阅读说明：本技术 一种全自动水下云台 (Full-automatic underwater cradle head ) 是由 钟世权 陈军校 刘红佳 田方 曾健 于 2021-09-03 设计创作，主要内容包括：本发明公开了一种全自动水下云台,包括云台壳体和支撑装置。云台壳体包括上腔体和下腔体；上腔体内设有垂直方向转动伺服电机、垂直方向转动减速机和垂直方向转动输出轴,垂直方向转动输出轴外壁通过轴承连接于上腔体,垂直方向转动输出轴顶部连接有支撑杆连接座；下腔体内设有水平方向转动伺服电机、水平方向转动减速机和水平方向转动输出轴,水平方向转动减速机外壁通过轴承连接于下腔体,水平方向转动输出轴端部连接有传感器固定座,下腔体右端的顶部设有防水LEMO头底座；支撑装置连接支撑杆连接座。可以多个角度自由转动,转动角度更加精准,结构简单且紧凑,便于后期拆装和维护。(The invention discloses a full-automatic underwater cradle head, which comprises a cradle head shell and a supporting device. The holder shell comprises an upper cavity and a lower cavity; a vertical direction rotation servo motor, a vertical direction rotation speed reducer and a vertical direction rotation output shaft are arranged in the upper cavity, the outer wall of the vertical direction rotation output shaft is connected to the upper cavity through a bearing, and the top of the vertical direction rotation output shaft is connected with a support rod connecting seat; a horizontal direction rotation servo motor, a horizontal direction rotation speed reducer and a horizontal direction rotation output shaft are arranged in the lower cavity, the outer wall of the horizontal direction rotation speed reducer is connected to the lower cavity through a bearing, the end part of the horizontal direction rotation output shaft is connected with a sensor fixing seat, and a waterproof LEMO head base is arranged at the top of the right end of the lower cavity; the supporting device is connected with the supporting rod connecting seat. Can a plurality of angles free rotation, turned angle is more accurate, simple structure and compactness, later stage dismouting and maintenance of being convenient for.)

1. A full-automatic underwater cradle head is characterized by comprising a cradle head shell (1) and a supporting device (2);

the holder shell (1) comprises an upper cavity (111) and a lower cavity (112) which are vertically connected;

a vertical direction rotating sealing cover (17) is arranged at the top of the upper cavity (111), a vertical direction rotating servo motor (10), a vertical direction rotating speed reducer (11) and a vertical direction rotating output shaft (13) are sequentially arranged in the upper cavity (111) from bottom to top, the outer wall of the vertical direction rotating output shaft (13) is connected to the inner wall of the upper cavity (111) through two bearings (14) assembled in parallel, and a supporting rod connecting seat (4) is connected to the top of the vertical direction rotating output shaft (13) after penetrating through the vertical direction rotating sealing cover (17);

the two ends of the lower cavity (112) are respectively provided with a rear sealing cover (19) and a horizontal rotating sealing cover (18), the lower cavity (112) is internally sequentially provided with a horizontal rotating servo motor (8), a horizontal rotating speed reducer (9) and a horizontal rotating output shaft (12) from right to left, the outer wall of the horizontal rotating speed reducer (9) is connected to the inner wall of the lower cavity (112) through two bearings (14) assembled in parallel, the end part of the horizontal rotating output shaft (12) penetrates through the horizontal rotating sealing cover (18) and then is connected with a sensor fixing seat (5), the sensor fixing seat (5) is used for connecting a sonar or a camera, the top of the right end of the lower cavity (112) is provided with a waterproof LEMO head base (7), and the waterproof LEMO head base (7) is used for inserting a waterproof LEMO head plug;

the supporting device (2) is connected with the supporting rod connecting seat (4) and used for adjusting the height of the cradle head shell (1).

2. A fully automatic underwater head according to claim 1, wherein the outer wall of the vertical rotary output shaft (13) is further provided with a dustproof ring (16) and two star-shaped sealing rings (15), the dustproof ring (16) and the star-shaped sealing rings (15) being located inside the vertical rotary sealing cover (17) and above the bearing (14).

3. A fully automatic underwater platform according to claim 1, wherein the outer wall of the horizontal rotation output shaft (12) is further provided with a dustproof ring (16) and two star-shaped sealing rings (15), and the dustproof ring (16) and the star-shaped sealing rings (15) are positioned in the horizontal rotation sealing cover (18) and are positioned on the left side of the bearing (14).

4. The fully automatic underwater platform according to claim 1, wherein rubber gaskets are disposed between the vertical rotary seal cover (17) and the upper chamber (111), between the rear seal cover (19) and the lower chamber (112), and between the horizontal rotary seal cover (18) and the lower chamber (112), and the vertical rotary seal cover (17), the rear seal cover (19), and the horizontal rotary seal cover (18) are all fixedly connected to the platform housing (1) by bolts.

5. A fully automatic underwater platform according to claim 1, wherein the horizontal rotation servomotor (8) and the horizontal rotation reducer (9) are fixed together by means of bolts, and the vertical rotation servomotor (10) and the vertical rotation reducer (11) are fixed together by means of bolts.

6. The fully automatic underwater platform according to claim 1, wherein the sensor fixing seat (5) and the support rod connecting seat (4) are respectively connected to the platform housing (1) through bolts.

7. The fully automatic underwater platform according to claim 1, wherein the waterproof LEMO head base (7) is screwed to the platform housing (1), and a rubber ring is provided between the waterproof LEMO head base (7) and the platform housing (1).

8. A fully automatic underwater platform according to any one of claims 1 to 7, wherein the supporting device (2) comprises a square frame (24), a first motor (21), a second motor (22), a sawtooth rack (23) and a pulley block (3), an output shaft of the first motor (21) penetrates through one side wall of the square frame (24) and is connected with a long column (25), the other end of the long column (25) is rotatably matched with the square frame (24), a thread groove (251) is formed in the outer side wall of the long column (25), an elongated gear (26) is connected with the second motor (22) after penetrating through one side wall of the square frame (24), the other end of the elongated gear (26) is rotatably matched with the square frame (24), the long column (25) is positioned above the elongated gear (26), a supporting plate (6) is arranged at the top of the square frame (24), and the pulley block (3) is arranged on the front wall of the supporting plate (6), the pulley block (3) is divided into a first pulley (31), a second pulley (32) and a third pulley (33), the first pulley (31) and the second pulley (32) are connected through a first hinged rod (321), the second pulley (32) and the third pulley (33) are connected through a second hinged rod (322), one end, close to the first pulley (31), of the first hinged rod (321) is in rotating fit with the support plate (6), the first pulley (31) is connected with the second pulley (32) through a first belt (34), the third pulley (33) is connected with the second pulley (32) through a second belt (35), the bottom of the third pulley (33) is fixedly connected with a sawtooth strip (23), the sawtooth strip (23) is in meshing fit with the elongated gear (26), a sliding sleeve (231) is arranged outside the sawtooth strip (23), a sliding block (232) is arranged on the rear wall of the sliding sleeve (231), and a guide column (233) is arranged on the inner wall of the sliding block (232), the guide post (233) is arranged in the thread groove (251), the bottom of the sawtooth strip (23) is provided with a connecting rod (234), and the connecting rod (234) is connected with the support rod connecting seat (4) through a bolt.

9. A fully automatic underwater head according to claim 1, wherein the front wall of the supporting plate (6) is provided with a first trajectory groove (61) and a second trajectory groove (62), the other end of the first articulated rod (321) is arranged in the first trajectory groove (61) through a driving wheel (323), and the end of the second articulated rod (322) close to the third pulley (33) is arranged in the second trajectory groove (62) through the driving wheel (323).

10. The fully automatic underwater platform according to claim 1, wherein a railing (241) is provided on the front wall of the square frame (24), and the sliding sleeve (231) is located between the square frame (24) and the railing (241).

Technical Field

The invention relates to the technical field of underwater cloud platforms, in particular to a full-automatic underwater cloud platform.

Background

Underwater sonar needs to be observed from different angles and different water depths when observing the motion state of a fish school underwater, however, the common method needs to lift the stand of the fixed sonar by one person, then manually rotate the stand to adjust the angle, lift the stand up and down to adjust the depth, so that the operation is time-consuming and labor-consuming, and at least two people are needed to cooperate to complete the operation. In addition, the angle control of the underwater cradle head in the prior art in all directions is not accurate, the structure is complex, and later-stage disassembly and maintenance are not convenient.

Disclosure of Invention

In order to solve the defects of the prior art, the invention provides the full-automatic underwater cradle head which can freely rotate at a plurality of angles, is more accurate in rotation angle, simple and compact in structure and convenient to disassemble, assemble and maintain at the later stage.

In order to realize the purpose of the invention, the following scheme is adopted:

a full-automatic underwater cradle head comprises a cradle head shell and a supporting device.

The holder shell comprises an upper cavity and a lower cavity which are vertically connected;

the top of the upper cavity is provided with a vertical direction rotating sealing cover, a vertical direction rotating servo motor, a vertical direction rotating speed reducer and a vertical direction rotating output shaft are sequentially arranged in the upper cavity from bottom to top, the outer wall of the vertical direction rotating output shaft is connected to the inner wall of the upper cavity through two bearings which are assembled in parallel, and the top of the vertical direction rotating output shaft penetrates through the vertical direction rotating sealing cover and then is connected with a supporting rod connecting seat;

the two ends of the lower cavity are respectively provided with a rear sealing cover and a horizontal direction rotating sealing cover, a horizontal direction rotating servo motor, a horizontal direction rotating speed reducer and a horizontal direction rotating output shaft are sequentially arranged in the lower cavity from right to left, the outer wall of the horizontal direction rotating speed reducer is connected to the inner wall of the lower cavity through two bearings which are assembled in parallel, the end part of the horizontal direction rotating output shaft penetrates through the horizontal direction rotating sealing cover and is connected with a sensor fixing seat, the sensor fixing seat is used for connecting a sonar or a camera, the top of the right end of the lower cavity is provided with a waterproof LEMO head base, and the waterproof LEMO head base is used for inserting and connecting a waterproof LEMO head plug;

the supporting device is connected with the supporting rod connecting seat and used for adjusting the height of the cradle head shell.

Furthermore, the outer wall of the vertical rotating output shaft is also provided with a dustproof ring and two star-shaped sealing rings, and the dustproof ring and the star-shaped sealing rings are positioned in the vertical rotating sealing cover and above the bearing.

Furthermore, the outer wall of the horizontal rotating output shaft is also provided with a dustproof ring and two star-shaped sealing rings, and the dustproof ring and the star-shaped sealing rings are positioned in the horizontal rotating sealing cover and are positioned on the left side of the bearing.

Furthermore, rubber pads are arranged between the vertical rotary sealing cover and the upper cavity, between the rear sealing cover and the lower cavity and between the horizontal rotary sealing cover and the lower cavity, and the vertical rotary sealing cover, the rear sealing cover and the horizontal rotary sealing cover are fixedly connected to the holder shell through bolts.

Furthermore, the horizontal direction rotation servo motor and the horizontal direction rotation speed reducer are fixedly connected through bolts, and the vertical direction rotation servo motor and the vertical direction rotation speed reducer are fixedly connected through bolts.

Further, sensor fixing base, bracing piece connecting seat pass through bolted connection in cloud platform casing respectively.

Further, waterproof LEMO head base threaded connection is in cloud platform casing, is equipped with the rubber circle between waterproof LEMO head base and the cloud platform casing.

Further, the supporting device comprises a square frame, a first motor, a second motor, a sawtooth strip and an assembly pulley, wherein a strip-shaped cylinder is connected to the output shaft of the first motor after penetrating through one side wall of the square frame, the other end of the strip-shaped cylinder is in running fit with the square frame, a thread groove is formed in the outer side wall of the strip-shaped cylinder, a strip-shaped gear is connected to the second motor after penetrating through one side wall of the square frame, the other end of the strip-shaped gear is in running fit with the square frame, the strip-shaped cylinder is located above the strip-shaped gear, a supporting plate is arranged at the top of the square frame, the assembly pulley is arranged on the front wall of the supporting plate, the assembly pulley is divided into a first pulley, a second pulley and a third pulley, the first pulley and the second pulley are connected through a first hinge rod, the second pulley and the third pulley are connected through a second hinge rod, one end of the first hinge rod, close to the first pulley, is in running fit with the supporting plate, the first pulley is connected with the second pulley through a first belt, the third pulley passes through the second belt and connects the second pulley, third pulley bottom fixed connection sawtooth rack, sawtooth rack and rectangular shape gear engagement cooperation, the sawtooth rack is equipped with the sliding sleeve outward, the wall is equipped with the slider behind the sliding sleeve, the slider inner wall is equipped with the guide post, the guide post is located in the thread groove, the sawtooth rack bottom is equipped with the connecting rod, the connecting rod passes through bolted connection bracing piece connecting seat.

Furthermore, a first track groove and a second track groove are formed in the front wall of the supporting plate, the other end of the first hinge rod is arranged in the first track groove through a driving wheel, and one end, close to the third pulley, of the second hinge rod is arranged in the second track groove through a driving wheel.

Furthermore, the square frame antetheca is equipped with the railing, and the sliding sleeve is located between square frame and the railing.

The invention has the beneficial effects that: the horizontal direction rotation servo motor and the horizontal direction rotation speed reducer adjust the angle of the cradle head shell in the horizontal direction, the vertical direction rotation servo motor and the vertical direction rotation speed reducer adjust the angle of the cradle head shell in the vertical direction, and the supporting device can adjust the left, right, up and down positions of the cradle head shell; the invention has more compact and simple integral structure; the control of the rotating angle in each direction is more accurate, and the rotating angle of the holder in each direction can be accurately judged under the condition that a sensor is not additionally arranged; the waterproof structure is more beneficial to later-stage disassembly and maintenance under the condition of meeting the waterproof requirement.

Drawings

FIG. 1 is a front view of a pan and tilt head housing of an embodiment;

fig. 2 is a right side view of the head housing of the embodiment;

FIG. 3 is a cross-sectional view A of FIG. 2;

FIG. 4 is a left side view of the head housing of the embodiment;

FIG. 5 is a top view of a pan and tilt head housing of an embodiment;

FIG. 6 is a bottom view of the holder housing of the embodiment;

FIG. 7 is a front view of the support device of the embodiment;

FIG. 8 is an internal structure view of a square frame of the embodiment;

FIG. 9 is a partial enlarged view of B in FIG. 8;

FIG. 10 is a block diagram of a rear wall of the pulley block of the embodiment;

FIG. 11 is a view showing a sonar-mounted structure of a sensor holder according to the embodiment;

FIG. 12 is a plan view of a sensor holder mounting sonar according to an embodiment;

FIG. 13 is a block diagram of a sensor mount mounted camera of an embodiment;

fig. 14 is a plan view of the sensor holder mounting camera of the embodiment.

Detailed Description

As shown in fig. 7, the present embodiment provides a fully automatic underwater cradle head, which includes a cradle head housing 1 and a supporting device 2.

Specifically, as shown in fig. 1, the internal cavity of the holder housing 1 includes an upper cavity 111 and a lower cavity 112 that are vertically connected, as shown in fig. 2, 4, 5, and 6, which are multiple views of the holder housing 1, and as shown in fig. 3, which is an internal structure of the holder housing 1, the holder housing 1 specifically includes the following components: the sensor comprises a vertical rotary sealing cover 17, a horizontal rotary sealing cover 18, a support rod connecting seat 4, a sensor fixing seat 5, a rear sealing cover 19, a waterproof LEMO head base 7, a horizontal rotary servo motor 8, a horizontal rotary speed reducer 9, a vertical rotary servo motor 10, a vertical rotary speed reducer 11, a horizontal rotary output shaft 12, a vertical rotary output shaft 13, a bearing 14, a star-shaped sealing ring 15 and a dust ring 16.

Specifically, the vertical direction rotation servo motor 10 and the vertical direction rotation speed reducer 11 are fixedly connected together through bolts, and are placed inside the upper cavity 111 and tightly attached to four side walls inside the upper cavity 111; a vertical direction rotation output shaft 13 is sleeved on an output shaft at the upper end of the vertical direction rotation speed reducer 11 and used for transmitting the output torque; the cylindrical surface at the lower part of the vertical direction rotating output shaft 13 is in interference fit with two bearings 14 in parallel, and the excircle of the bearing 14 is in transition fit with a vertical direction rotating sealing cover 17; the upper part of the vertical rotary sealing cover 17 is sequentially provided with a dustproof ring 16 and two star-shaped sealing rings 15, wherein the dustproof ring 16 and the star-shaped sealing rings 15 are also tightly pressed and sealed with the cylindrical surface on the upper part of the vertical rotary output shaft 13; a rubber pad is arranged between the rotary sealing cover 17 in the vertical direction and the upper end surface of the holder shell 1, and is fastened, pressed and sealed through surrounding bolts; the support rod connecting seat 4 is sleeved at the upper end of the vertical rotating output shaft 13 and fixed through a bolt, and can transmit torque output by the vertical rotating output shaft 13; the support rod connecting seat 4 is used for connecting the support rod connecting seat 4, and the support rod connecting seat 4 is used for adjusting the height of the holder shell 1.

Specifically, the horizontal rotation servo motor 8 and the horizontal rotation speed reducer 9 are fixedly connected together through bolts, and are placed inside the lower cavity 112 and tightly attached to four side walls inside the lower cavity 112; the horizontal direction rotation output shaft 12 is sleeved on an output shaft at the upper end of the horizontal direction rotation speed reducer 9 and used for transmitting the output torque; the cylindrical surface at the lower part of the horizontal rotating output shaft 12 is in interference fit with two bearings 14 in parallel, and the excircle of the bearing 14 is in transition fit with a horizontal rotating sealing cover 18; a dustproof ring 16 and two star-shaped sealing rings 15 are sequentially arranged on the upper part of the horizontal rotary sealing cover 18, wherein the dustproof ring 16 and the star-shaped sealing rings 15 are also tightly pressed and sealed with the cylindrical surface on the upper part of the horizontal rotary output shaft 12; a rubber pad is arranged between the horizontal rotary sealing cover 18 and the left end face of the holder shell 1, and is fastened, pressed and sealed through surrounding bolts; the sensor fixing seat 5 is sleeved at the upper end of the horizontal rotating output shaft 12 and fixed through a bolt, and can transmit torque output by the horizontal rotating output shaft 12; as shown in fig. 11, 12, 13 and 14, the upper end of the sensor fixing base 5 can be provided with various types of underwater sonars or cameras.

Specifically, the waterproof LEMO head base 7 is arranged on a plane at the tail of the holder shell 1, the LEMO head base 7 is connected with the holder shell 1 through threads, and a rubber ring on the waterproof LEMO head base 7 is compressed for sealing, so that the waterproof effect is achieved; each contact pin of waterproof LEMO head 7 lower part rotates servo motor 8 and vertical direction and rotates servo motor 10's power cord with the horizontal direction and weld fixture, and waterproof LEMO head base 7 upper end can connect and insert waterproof LEMO head plug and be used for the horizontal direction to rotate servo motor 8 and vertical direction and rotate servo motor 10 power supply and transmission control signal etc..

Specifically, a rubber pad is arranged between the rear sealing cover 19 and the right end face of the holder shell 1, and the rear sealing cover and the right end face of the holder shell are fastened, compressed and sealed through surrounding bolts, so that a waterproof effect is achieved.

Specifically, as shown in fig. 7, the supporting device 2 includes a square frame 24, a first motor 21, a second motor 22, a sawtooth rack 23 and a pulley block 3, as shown in fig. 8, the square frame 24 is in a shape of a Chinese character 'ri', and is divided into an upper frame and a lower frame, an output shaft of the first motor 21 penetrates through a side wall of the upper frame and is connected with a long-strip-shaped cylinder 25, the other end of the long-strip-shaped cylinder 25 is in running fit with the square frame 24, a thread groove 251 is formed in the outer side wall of the long-strip-shaped cylinder 25, the second motor 22 penetrates through a side wall of the lower frame and is connected with a long-strip-shaped gear 26, and the other end of the long-strip-shaped gear 26 is in running fit with the square frame 24.

Specifically, the top of the square frame 24 is provided with the support plate 6, the pulley block 3 is arranged on the front wall of the support plate 6, as shown in fig. 10, the pulley block 3 is divided into a first pulley 31, a second pulley 32 and a third pulley 33, the first pulley 31 and the second pulley 32 are connected through a first hinge rod 321, the second pulley 32 and the third pulley 33 are connected through a second hinge rod 322, one end of the first hinge rod 321, which is close to the first pulley 31, is rotatably matched with the support plate 6, the first pulley 31 is connected with the second pulley 32 through a first belt 34, the third pulley 33 is connected with the second pulley 32 through a second belt 35, the bottom of the third pulley 33 is fixedly connected with the sawtooth strip 23, and the sawtooth strip 23 is engaged with the elongated gear 26.

Specifically, as shown in fig. 9, a sliding sleeve 231 is arranged outside the sawtooth rack 23, the sawtooth rack 23 can slide up and down in the sliding sleeve 231, the inner wall of the sliding sleeve 231 is arranged to be closely attached to the outer wall of the square frame 24, a sliding block 232 is arranged on the rear wall of the sliding sleeve 231, the sliding block 232 is in sliding fit with the upper frame, a guide post 233 is arranged on the inner wall of the sliding block 232, and the guide post 233 is arranged in the thread groove 251.

That is, the first motor 21 drives the elongated cylinder 25 to rotate, and the saw-toothed bar 23 can move left and right by the cooperation of the guide post 233 and the threaded groove 251; the second motor 22 drives the elongated gear 26 to rotate, and the sawtooth rack 23 can move up and down through the sliding fit of the elongated gear 26 and the sawtooth rack 23; if the first motor 21 and the second motor 22 are rotated at the same time, the rack gears 23 are moved obliquely upward or downward.

Specifically, the bottom of the sawtooth rack 23 is provided with a connecting rod 234, the connecting rod 234 is connected with the support rod connecting seat 4 through a bolt, and when the first motor 21 and the second motor 22 rotate, the cradle head shell 1 moves left and right, up and down, and inclines upwards or downwards through the sawtooth rack 23.

In order to improve the stability of the sawtooth rack 23 during movement, the front wall of the square frame 24 is provided with a rail 241, the front wall of the sliding sleeve 231 is tightly attached to the rear wall of the rail 241, so that the sliding sleeve 231 slides left and right in the rail 241, and the sliding block 232 slides left and right in the upper frame.

Specifically, the front wall of the support plate 6 is provided with a first track groove 61 and a second track groove 62, the other end of the first hinge rod 321 is arranged in the first track groove 61 through a driving wheel 323, the first track groove 61 is shaped like an arc groove with the first pulley 31 as a center and the first hinge rod 321 as a radius, one end of the second hinge rod 322 close to the third pulley 33 is arranged in the second track groove 62 through the driving wheel 323, and the second track groove 62 can be in various shapes, and the shape can be set according to actual requirements, for example, when only the first motor 21 and the second motor 22 are required to rotate independently, the second track groove 62 is in an L shape, and the right angle faces the left side; when the first motor 21 and the second motor 22 only need to rotate simultaneously and the vertical and horizontal moving rates of the sawtooth rack 23 are the same, the second track groove 62 is an inclined straight line; when the first motor 21 and the second motor 22 only need to rotate simultaneously and the vertical and horizontal moving rates of the sawtooth racks 23 are different, the second track groove 62 is an inclined curve; when it is required that the first motor 21 and the second motor 22 can rotate independently or simultaneously and the up-down and left-right movement rates of the sawtooth rack 23 are the same, the second track groove 62 is a right triangle, which is shown in fig. 7 in this embodiment.

When the cradle head is used, the first motor 21 and the second motor 22 are firstly utilized to adjust the sawtooth strips 23 to the highest position, so that the cradle head shell 1 is convenient to mount; then, the cradle head shell 1 is installed at the bottom of the sawtooth strip 23 through bolts, an underwater sonar or a camera is installed on the sensor fixing seat 5, and various conducting wires and electric wires of the cradle head shell 1 are arranged; then, the holder shell 1 is lowered to a proper position in the water by using the first motor 21 and the second motor 22; the horizontal direction rotates servo motor 8, the horizontal direction rotates speed reducer 9 and adjusts the angle of the holder shell 1 in the horizontal direction, the vertical direction rotates servo motor 10, the vertical direction rotates speed reducer 11 and adjusts the angle of the holder shell 1 in the vertical direction, and the supporting device 2 can adjust the left, right, up and down positions of the holder shell 1.

In conclusion, the whole structure of the embodiment is more compact and simple; the control of the rotating angle in each direction is more accurate, and the rotating angle of the holder in each direction can be accurately judged under the condition that a sensor is not additionally arranged; the waterproof structure is more beneficial to later-stage disassembly and maintenance under the condition of meeting the waterproof requirement.

The above embodiments are only for illustrating the technical ideas and features of the present invention, and are not meant to be exclusive or limiting of the present invention. It will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention.