Kinematics analysis method for fire rescue expander

Abstract

The invention provides a fire rescue expander kinematics analysis method. The fire rescue expander kinematics analysis method comprises the following steps: performing kinematics modeling on an expander; position coordinates (x3, y3), (x7, y7), a connector expansion distance d and a connector movement distance y of a revolute pair between the connector and the upper expansion arm and the vertex of the upper expansion arm are obtained; and the transmission distance ratio kappa d, the transmission distance ratio kappa v and the transmission acceleration ratio kappa of the expander are obtained. The dilator has the beneficial effects that the structure of the dilator is simplified, kinematics modeling is carried out, the expansion distance of the connector and the movement distance of the connector are obtained according to a rotating pair between the connector and the upper dilation arm and the position of the vertex of the upper dilation arm, and then the transmission distance ratio, the transmission distance ratio and the transmission acceleration ratio of the dilator are obtained; therefore, the transmission effect of the dilator with any given size can be calculated; and the influence rule of each parameter on the transmission efficiency can be researched, and the method is used for structural design of the dilator.

Description

Technical Field

[0001] The present invention belongs to the technical field of expanders, and in particular relates to a kinematic analysis method for an expander used in fire rescue. Background Art

[0002] In fire rescue, expanders are mainly used for the rapid demolition of solid obstacles such as doors and beds, and are important fire-fighting equipment indispensable at the scene of emergencies such as fires, earthquakes, and car accidents. An expander includes a driving mechanism, a connecting head, a transmission rod, and two expansion arms arranged oppositely and in a triangular shape. Both the upper and lower sides of the front end of the driving mechanism are connected to the rear ends of the corresponding transmission rods, and the rear end of each transmission rod can rotate and move along a strip-shaped groove at the driving mechanism, ensuring that the expansion arms can expand. The front ends of the two transmission rods are respectively rotatably connected to the outer parts of the rear ends of the corresponding expansion arms. The connecting head is located in the middle of the two transmission rods and is fixedly connected to the front end of the driving mechanism, and the upper and lower ends of the connecting head are respectively rotatably connected to the inner parts of the rear ends of the corresponding expansion arms. By linearly driving the connecting head through a driving mechanism (such as a hydraulic mechanism or an electric mechanism, etc.), the two expansion arms are driven to expand or reset by the movement of the connecting head. The expansion efficiency and weight of the expander directly affect the emergency handling efficiency and the physical strength of firefighters. However, at present, there is very little research on expanders. Therefore, conducting kinematic analysis of expanders is of great significance for the design of expanders. Summary of the Invention

[0003] In view of this, the present invention aims to overcome the above-mentioned deficiencies in the prior art and proposes a kinematic analysis method for an expander used in fire rescue.

[0004] To achieve the above object, the technical solution of the present invention is realized as follows:

[0005] A kinematic analysis method for an expander used in fire rescue includes the following steps:

[0006] S1. Conduct kinematic modeling on the expander, simplify the expander into a linkage mechanism connected by rotating pairs, and set the handle of the expander to be fixed;

[0007] S2. Obtain the position coordinates of the rotating pair between the connecting head and the upper expansion arm and the vertex of the upper expansion arm as (x3, y3) and (x7, y7) respectively. The expansion distance d of the connecting head is d = 2(x7 - x 7,0 ), and the movement distance y of the connecting head is y = y3 - y 3,0 ;

[0008] S3. Obtain the transmission distance ratio κ d of the expander as,

[0009]

[0010] The transmission distance ratio κ of the expander v is

[0011]

[0012] where v y is the input speed of the expander, and v d is the output speed of the expander;

[0013] The transmission acceleration ratio κ of the expander a is

[0014]

[0015] where a y is the input acceleration of the expander, and a d is the output acceleration of the expander.

[0016] Furthermore, in step S1, the revolute pairs and vertices are numbered. The revolute pair between the upper handle and the upper transmission rod is numbered 1, the revolute pair between the upper transmission rod and the upper expansion arm is numbered 2, the revolute pairs between the connector and the upper and lower expansion arms are numbered 3 and 4 respectively, the revolute pair between the lower handle and the lower transmission rod is numbered 6, the revolute pair between the lower transmission rod and the lower expansion arm is numbered 5, and the vertices of the upper and lower expansion arms are numbered 7 and 8 respectively; and an XY coordinate system is set, with the forward movement direction of the connector as the positive direction of the Y-axis and the upward expansion direction of the upper expansion arm as the positive direction of the X-axis.

[0017] Furthermore, in step S2, define l ij to represent the length of the connecting rod, where i and j represent two different numbers from 1 to 8; in the initial state, the angles of the connecting rods l 12 , l 23 and l 37 are α0, β0 and γ0 respectively,

[0018] The distance that the connector moves along the Y-axis is y. Denote the rotation angles of the connecting rods l 12 and l 23 as α and β respectively. The position coordinates of vertex 7 are,

[0019]

[0020] In the formula, ‘s’ represents ‘sin’ and ‘c’ represents ‘cos’,

[0021] The position coordinates of revolute pair 3 are,

[0022]

[0023] In the initial state, α = β = 0, and the coordinates of vertex 7 and revolute pair 3 are,

[0024]

[0025] When the moving distance of the connector is y, the expansion distance d of the expander is

[0026] d = 2(x7 - x 7,0 ) = 2(l 37 c(γ0 + β) + l 34 / 2) (4)

[0027] The moving distance y of the connector is

[0028]

[0029] Furthermore, in step S3, the value of the moving distance y of the connector is the moving distance of the driving mechanism. According to equations (2) and (5), the transmission distance ratio κ d can be uniquely determined according to the value of y;

[0030] By taking the derivative of both sides of equations (4) and (5) with respect to time, the input speed v y and output speed v d of the expander are respectively

[0031] v y = l 12 ω α c(α0 + α) + l 23 ω β c(β0 + β) (6)

[0032] v d = -2l 37 ω β s(γ0 + β) (7)

[0033] In the formula, ω α and ω β respectively represent the angular velocities of angles α and β;

[0034] At the same time, by taking the derivative of the equation in the X-axis direction in equation (2) with respect to time, the angular velocity constraint is obtained as

[0035] l 12 ω α s(α0 + α) + l 23 ω β s(β0 + β) = 0 (8)

[0036] For the transmission distance ratio κ v of the expander, the input speed v y of the expander is known. According to equations (6) and (8), ω β can be uniquely determined according to the value of v y , and the value of κ v can be determined according to the value of vy The value is uniquely determined;

[0037] Taking the derivative of both sides of equations (6) and (7) with respect to time respectively, the input acceleration a of the expander is obtained y and the output acceleration a d are respectively

[0038]

[0039] wherein, a α and a β respectively represent the angular accelerations of α and β;

[0040] At the same time, taking the derivative of both sides of equation (8) with respect to time, the angular acceleration constraint is obtained as

[0041]

[0042] For the transmission acceleration ratio κ a of the expander, the input acceleration a y of the expander is known. According to equations (9) and (11), it can be uniquely determined according to the value of a y , and the value of κ a can be uniquely determined according to the value obtained from a y .

[0043] Furthermore, in steps S2 and S3, a kinematic analysis is performed on the upper expansion arm of the expander.

[0044] Compared with the prior art, the present invention has the following advantages:

[0045] The kinematic analysis method of the expander for fire rescue according to the present invention simplifies the structure of the expander and conducts kinematic modeling. According to the rotating pair between the connector and the upper expansion arm and the position of the vertex of the upper expansion arm, the expansion distance of the connector and the movement distance of the connector are obtained, and then the transmission distance ratio, transmission distance ratio, and transmission acceleration ratio of the expander are obtained; accordingly, for expanders of any size, their transmission effects can be calculated; and the influence rules of various parameters on the transmission efficiency can be studied for the structural design of the expander. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0047] Figure 1 is a sectional view of the expander;

[0048] Figure 2 is a modeling diagram of the expander according to the embodiment of the present invention;

[0049] Figure 3 Schematic diagram of the movement of the expander according to an embodiment of the present invention;

[0050] Figure 4 Position diagram of the expander mechanism according to an embodiment of the present invention;

[0051] Figure 5 Graph of the change of the transmission distance ratio of the expander with the movement distance;

[0052] Figure 6 Graph of the change of the transmission speed ratio of the expander with the movement distance;

[0053] Figure 7 Graph of the change of the transmission acceleration ratio of the expander with the movement distance;

[0054] Figure 8 Curve of the speed of the connector head changing with the movement distance.

[0055] Explanation of the reference numerals:

[0056] 10. Handle; 20. Driving mechanism; 30. Upper transmission rod; 40. Connector head; 50. Upper expansion arm; Detailed implementation manners

[0057] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0058] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0059] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0060] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments.

[0061] As shown in the figure, a kinematic analysis method for a fire rescue expander includes the following steps:

[0062] S1. Conduct kinematic modeling on the expander, simplify the expander into a linkage mechanism connected by rotating pairs, and set the handle of the expander to be fixed. Describe the movement of the expansion arm as the movement relative to the handle, and the movement state of the expander does not change; in this embodiment, in the linkage mechanism, the upper expansion arm 50, each side of the lower expansion arm, and the upper transmission rod 30, the lower transmission rod, and the connector are regarded as linkages. And between the front end of the upper transmission rod 30 and the upper rear side of the upper expansion arm 50, between the rear end of the upper transmission rod 30 and the upper handle 10, between the upper side of the connector and the lower rear side of the upper expansion arm 50, between the front end of the lower transmission rod and the lower rear side of the lower expansion arm, between the rear end of the lower transmission rod and the lower handle, and between the lower side of the connector and the upper rear side of the lower expansion arm are all connected by rotating pairs;

[0063] Number the rotating pairs and vertices. The rotating pair between the upper handle 10 and the upper transmission rod 30 is numbered 1, the rotating pair between the upper transmission rod and the upper expansion arm 50 is numbered 2, the rotating pairs between the connector 40 and the upper and lower expansion arms are numbered 3 and 4 respectively, the rotating pair between the lower handle and the lower transmission rod is numbered 6, the rotating pair between the lower transmission rod and the lower expansion arm is numbered 5, and the vertices of the upper and lower expansion arms are numbered 7 and 8 respectively;

[0064] Set the XY coordinate system, and the forward movement direction of the connector is the positive direction of the Y-axis, and the upward expansion direction of the upper expansion arm is the positive direction of the X-axis;

[0065] S2. Obtain the position coordinates of the rotating pair 3 and the vertex 7 as (x3, y3), (x7, y7) respectively. The expansion distance d of the connector = 2(x7 - x 7,0 ), and the movement distance y of the connector = y3 - y 3,0 ;

[0066] S3. Obtain the transmission distance ratio κ d of the expander as

[0067]

[0068] The transmission distance ratio κ of the expander v is

[0069]

[0070] where v y is the input speed of the expander, and v d is the output speed of the expander;

[0071] The transmission acceleration ratio κ of the expander a is

[0072]

[0073] where a y is the input acceleration of the expander, and a d is the output acceleration of the expander.

[0074] In step S2, define l ij to represent the length of the connecting rod between two numbers i and j, where i and j represent two different numbers from 1 to 8; in the initial state, the angles of the connecting rods l 12 , l 23 and l 37 are α0, β0 and γ0 respectively,

[0075] Assume that the connector moves a distance y along the Y-axis under the action of the force F. Denote the rotation angles of the connecting rods l 12 and l 23 as α and β respectively. Since the connecting rods l 23 and l 37 are both on the upper expansion arm, so l 37 also rotates by β. The position coordinates of vertex 7 are

[0076]

[0077] In the formula, ‘s’ represents ‘sin’ and ‘c’ represents ‘cos’.

[0078] The position coordinates of the rotating pair 3 are

[0079]

[0080] In the initial state, α = β = 0, and the coordinates of vertex 7 and the rotating pair 3 are respectively

[0081]

[0082] When the connector moves a distance y, the expansion distance d of the expander is

[0083] d = 2(x7 - x 7,0) = 2(l 37 c(γ0 + β) + l 34 / 2) (4)

[0084] The movement distance y of the connector is

[0085]

[0086] In step S3, the value of the movement distance y of the connector is the movement distance of the driving mechanism 20 (known). According to Figure 2 , the value range of β can be obtained. Then, according to equations (2) and (5), β can be uniquely determined according to the value of y. Therefore, the transmission distance ratio κ d can be uniquely determined according to the value of y, which reflects that the larger the transmission distance ratio of the expander, the longer the transmission distance of the expander;

[0087] By taking the derivatives of both ends of equations (4) and (5) with respect to time, the input speed v y and the output speed v d of the expander are respectively

[0088] v y = l 12 ω α c(α0 + α) + l 23 ω β c(β0 + β) (6)

[0089] v d = -2l 37 ω β s(γ0 + β) (7)

[0090] In the formula, ω α and ω β respectively represent the angular velocities of angles α and β;

[0091] At the same time, by taking the derivative of the equation in the X-axis direction in equation (2) with respect to time, the angular velocity constraint is obtained as

[0092] l 12 ω α s(α0 + α) + l 23 ω β s(β0 + β) = 0 (8)

[0093] For the transmission distance ratio κ v of the expander, the input speed v y of the expander is known. According to equations (6) and (8), ω β can be uniquely determined according to the value of v y . v d can be obtained according to ω β . Therefore, κ vThe value can be based on v y The value is uniquely determined, which reflects that the greater the transmission speed ratio of the expander, the faster the transmission speed of the expander;

[0094] Taking the derivative of both ends of equations (6) and (7) with respect to time respectively, the input acceleration a y and the output acceleration a d of the expander are obtained respectively as follows:

[0095]

[0096] In the formula, a α and a β respectively represent the angular accelerations of α and β;

[0097] At the same time, taking the derivative of both ends of equation (8) with respect to time, the angular acceleration constraint is obtained as,

[0098]

[0099] For the transmission acceleration ratio κ a of the expander, the input acceleration a y of the expander is known. According to equations (9) and (11), it can be uniquely determined according to the value of a y . The value of κ a can be uniquely determined according to the value of a y . It reflects that the greater the transmission acceleration ratio of the expander, the faster the transmission acceleration of the expander. Accordingly, for expanders of any size, their transmission effects can be calculated. Based on this, the influence laws of various parameters on the transmission efficiency can be studied and used for the structural design of the expander.

[0100] In steps S2 and S3, since the movements of the upper and lower expansion arms of the expander are strictly symmetric, the kinematic analysis of the upper expansion arm of the expander is carried out.

[0101] Table 1 gives the basic dimension parameters of a certain type of expander. Next, taking this as an example, the transmission efficiency is analyzed to further illustrate the above specific analysis process.

[0102] Table 1 Basic Dimension Parameter Table of a Certain Type of Expander

[0103]

[0104] In order to better solve the angular displacement, angular velocity and angular acceleration values according to the constraints for the transmission efficiency analysis, the value ranges of the two angular displacements α and β of the expander are analyzed and calculated. When the expander reaches the singular position where the angular displacements α and β reach the maximum values, as Figure 4 shown, at the extreme position, the quadrilateral 1346 is an isosceles trapezoid. According to the properties of the isosceles trapezoid, the maximum angular displacement αmax For

[0105]

[0106] At the extreme position, connecting rod l 12 and connecting rod l 23 have the same position angle, and

[0107] α0 + α max = β0 + β max ,

[0108] It can be obtained that β max = -83.3°. At this time, the farthest movement distance y of the connector can also be obtained max For

[0109]

[0110] In the actual working process, the end of the maximum stroke of the expander is basically not involved. Therefore, for the transmission distance ratio of the expander when the movement distance of the connector is within 1 mm to 90 mm, as well as the speed and acceleration are 1 mm / s and 1 mm / s 2 respectively, the transmission speed ratio and transmission acceleration ratio of the expander are simulated and analyzed when the movement distance of the connector is within 1 mm to 90 mm. The simulation results are as Figures 5 - 7 shown. It can be analyzed that: the transmission distance ratio first increases and then decreases as the movement distance y of the connector increases, and the transmission speed ratio and transmission acceleration ratio first decrease and then increase as the movement distance y of the connector increases, and the variation rules are the same.

[0111] After clarifying the rules of the transmission distance ratio, transmission speed ratio and transmission acceleration ratio of the expander, the movement form of the drive mechanism to drive the connector can be designed according to actual needs. During the actual demolition process, it is hoped that the movement of the expansion arm is as stable as possible. In other words, it is hoped that the expansion arm moves at a constant speed in the X direction, so that the safety of the demolition process can be ensured as much as possible. Accordingly, assuming that the expander always expands at a speed of 1 mm / s in the X direction, the curve of the connector speed changing with the movement distance y designed according to the expander transmission distance rule is as Figure 8 shown, and a drive mechanism is required to drive the connector to perform variable-speed motion.

[0112] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A kinematic analysis method for an expander for fire rescue, characterized in that: The following steps are involved: S1. Perform kinematic modeling on the expander, simplify the expander into a connecting rod mechanism connected by a revolute joint, and set the expander to be fixed at the handle; S2. Obtain the position coordinates of the rotational pair between the connector and the upper expansion arm and the vertex of the upper expansion arm, respectively (x3, y3) and (x7, y7). The expansion distance of the connector is d = 2 (x7-x 7,0 ), the movement distance of the connector y = y3-y 3,0 ; S3. Obtain the transmission distance ratio κ of the expander d for, Transmission distance ratio of expander κ v for, where v y is the input speed of the expander, v d is the output speed of the expander; Transmission acceleration ratio of expander κ a for, where a y is the input acceleration of the expander, a d is the output acceleration of the expander.

2. The kinematic analysis method of the expander for fire rescue according to claim 1, characterized in that: In step S1, the rotation pairs and vertices are numbered, and the rotation pair between the upper handle and the upper transmission rod is numbered 1, the rotation pair between the upper transmission rod and the upper expansion arm is numbered 2, the rotation pair between the connecting head and the upper and lower expansion arms are numbered 3 and 4 respectively, the rotation pair between the lower handle and the lower transmission rod is numbered 6, the rotation pair between the lower transmission rod and the lower expansion arm is numbered 5, and the vertices of the upper and lower expansion arms are numbered 7 and 8 respectively; and the XY coordinate system is set, and the forward movement direction of the connecting head is the positive direction of the Y axis, and the upward expansion direction of the upper expansion arm is the positive direction of the X axis.

3. The kinematic analysis method of the expander for fire rescue according to claim 2, characterized in that: In step S2, define l ij Indicates the length of the connecting rod, where i and j represent two different numbers from 1 to 8; in the initial state, the connecting rod l 12 , l 23 and l 37 The angles are α0, β0 and γ0 respectively, The distance the connector moves along the Y axis is y, and the connecting rod l 12 and l 23 The rotation angles are α and β respectively, and the position coordinates of vertex 7 are, In the formula, 's' represents 'sin', 'c' represents 'cos', The position coordinates of the revolute joint 3 are: In the initial state, α=β=0, and the coordinates of vertex 7 and revolute pair 3 are, When the connector moves a distance y, the expansion distance d of the expander is, d=2(x7-x 7,0 )=2(l 37 c(γ0+β)+l 34 / 2) (4) The movement distance y of the connector is, 4. The kinematic analysis method of the expander for fire rescue according to claim 3, characterized in that: In step S3, the value of the connector movement distance y is the driving mechanism movement distance. According to equations (2) and (5), the transmission distance ratio κ d It can be uniquely determined based on the y value of; According to equations (4) and (5), the time derivatives of both ends are obtained to obtain the input velocity v of the expander: y and output speed v d They are respectively, v y =l 12 oh α c(α0+α)+l 23 oh β c(β0+β) (6) v d =-2l 37 oh β s(γ0+β) (7) In the formula, ω α and ω β denote the angular velocities of angles α and β respectively; At the same time, the equation in the X-axis direction in equation (2) is derived with respect to time to obtain the angular velocity constraint: l 12 oh α s(α0+α)+l 23 oh β s(β0+β)=0 (8) For the transmission distance ratio of the expander κ v , the input speed v of the expander y It is known that according to equations (6) and (8), ω β According to v y The value of is uniquely determined, κ v The value can be based on v y The value is uniquely determined; The time derivatives of both ends of equations (6) and (7) are calculated to obtain the input acceleration a of the expander: y and output acceleration a d They are respectively, In the formula, a α and a β denote the angular accelerations of α and β respectively; At the same time, taking the derivative of both ends of equation (8) with respect to time, the angular acceleration constraint is: For the transmission acceleration ratio of the expander κ a , the input acceleration of the expander a y It is known that according to equations (9) and (11), According to a y The value of is uniquely determined, κ a The value can be based on a y The value is uniquely determined.

5. The kinematic analysis method of the expander for fire rescue according to claim 1, characterized in that: In steps S2 and S3, kinematic analysis is performed on the upper expansion arm of the expander.

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