阅读说明：本技术 一种直线驱动器 (Linear driver ) 是由 汤志强 汤浩琪 张大伟 于 2020-06-15 设计创作，主要内容包括：本发明公开了一种直线驱动器,涉及驱动器技术领域,包括丝杠,所述丝杠底端通过法兰连接有无框电机转子,无框电机转子的外部套设有无框电机定子,丝杠底端的外表面套设有第一驱动器后壳,且无框电机定子螺栓连接于第一驱动器后壳的内部,无框电机定子的底端铆接连接有编码器,第一驱动器后壳的底面固定连接有驱动器固定轴承。该直线驱动器,通过设置无框电机定子,在无框电机转子、丝械、螺母、导向套筒和气缸导向杆的共同作用下,能将动力传导给鱼眼轴承,从而达到给目标件的轴施加动力的目的,且配合鱼眼轴承的作用,能给驱动器的减负的同时,使得整个系统可以提高更大负载能力。(The invention discloses a linear driver, which relates to the technical field of drivers and comprises a lead screw, wherein the bottom end of the lead screw is connected with a frameless motor rotor through a flange, a frameless motor stator is sleeved outside the frameless motor rotor, a first driver rear shell is sleeved on the outer surface of the bottom end of the lead screw, the frameless motor stator is connected inside the first driver rear shell through a bolt, the bottom end of the frameless motor stator is connected with an encoder in a riveting mode, and a driver fixing bearing is fixedly connected to the bottom surface of the first driver rear shell. According to the linear driver, the frameless motor stator is arranged, and under the combined action of the frameless motor rotor, the screw mechanism, the nut, the guide sleeve and the cylinder guide rod, power can be transmitted to the fisheye bearing, so that the purpose of applying power to a shaft of a target part is achieved, the action of the fisheye bearing is matched, the load of the driver can be reduced, and meanwhile, the whole system can be improved in larger load capacity.)

1. A linear drive comprising a lead screw (5), a PID control and a mechanical arm mechanism (22), characterized in that: the bottom end of the lead screw (5) is connected with a frameless motor rotor (4) through a flange, a frameless motor stator (3) is sleeved outside the frameless motor rotor (4), a first driver rear shell (2) is sleeved on the outer surface of the bottom end of the lead screw (5), the frameless motor stator (3) is connected inside the first driver rear shell (2) through a bolt, the bottom end of the frameless motor stator (3) is connected with an encoder (1) in a riveting mode, a driver fixing bearing (19) is fixedly connected to the bottom surface of the first driver rear shell (2), a driver shell (9) is fixedly connected to the top end of the first driver rear shell (2), the lead screw (5) is located inside the driver shell (9), a bearing (6) is fixedly embedded inside the bottom end of the driver shell (9), and the inner ring of the bearing (6) is fixedly connected with the outer surface of the bottom optical axis of the lead screw (5), the mechanical arm mechanism (22) comprises a mechanical arm base (2201), a balance cylinder (2202), a linear driver I (2203), a mechanical arm waist (2204), a mechanical arm big arm (2205), a linear driver II (2206), a mechanical arm small arm (2207), a small arm posture control rod piece (2208), a small arm posture rod piece (2209), a tail end posture control rod piece (2210), a tail end posture rod piece (2211) and a big arm posture control rod piece (2212).

2. A linear actuator as claimed in claim 1, wherein: the outer surface of the lead screw (5) is in threaded connection with a nut (7) matched with the lead screw (5), the top end of the nut (7) is fixedly connected with a guide sleeve (8), the guide sleeve (8) and the nut (7) are both located inside a driver shell (9), the top end of the driver shell (9) is fixedly connected with a second driver rear shell (12), the second driver rear shell (12) is sleeved on the outer surface of the guide sleeve (8), the top end of the guide sleeve (8) is in threaded connection with a stud bolt (13), the other end of the stud bolt (13) is in threaded connection with a first fisheye bearing (14), a bearing flange (17) is arranged outside the first fisheye bearing (14), the top end of the bearing flange (17) is fixedly connected with two symmetrical second fisheye bearings (21), and the two second fisheye bearings (21) are hinged to the first fisheye bearing (14), the bottom of the bearing flange (17) is in threaded connection with a cylinder guide rod (15), the outer surface of the cylinder guide rod (15) is sleeved with a cylinder shell (16) matched with the cylinder guide rod (15), and the bottom end of the cylinder shell (16) is fixedly connected with a balance cylinder fixing bearing (20).

3. A linear actuator as claimed in claim 2, wherein: a guide cylinder graphite copper sleeve (11) is fixedly embedded in the second driver rear shell (12), and the guide cylinder graphite copper sleeve (11) is matched with the guide sleeve (8).

4. A linear actuator as claimed in claim 3, wherein: the lead screw graphite sleeve (10) matched with the guide sleeve (8) is sleeved at the optical axis at the top end of the lead screw (5), and the lead screw graphite sleeve (10) is connected to the inside of the guide sleeve (8) in a sliding mode.

5. A linear actuator as claimed in claim 4, characterized in that: pressure sensors (18) are arranged between the bearing flange (17) and the cylinder guide rod (15) and between the stud bolt (13) and the first fisheye bearing (14).

6. A linear actuator as claimed in claim 5, characterized in that: the PID control comprises a position type PID control algorithm and an increment type PID control algorithm.

7. A linear actuator as claimed in claim 5, characterized in that: the formula of the position type PID control algorithm is as follows:

E_k＝F-F_k

wherein: k_pIs a proportionality coefficient, K_iIs the integral coefficient, K_dIs a differential coefficient, E_kIs the deviation value, T is the PID calculation period, T_iFor integration time, T_dIs the differential time.

8. A linear actuator as claimed in claim 5, characterized in that: the formula of the incremental PID control algorithm is as follows:

E_k＝F-F_k

ΔF_out＝K_p(E_k-E_k-1)+K_iE_k+K_d(E_k-2E_k-1+E_k-2)

wherein: k_pIs a proportionality coefficient, K_iIs the integral coefficient, K_dIs a differential coefficient, E_kIs the deviation value, T is the PID calculation period, T_iFor integration time, T_dIs differential time, Δ F_outIs the increment (can be positive or negative) of the two adjacent outputs.

9. A linear actuator as claimed in claim 1, wherein: the robot arm waist (2204) and the large arm posture control rod piece (2212) are hinged to a robot arm base (2201), the large arm (2205) and the small arm posture control rod piece (2208) are hinged to the robot arm waist (2204), the other end of the robot arm is hinged to the small arm posture rod piece (2209) to form a parallelogram, the balance cylinder (2202) and the linear driver I (2203) are hinged to the robot arm base (2201), the linear driver II (2206) is hinged to the robot arm waist (2204), the small arm (2207) of the robot arm is hinged to the large arm (2205), and the small arm (2207) of the robot arm is hinged to the small arm posture rod piece (2209), the tail end posture control rod piece (2210) and the tail end posture rod piece (2211) to form a parallelogram so as to guarantee the posture of the tail end posture rod piece (2211).

Technical Field

The invention relates to the technical field of drivers, in particular to a linear driver.

Background

The linear driver on the market at present has liquid drive (pneumatic cylinder), gas drive (pneumatic cylinder) to and motor drive (the more common form of ware is mainly linear motor or by conventional servo motor or step motor driven lead screw, its structure mainly through integrated step motor or servo motor, be connected through shaft coupling and lead screw nut slip table, in addition end connection spare combination forms).

The general disadvantages of the existing drivers are that: parts are not integrated, and partial space is lost, so that the space requirement cannot be met under some working conditions; moreover, the driving part motor and the driven part screw rod sliding table are linked through a coupler, so that part of space is lost, and the coupler is also a vulnerable part, so that the stability of product equipment is reduced; finally, when heavy equipment is intended to use an electric drive, the load is not as demanding.

Disclosure of Invention

Technical problem to be solved

Aiming at the defects of the prior art, the invention provides a linear driver, which solves the problems that the existing driver occupies large space and the load can not meet the requirement.

(II) technical scheme

In order to achieve the purpose, the invention provides the following technical scheme: the utility model provides a linear actuator, includes the lead screw, there is frameless electric motor rotor lead screw bottom through flange joint, frameless electric motor rotor's outside cover is equipped with frameless electric motor stator, the surface cover of lead screw bottom is equipped with first driver backshell, and frameless electric motor stator bolted connection is in the inside of first driver backshell, frameless electric motor stator's bottom riveting is connected with the encoder, the bottom surface fixedly connected with driver fixing bearing of first driver backshell, the top fixedly connected with driver casing of first driver backshell, and the lead screw is located the inside of driver casing, the inside fixed of driver casing bottom is inlayed and is had the bearing, and the inner circle of bearing is connected with the surface fixed connection of lead screw bottom optical axis department, mechanical arm mechanism includes arm base, balance cylinder, linear actuator one, arm waist, arm forearm, arm, The linear driver II, the mechanical arm small arm, the small arm posture control rod piece, the small arm posture rod piece, the tail end posture control rod piece, the tail end posture rod piece and the large arm posture control rod piece.

The outer surface of the lead screw is in threaded connection with a nut matched with the lead screw, the top end of the nut is fixedly connected with a guide sleeve, the guide sleeve and the nut are both positioned in a driver shell, the top end of the driver shell is fixedly connected with a second driver rear shell, the second driver rear shell is sleeved on the outer surface of the guide sleeve, the top end of the guide sleeve is in threaded connection with a stud bolt, the other end of the stud bolt is in threaded connection with a first fisheye bearing, a bearing flange is arranged outside the first fisheye bearing, the top end of the bearing flange is fixedly connected with two symmetrical second fisheye bearings, the two second fisheye bearings are hinged with the first fisheye bearing, the bottom of the bearing flange is in threaded connection with an air cylinder guide rod, and the outer surface of the air cylinder guide rod is sleeved with an air cylinder shell matched with the air cylinder guide rod, and the bottom end of the cylinder shell is fixedly connected with a balance cylinder fixing bearing.

As a further description of the above technical solution, the inside of the rear shell of the second driver is fixedly embedded with the graphite copper sleeve of the guide cylinder, and the graphite copper sleeve of the guide cylinder is matched with the guide sleeve, so that friction between the rear shell of the second driver and the guide sleeve can be reduced by arranging the graphite copper sleeve of the guide cylinder, and the inclination of the guide sleeve can be reduced to the greatest extent by the guiding effect of the graphite copper sleeve of the guide cylinder.

As the further description of the technical scheme, the lead screw graphite sleeve matched with the guide sleeve is sleeved at the optical axis at the top end of the lead screw, the lead screw graphite sleeve is connected inside the guide sleeve in a sliding mode, the lead screw can be guided by the lead screw graphite sleeve, and the lead screw is prevented from inclining inside the guide sleeve.

As a further description of the above technical solution, pressure sensors are respectively disposed between the bearing flange and the cylinder guide rod and between the stud bolt and the first fisheye bearing, and by providing the pressure sensors, the output force can be fed back and adjusted, so as to prevent excessive damage to the device due to excessive movement.

As a further description of the above technical solution, the waist of the mechanical arm and the large arm posture control rod are hinged on the mechanical arm base, the large arm and the small arm posture control rod of the mechanical arm are hinged on the waist of the mechanical arm, the other end of the mechanical arm is hinged on the small arm posture rod to form a parallelogram, the balance cylinder and the linear driver one are hinged on the mechanical arm base, the linear driver two is hinged on the waist of the mechanical arm, the small arm of the mechanical arm is hinged on the large arm of the mechanical arm, and the small arm of the mechanical arm is hinged with the small arm posture rod, the terminal posture control rod and the terminal posture rod to form a parallelogram, so as to ensure the posture of the terminal posture.

(III) advantageous effects

The invention provides a linear driver, which has the following beneficial effects:

this linear actuator through setting up frameless motor stator, under the combined action of frameless motor rotor, silk machinery, nut, guide sleeve and cylinder guide bar, can transmit motor power and pneumatic power for first flake bearing and second flake bearing to reach the purpose of applying hybrid for the axle of target piece, and the effect of cooperation flake bearing, can give the subtracting of driver, make entire system can improve bigger load capacity, the device is owing to adopt V style of calligraphy shape, its space occupies lessly.

This linear actuator, through setting up guide cylinder graphite copper sheathing, can not only reduce the frictional force between second driver backshell and the guide sleeve, and can take place through the guide effect of guide cylinder graphite copper sheathing can furthest's reduction guide sleeve slope phenomenon, through setting up lead screw graphite sheathing, can play the guide effect to the lead screw, avoid the lead screw at the inside slope of guide sleeve, through setting up pressure sensor, can carry out feedback control to exerting oneself, in order to avoid excessive motion to cause the excessive damage of equipment.

Drawings

FIG. 1 is a schematic front view in full section of the present invention;

FIG. 2 is a schematic external view of the present invention;

FIG. 3 is a perspective view of the present invention;

FIG. 4 is a schematic external view of a drive unit according to the present invention;

FIG. 5 is an internal schematic view of the drive member of the present invention;

FIG. 6 is a schematic of the PID controlled force of the present invention;

FIG. 7 is a flow chart of the PID control principle of the invention;

FIG. 8 is a first schematic view of a rear-mounted robotic arm mechanism according to the present invention;

FIG. 9 is a second schematic view of a rear-mounted robotic arm mechanism of the present invention;

FIG. 10 is a schematic view of a front-mounted attitude maintaining robotic arm mechanism of the present invention;

fig. 11 is a schematic view of the rear posture maintaining robot arm mechanism of the present invention.

In the figure: 1-encoder, 2-first driver rear shell, 3-frameless motor stator, 4-frameless motor rotor, 5-lead screw, 6-bearing 7-nut, 8-guide sleeve, 9-driver shell, 10-lead screw graphite sleeve, 11-guide sleeve graphite copper sleeve 12-second driver rear shell, 13-stud bolt, 14-first fisheye bearing, 15-cylinder guide rod, 16-cylinder shell 17-bearing flange 18-pressure sensor, 19-driver fixed bearing, 20-balance cylinder fixed bearing, 21-second fisheye bearing, 22-mechanical arm mechanism, 2201-mechanical arm base, 2202-balance cylinder, 2203-linear driver I, 2204-mechanical arm waist, 2205-big arm of mechanical arm, 2206-second linear driver, 2207-small arm of mechanical arm, 2208-small arm attitude control rod, 2209-small arm attitude rod, 2210-tail end attitude control rod, 2211-tail end attitude rod and 2212-big arm attitude control rod.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-11, the present invention provides a technical solution: a linear driver comprises a lead screw 5, the bottom end of the lead screw 5 is connected with a frameless motor rotor 4 through a flange, the exterior of the frameless motor rotor 4 is sleeved with a frameless motor stator 3, the outer surface of the bottom end of the lead screw 5 is sleeved with a first driver rear shell 2, the frameless motor stator 3 is connected with the interior of the first driver rear shell 2 through a bolt, the bottom end of the frameless motor stator 3 is connected with an encoder 1 in a riveting mode, the bottom surface of the first driver rear shell 2 is fixedly connected with a driver fixing bearing 19, the top end of the first driver rear shell 2 is fixedly connected with a driver shell 9, the lead screw 5 is located in the driver shell 9, a bearing 6 is fixedly embedded in the interior of the bottom end of the driver shell 9, the inner ring of the bearing 6 is fixedly connected with the outer surface of the optical axis at the bottom end of the lead screw 5, and a mechanical arm mechanism 22 comprises a, A waist 2204 of mechanical arm, a large 2205 arm, a second 2206 linear driver, a small 2207 arm, a small arm attitude control rod 2208, a small arm attitude rod 2209, a tail end attitude control rod 2210, a tail end attitude rod 2211 and a large arm attitude control rod 2212.

The outer surface of the screw 5 is in threaded connection with a nut 7 matched with the screw 5, the top end of the nut 7 is fixedly connected with a guide sleeve 8, the guide sleeve 8 and the nut 7 are both positioned inside a driver shell 9, a screw graphite sleeve 10 matched with the guide sleeve 8 is sleeved at the optical axis of the top end of the screw 5, the screw graphite sleeve 10 is connected inside the guide sleeve 8 in a sliding manner, the screw 5 can be guided by arranging the screw graphite sleeve 10, the lead screw 5 is prevented from inclining inside the guide sleeve 8, the top end of the driver shell 9 is fixedly connected with a second driver rear shell 12, the second driver rear shell 12 is sleeved on the outer surface of the guide sleeve 8, a guide cylinder graphite copper sleeve 11 is fixedly embedded inside the second driver rear shell 12, the guide cylinder graphite copper sleeve 11 is matched with the guide sleeve 8, by arranging the guide cylinder graphite copper sleeve 11, the friction force between the second driver rear shell 12 and the guide sleeve 8 can be reduced, and the inclination phenomenon of the guide sleeve 8 can be reduced to the maximum extent by the guide effect of the guide cylinder graphite copper sleeve 11.

The top end of the guide sleeve 8 is connected with a stud bolt 13 in a threaded manner, the other end of the stud bolt 13 is connected with a first fisheye bearing 14 in a threaded manner, a bearing flange 17 is arranged outside the first fisheye bearing 14, the top end of the bearing flange 17 is fixedly connected with two symmetrical second fisheye bearings 21, and two second fisheye bearings 21 are hinged with the first fisheye bearing 14, the bottom of the bearing flange 17 is connected with a cylinder guide rod 15 through threads, and the outer surface of the cylinder guide rod 15 is sleeved with a cylinder shell 16 matched with the cylinder guide rod 15, the bottom end of the cylinder shell 16 is fixedly connected with a balance cylinder fixed bearing 20, pressure sensors 18 are respectively arranged between the bearing flange 17 and the cylinder guide rod 15 and between the stud bolt 13 and the first fisheye bearing 14, by providing the pressure sensor 18, the output force can be feedback regulated to avoid excessive damage to the device caused by excessive movement.

As shown in FIG. 6, the linear actuator is maintained in the optimum operating state by PID control of the cylinder, and the output F₁And can output resultant force F meeting working requirements_SAnd PID control is adopted, so that the cylinder automatically adjusts the magnitude of the output F according to the working condition:

F_s＝F₁cos b+F cos a

as shown in FIG. 7, the expected force F is determined according to the working state, such as position, etc., the sensor obtains the current force output value through detection, and the force F which should be output is calculated through a PID control algorithm_outAnd (4) giving an actuator, controlling the controlled object to act according to the requirement by the actuator, measuring data again by the sensor, feeding the data back to the input end, adjusting again, and finally achieving accurate control.

The formula of the position type PID control algorithm is as follows:

E_k＝F-F_k

wherein: k_pIs a proportionality coefficient, K_iIs the integral coefficient, K_dIs a differential coefficient, E_kIs the deviation value, T is the PID calculation period, T_iFor integration time, T_dIs the differential time.

The formula of the incremental PID control algorithm is as follows:

E_k＝F-F_k

ΔF_out＝K_p(E_k-E_k-1)+K_iE_k+K_d(E_k-2E_k-1+E_k-2)

wherein: k_pIs a proportionality coefficient, K_iIs the integral coefficient, K_dIs a differential coefficient, E_kIs a deviation value, T is a PID meterCalculating the period, T_iFor integration time, T_dIs differential time, Δ F_outIs the increment (can be positive or negative) of the two adjacent outputs.

As shown in fig. 8, in this embodiment, the arm waist 2204 is mounted on the arm base 2201, the arm big arm 2205 is hinged to the arm waist 2204, the balance cylinder 2202 is hinged to the arm base 2201 with the linear actuator one 2203, the linear actuator two 2206 is hinged to the arm waist 2204, the arm small arm 2207 is hinged to the arm big arm 2205, the arm big arm 2205 is driven to rotate by the balance cylinder 2202 and the linear actuator one 2203, the arm small arm 2207 is driven to rotate by the linear actuator two 2206, and the balance cylinder 2202 can be implemented in various ways: such as a mechanical tension spring, a constant force spring, a magnetic spring, a nitrogen balance bar, an air bearing cylinder, a cord cylinder, etc.

As shown in fig. 9, in this embodiment, the waist 2204 and the large arm posture control rod 2212 of the mechanical arm are hinged to the base 2201 of the mechanical arm, the large arm 2205 of the mechanical arm is hinged to the waist 2204 of the mechanical arm, the balancing cylinder 2202 and the first linear driver 2203 are hinged to the base 2201 of the mechanical arm, the second linear driver 2206 is hinged to the waist 2204 of the mechanical arm, the small arm 2207 of the mechanical arm is hinged to the large arm 2205 of the mechanical arm, the waist 2204 of the mechanical arm is driven to rotate by the balancing cylinder 2202 and the first linear driver 2203, the large arm posture control rod 2212 of the mechanical arm synchronously rotates, the large arm 2205 of the mechanical arm keeps posture movement, the second linear driver 2206 drives the small arm 2207 of the mechanical arm: such as a mechanical tension spring, a constant force spring, a magnetic spring, a nitrogen balance bar, an air bearing cylinder, a cord cylinder, etc.

As shown in fig. 10, in this embodiment, a waist 2204 of the robot arm is mounted on a base 2201 of the robot arm, a large arm 2205 and a small arm attitude control rod 2208 of the robot arm are hinged on the waist 2204 of the robot arm, the other end of the robot arm is hinged on the small arm attitude control rod 2209 to form a parallelogram, so as to ensure the attitude of the small arm attitude rod 2209, a balance cylinder 2202 and a linear driver 2203 are hinged on the base 2201 of the robot arm, a linear driver 2206 and a small arm attitude control rod 2208 are hinged on the waist 2204 of the robot arm, a small arm 2207 of the robot arm is hinged on the large arm 2205 of the robot arm, a small arm 2207 of the robot arm is hinged on the small arm attitude rod 2209, a tail end attitude control rod 2210 and a tail end attitude rod 2211 to form a parallelogram, so as to ensure the attitude of the tail end attitude rod 2211 of the robot arm, the large arm 2205 is driven to rotate by the balance, the balancing cylinder 2202 may take a variety of forms: such as a mechanical tension spring, a constant force spring, a magnetic spring, a nitrogen balance bar, an air bearing cylinder, a cord cylinder, etc.

As shown in fig. 11, in this embodiment, a waist 2204 of the mechanical arm is mounted on a base 2201 of the mechanical arm, a large arm 2205 and a small arm attitude control rod 2208 of the mechanical arm are hinged on the waist 2204 of the mechanical arm, the other end of the mechanical arm is hinged on the small arm attitude control rod 2209 to form a parallelogram, the attitude of the small arm attitude rod 2209 is ensured, a balance cylinder 2202 and a linear driver 2203 are hinged on the base 2201 of the mechanical arm, a linear driver 2206 and a small arm attitude control rod 2208 are hinged on the waist 2204 of the mechanical arm, a small arm 2207 of the mechanical arm is hinged on the large arm 2205 of the mechanical arm, a small arm 2207 of the mechanical arm is hinged on the small arm attitude rod 2209, a tail end attitude control rod 2210 and a tail end attitude rod 2211 to form a parallelogram, the attitude of the tail end attitude rod 2211 is ensured, the large arm 2205 of the mechanical arm is driven to rotate by the balance cylinder 2202 and the, the balancing cylinder 2202 may take a variety of forms: such as a mechanical tension spring, a constant force spring, a magnetic spring, a nitrogen balance bar, an air bearing cylinder, a cord cylinder, etc.

The working principle is as follows: the frameless motor stator 3 is controlled by the encoder 1, the frameless motor rotor 4 rotates for a certain number of turns at a certain speed according to requirements, the lead screw 5 which is fixedly connected with the frameless motor stator 3 is driven to rotate, the nut 7 on the lead screw 5 is pushed to axially move on the lead screw 5, the guide sleeve 8 which is connected with the lead screw nut 7 stretches, power is transmitted to the stud bolt 13 and the first fisheye bearing 14, power is applied to a shaft of a target piece, meanwhile, the balance cylinder transmits the power to the fisheye bearing flange 17 and the second fisheye bearing 21 through the cylinder guide rod 15, the power is applied to the shaft of the target piece through the second fisheye bearing 21, the purpose of reducing the load of the driver is achieved, the whole system can improve larger load capacity, two pressure sensors 18 are placed at proper positions outside the driver shell 9 to perform feedback adjustment, and excessive damage of equipment caused by excessive movement is avoided, the device can form PID control through the linear driver, the air cylinder and the sensor, so that the air cylinder of the driver can automatically adjust the output according to the working condition, and finally the aim of accurate control is achieved.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.