Water and fertilizer integrated drip irrigation device for vegetables

Abstract

The utility model discloses a water and fertilizer integrated drip irrigation device for vegetables. The water and fertilizer integrated drip irrigation device structurally comprises an assembly rack, a traction mechanism, a lifting assembly, a reversing assembly and a spacing adjusting assembly, the traction mechanism is matched with the assembling rack to drive the device to advance, and the lifting assembly is installed on the rack to adjust the height of the reversing assembly and the height of the distance adjusting assembly. The reversing assembly is composed of a reversing frame plate and a reversing motor and installed on the lifting assembly to achieve power connection. The distance adjusting assembly is composed of a sliding frame plate, a shear fork type telescopic support, a telescopic cylinder and a drip irrigation nozzle, and the movable end of the telescopic cylinder is connected with the sliding frame plate so that the drip irrigation nozzle can be adjusted according to the distance between crops. According to the device, by accurately adjusting the drip irrigation height and distance, water and fertilizer distribution is optimized, the utilization rate is increased, healthy growth of crops is promoted, and agricultural production is supported to develop towards the environment-friendly, efficient and intelligent direction.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of vegetable planting, and specifically relates to a vegetable water and fertilizer integrated drip irrigation device. BACKGROUND

[0002] With the rapid development of modern agricultural technology, drip irrigation technology is widely used in the production of crops such as vegetables, fruit trees and flowers due to its water-saving, yield-increasing and energy-saving advantages. Traditional drip irrigation systems are mainly divided into two types: underground buried type and hanging type. However, both systems have obvious limitations, especially in dense planting environments such as greenhouses.

[0003] The underground buried drip irrigation system can effectively utilize water resources and reduce water evaporation, but the installation and maintenance process is complicated, and once buried, it is extremely inconvenient to adjust the planting mode of crops in the greenhouse. More importantly, when soil renovation, plowing and other farmland management operations are needed, the underground pipe network often becomes an obstacle, not only increasing the labor intensity, but also possibly causing pipe network damage, affecting the normal operation of the irrigation system.

[0004] On the other hand, although the existing hanging drip irrigation device solves part of the problem of the underground buried system, making the management operation of farmland more convenient, they are usually designed simply and have limited functions. Most hanging drip irrigation systems cannot be adjusted according to the growth height of crops or the change of plant row spacing, which limits the precision and applicability of irrigation. Especially in high-value crop planting areas such as greenhouses, different types of vegetables have different water and fertilizer needs, and fixed drip irrigation points and spacing often cannot meet the needs of all crops, resulting in low water and fertilizer utilization rate and even affecting the growth and development of crops.

[0005] In addition, in order to ensure comprehensive coverage of crops in the greenhouse, the hanging drip irrigation device often needs to be designed with a large span, which not only increases the manufacturing cost, but also affects the stability and reliability of the device. In actual application, due to the influence of wind force, self-weight and other factors, the large-span drip irrigation device is prone to deformation, thereby affecting the uniformity and precision of drip irrigation.

[0006] Based on the above problems, there is an urgent need for a new type of drip irrigation system that can flexibly adapt to the growth needs of different crops in the greenhouse, while taking into account the convenience of installation, flexibility of operation and efficient use of water and fertilizer resources. The ideal system should be easy to install and adjust, automatically adjust the position and spacing of drip irrigation points according to the change of crop row spacing and growth height, to realize more precise and efficient water and fertilizer supply, thereby improving crop yield and quality and reducing production cost. SUMMARY

[0007] In view of the above-mentioned deficiencies in the prior art, the utility model aims at providing a vegetable water and fertilizer integrated drip irrigation device which can flexibly adapt to the growth requirements of different crops in the greenhouse, and simultaneously takes into account the characteristics of convenient installation, flexible operation and efficient utilization of water and fertilizer resources.

[0008] The utility model discloses a technical scheme for realizing the above-mentioned purpose is: a vegetable water and fertilizer integrated drip irrigation device, including assembly frame, traction mechanism, lifting assembly, the traction mechanism is matched with assembly frame combination for driving assembly frame to go, lifting assembly is matched and installed on the assembly frame.

[0009] Still include the reversing assembly, interval adjustment assembly, the reversing assembly includes reversing frame board, reversing motor, the reversing frame board rotation is installed on the movable part of lifting assembly, reversing motor and reversing frame board keep power connection.

[0010] The interval adjustment assembly includes sliding frame board, scissor type telescopic support, telescopic cylinder, drip irrigation nozzle, both ends of scissor type telescopic support are assembled on the reversing frame board and sliding frame board, the drip irrigation nozzle is assembled on the scissor type telescopic support, and the drip irrigation nozzle keeps vertical downward arrangement, the telescopic cylinder is fixedly installed on the reversing frame board, and the movable end of telescopic cylinder is fixedly connected with sliding frame board.

[0011] In some implementations, to ensure that the traction mechanism can drive the assembly frame to stably go, and ensure that the assembly frame can stably run along the length direction of the vegetable greenhouse, the following technical scheme is provided.

[0012] The assembly frame is erected with the travel guide rail that keeps parallel arrangement on both sides, and the support wheel that keeps matched combination with the travel guide rail is rotationally installed on the assembly frame;The traction mechanism includes traction motor, winding drum, reversing wheel, guide wheel and traction rope, the winding drum is rotationally installed on the assembly frame and is power connected with the traction motor, two groups of guide wheels that are rotationally installed on the assembly frame are arranged on both sides of the winding drum, the reversing wheel is rotationally installed on both ends of the stroke of the assembly frame, the traction rope is wound on the winding drum, and both ends of the traction rope sequentially pass the guide wheel and the reversing wheel on the corresponding side and are fixedly connected with the assembly frame.

[0013] In some implementations, to ensure that the lifting assembly can be stably assembled on the assembly frame and realize lifting adjustment, the following technical scheme is provided.

[0014] The lifting assembly comprises a fixed support, a lifting support and an adjusting screw rod and a lifting motor, the fixed support is vertically arranged and fixedly installed on the assembly rack, the adjusting screw rod is rotatably installed in the fixed support and rotatably connected with the top end of the lifting support, and the lifting motor is fixedly installed in the assembly rack and connected with the adjusting screw rod.

[0015] In some embodiments, in order to ensure that the reversing assembly can be stably assembled on the movable part of the lifting assembly, ensure the stability and reliability of the annular operation of the reversing assembly, the following technical solutions are provided.

[0016] The reversing support plate is fixedly connected with a rotating seat and a counterweight seat, the rotating seat is rotatably installed at the bottom of the lifting support, the counterweight seat and the spacing adjustment assembly are arranged on the two sides of the rotating seat respectively, and the reversing motor is fixedly installed at the bottom of the lifting support; the reversing assembly further comprises a worm gear and a worm, the worm gear is fixedly connected with the rotating seat, and the worm is rotatably installed at the bottom of the lifting support and connected with the reversing motor.

[0017] In some embodiments, in order to ensure that the spacing adjustment assembly can be stably assembled and operated on the reversing support plate, ensure the stable operation of the scissor-type telescopic support, and provide an implementation scheme for assembling the drip irrigation nozzle on the scissor-type telescopic support, the following technical solutions are provided.

[0018] The reversing support plate is provided with a guide sliding groove, the sliding support plate is fixedly connected with a guide sliding seat which is slidably installed in the guide sliding groove, the movable end of the telescopic cylinder is fixedly connected with the guide sliding seat, the scissor-type telescopic support comprises a plurality of connecting rods which are hingedly arranged in a scissor-type, and the drip irrigation nozzle is rotatably installed at the middle hinged point of the connecting rod.

[0019] The utility model discloses the beneficial effects of:

[0020] 1. Precise drip irrigation brought by height self-adaptive adjustment: through the design of the lifting assembly, the device can automatically adjust the height of the drip irrigation nozzle according to the actual height of the vegetable plants, and the distance between the drip irrigation nozzle and the plants is minimized. This fine adjustment of height can significantly improve the water and fertilizer utilization efficiency, reduce the waste of water and fertilizer, and ensure that each plant can receive uniform and sufficient water and fertilizer supply, thereby promoting the healthy growth of crops and increasing the yield.

[0021] 2. The spacing adjustment assembly enables adaptive irrigation: The device allows users to flexibly adjust the spacing of the drip irrigation emitters according to the row spacing of the vegetable plants through the spacing adjustment assembly. This design not only enhances the applicability of the device to different types and arrangement densities of crops, but also further improves the application accuracy of water and fertilizer. For diversified crop planting patterns, this function ensures that all rows of vegetable plants can receive balanced and sufficient drip irrigation, optimizing resource allocation and utilization.

[0022] 3. The innovative design of the reversing assembly optimizes device performance: Through the reversing assembly, the device realizes flexible conversion of the irrigation direction of the drip irrigation emitters, enabling a single device to cover the vegetable plants on both sides of the assembly rack. This design greatly reduces the overall size and span requirements of the device, reduces the space occupation, and improves the stability and operating efficiency of the device. In the same working area, it can more accurately and uniformly complete the drip irrigation task, reducing the dependence on physical space and the requirement for structural strength. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural schematic diagram of the utility model;

[0024] Figure 2 is a structural schematic diagram of the assembly rack and traction mechanism in matched combination;

[0025] Figure 3 is a structural schematic diagram of the internal structure of the lifting mechanism;

[0026] Figure 4 is a structural schematic diagram of the reversing mechanism;

[0027] Figure 5 is a structural schematic diagram of the spacing adjustment assembly.

[0028] In the figure: 1 assembly rack, 11 travel guide rail, 12 support wheel, 2 traction mechanism, 21 traction motor, 22 winding drum, 23 reversing wheel, 24 guide wheel, 25 traction rope, 3 lifting assembly, 31 fixed support, 32 lifting support, 33 adjusting lead screw, 331 transmission bevel gear, 34 lifting motor, 341 drive bevel gear, 4 reversing assembly, 41 reversing rack plate, 411 rotating seat, 412 counterweight seat, 413 guide sliding groove, 42 reversing motor, 43 worm gear, 44 worm, 5 spacing adjustment assembly, 51 sliding rack plate, 511 guide sliding seat, 52 scissor-type telescopic support, 521 connecting rod, 522 guide support, 523 sliding sleeve, 53 telescopic cylinder, 54 drip irrigation emitter. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of the present application.

[0030] Please refer to Figures 1-5 The vegetable water and fertilizer integrated drip irrigation device comprises an assembly frame 1, a traction mechanism 2 and a lifting assembly 3.

[0031] The vegetable water and fertilizer integrated drip irrigation device further comprises a reversing assembly 4 and a spacing adjustment assembly 5.

[0032] The spacing adjustment assembly 5 comprises a sliding frame plate 51, a scissor-type telescopic support 52, a telescopic cylinder 53 and a drip irrigation nozzle 54.

[0033] The vegetable water and fertilizer integrated drip irrigation device provided in the present application is mainly applied in a vegetable greenhouse and is assembled at the top of crops such as vegetables.

[0034] The active part of the lifting assembly 3 extends from the bottom of the assembly frame 1 and realizes up-and-down lifting movement, thereby driving the reversing assembly 4 and the spacing adjustment assembly 5 assembled on the active part of the lifting assembly 3 to realize synchronous lifting.

[0035] For the reversing assembly 4, the reversing motor 42 drives the reversing frame plate 41 to stably operate around the movable part of the lifting assembly 3 in the horizontal plane, and the spacing adjustment assembly 5 is arranged on one side of the lifting assembly 3, which, under the cooperation of the reversing assembly 4, enables the water, fertilizer or water-fertilizer mixture output by the drip irrigation emitter 54 in the spacing adjustment assembly 5 to be drip irrigated to the vegetable plants on both sides of the assembly rack 1. Under the premise that the overall size of the drip irrigation device is limited, the vegetable plants in the vegetable greenhouse can be comprehensively drip irrigated.

[0036] For the spacing adjustment assembly 5, by adjusting the extension and retraction posture of the telescopic cylinder 53, the sliding frame plate 51 can be driven to slide along the length direction of the reversing frame plate 41, and then the telescopic motion of the scissor-type telescopic support 52 is driven. The drip irrigation emitters 54 are uniformly distributed along the length direction of the sliding frame plate 51 and the reversing frame plate 41, and are arranged on different parts of the scissor-type telescopic support 52. During the telescopic motion of the scissor-type telescopic support 52, the spacing between the drip irrigation emitters 54 can be adjusted to keep the drip irrigation emitters 54 vertically relative to the vegetable plants below. The spacing of the drip irrigation emitters 54 can be accurately adjusted according to the different spacing between the vegetable plants, so that each vegetable plant can effectively receive the output water and fertilizer.

[0037] It should be noted that each drip irrigation emitter 54 is connected with a connecting hose, and each connecting hose is connected to a pressure pump. The pressure pump is used to extract water and fertilizer and convey it to each drip irrigation emitter 54 along the connecting hose. The arrangement of the connecting hose can ensure the stable transmission of water and fertilizer to the drip irrigation emitters 54 during the operation of the spacing adjustment assembly 5.

[0038] In order to ensure that the traction mechanism 2 can drive the assembly rack 1 to stably move and ensure that the assembly rack 1 can stably operate along the length direction of the vegetable greenhouse, the following technical solutions are provided.

[0039] The assembly rack 1 is provided with two parallel running rails 11, and the assembly rack 1 is provided with a support wheel 12 rotatably installed on the assembly rack 1 and matched with the running rail 11; the traction mechanism 2 includes a traction motor 21, a winding drum 22, a reversing wheel 23, a guide wheel 24 and a traction rope 25. The winding drum 22 is rotatably installed on the assembly rack 1 and is power-connected with the traction motor 21. Two groups of guide wheels 24 are arranged on both sides of the winding drum 22 and are rotatably installed on the assembly rack 1. The reversing wheel 23 is rotatably installed on both ends of the stroke of the assembly rack 1. The traction rope 25 is wound on the winding drum 22, and both ends of the traction rope 25 sequentially pass through the corresponding guide wheel 24 and the reversing wheel 23 on one side and are fixedly connected with the assembly rack 1.

[0040] The design and matching combination of the running rail 11 and the support wheel 12 can ensure that the assembly rack 1 stably moves along the straight line direction of the running rail 11.

[0041] When the traction motor 21 drives the winch 22 to rotate in a certain direction, one end of the traction rope 25 is wound on the winch 22 and pulls the assembly support to move in the direction, and the other end of the traction rope 25 is unwound from the winch 22 to compensate for the length of the traction rope 25 outside the winch 22.

[0042] The reversing wheel 23 changes the direction of the traction force of the traction rope 25, and the guide wheel 24 winds and unwinds the traction rope 25 from both ends of the winch 22 while avoiding the spatial interference between the traction rope 25 and the lifting assembly 3 assembled on the assembly support 1.

[0043] To ensure that the lifting assembly 3 can be stably assembled on the assembly support 1 and achieve lifting adjustment, the following technical solutions are provided.

[0044] The lifting assembly 3 comprises a fixed support 31 for holding a sliding combination, a lifting support 32, and an adjusting lead screw 33 and a lifting motor 34. The fixed support 31 is vertically arranged and fixedly installed on the assembly support 1. The adjusting lead screw 33 is rotatably installed in the fixed support 31 and rotatably connected to the top end of the lifting support 32. The lifting motor 34 is fixedly installed in the assembly support 1 and power-connected to the adjusting lead screw 33.

[0045] The output shaft of the lifting motor 34 is fixedly connected with a driving bevel gear 341, and the bottom of the adjusting lead screw 33 is fixedly connected with a transmission bevel gear 331 meshing with the driving bevel gear 341. When the lifting motor 34 operates, it can drive the adjusting lead screw 33 to rotate, thereby driving the lifting support 32 to stably lift along the fixed support 31. The bottom of the lifting support 32 extends below the assembly support 1, which can ensure that the reversing assembly 4 and the spacing adjustment assembly 5 are stably assembled at the bottom of the lifting support 32.

[0046] To ensure that the reversing assembly 4 can be stably assembled on the movable part of the lifting assembly 3 and ensure the stability and reliability of the ring-shaped operation of the reversing assembly 4, the following technical solutions are provided.

[0047] The reversing support plate 41 is fixedly connected with a rotating seat 411 and a counterweight seat 412. The rotating seat 411 is rotatably installed at the bottom of the lifting support 32. The counterweight seat 412 and the spacing adjustment assembly 5 are arranged on both sides of the rotating seat 411. The reversing motor 42 is fixedly installed at the bottom of the lifting support 32. The reversing assembly 4 further comprises a worm gear 43 and a worm 44 for holding a matched combination. The worm gear 43 is fixedly connected with the rotating seat 411. The worm 44 is rotatably installed at the bottom of the lifting support 32 and power-connected with the reversing motor 42.

[0048] The rotating seat 411 can ensure that the reversing rack plate 41 is stably installed at the bottom of the lifting support 32, and the counterweight seat 412 is arranged on the opposite side of the spacing adjustment assembly 5, so that the overall center of the reversing rack plate 41 and the components assembled thereon is located at the position of the rotating seat 411 as much as possible, so as to adjust the stability of the reversing assembly 4 and the spacing adjustment assembly 5. When the reversing motor 42 drives the worm 44 to operate, the worm gear 43, the rotating seat 411 and the reversing rack plate 41 can be driven to operate as a whole.

[0049] The combination structure of the worm gear 43 and the worm 44 also has the effect of speed reduction and torque increase, which can ensure that a large enough torque drives the reversing rack plate 41 to operate when the power of the reversing motor 42 is transmitted to the reversing rack plate 41. At the same time, the combination of the worm gear 43 and the worm 44 can also realize the function of one-way power transmission from the worm 44 to the worm 44. When the reversing rack plate 41 is adjusted in the direction and the reversing motor 42 is in the shutdown state, the reversing rack plate 41 is in the locked state under the action of the combination of the worm gear 43 and the worm 44, which ensures the stability and accuracy of the drip irrigation of the vegetable plants in the vegetable greenhouse.

[0050] In order to ensure that the spacing adjustment assembly 5 can be stably assembled and operated on the reversing rack plate 41, ensure the stable operation of the scissor-type telescopic support 52, and provide an implementation scheme for assembling the drip irrigation nozzle 54 on the scissor-type telescopic support 52, the following technical solutions are provided.

[0051] The reversing rack plate 41 is provided with a guide sliding groove 413, the sliding rack plate 51 is fixedly connected to a guide sliding seat 511 which is slidingly installed in the guide sliding groove 413, the movable end of the telescopic cylinder 53 is fixedly connected to the guide sliding seat 511, the scissor-type telescopic support 52 includes a plurality of groups of connecting rods 521 which are distributed in a scissor-type hinge connection mode, and the drip irrigation nozzle 54 is rotatably installed at the middle hinge joint position of the connecting rod 521.

[0052] The arrangement of the guide sliding groove 413 and the guide sliding seat 511 can effectively improve the stability of the sliding operation of the sliding rack plate 51 on the reversing rack plate 41. The drip irrigation nozzle 54 can be subjected to galvanizing or other strengthening treatment, and can serve as a hinge pin seat at the middle part of the connecting rod 521.

[0053] The same as the conventional scissor-type telescopic support 52, two groups of connecting rods 521 are arranged at the two ends, respectively, and guide supports 522 are fixedly connected to the sliding rack plate 51 and the reversing rack plate 41. The end of one group of connecting rods 521 is hingedly connected to the corresponding guide support 522, and the end of the other group of connecting rods 521 is hingedly connected to a sliding sleeve 523 which is in sliding combination with the guide support 522.

[0054] It is apparent for a person skilled in the art that the present application is not limited to the details of the above-described exemplary embodiments, but that it can be implemented in other concrete forms without departing from the spirit or the essential characteristics of the present application. Therefore, the embodiments should be considered as exemplary and non-limiting, the scope of the present application being defined by the claims appended hereto rather than by the above description, and all the changes which fall within the meaning and the scope of the equivalent elements of the claims are intended to be embraced therein. Any reference signs in the claims should not be construed as limiting the claims to the figures in which the reference signs are used.

[0055] Furthermore, it should be understood that although the present specification is described in terms of embodiments, not every embodiment according to the present specification needs to exhibit each and every characteristic specified in the present specification. The specification can also be described in terms of a single independent technical solution, but this does not mean that each embodiment only contains one independent technical solution. The specification is described in this way only for the sake of clarity, and a person skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by a person skilled in the art.

Claims

1. A vegetable water and fertilizer integrated drip irrigation device, characterized by: The utility model comprises an assembly frame (1), a traction mechanism (2), and a lifting assembly (3), wherein the traction mechanism (2) and the assembly frame (1) are matched and combined to drive the assembly frame (1) to move, and the lifting assembly (3) is matched and installed on the assembly frame (1); and further comprises a reversing assembly (4) and a spacing adjustment assembly (5), wherein the reversing assembly (4) comprises a reversing frame plate (41) and a reversing motor (42), wherein the reversing frame plate (41) is rotatably mounted on a movable part of the lifting assembly (3), and the reversing motor (42) maintains power connection with the reversing frame plate (41). The spacing adjustment assembly (5) includes a sliding frame plate (51), a scissor-type telescopic bracket (52), a telescopic cylinder (53), and a drip irrigation nozzle (54). The two ends of the scissor-type telescopic bracket (52) are respectively mounted on the reversing frame plate (41) and the sliding frame plate (51). The drip irrigation nozzle (54) is mounted on the scissor-type telescopic bracket (52), and the drip irrigation nozzle (54) is kept vertically downward. The telescopic cylinder (53) is fixedly mounted on the reversing frame plate (41), and the movable end of the telescopic cylinder (53) is fixedly connected to the sliding frame plate (51).

2. The vegetable water and fertilizer integrated drip irrigation device according to claim 1, characterized in that: Travel guide rails (11) arranged in parallel are provided on both sides of the assembly frame (1), and support wheels (12) which are matched with the travel guide rails (11) are rotatably mounted on the assembly frame (1); the traction mechanism (2) comprises a traction motor (21), a winch (22), a reversing wheel (23), a guide wheel (24) and a traction rope (25); the winch (22) is rotatably mounted on the assembly frame (1) and is power-connected to the traction motor (21); two groups of guide wheels (24) rotatably mounted on the assembly frame (1) are arranged on both sides of the winch (22); the reversing wheel (23) is rotatably mounted at both ends of the travel of the assembly frame (1); the traction rope (25) is wound around the winch (22), and both ends of the traction rope (25) are sequentially passed around the guide wheel (24) and the reversing wheel (23) on the corresponding side and then fixedly connected to the assembly frame (1).

3. The vegetable water and fertilizer integrated drip irrigation device according to claim 1, characterized in that: The lifting assembly (3) includes a fixed bracket (31) for maintaining a sliding combination, a lifting bracket (32), an adjusting screw (33), and a lifting motor (34). The fixed bracket (31) is vertically arranged and fixedly mounted on the assembly frame (1). The adjusting screw (33) is rotatably mounted in the fixed bracket (31) and is kept in rotational connection with the top end of the lifting bracket (32). The lifting motor (34) is fixedly mounted in the assembly frame (1) and is kept in power connection with the adjusting screw (33).

4. The vegetable water and fertilizer integrated drip irrigation device according to claim 3, characterized in that: A rotating seat (411) and a counterweight seat (412) are fixedly connected to the reversing frame plate (41); the rotating seat (411) is rotatably mounted on the bottom of the lifting bracket (32); the counterweight seat (412) and the spacing adjustment assembly (5) are respectively arranged on both sides of the rotating seat (411); the reversing motor (42) is fixedly mounted on the bottom of the lifting bracket (32); the reversing assembly (4) also includes a worm wheel (43) and a worm (44) that maintain a matching combination; the worm wheel (43) is fixedly connected to the rotating seat (411); the worm (44) is rotatably mounted on the bottom of the lifting bracket (32) and is power-connected to the reversing motor (42).

5. The vegetable water and fertilizer integrated drip irrigation device according to claim 1, characterized in that: A guide slot (413) is provided on the reversing frame plate (41), the sliding frame plate (51) is fixedly connected to a guide slide (511) slidably installed in the guide slot (413), the movable end of the telescopic cylinder (53) is fixedly connected to the guide slide (511), the scissor-type telescopic bracket (52) includes a plurality of connecting rods (521) that are hingedly distributed in a scissor-type manner, and the drip irrigation nozzle (54) is rotatably installed at a middle hinge point of the connecting rod (521).

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