10), a slide (20) which can be moved along the linear guide (60), and a first clamping device, coordinated by the control unit (110), of the slide (20) for alternating coupling and decoupling of the slide (20) to and from the push rod (10). During the coupling, a slide advance of the slide (20) is produced in a first coupling state in accordance with the longitudinal stroke of the push rod (10) which can be moved from an axial starting position. In the first decoupling state, the push rod (10) is released for a movement which is separate from the slide (20). According to the disclosure, the first clamping device has at least one second piezo-actuator which is connected to the control unit (110) in order to actuate said first clamping device, wherein the at least one second piezo-actuator is configured to bring about at least the first coupling state by way of expanding or contracting.