A kneading clamp based on bennett mechanism

Abstract

This invention discloses a pinching clamp based on a Bennett mechanism, relating to the field of medical devices. This design employs a pinching clamping method, and utilizes a variant of the Bennett mechanism. By manipulating a drive rocker arm at the rear end of the lumen, one movable clamping arm at the front end can be moved closer to the other fixed clamping arm, thus achieving the clamping action. Compared to traditional scissor-type structures, the pinching clamping method effectively prevents the object from being squeezed out during operation. Compared to traditional pinching gripper structures, the transmission system based on the Bennett mechanism can be completely accommodated within slender lumens, overcoming the limitation of excessive size. This clamp can be used as a handheld tool by the operator or mounted on the end of a robotic arm, suitable for performing surgical tasks such as grasping and dissection in confined spaces. Therefore, this clamp achieves a comprehensive solution for miniaturized structure, simplified operation, and high performance in applications such as minimally invasive surgery.

Description

Technical Field

[0001] This invention relates to the field of medical devices, and more specifically to a pinch clamp based on a Bennett mechanism. Background Technology

[0002] In confined space operations such as minimally invasive surgery, clamps are needed to enter cavities through narrow channels to perform various surgical procedures such as tissue clamping, separation, and traction. Clamps need to be small enough to pass through minimally invasive incisions, have a streamlined structure for easy assembly, maintenance, and sterilization, and have efficient transmission to open and close the clamps with a single reciprocating motion.

[0003] Traditional clamps primarily employ scissor-like and pinching motions. While scissor-like clamps are simple in structure and can apply significant force, they are prone to squeezing and pushing slippery objects outwards during the closing process, leading to clamping failure. Pinch-like clamps require substantial lateral movement space and require precise motion transitions, resulting in mechanisms typically ranging from centimeters to decimeters in size, making miniaturization difficult. Furthermore, conventional surgical clamps struggle to balance efficiency (rapidly completing an opening and closing cycle) with precision (meticulous control of the opening and closing stroke). Therefore, there is an urgent need for a minimally invasive surgical clamp that is more compact, has more efficient transmission, more precise control, and maintains sufficient clamping force to effectively address the limitations of existing clamps in confined spaces. Summary of the Invention

[0004] To meet the demands for miniaturized, simplified, and high-performance surgical clamps in confined spaces such as minimally invasive surgery, this invention provides a miniature clamp that employs a pinching motion and is based on a variant of the Bennett mechanism design.

[0005] To address the shortcomings of existing technologies, this invention adopts the following technical solution: a pinching clamp based on a Bennett mechanism, comprising a tubular base, a mounting base, a drive rocker arm, a transmission link, a swing arm, a movable clamping arm, a fixed clamping arm, and four eccentric rotating shafts.

[0006] The tubular base is hollow, accommodating various components and providing support and fixation. The mounting base is fixedly installed inside the rear end of the tubular base. The four eccentric rotating shafts include a first rotating shaft, a second rotating shaft, a third rotating shaft, and a fourth rotating shaft. The first rotating shaft is fixed to the mounting base, the fixed clamping arm is fixedly installed at the front end of the tubular base, and the fourth rotating shaft is fixed to the fixed clamping arm.

[0007] The drive rocker arm is located at the rear end of the tubular base. It forms a first rotating pair with the mounting base through a first rotating shaft, forms a second rotating pair with the rear end of the transmission link through a second rotating shaft, forms a third rotating pair with the swing arm through a third rotating shaft, and forms a fourth rotating pair with the fixed clamp arm through a fourth rotating shaft. The swing arm and the fourth rotating shaft have two hinge points, one above the other.

[0008] The torsion angles of the first and second rotating shafts are equal to the torsion angles of the third and fourth rotating shafts, and the torsion angles of the first and fourth rotating shafts are equal to the torsion angles of the second and third rotating shafts.

[0009] The movable clamping arm is positioned above the fixed clamping arm, and its rear end is sleeved on the fourth rotating shaft via a bushing. The bushing is located between the upper and lower hinge points formed between the rocker arm and the fourth rotating shaft. When the rocker arm swings, the second rotating shaft moves accordingly, causing the rear end of the transmission link to move along the second rotating shaft. The front end of the transmission link drives the rocker arm to move, and the rocker arm drives the movable clamping arm to move along the fourth rotating shaft, thereby completing the opening and closing action with the fixed clamping arm.

[0010] Preferably, the drive rocker includes a first rod segment and a second rod segment connected to each other, and a hole is provided at the connection of the two rod segments for fitting the drive rocker onto the first rotating shaft; the first rod segment extends out of the tubular base as the operating end, and the second rod segment forms a second rotating pair with the transmission connecting rod through the second rotating shaft.

[0011] Preferably, the common perpendicular line between the fourth rotating axis and the first rotating axis is defined as the first common perpendicular line, the common perpendicular line between the first rotating axis and the second rotating axis is defined as the second common perpendicular line, the common perpendicular line between the second rotating axis and the third rotating axis is defined as the third common perpendicular line, and the common perpendicular line between the third rotating axis and the fourth rotating axis is defined as the fourth common perpendicular line; the distance between the first and second common perpendicular lines and the distance between the third and fourth common perpendicular lines are equal, and are denoted as d1, where d1 is a preset constant; the distance between the first and fourth common perpendicular lines and the distance between the second and third common perpendicular lines are equal, and are denoted as d2.

[0012] The torsion angle and distance between the first and fourth shafts, and between the second and third shafts are equal. Let the torsion angle be α and the distance be l1. The torsion angle and distance between the first and second shafts, and between the third and fourth shafts are equal. Let the torsion angle be β and the distance be l2. Here, α, l1, β, and l2 are all preset constants. Let η = sin β / sin α, Δl = (l1– l2 / η).

[0013] When the moving clamp arm and the fixed clamp arm are in a pinched state, the angle θ between the second common perpendicular and the first common perpendicular is at its minimum value (greater than or equal to 0°); when the driving rocker arm swings, the angle θ varies between the minimum value and the maximum value (less than or equal to 180°), and d2 changes with the change of the angle θ, and is never zero.

[0014] Preferably, the pinch clamp has a d1 of zero and a Δl of non-zero, and the pinch clamp's d2 / Δl changes with θ, satisfying the following:

[0015]

[0016] Wherein, φ is the angle between the fourth common perpendicular and the first common perpendicular; and as θ increases, d2 / Δl first increases and then decreases. When the moving clamp arm and the fixed clamp arm are opened to the maximum (d2 takes the maximum value), the object to be clamped is placed between the moving clamp arm and the fixed clamp arm. At this time, no matter whether it decreases or continues to increase, d2 will decrease, that is, the closing of the moving clamp arm and the fixed clamp arm can be controlled in both directions.

[0017] Preferably, the pinch clamp has a non-zero d1 and a zero Δl; d2 / d1 changes with θ, satisfying:

[0018]

[0019] Wherein, φ is the angle between the fourth common perpendicular and the first common perpendicular, and as θ increases, d2 / d1 decreases monotonically, and the moving clamp arm and the fixed clamp arm gradually come together.

[0020] Preferably, the pinch clamp's d1 and Δl are both non-zero, and d2 changes with θ. By adjusting the values ​​of d1 and Δl, the clamp is configured to have two working characteristic curves between the minimum (not less than 0°) and the maximum (not greater than 180°) of θ, and the two curves have different rates of change. One curve is used for fine adjustment of the pinch clamp's opening and closing stroke, and the other curve is used for rapid opening and closing of the pinch clamp.

[0021] Preferably, the value of η in the pinch clamp is in the range of 0 to 1; the value of Δl is in the range of greater than l2 / η. By selecting a smaller value of η and a larger value of Δl within the above range, the pinch clamp obtains a shorter drive rocker arm and swing arm, as well as a longer tubular base and transmission link, thereby shrinking the clamp mechanism into a slender tubular space.

[0022] The beneficial effects of this invention are as follows:

[0023] (1) By moving the drive rocker arm, the moving clamp arm and the fixed clamp arm can be controlled to complete the opening and closing motion. The pinching clamping method effectively prevents the clamped object from being squeezed out during operation.

[0024] (2) The structural design of the Bennett mechanism is adopted, and by adjusting the values ​​of η and Δl, the length of the swing arm and the drive rocker arm is compressed, and the transmission mechanism is compressed into the tubular space, giving it the ability to operate in narrow spaces and adapting to restricted space operation scenarios such as minimally invasive surgery;

[0025] (3) By adjusting the parameters d1, η, and Δl, the fine control capability of the clamp opening and closing motion is improved, and it can open and close quickly, taking into account both efficiency and fine control of the opening and closing stroke. It provides two closing modes (half-closed / full-closed), which is conducive to better clamping different types of objects and preventing damage to the clamped objects caused by the simple full-closed mode.

[0026] (4) The clamping mechanism has fewer parts and a relatively simple assembly relationship, making it easy to install and improving the reliability of operation. Attached Figure Description

[0027] Figure 1 Perspective view of the clamps;

[0028] Figure 2 This is a schematic diagram of the working principle of the clamps;

[0029] Figure 3 This is a schematic diagram of the working principle of the clamps;

[0030] Figure 4 This is a diagram of the kinematic model of the clamp;

[0031] Figure 5 This is a graph showing the working characteristics of the clamp.

[0032] Figure 6 The two-segment working characteristic curves are for the optimized clamp.

[0033] In the diagram: 1. Base, 2. Drive rocker arm, 3. Transmission link, 4. Swing arm, 5. Moving clamp arm, 6. Fixed clamp arm, 7. Tubular base, 11. First rotating shaft, 21. Second rotating shaft, 31. Third rotating shaft, 41. Fourth rotating shaft. Detailed Implementation

[0034] The present invention will be further described and illustrated below with reference to specific embodiments. The embodiments described are merely examples of the content of this disclosure and do not limit the scope of the invention. The technical features of each embodiment in the present invention can be combined accordingly, provided that there is no mutual conflict.

[0035] To address the problem that existing medical clamps cannot simultaneously achieve both efficiency (quickly completing an opening and closing cycle) and precision (fine-grained control of the opening and closing stroke), this invention provides a pinching clamp based on the Bennett mechanism. Through a variant design of the Bennett mechanism and by adjusting relevant parameters, the clamp can be configured to have two working characteristics: one for finely adjusting the opening and closing stroke of the clamp, and the other for controlling the clamp to open and close quickly. Figure 1 , Figure 2 and Figure 3 This invention demonstrates a pinching clamp based on a Bennett mechanism, comprising a mounting base 1, a drive rocker arm 2, a transmission link 3, a swing arm 4, a movable clamping arm 5, a fixed clamping arm 6, a tubular base 7, and four rotating shafts. For ease of description, the direction of the clamping end is defined as the front end, and the direction of the other end is defined as the rear end.

[0036] like Figure 2 and Figure 3As shown, the tubular base 7 is hollow, accommodating various components and providing support and fixation. The mounting base 1 is fixedly installed inside the rear end of the tubular base 7. The four rotating shafts are all out of plane, including the first rotating shaft 11, the second rotating shaft 21, the third rotating shaft 31, and the fourth rotating shaft 41. The first rotating shaft 11 is fixed on the mounting base 1, the fixed clamping arm 6 is fixedly installed on the front end of the tubular base 7, and the fourth rotating shaft 41 is fixed on the fixed clamping arm 6.

[0037] The drive rocker arm 2 is located at the rear end of the tubular base 7. It forms a first rotating pair with the mounting base through the first rotating shaft 11 and a second rotating pair with the transmission link 3 through the second rotating shaft 21. The front end of the transmission link 3 forms a third rotating pair with the swing arm 4 through the third rotating shaft 31. The swing arm 4 is located at the front end of the tubular base 7 and forms a fourth rotating pair with the fixed clamp arm 6 through the fourth rotating shaft 41. The connection end between the swing arm 4 and the fourth rotating shaft 41 is "C" shaped.

[0038] In this embodiment, the drive rocker 2 is composed of a first rod segment and a second rod segment of different lengths connected together. The first rod segment extends out of the tubular base 7 and forms a fixed angle with the second rod segment, which is convenient for doctors to hold and operate. The second rod segment forms a second rotating pair with the transmission connecting rod 3 through the second rotating shaft 21. The welded joint is provided with a hole for fitting onto the first rotating shaft 11.

[0039] A fourth rotating shaft 41 is fixed at the rear end of the fixed clamping arm 6. The movable clamping arm 5 is positioned above the fixed clamping arm 6. The front end of the movable clamping arm 5 is used to perform a pinching action with the fixed clamping arm 6, and the rear end is connected to the fourth rotating shaft 41 and held by the "C"-shaped end of the swing rod 4. The rear part of the movable clamping arm 5 has two through holes, which are clearance-fitted with two parallel guide shafts on the fixed clamping arm 6 and the fourth rotating shaft, to assist in positioning and increase stability during sliding. The swing rod 4 and the movable clamping arm 5 can move synchronously along the direction of the fourth rotating shaft 41.

[0040] As mentioned earlier, there is a torsion angle between each rotating shaft. Therefore, when the operating end of the drive rocker 2 is turned, the left and right swing of the drive rocker 2 is transmitted to the swing arm 4 through the transmission link 3, which causes the movement direction of the swing arm 4 to change. It rotates around the fourth rotating shaft 41 and moves up and down along the direction of the fourth rotating shaft 41, thereby driving the front end of the moving clamp arm 5 and the fixed clamp arm 6 to complete the opening and closing action, so as to realize the clamping of the target object.

[0041] The following uses Figure 4The kinematic model of the clamp further illustrates the working principle of the clamp provided by this invention: the common perpendicular line between the fourth rotating shaft and the first rotating shaft is defined as the first common perpendicular line, the common perpendicular line between the first rotating shaft and the second rotating shaft is defined as the second common perpendicular line, the common perpendicular line between the second rotating shaft and the third rotating shaft is defined as the third common perpendicular line, and the common perpendicular line between the third rotating shaft and the fourth rotating shaft is defined as the fourth common perpendicular line; wherein, the distance between the first and second common perpendicular lines and the distance between the third and fourth common perpendicular lines are equal, and are both set as d1, where d1 is a preset constant; the distance between the first and fourth common perpendicular lines and the distance between the second and third common perpendicular lines are equal, and are both set as d2.

[0042] The torsion angles between the first rotating shaft 11 and the fourth rotating shaft 41, and between the second rotating shaft 21 and the third rotating shaft 31 are equal, denoted as α, and their distances are also equal, denoted as l1; the torsion angles between the first rotating shaft 11 and the second rotating shaft 21, and between the third rotating shaft 31 and the fourth rotating shaft 41 are equal, denoted as β, and their distances are also equal, denoted as l2. Here, α, l1, β, and l2 are all preset constants. Let η = sin β / sin α, and Δl = (l1 – l2 / η).

[0043] When d1 and d2 are both zero and l2 is equal to η·l1, the tubular base 7, the driving rocker 2, the transmission link 3 and the swing arm 4 constitute a Bennett mechanism with one degree of freedom. At this time, the swing driving rocker 2 can drive the swing arm 4 to rotate relative to the tubular base 7 through the transmission link 3, without producing movement along the fourth rotation axis 41. That is, at this time, the moving clamp arm 5 cannot complete the pinching motion with the fixed clamp arm 6.

[0044] The device of the present invention is a variant of the Bennett mechanism, wherein d2 is not zero and d1 = 0 and Δl = 0 cannot be true simultaneously. Since the transmission link 3 moves relative to the drive rocker 2 along the direction of the second rotating shaft 21, and the swing arm 4 moves relative to the fixed clamping arm 6 along the direction of the fourth rotating shaft 41, d2 is a variable. Let the angle between the first and second common perpendiculars be θ, and the angle between the fourth and first common perpendiculars be φ. When the moving clamping arm 5 and the fixed clamping arm 6 are in a pinched state, the angle θ is 0°. When the drive rocker 2 swings, the angle θ varies between 0° and 180°, and d2 changes with the angle θ, and is never zero.

[0045] The drive rocker arm 2, transmission link 3, swing arm 4, and base 1 constitute a single-chain closed-loop mechanism, which can be divided into two completely equal half-loops. The homogeneous matrix describing the coordinate transformation of one half-loop can be expressed as:

[0046]

[0047] Where, R(ν, θ) ν Let be a three-dimensional rotation matrix, representing a rotation θ about the ν axis in three-dimensional space. νLet p represent translational motion in three-dimensional space. Since the two semi-rings form a closed loop, we have:

[0048]

[0049] Where I is the identity matrix. Therefore, T is an involutional matrix, satisfying condition 1:

[0050]

[0051] (i.e., two rotations to return to the origin), and condition 2:

[0052]

[0053] (That is, the two translation transformations are superimposed to return to the origin). Because θ ν = 180°, condition 2 indicates that p rotates 180° around the ν axis, which is -p, meaning p is perpendicular to ν, satisfying:

[0054]

[0055] According to condition 1, R(ν, θ) ν This can be expanded as follows:

[0056]

[0057] Where ν x ,ν y ,ν z These are the components of ν on the x, y, and z coordinate axes, respectively.

[0058] At the same time, R(ν, θ) ν The mechanism parameters can be expressed as follows:

[0059]

[0060]

[0061] in, and These are abbreviations for cos θ and sin θ, respectively, and the same applies to other variables.

[0062] From the formula It can be seen that R(ν, θ) ν The trace of a matrix satisfies:

[0063]

[0064] Therefore, the formula satisfy:

[0065]

[0066] Summarized as follows:

[0067]

[0068] Note that the four parts of the above equation satisfy the following:

[0069]

[0070] The solutions for variables θ and φ satisfy:

[0071]

[0072] The two equations are equivalent. Rearranging the second equation and separating the variables θ and φ, we get:

[0073]

[0074] Mode Let θ and φ be the constraints of the Bennett mechanism variables.

[0075] Consider condition 2 again, and note the equation In the formula, ν can be extracted from the 3rd column. ν can be represented as:

[0076]

[0077] Here, unit represents a unit vector.

[0078] p can be represented by the mechanism parameters as follows:

[0079]

[0080] To satisfy condition 2, we have:

[0081]

[0082]

[0083] Organizing , will Substituting the equation into the given equation, we get:

[0084]

[0085] Mode This reflects the constraint relationship between the Bennett mechanism constants l1 and l2: l2 = η·l1. (The equation is...) Substitution After simplification, the functional relationship between d2 and θ when the Bennett mechanism constraints are not satisfied is:

[0086]

[0087] That is, d2 changes with θ and φ, and its expression can be adjusted by constants Δl and d1.

[0088] Where θ and φ satisfy:

[0089]

[0090] like Figure 5 As shown, when the Bennett mechanism constraint is broken, and the d1 of the pinch clamp is zero while Δl is not zero, the d2 / Δl of the pinch clamp changes with θ, satisfying:

[0091]

[0092] As θ increases, d2 / Δl first increases and then decreases. When the moving and fixed clamping arms are fully open (d2 reaches its maximum value), the object to be clamped is placed between the moving and fixed clamping arms. At this point, regardless of whether θ decreases or continues to increase, d2 will decrease, meaning that the closing of the moving and fixed clamping arms can be controlled bidirectionally. At this time, selecting... If the angle is 90°, a clamping mechanism for rapid pinching can be obtained; if η is selected as 0.1, a clamping mechanism for fine adjustment of the opening and closing stroke can be obtained.

[0093] When the Bennett mechanism constraint is broken, and the pinch clamp's d1 is not zero and Δl is zero, d2 / d1 changes with θ, satisfying:

[0094]

[0095] As θ increases, d2 / d1 monotonically decreases. At this point, the opening and closing states of the moving and fixed clamping arms correspond to the magnitude of θ. As θ increases, the moving and fixed clamping arms gradually close, making the operation relatively simple. At this time, selecting... If the angle is 90°, a clamping mechanism that opens quickly can be obtained; if the angle is 0.1, a clamping mechanism for fine adjustment of the opening and closing stroke can be obtained.

[0096] Therefore, by setting the values ​​of α and β (or η = sin β / sin α), the rate of change of d2 with respect to θ can be configured, thereby obtaining clamping mechanisms with different opening and closing strokes. When both d1 and Δl of the pinching clamp are not zero, d2 changes with θ. By adjusting the values ​​of d1 and Δl, the clamp can be configured to have two operating characteristic curves when θ is between its minimum value (not less than 0°) and maximum value (not greater than 180°). In this embodiment, as shown... Figure 6By selecting the orange (when d1 of the pinch clamp is zero and Δl is not zero) and yellow (when Δl of the pinch clamp is zero and d1 is not zero) curves with α = 90° and η = 0.1, two blue curves with different rates of change are obtained: one with a gentle slope for fine-tuning the opening and closing stroke, and the other with a steep slope for rapid opening and closing. Simultaneously, increasing the value of Δl can expand the clamp's stroke while making the rod more elongated, facilitating the clamp's insertion into narrow cavities. Increasing the value of d1 can further enhance the clamp's stroke, but it should not be too large to avoid excessively large radial dimensions of the tubular base 7.

[0097] The present invention also arranges a return spring between the drive rocker 2 and the base 1, so that when the drive rocker is not touched, the drive rocker 2 automatically returns to the state in which the moving clamp arm 5 and the fixed clamp arm 6 are opened.

[0098] In order to monitor the clamping situation during operation, a displacement sensor is arranged between the drive rocker arm 2 and the transmission link 3 to record the change of displacement d2 of the transmission link 3 relative to the drive rocker arm 2 in the direction of the second rotating shaft 21. The change of d2 synchronously reflects the displacement change of the moving clamp arm 5 relative to the fixed clamp arm 6.

[0099] In this embodiment, the value of η of the pinch clamp is in the range of 0 to 1, and the value of Δl is greater than l2 / η. By selecting a suitable combination of η and Δl values ​​within this range, the pinch clamp can obtain a shorter drive rocker arm 2 and swing arm 4, as well as a longer tubular base 7 and transmission link 3. This allows the clamp mechanism to be contracted into a slender tubular space, thus solving the limitation of existing clamps being difficult to miniaturize and adapting to confined space operation scenarios such as minimally invasive surgery.

[0100]

Example 1

[0101] The base 1 is designed as a slender hollow tube with an easy-to-grip structure at the rear end for doctors to hold. Doctors hold the clamp in their palm and control the pinching action of the moving clamp arm 5 and the fixed clamp arm 6 by turning the drive rocker 2 with their thumb. The doctor can also adjust the turning amplitude by monitoring the pinching situation, thereby clamping the tissue to perform surgical operations.

[0102]

Example 2

[0103] The base 1 is designed as a slender hollow tube, with a motor at the rear. The motor controls the rotation of the rocker arm 2 and receives monitoring signals of the clamp's clamping status. Commands can then be used to control the motor's rotation to open and close the clamp. This module can be integrated with a surgical robot system to enable remote-controlled or automated surgery.

[0104] The working principle of the pinch clamp based on the Bennett mechanism is explained below:

[0105] The clamps are fabricated by selecting appropriate d1, η, and Δl values ​​according to the clamping requirements. The lever 2 is manually operated by the doctor or controlled by a motor to slowly increase θ within the range of 0° to 180°. Figure 6 The customized blue function curve indicates that the clamp will first open to its maximum state. At this point, increasing or decreasing θ will cause the clamp to close. Increasing θ allows the clamp to close completely more quickly, which is suitable for gripping thinner objects. Decreasing θ causes the clamp to close slowly, and the clamp will not fully close at its extreme position (such as 0°), but will leave a gap, which is suitable for precisely gripping objects of a certain thickness, such as granular objects like bone fragments. This design, where the drive joystick 2 provides the clamp to open and then close within a certain stroke, offers two closing modes (partially closed / fully closed), which is beneficial for better gripping different types of objects and prevents damage to the gripped object caused by a purely fully closed mode.

[0106] Those skilled in the art can readily make various changes and modifications based on the provided textual description, drawings, and claims, without departing from the spirit and scope of the invention as defined by the claims. Any modifications or equivalent variations made to the above embodiments based on the technical concept and essence of the invention fall within the protection scope defined by the claims of this invention.

Claims

1. A pinching clamp based on a Bennett mechanism, characterized in that, It includes a tubular base, mounting base, drive rocker arm, transmission link, swing arm, moving clamp arm, fixed clamp arm, and four non-planar rotating shafts; The tubular base is hollow, accommodating various components and providing support and fixation. The mounting base is fixedly installed inside the rear end of the tubular base. The four eccentric rotating shafts include a first rotating shaft, a second rotating shaft, a third rotating shaft, and a fourth rotating shaft. The first rotating shaft is fixed to the mounting base, the fixed clamping arm is fixedly installed at the front end of the tubular base, and the fourth rotating shaft is fixed to the fixed clamping arm. The drive rocker arm is located at the rear end of the tubular base. It forms a first rotating pair with the mounting base through a first rotating shaft, forms a second rotating pair with the rear end of the transmission link through a second rotating shaft, forms a third rotating pair with the swing arm through a third rotating shaft, and forms a fourth rotating pair with the fixed clamp arm through a fourth rotating shaft. The swing arm and the fourth rotating shaft have two hinge points, one above the other. The torsion angles of the first and second rotating shafts are equal to the torsion angles of the third and fourth rotating shafts; the distance between the first and second rotating shafts is equal to the distance between the third and fourth rotating shafts; the torsion angles of the first and fourth rotating shafts are equal to the torsion angles of the second and third rotating shafts; the distance between the first and fourth rotating shafts is equal to the distance between the second and third rotating shafts. Define the common perpendicular line between the fourth and first rotating axes as the first common perpendicular line, the common perpendicular line between the first and second rotating axes as the second common perpendicular line, the common perpendicular line between the second and third rotating axes as the third common perpendicular line, and the common perpendicular line between the third and fourth rotating axes as the fourth common perpendicular line; the distance between the first and second common perpendicular lines and the distance between the third and fourth common perpendicular lines are equal, denoted as d1, where d1 is a preset constant; the distance between the first and fourth common perpendicular lines and the distance between the second and third common perpendicular lines are equal, denoted as d2; d2 is not 0; Define the torsion angle and distance between the first and fourth axes, and between the second and third axes as equal, denoted by α and l1 respectively; define the torsion angle and distance between the first and second axes, and between the third and fourth axes as equal, denoted by β and l2 respectively; where α, l1, β, and l2 are all preset constants; let η = sin β / sin α, Δl = (l1 – l2 / η); d1 and Δl are not simultaneously 0; The movable clamping arm is positioned above the fixed clamping arm, and its rear end is sleeved on the fourth rotating shaft via a bushing. The bushing is located between the upper and lower hinge points formed between the rocker arm and the fourth rotating shaft. When the rocker arm swings, the second rotating shaft moves accordingly, causing the rear end of the transmission link to move along the second rotating shaft. The front end of the transmission link drives the rocker arm to move, and the rocker arm drives the movable clamping arm to move along the fourth rotating shaft, thereby completing the opening and closing action with the fixed clamping arm.

2. A pinching clamp based on a Bennett mechanism according to claim 1, characterized in that, The drive rocker includes a first rod segment and a second rod segment connected to each other. A hole is provided at the connection of the two rod segments for fitting the drive rocker onto the first rotating shaft. The first rod segment extends out of the tubular base as the operating end, and the second rod segment forms a second rotating pair with the transmission connecting rod through the second rotating shaft.

3. A pinching clamp based on a Bennett mechanism according to claim 1, characterized in that, The movable clamping arm has two through holes at the rear. The two through holes are in clearance fit with two guide shafts parallel to the fourth rotating shaft on the fixed clamping arm to assist in positioning and increase stability during sliding.

4. A pinching clamp based on a Bennett mechanism according to claim 1, characterized in that, When the moving clamp arm and the fixed clamp arm are in a pinched state, the angle θ between the second common perpendicular and the first common perpendicular is at its minimum value; when the driving rocker arm swings, the angle θ changes, and d2 changes with the change of the angle θ, and is never zero, wherein the minimum value of the angle θ is greater than or equal to 0°, and the maximum value is less than or equal to 180°.

5. A pinching clamp based on a Bennett mechanism according to claim 4, characterized in that: The pinch clamp has a d1 of zero and a Δl of non-zero value. The pinch clamp's d2 / Δl changes with θ and satisfies the following: ； Where φ is the angle between the fourth common perpendicular and the first common perpendicular; and as θ increases, d2 / Δl first increases and then decreases. When the moving clamp arm and the fixed clamp arm are opened to the maximum, that is, when d2 reaches its maximum value, the object to be clamped is placed between the moving clamp arm and the fixed clamp arm. At this time, no matter whether it decreases or continues to increase, d2 will decrease, that is, bidirectional control closes the moving clamp arm and the fixed clamp arm.

6. A pinching clamp based on a Bennett mechanism according to claim 4, characterized in that: The pinch clamp has a non-zero d1 and a zero Δl; d2 / d1 changes with θ, satisfying: ； Wherein, φ is the angle between the fourth common perpendicular and the first common perpendicular, and as θ increases, d2 / d1 decreases monotonically, and the moving clamp arm and the fixed clamp arm gradually come together.

7. A pinching clamp based on a Bennett mechanism according to claim 4, characterized in that, The pinch clamp has non-zero values ​​for d1 and Δl, and d2 changes with θ. By adjusting the values ​​of d1 and Δl, the clamp is configured to have two working characteristic curves between the minimum and maximum values ​​of θ, and the two curves have different rates of change. One curve is used for fine adjustment of the opening and closing stroke of the pinch clamp, and the other curve is used for rapid opening and closing of the pinch clamp.

8. A pinching clamp based on a Bennett mechanism according to claim 4, characterized in that, A displacement sensor is placed between the drive rocker arm and the transmission link to record the change in displacement d2 of the transmission link relative to the drive rocker arm in the second rotation axis direction. This change synchronously reflects the displacement change of the moving clamp arm relative to the fixed clamp arm.

9. A pinching clamp based on a Bennett mechanism according to claim 4, characterized in that, The value of η in the pinch clamp ranges from 0 to 1; the value of Δl ranges from greater than l² / η. By selecting a smaller value of η and a larger value of Δl within the above range, the pinch clamp obtains a shorter drive rocker arm and swing arm, as well as a longer tubular base and transmission link, thereby shrinking the clamp mechanism into a slender tubular space.

10. A pinching clamp based on a Bennett mechanism according to claim 1, characterized in that, A return spring is arranged between the drive rocker arm and the mounting base so that when the drive rocker arm is not touched, the drive rocker arm automatically returns to the state where the moving clamp arm and the fixed clamp arm are open.

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