CN105605022B - A kind of Multi-cylinder sequential telescopic mechanism and engineering machinery - Google Patents

Abstract

The invention discloses a multi-cylinder sequential telescoping mechanism and engineering machinery, which include a first oil cylinder, a second oil cylinder and a third oil cylinder, and the first oil cylinder, the second oil cylinder and the third oil cylinder all include a piston rod, a cylinder barrel, Rod cavity oil circuit and rod cavity oil circuit, travel valves are arranged between the first oil cylinder and the second oil cylinder, between the second oil cylinder and the third oil cylinder, and the second oil cylinder and the third oil cylinder A stroke valve limit plate is arranged on the tail end of the cylinder, and the stroke valve realizes the switching of the working position by contacting the stroke valve limit plate; The connecting pipe adjacent to the oil cylinder; the first oil cylinder and the second oil cylinder are all provided with an oil guide pipeline, wherein the oil guide pipeline includes an outer pipe and an inner pipe, and the M end of the outer pipe is connected with the piston rod, so The N end of the inner tube is connected with the cylinder. The present invention can easily realize the expansion and contraction of multi-stage (the number of oil cylinders is more than 2) oil cylinders without increasing the pressure of the system.

Description

A multi-cylinder sequential telescopic mechanism and construction machinery

technical field

The invention relates to the technical field of multi-cylinder sequential control, in particular to a multi-cylinder sequential telescopic mechanism and construction machinery including the telescopic mechanism.

Background technique

At present, most crane telescopic mechanisms are driven by hydraulic cylinders. Among them, cranes with four-section telescopic booms use two-stage telescopic cylinders, and cranes with five-section telescopic booms use three-stage telescopic cylinders. The bending section modulus is different), so the sequential expansion and contraction of the oil cylinder can reduce the stress of the jib with a smaller section modulus, thereby improving the lifting performance of the entire jib.

At present, the two-stage oil cylinder expansion mechanism based on the sequence valve 20 and the stroke valve 7 shown in Figure 1 is mostly used in China. Under the same force, there is a pressure difference between the inlet and outlet pressure of the pressure reducing valve (assumed to be P), so The pressure required for the expansion and contraction of the first oil cylinder 1 is lower than that of the second oil cylinder 2 by P, so the first oil cylinder 1 can be extended first, and after the first oil cylinder 1 is fully extended, the second oil cylinder 2 can be extended again, thereby realizing sequential expansion and contraction. However, under the same external force, due to the need to overcome the pressure difference of the pressure reducing valve, the pressure of the entire hydraulic system will significantly increase (increase P) when the second oil cylinder 2 is stretched out. As a result, unfavorable factors such as large heating of the hydraulic system are caused. In addition, if this mechanism is used to realize the sequential expansion and contraction of N oil cylinders (that is, the sequential expansion and contraction of multiple oil cylinders), additional (N-1)*P sequence valve pressures are required to overcome the resistance of N-1 sequence valves. As far as the hydraulic system is concerned, when N is greater than 2, it is basically impossible to achieve because the force required for pressure is too high.

Contents of the invention

In view of this, the present invention proposes a multi-cylinder sequential telescoping mechanism and construction machinery to solve the technical problems of the hydraulic system of the existing multi-cylinder telescoping mechanism, which generates a lot of heat and requires high pressure when the cylinders stretch.

In one aspect, the present invention provides a multi-cylinder sequential telescoping mechanism, comprising a first oil cylinder, a second oil cylinder and a third oil cylinder, each of which includes a piston rod, a cylinder barrel, Rod chamber oil circuit and rod chamber oil circuit, stroke valves are arranged between the first oil cylinder and the second oil cylinder, between the second oil cylinder and the third oil cylinder, and the valves of the second oil cylinder and the third oil cylinder The end of the cylinder is provided with a stroke valve limit plate, and the stroke valve realizes the switching of the working position by contacting the stroke valve limit plate; the first oil cylinder, the second oil cylinder and the third oil cylinder are provided with a valve for communicating with each other. The connecting pipe adjacent to the oil cylinder; the first oil cylinder and the second oil cylinder are all provided with an oil guide pipeline, wherein the oil guide pipeline includes an outer pipe and an inner pipe, and the M end of the outer pipe is connected with the piston rod, so The N end of the inner tube is connected with the cylinder.

Further, the connecting pipe includes a first connecting pipe and a second connecting pipe, the rod chamber oil passage of the first oil cylinder communicates with the rod chamber oil passage of the second oil cylinder through the first connecting pipe, and the first oil cylinder The oil circuit in the rodless chamber of the second oil cylinder communicates with the oil guide line of the first oil cylinder through the second connecting pipe.

Further, the connecting pipe includes a third connecting pipe and a fourth connecting pipe, the rod chamber oil passage of the third oil cylinder communicates with the rod chamber oil passage of the second oil cylinder through the third connecting pipe, and the first oil cylinder The rodless chamber oil circuit of the three oil cylinders communicates with the oil guide pipeline of the second oil cylinder through the fourth connecting pipe.

Further, the first oil cylinder, the second oil cylinder and the third oil cylinder are respectively provided with an A port and a B port, and the rodless cavity oil passages of the first oil cylinder, the second oil cylinder and the third oil cylinder are respectively connected to the B port The rod cavity oil passages of the first oil cylinder, the second oil cylinder and the third oil cylinder are respectively connected with their A ports.

Further, a first one-way valve is provided between the rodless chamber oil passage of the first oil cylinder and its B port, the oil flows into the rodless chamber oil passage from the B port, and the oil guide pipe of the first oil cylinder and its B port There is a second one-way valve between the ports, and the oil flows from the oil guide line to the B port.

Further, a first one-way valve is provided between the rodless chamber oil passage of the second oil cylinder and its B port, and the oil flows into the rodless chamber oil passage from the B port, and the oil guide pipe of the second oil cylinder and its B port There is a second one-way valve between the ports, and the oil flows from the oil guide line to the B port.

Further, the first one-way valve is set close to port B; and/or, the second one-way valve is set close to port B.

Further, the inner tube is also provided with an inner tube oil port through which the oil flows in or out.

In summary, the present invention provides a multi-cylinder sequential telescopic mechanism, which includes a first cylinder, a second cylinder, a third cylinder, a stroke valve, a stroke valve limit plate and a connecting pipe, wherein the first Stroke valves are arranged between the oil cylinder and the second oil cylinder, between the second oil cylinder and the third oil cylinder, and stroke valve limit plates are arranged on the cylinder ends of the second oil cylinder and the third oil cylinder. Switching of the working position is realized by contacting the limit plate of the stroke valve. A connecting pipe for communicating with adjacent oil cylinders is arranged between the first oil cylinder, the second oil cylinder and the third oil cylinder. At the same time, the first oil cylinder includes a piston rod, a cylinder barrel , guide oil pipe, rodless chamber oil circuit and rod chamber oil circuit, the second oil cylinder includes piston rod, cylinder barrel, guide oil pipe, rodless chamber oil circuit and rod chamber oil circuit, the third oil cylinder includes piston rod, cylinder barrel , the rodless cavity oil circuit and the rod cavity oil circuit, in addition, the oil guide pipeline includes an outer tube and an inner tube, the M end of the outer tube is connected with the piston rod, so that the outer tube moves with the piston rod, and the inner tube moves with the piston rod. The N end of the tube is connected to the cylinder such that the inner tube moves with the cylinder. Compared with the prior art, since the present invention does not adopt sequential valve control, the system pressure will not increase due to the pressure difference between the inlet and outlet ports of the sequential valve. Therefore, it is easy to realize the sequential expansion and contraction of three oil cylinders, or even the sequence of more oil cylinders Retractable without increasing system stress.

On the other hand, the present invention also provides a construction machine including a multi-cylinder sequential telescopic mechanism, and the multi-cylinder sequential telescopic mechanism is the multi-cylinder sequential telescopic mechanism described in any one of the above items.

Further, the construction machine is a crane.

The construction machinery mentioned above obviously has all the beneficial effects of the aforementioned multi-cylinder sequential telescoping mechanism, which will not be repeated here.

Description of drawings

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

Fig. 1 is a schematic structural view of a two-stage oil cylinder telescoping mechanism in the related art;

Fig. 2 is a schematic structural view of the multi-cylinder sequential telescoping mechanism of the present invention;

Fig. 3 is a structural schematic diagram of the oil guide pipeline in Fig. 2;

Fig. 4 is a schematic diagram of the use state of the multi-cylinder sequential telescoping mechanism when the first cylinder is fully extended in the present invention;

Fig. 5 is a schematic diagram of the use state of the multi-cylinder sequential expansion and contraction mechanism when the first oil cylinder and the second oil cylinder are fully extended;

6 is a schematic diagram of the use state of the multi-cylinder sequential expansion and contraction mechanism when the first oil cylinder, the second oil cylinder and the third oil cylinder are fully extended in the present invention;

Fig. 7 is a schematic diagram of the use state of the multi-cylinder sequential expansion and contraction mechanism when the first oil cylinder and the second oil cylinder are fully extended and the third oil cylinder is fully retracted;

Fig. 8 is a schematic diagram of the use state of the multi-cylinder sequential expansion and contraction mechanism when the first oil cylinder is fully extended and the second and third oil cylinders are fully retracted according to the present invention.

Figure 1 Explanation of Reference Signs

1 first oil cylinder 2 second oil cylinder 7 stroke valve

20 sequence valve

Figure 2 to Figure 8 Reference Number Explanation

1 first oil cylinder 2 second oil cylinder 3 third oil cylinder

4 Oil circuit with rod cavity 5 Oil circuit without rod cavity 6 Oil guide line

7 stroke valve 8 stroke valve limit plate 9 piston rod

10 Cylinder 11 First connecting pipe 12 Second connecting pipe

13 The third connecting pipe 14 The fourth connecting pipe 15 The first one-way valve

16 second one-way valve 17 rod chamber 18 rodless chamber

61 outer pipe 62 inner pipe 63 inner pipe oil port

Detailed ways

It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and examples.

As shown in Figure 2, a multi-cylinder sequential telescoping mechanism includes a first oil cylinder 1, a second oil cylinder 2 and a third oil cylinder 3, wherein the first oil cylinder 1 includes a piston rod 9, a cylinder barrel 10, a rod cavity 17, Rodless chamber 18, rod chamber oil passage 4, rodless chamber oil passage 5 and oil guide pipeline 6, the second oil cylinder 2 also includes piston rod 9, cylinder barrel 10, rod chamber 17, rodless chamber 18, rod chamber oil passage 4, rodless chamber oil passage 5 and oil guide pipe 6, and the third oil cylinder 3 includes piston rod 9, cylinder barrel 10, rod chamber 17, rodless chamber 18, rodless chamber oil passage 5 and rod The cavity oil circuit 4, specifically, the aforementioned oil guide pipeline 6 includes an outer tube 61 and an inner tube 62, and the M end (shown as the left end in FIG. 3 ) of the outer tube 61 is connected with the piston rod 9, so that the outer tube 61 is accompanied by the piston rod 9 movement, the N end of the inner tube 62 (shown as the right end in Fig. 3) is connected with the cylinder 10, so that the inner tube 62 moves with the cylinder 10, and an inner tube oil port 63 is also arranged in the inner tube 62, and the oil Inflow or outflow through the oil port 63 of the inner pipe; in addition, stroke valves 7 are arranged between the first oil cylinder 1 and the second oil cylinder 2, between the second oil cylinder 2 and the third oil cylinder 3, and the second oil cylinder 2 and the second oil cylinder The cylinder barrel 10 tail end of the three oil cylinders 3 is also provided with a stroke valve limit plate 8, and the stroke valve 7 realizes the switching of the working position by contacting the stroke valve limit plate 8; in addition, the first oil cylinder 1, the second oil cylinder 2 and the third oil cylinder 3 are provided with communication pipes for communicating with adjacent oil cylinders. It should be noted that the travel valve 7 arranged between the first oil cylinder 1 and the second oil cylinder 2 is specifically installed at the tail end of the cylinder barrel 10 of the first oil cylinder 2; it is arranged between the second oil cylinder 2 and the third oil cylinder 3 The stroke valve 7 is specifically installed on the tail end of the cylinder barrel 10 of the second oil cylinder 2 .

Simultaneously, as shown in Figure 2, the first oil cylinder 1, the second oil cylinder 2 and the third oil cylinder 3 are respectively provided with A port and B port, the rodless cavity of the first oil cylinder 1, the second oil cylinder 2 and the third oil cylinder 3 The oil passage 5 communicates with its B port respectively, and the rod cavity oil passage 4 of the first oil cylinder 1 , the second oil cylinder 2 and the third oil cylinder 3 communicates with its A port respectively.

In a further technical solution, the aforementioned connecting pipes include a first connecting pipe 11, a second connecting pipe 12, a third connecting pipe 13 and a fourth connecting pipe 14, and the rod chamber oil circuit 4 of the first oil cylinder 1 passes through the first connecting pipe. The pipe 11 communicates with the rod chamber oil passage 4 of the second oil cylinder 2, the rodless chamber oil passage 5 of the second oil cylinder 2 communicates with the oil guide pipe 6 of the first oil cylinder 1 through the second connecting pipe 12, and the third oil cylinder 3 through the third connecting pipe 13 and the rod chamber oil passage 4 of the second oil cylinder 2, and the rodless chamber oil passage 5 of the third oil cylinder 3 communicates with the second oil cylinder through the fourth connecting pipe 14 The oil guide line 6 of 2 is connected.

With the above settings, when the high-pressure hydraulic oil enters the port B of the first cylinder 1, the high-pressure hydraulic oil passes through the rodless chamber oil circuit 5 inside the piston rod 9 of the first cylinder 1 to the rodless chamber 18, pushing the first cylinder 1 to extend At this time, since the oil path of the stroke valve 7 arranged between the first oil cylinder 1 and the second oil cylinder 2 is in a conduction state, as shown in Figure 4, the second oil cylinder 2 and the third oil cylinder 3 will also Extend a small distance (that is, the stroke of the stroke valve 7), after the second oil cylinder 2 and the third oil cylinder 3 extend a small distance, the oil circuit of the stroke valve 7 is closed, and only the first oil cylinder 1 continues to extend until it is fully extended, as shown in Figure 4. Fig. 4 is a schematic diagram of the use state of the multi-cylinder sequential telescoping mechanism when the first cylinder is fully extended.

Since the first oil cylinder 1 is extending out, the inner pipe 62 of the oil guide line 6 is also extended synchronously. When the first oil cylinder 1 is fully extended, as shown in FIG. 4 , the oil guide line 6 of the first oil cylinder 1 The inner pipe oil port 63 in the cylinder will enter the rodless chamber 18 of the first oil cylinder 1. At this time, the high-pressure hydraulic oil in the rodless cavity 18 of the first oil cylinder 1 will enter the oil guide line 6 of the first oil cylinder 1 through the inner pipe oil port 63, then enter the second connecting pipe 12, and then enter the second oil cylinder The B port of 2 is the same as the working principle of the extension of the first oil cylinder 1 above. When the high-pressure hydraulic oil enters the B port of the second oil cylinder 2, the high-pressure hydraulic oil passes through the rodless cavity oil circuit inside the piston rod 9 of the second oil cylinder 2 5 reaches the rodless cavity 18, and pushes the second oil cylinder 2 out. At this time, since the oil circuit of the travel valve 7 arranged between the second oil cylinder 2 and the third oil cylinder 3 is in a conduction state, the third oil cylinder 3 It will also stretch out a small distance (i.e. the stroke of the stroke valve 7). After the third oil cylinder 3 stretches out a small distance, the oil circuit of the stroke valve 7 is closed. At this moment, only the second oil cylinder 2 continues to stretch out until The second oil cylinder 2 is fully stretched out, specifically as shown in FIG. 5 . Fig. 5 is a schematic diagram of the use state of the multi-cylinder sequential expansion and contraction mechanism when the first oil cylinder and the second oil cylinder are fully extended.

After the second oil cylinder 2 is fully stretched out, in the same way, the inner pipe oil port 63 in the oil guide line 6 of the second oil cylinder 2 will enter the rodless cavity 18 of the second oil cylinder 2. At this time, the second oil cylinder 2 The high-pressure hydraulic oil in the rodless chamber 18 will enter the oil guide line 6 of the second oil cylinder 2 through the inner pipe oil port 63, then enter the fourth connecting pipe 14, and then enter the B port of the third oil cylinder 3; similarly, When the high-pressure hydraulic oil enters the B port of the third oil cylinder 3, the high-pressure hydraulic oil passes through the rodless chamber oil circuit 5 inside the piston rod 9 of the third oil cylinder 3 to the rodless chamber 18, pushing the third oil cylinder 3 out until the third oil cylinder 3 Three oil cylinders 3 all stretch out, specifically as shown in Figure 6. Fig. 6 is a schematic diagram of the use state of the multi-cylinder sequential expansion and contraction mechanism when the first oil cylinder, the second oil cylinder and the third oil cylinder are fully extended.

In the present invention, as shown in FIG. 2 , a first check valve 15 is provided between the rodless chamber oil passage 5 of the first oil cylinder 1 and its B port, the oil flows into the rodless chamber oil passage 5 from the B port, and A second check valve 16 is arranged between the oil guide line 6 of the first oil cylinder 1 and its B port, and the oil flows from the oil guide line 6 to the B port; A first one-way valve 15 is arranged between them, the oil flows into the rodless cavity oil passage 5 from the B port, and a second one-way valve 16 is arranged between the oil guide line 6 of the second oil cylinder 2 and its B port, and the oil flows from the B port The oil guide line 6 flows to port B. Preferably, the first one-way valve 15 is set close to port B; and/or the second one-way valve 16 is set close to port B.

When the high-pressure hydraulic oil enters from the A port of the first oil cylinder 1, the high-pressure hydraulic oil will enter the rod chamber 17 of the first oil cylinder 1 through the rod chamber oil passage 4 of the first oil cylinder 1, and then pass through the first connecting pipe 11 Enter the rod cavity 17 of the second oil cylinder 2, and then enter the rod cavity 17 of the third oil cylinder 3 through the third connecting pipe 13, because the first oil circuit 5 of the rodless cavity of the first oil cylinder 1 is designed near the B port. With the check valve 15, the hydraulic oil in the rodless chamber 18 of the first oil cylinder 1 cannot return from port B, thereby forming a closed cavity, so the first oil cylinder 1 cannot retract; The first check valve 15 is designed near the port B of the rodless chamber oil circuit 5, and the hydraulic oil in the rodless chamber 18 of the second oil cylinder 2 cannot return from the B port, and then the second oil cylinder 2 also forms a A closed space, so the second oil cylinder 2 cannot retract; when the high-pressure hydraulic oil enters the rod chamber 17 of the third oil cylinder 3, the hydraulic oil in the rodless chamber 18 of the third oil cylinder 3 will pass through the rodless chamber oil circuit 5 and the fourth connecting pipe 14 enter the oil guide line 6 of the second oil cylinder 2, then pass through the second connecting pipe 12 and the oil guide line 6 of the first oil cylinder 1, and pass through the second check valve 16 from the B of the first oil cylinder 1 The outlet flows out to realize the retraction of the third oil cylinder 3 until the third oil cylinder 3 is fully retracted, as shown in FIG. 7 . Fig. 7 is a schematic diagram of the use state of the multi-cylinder sequential expansion and contraction mechanism when the first oil cylinder and the second oil cylinder are fully extended and the third oil cylinder is fully retracted according to the present invention.

When the third oil cylinder 3 is fully retracted, the stroke valve limit plate 8 installed on the third oil cylinder 3 will push the stroke valve 7 arranged on the cylinder barrel 10 of the second oil cylinder 2, so that the stroke valve 7 enters and exits the oil port Therefore, the hydraulic oil in the rodless chamber 18 of the second oil cylinder 2 will enter the oil guide line 6 of the second oil cylinder 2 through the stroke valve 7, and finally pass through the B port of the second oil cylinder 2, the second connecting pipe 12 . The oil guide line 6 of the first oil cylinder 1 flows out to the B port of the first oil cylinder 1, and finally realizes the full contraction of the second oil cylinder 2, as shown in FIG. 8 . Fig. 8 is a schematic diagram of the use state of the multi-cylinder sequential expansion and contraction mechanism when the first oil cylinder is fully extended and the second and third oil cylinders are fully retracted in the present invention.

Similarly, when the second oil cylinder 2 is fully retracted, the stroke valve limit plate 8 installed on the second oil cylinder 2 will push the stroke valve 7 arranged on the cylinder barrel 10 of the first oil cylinder 1, so that the stroke valve 7 The oil inlet and outlet ports are connected, so the hydraulic oil in the rodless chamber 18 of the first oil cylinder 1 will enter the oil guide line 6 of the first oil cylinder 1 through the stroke valve 7, and finally flow out to the B port of the first oil cylinder 1, and finally A complete retraction of the first cylinder 1 is achieved.

In addition, it is worth mentioning that the number of oil cylinders in the present invention is not limited to three (the first oil cylinder 1, the second oil cylinder 2 and the third oil cylinder 3), it can also be four, five or more, It is only necessary to add an oil cylinder, a travel valve and a connecting pipe consistent with the structure of the second oil cylinder 2 between the first oil cylinder 1 and the third oil cylinder 3, and the expansion and contraction principle of the additional oil cylinder is consistent with that of the second oil cylinder.

To sum up, the multi-cylinder sequential expansion mechanism provided by the present invention, compared with the prior art, under the same conditions, the pressure required for the expansion and contraction of the second oil cylinder 2 and the third oil cylinder 3 is basically the same as that of the first oil cylinder 1. It will not increase the system pressure, and solves the technical problems of the existing hydraulic system of the multi-cylinder telescopic mechanism, which generates heat and requires high pressure when the cylinder is telescopic. At the same time, it also realizes multi-stage (the number of cylinders is greater than 2) cylinders stretching.

On the other hand, the present invention also provides a construction machine including a multi-cylinder sequential telescopic mechanism, and the multi-cylinder sequential telescopic mechanism is the above-mentioned multi-cylinder sequential telescopic mechanism. Further, the construction machine is a crane, and other structures of the crane can refer to existing and improved technologies, which will not be repeated here.

The above-mentioned engineering machinery obviously has all the beneficial effects of the aforementioned multi-cylinder sequential expansion mechanism, and can easily realize multi-stage (the number of oil cylinders is greater than 2) oil cylinder expansion and contraction without increasing the pressure of the system.

The above descriptions are only 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 principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (8)

1. A multi-cylinder sequential telescoping mechanism, comprising a first oil cylinder (1), a second oil cylinder (2) and a third oil cylinder (3), and the first oil cylinder (1), the second oil cylinder (2) and the third oil cylinder The oil cylinders (3) all include a piston rod (9), a cylinder barrel (10), a rodless cavity oil circuit (5) and a rod cavity oil circuit (4), and it is characterized in that: the first oil cylinder (1) and the second A stroke valve (7) is arranged between the two oil cylinders (2), between the second oil cylinder (2) and the third oil cylinder (3), the second oil cylinder (2) and the third oil cylinder (3) A stroke valve limit plate (8) is arranged on the tail end of the cylinder barrel (10), and the stroke valve (7) realizes working position switching by contacting with the stroke valve limit plate (8); the first oil cylinder (1 ), the second oil cylinder (2) and the third oil cylinder (3) are provided with connecting pipes for communicating with adjacent oil cylinders; the first oil cylinder (1) and the second oil cylinder (2) are all provided with oil guide pipelines (6), wherein, the oil guiding pipeline (6) comprises an outer pipe (61) and an inner pipe (62), the M end of the outer pipe (61) is connected with the piston rod (9), and the inner pipe ( 62) the N end links to each other with the cylinder barrel (10); An inner pipe oil port (63) is also provided in the inner pipe (62), and the oil flows in or out through the inner pipe oil port (63); The connecting pipe includes a first connecting pipe (11) and a second connecting pipe (12), and the rod chamber oil circuit (4) of the first oil cylinder (1) passes through the first connecting pipe (11) and the second oil cylinder (2) The rod chamber oil circuit (4) is connected, the rodless chamber oil circuit (5) of the second oil cylinder (2) is connected with the oil guide pipe of the first oil cylinder (1) through the second connecting pipe (12) Road (6) is connected. 2. The multi-cylinder sequential telescoping mechanism according to claim 1, characterized in that: said connecting pipe comprises a third connecting pipe (13) and a fourth connecting pipe (14), and said third oil cylinder (3) has The rod chamber oil circuit (4) communicates with the rod chamber oil circuit (4) of the second oil cylinder (2) through the third connecting pipe (13), and the rod chamber oil circuit (5) of the third oil cylinder (3) ) communicates with the oil guide line (6) of the second oil cylinder (2) through the fourth connecting pipe (14). 3. The multi-cylinder sequential telescoping mechanism according to any one of claims 1 to 2, characterized in that: the first oil cylinder (1), the second oil cylinder (2) and the third oil cylinder (3) are respectively provided with There are port A and port B, and the rodless cavity oil passages (5) of the first oil cylinder (1), the second oil cylinder (2) and the third oil cylinder (3) are respectively connected with port B, and the first oil cylinder (1), the rod chamber oil passages (4) of the second oil cylinder (2) and the third oil cylinder (3) are respectively connected with the A port thereof. 4. The multi-cylinder sequential telescoping mechanism according to claim 3, characterized in that: a first check valve (15) is arranged between the rodless chamber oil passage (5) of the first cylinder (1) and its B port ), the oil flows into the rodless cavity oil circuit (5) from the B port, and a second check valve (16) is arranged between the oil guide line (6) of the first oil cylinder (1) and its B port, and the oil Flow from the oil guide line (6) to port B. 5. The multi-cylinder sequential telescoping mechanism according to claim 4, characterized in that: a first one-way valve (15) is arranged between the rodless chamber oil passage (5) of the second cylinder (2) and its B port ), the oil flows into the rodless chamber oil circuit (5) from the B port, and a second check valve (16) is arranged between the oil guide line (6) of the second oil cylinder (2) and its B port, and the oil Flow from the oil guide line (6) to port B. 6. The multi-cylinder sequential telescoping mechanism according to claim 5, characterized in that: the first one-way valve (15) is arranged close to B port; and/or, the second one-way valve (16) is close to B port port settings. 7. A construction machine, comprising a multi-cylinder sequential telescopic mechanism, characterized in that: the multi-cylinder sequential telescopic mechanism is the multi-cylinder sequential telescopic mechanism described in any one of claims 1-6. 8. The construction machine according to claim 7, wherein the construction machine is a crane.