Hydraulic system for a boom, boom and engineering vehicle

Abstract

The application discloses a hydraulic system of a telescopic arm support, the telescopic arm support and an engineering vehicle, comprising a first oil path, multiple-stage telescopic cylinders, a second oil path, a balance valve, a back pressure valve and a control oil path; rodless cavities of the multiple telescopic cylinders are communicated with the first oil path, and the rodless cavities of the multiple telescopic cylinders are synchronously filled with oil or return oil through the first oil path; rod cavities of the multiple telescopic cylinders are communicated with the second oil path, and the rod cavities of the multiple telescopic cylinders are synchronously filled with oil or return oil through the second oil path; the balance valve is arranged on the first oil path, the control oil path is communicated with a control end of the balance valve and the second oil path; the back pressure valve is arranged on the first oil path, and the back pressure valve is arranged on an oil inlet side of the balance valve, so that a preset return oil back pressure can be generated on the first oil path. The hydraulic system of the telescopic arm support, the telescopic arm support and the engineering vehicle can effectively reduce shaking.

Description

Technical Field

[0001] This application relates to a hydraulic system, and more particularly to a hydraulic system for a telescopic boom, a telescopic boom, and an engineering vehicle. Background Technology

[0002] In existing technologies, equipment used for aircraft de-icing and other maintenance operations is generally a maintenance vehicle. This vehicle mainly includes a truck chassis, a slewing mechanism, a turntable, a boom, a luffing mechanism, and a work bucket. The boom includes a main boom and a boom extension connected to the end of the main boom. The luffing mechanism includes a main luffing mechanism and a boom luffing mechanism. The slewing mechanism is mounted on the truck chassis, the turntable is mounted on the slewing mechanism, and the boom is mounted on the turntable. The main luffing mechanism is installed between the turntable and the main boom to change the pitch angle of the main boom, and the boom luffing mechanism is installed between the main boom and the boom to change the pitch angle of the boom. The work bucket is installed at the end of the boom. In the traveling state, the boom is retracted to the top of the aerial work platform. The boom is driven by multiple telescopic cylinders during extension and retraction; the large flow differences between the hydraulic lines cause vibration. Summary of the Invention

[0003] In view of this, embodiments of this application aim to provide a hydraulic system for a telescopic boom, a telescopic boom, and an engineering vehicle to reduce vibration.

[0004] To achieve the above objectives, the technical solution of this application embodiment is implemented as follows:

[0005] The hydraulic system of the telescopic boom includes a first oil circuit, a multi-stage telescopic cylinder, a second oil circuit, a balance valve, a back pressure valve, and a control oil circuit. The rodless chambers of the multiple telescopic cylinders are connected to the first oil circuit, and the rodless chambers of the multiple telescopic cylinders synchronously receive or return oil through the first oil circuit. The rod-side chambers of the multiple telescopic cylinders are connected to the second oil circuit, and the rod-side chambers of the multiple telescopic cylinders synchronously receive or return oil through the second oil circuit. The balance valve is located on the first oil circuit, and the control oil circuit connects the control end of the balance valve to the second oil circuit. The back pressure valve is located on the first oil circuit and is positioned on the inlet side of the balance valve to generate a preset return back pressure on the first oil circuit.

[0006] Furthermore, the control oil circuit includes a first throttle orifice.

[0007] Furthermore, the hydraulic system includes a diverter oil passage with a second throttle orifice, the first end of the diverter oil passage being connected to a control oil passage between the first throttle orifice and the control end, and the second end of the diverter oil passage being connected to the first oil passage on the oil inlet side of the balance valve.

[0008] Furthermore, the hydraulic system includes a diversion oil circuit with a second throttle orifice, the first end of the diversion oil circuit being connected to the control oil circuit, and the second end of the diversion oil circuit being connected to the first oil circuit located on the oil inlet side of the balance valve to achieve diversion.

[0009] Further, the telescopic cylinder includes a piston, a piston rod, and a cylinder body. The piston is movably disposed within the cylinder body to isolate the rodless chamber and the rod chamber. A first working oil port communicating with the rodless chamber is formed on the cylinder body. The telescopic cylinder forms a process flow channel penetrating the piston and the piston rod. The first end port of the process flow channel communicates with the rodless chamber, and the second end port of the process flow channel is disposed on a structure where the piston rod is located outside the cylinder body. Between two adjacent telescopic cylinders, the second end port of the process flow channel of the upper-level telescopic cylinder communicates with the first working oil port of the cylinder body of the lower-level telescopic cylinder. The first oil passage communicates with the first working oil port of the first-level telescopic cylinder, thereby enabling the rodless chambers of multiple telescopic cylinders to synchronously receive or return oil through the first oil passage.

[0010] Furthermore, the telescopic cylinder includes a piston, a piston rod, and a cylinder body. The piston is movably disposed within the cylinder body to isolate the rodless chamber and the rod chamber. The cylinder body has a second working hole and a third working hole communicating with the rod chamber. Between two adjacent telescopic cylinders, the third working hole of the cylinder body of the upper-level telescopic cylinder communicates with the second working hole of the cylinder body of the lower-level telescopic cylinder. The second oil passage communicates with the second working hole of the first-level telescopic cylinder, thereby enabling the rod chambers of multiple telescopic cylinders to synchronously receive or return oil through the second oil passage.

[0011] Furthermore, the balancing valve includes a first check valve and a sequence valve. The first inlet of the first check valve is connected to the first side of the first oil circuit, and the first outlet of the first check valve is connected to the second side of the first oil circuit. The second inlet of the sequence valve is connected to the second side of the first oil circuit, and the second outlet of the sequence valve is connected to the first side of the first oil circuit. The control terminal of the balancing valve is disposed on the sequence valve.

[0012] Furthermore, the connecting pipes between the multiple telescopic cylinders are rigid pipes.

[0013] Furthermore, the hydraulic system includes an accumulator disposed in the second oil circuit.

[0014] Furthermore, the hydraulic system includes a second check valve, a throttle valve, and a third oil circuit. The third oil circuit is connected between the first oil circuit and the second oil circuit. Both the second check valve and the throttle valve are located on the third oil circuit. The throttle valve is located on the outlet side of the second check valve. The oil in the third oil circuit can flow to the first oil circuit through the second check valve.

[0015] The telescopic boom includes multiple interconnected boom sections and the aforementioned hydraulic system; adjacent boom sections are connected by at least one telescopic cylinder, which can drive the corresponding boom section to extend or retract by extending or retracting; when the telescopic boom is in the retracted state, all the telescopic cylinders are spaced apart on the outer periphery of the outermost boom section.

[0016] The engineering vehicle includes a vehicle body and the aforementioned telescopic boom, which is mounted on the vehicle body.

[0017] In the hydraulic system of the telescopic boom of this application embodiment, the rodless chambers of multiple telescopic cylinders synchronously receive or return oil through the first oil circuit, and the rod chambers of multiple telescopic cylinders synchronously receive or return oil through the second oil circuit. This ensures the extension and retraction of the telescopic boom while saving oil circuits and control components, simplifying the hydraulic system setup. Furthermore, by setting a balance valve on the first oil circuit, when oil enters the second oil circuit and reaches the opening pressure at the control end, the balance valve opens the first oil circuit and adjusts its opening according to the pressure, keeping the flow rate of the first oil circuit constant and appropriately reducing vibration. Additionally, by setting a back pressure valve on the first oil circuit, a preset return back pressure is generated, ensuring stable oil circuit pressure in the hydraulic system. Through the balance valve and the back pressure valve, the hydraulic system is stabilized from multiple aspects, reducing vibration. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a hydraulic system in the prior art, in which the pump, oil tank and auxiliary connecting pipelines are omitted;

[0019] Figure 2 This is a schematic diagram of a hydraulic system according to an embodiment of this application, wherein the pump, oil tank and associated connecting pipelines are omitted;

[0020] Figure 3 for Figure 2 A partial view;

[0021] Figure 4 for Figure 2 B partial view;

[0022] Figure 5 This is a schematic diagram of a hydraulic system according to another embodiment of this application;

[0023] Figure 6 This is a schematic diagram of the structure of a telescopic boom according to an embodiment of this application; all telescopic cylinders in the figure are in the extended state, and the boom, luffing cylinder, water pipe winding disc, oil pipe winding disc and wire winding disc are also shown.

[0024] Figure 7 for Figure 6 C partial view;

[0025] Figure 8 This is a schematic diagram of the structure of a telescopic boom according to an embodiment of this application; all telescopic cylinders in the figure are in the retracted state, and the flying boom, water pipe winding disc, oil pipe winding disc and wire winding disc are also shown.

[0026] Figure 9 This is a schematic diagram of the structure of an engineering vehicle according to an embodiment of this application; in the figure, all telescopic cylinders are in the retracted state. Detailed Implementation

[0027] It should be noted that, unless otherwise specified, the embodiments and technical features in the embodiments of this application can be combined with each other, and the detailed descriptions in the specific implementation should be understood as explanations of this application and should not be regarded as undue limitations on this application.

[0028] In the description of the embodiments in this application, the orientations or positional relationships of "up", "down", "left", "right", "front", and "rear" are based on the appendix. Figure 6 The orientations or positional relationships shown are intended only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0029] like Figures 2 to 9 As shown, the telescopic boom 200 includes multi-stage boom sections 100 that are nested together and a hydraulic system; the hydraulic system includes a first oil circuit 1, a multi-stage telescopic cylinder 2, a second oil circuit 3, a balance valve 4, a back pressure valve 5, and a control oil circuit 7.

[0030] Multiple boom sections 100 are interconnected, and adjacent boom sections 100 are connected by at least one telescopic cylinder 2. The telescopic cylinder 2 can drive the corresponding boom section 100 to extend or retract by extending or retracting. All telescopic cylinders 2 are located on the outer side of the corresponding boom section 100, and can drive the corresponding boom section 100 to extend or retract by extending or retracting. When the telescopic boom is in the retracted state, that is, after all telescopic cylinders 2 have retracted to their positions, all telescopic cylinders 2 are spaced apart on the outer periphery of the outermost boom section 100.

[0031] Compared to the traditional arrangement where the telescopic cylinder 2' is placed within the cavity of the boom section 100, the arrangement of the telescopic cylinder 2 in this embodiment does not require utilizing the space within the boom section 100. Therefore, the interlocking boom sections 100 can be arranged more compactly in cross-section. Furthermore, since sufficient space needs to be reserved within the boom section 1 for installing the telescopic cylinder 2, the telescopic boom 100 in this embodiment can increase its total height after extension by connecting more smaller-diameter boom sections 1 without increasing its overall dimensions. Additionally, after prolonged use, the telescopic cylinder 2 may develop safety hazards such as cracking. Therefore, placing the telescopic cylinder 2 on the outside of the boom section 1 facilitates user observation of any abnormalities and allows for easier maintenance and replacement. In other embodiments, adjacent boom sections 1 can also be connected by multiple telescopic cylinders 2.

[0032] However, moving the telescopic cylinder 2 from the cavity of the boom 100 to the outside also changes the activation method of the telescopic cylinder 2. For example... Figure 1 As shown, the telescopic cylinders 2' in the traditional arrangement are connected to the pressure oil circuit in parallel, and each telescopic cylinder 2' is controlled by a separate control valve 21'. One boom section 100 corresponds to at least one telescopic cylinder 2'. When the telescopic boom needs to be extended, the control valve 21' opens, controlling the upper boom section 100 to extend from the lower boom section 100. After the upper boom section 100 has extended, the next boom section 100 extends, and so on. In this way, the number of telescopic cylinders 2' activated at the same time can be controlled to be a limited number of one or a few, and the oil pump only needs to meet the oil input of a single telescopic cylinder 2'. The changes in the input and output oil in the pressure oil circuit and return oil circuit are not significant.

[0033] In the arrangement of the telescopic boom 200 according to the embodiment of this application, all telescopic cylinders 2 are spaced apart on the outer periphery of the outermost boom section 100, such as... Figures 2 to 9 As shown, the rodless chambers 21 of the multiple telescopic cylinders 2 are connected to the first oil circuit 1, and the rodless chambers 21 of the multiple telescopic cylinders 2 synchronously receive or return oil through the first oil circuit 1; the rod chambers 22 of the multiple telescopic cylinders 2 are connected to the second oil circuit 3, and the rod chambers 22 of the multiple telescopic cylinders 2 synchronously receive or return oil through the second oil circuit 3.

[0034] When oil enters the rodless chamber 21 of multiple telescopic cylinders 2 and oil returns from the rod chamber 22, all telescopic cylinders 2 are in the extended state, and each boom section 100 simultaneously extends from its corresponding preceding boom section 100, thus extending the telescopic boom 200. Similarly, when oil enters the rod chamber 22 of multiple telescopic cylinders 2 and oil returns from the rodless chamber 21, all telescopic cylinders 2 are in the retracted state, and each boom section 100 simultaneously retracts into its corresponding preceding boom section 100. This ensures the successful extension and retraction of the telescopic boom 200 while saving on oil circuits and control components, simplifying the hydraulic system setup.

[0035] It is important to understand that the extension and retraction of the telescopic boom 200 are accomplished simultaneously by all the telescopic cylinders 2, rather than by a single cylinder 2. Therefore, during operation, the volume of oil entering or returning through the first hydraulic line 1 and the second hydraulic line 3 is greater than in a traditional arrangement, and the pressure changes are more drastic. Especially when the telescopic boom 200 is retracted under load, the excessive pressure fluctuations and flow imbalance between the first hydraulic line 1 and the second hydraulic line 3 cause vibration.

[0036] Therefore, it is necessary to install the balance valve 4 on the first oil circuit 1, and connect the control end 43 of the balance valve 4 with the second oil circuit 3 through the control oil circuit 7.

[0037] When oil enters the first oil circuit 1, the balance valve 4 is normally open, and when oil exits the second oil circuit 3, the telescopic boom 200 extends normally.

[0038] When the first oil circuit 1 stops supplying oil, the balance valve 4 is disconnected, and the hydraulic oil in the rodless chamber 21 of the telescopic cylinder 2 can keep the telescopic boom 200 stationary in that position, preventing it from falling down on its own.

[0039] When oil enters the second oil passage 3 and reaches the opening pressure of the control terminal 43, the balance valve 4 opens the first oil passage 1 and adjusts the opening according to the pressure to keep the flow of the first oil passage 1 constant and appropriately reduce vibration.

[0040] In addition, the back pressure valve 5 can be installed on the first oil circuit 1 and on the oil inlet side of the balance valve 4 so as to generate a preset return back pressure on the first oil circuit 1 to ensure the stability of the oil circuit pressure of the hydraulic system; the balance valve 4 and the back pressure valve 5 work together to stabilize the hydraulic system from multiple aspects and reduce the vibration of the hydraulic system.

[0041] In one possible embodiment, such as Figure 2 , Figure 4 and Figure 5As shown, the hydraulic system includes a flow divider oil passage 8 with a second throttle port 81. The first end of the flow divider oil passage 8 is connected to the control oil passage 7, and the second end of the flow divider oil passage 8 is connected to the first oil passage 1 located on the oil inlet side of the balance valve 4 to achieve flow division.

[0042] Specifically, when oil enters the second oil passage 3, hydraulic oil flows into the control terminal 43, causing the first oil passage 1 to be open. Part of the hydraulic oil flows through the control oil passage 7 into the diversion oil passage 8, and finally reaches the first oil passage 1 on the oil inlet side of the balance valve 4, thereby balancing the hydraulic oil flow between the first oil passage 1 and the second oil passage 3 and avoiding vibration caused by excessive flow difference.

[0043] When oil enters the first oil circuit 1, the balance valve 4 is normally open, and oil exits the second oil circuit 3. Some hydraulic oil flows into the control oil circuit 7 through the diversion oil circuit 8 and finally reaches the second oil circuit 3, balancing the hydraulic oil flow between the first oil circuit 1 and the second oil circuit 3 to avoid vibration caused by excessive flow difference.

[0044] It should be understood that the second throttle port 81 can generate a pressure difference on both sides. While the diversion oil circuit 8 plays a diversion role, the second throttle port 81 prevents the first oil circuit 1 from being directly connected to the second oil circuit 3. When oil is entering the second oil circuit 3, the second throttle port 81 can ensure that the hydraulic oil in the second oil circuit 3 provides the control terminal 43 with a suitable opening pressure, thereby enabling the first oil circuit 1 to be opened.

[0045] In one possible embodiment, such as Figure 2 , Figure 4 and Figure 5 As shown, the control oil circuit 7 includes a first throttle port 71 to prevent excessive flow from impacting the control terminal 43.

[0046] If the hydraulic system includes a diverter oil passage 8 with a second throttle port 81, the first end of the diverter oil passage 8 is connected to the control oil passage 7 between the first throttle port 71 and the control end 43, and the second end of the diverter oil passage 8 is connected to the first oil passage 1 on the oil inlet side of the balance valve 4. The functions of the diverter oil passage 8 and the second throttle port 81 are the same as above, and will not be repeated here. In specific settings, the diameter of the first throttle port 71 is larger than that of the second throttle port 81. For example, the first throttle port 71 can be set to 1.0 mm and the second throttle port 81 to 0.8 mm, thereby ensuring that the oil passage between the first throttle port 71 and the second throttle port 81 has appropriate pressure. That is, when oil enters the second oil passage 3, the hydraulic oil flowing into the control end 43 can reach the opening pressure, so that the first oil passage 1 is opened.

[0047] In one possible embodiment, such as Figure 2 , Figure 3 , Figure 5 , Figure 6 and Figure 8As shown, the telescopic cylinder 2 includes a piston 23, a piston rod 25, and a cylinder body 24. The piston 23 is movably disposed within the cylinder body 24 to isolate the rodless chamber 21 and the rod chamber 22. The piston rod 25 is disposed on the piston 23. The piston rod 25 and the piston 23 can be integrally formed, or they can be separately manufactured and then assembled and fixed together.

[0048] The piston rod 25 passes through the rod chamber 22 and extends to the outside of the cylinder body 24; the telescopic cylinder 2 forms a process flow channel 26 that passes through the piston 23 and the piston rod 25. The first end port of the process flow channel 26 is connected to the rodless chamber 21, and the second end port of the process flow channel 26 is located on the structure where the piston rod 25 is located outside the cylinder body 24, thereby connecting the rodless chamber 21 with the outside. A first working oil port 241 is formed on the cylinder body 24 that is connected to the rodless chamber 21, thereby connecting the rodless chamber 21 with the outside.

[0049] Between two adjacent telescopic cylinders 2, the second end port of the process flow channel 26 of the upper telescopic cylinder 2 is connected to the first working oil port 241 of the cylinder body 24 of the lower telescopic cylinder 2; the first oil circuit 1 is connected to the first working oil port 241 of the first telescopic cylinder 2, and all the rodless chambers 21 of the telescopic cylinders 2 are connected to the first oil circuit 1 in parallel, so as to realize that the rodless chambers 21 of multiple telescopic cylinders 2 can be synchronously fed or returned through the first oil circuit 1; the first working oil port 241 of the last stage and the second end port of the process flow channel 26 should be plugged.

[0050] In addition, a second working hole 242 and a third working hole 243 communicating with the rod chamber 22 can be formed on the cylinder body 24; between two adjacent telescopic cylinders 2, the third working hole 243 of the cylinder body 24 of the upper telescopic cylinder 2 is connected to the second working hole 242 of the cylinder body 24 of the lower telescopic cylinder 2; the second oil passage 3 is connected to the second working hole 242 of the first telescopic cylinder 2, and all the rod chambers 22 of the telescopic cylinders 2 are connected to the second oil passage 3 in parallel, so as to realize that the rod chambers 22 of multiple telescopic cylinders 2 can be synchronously fed or returned through the second oil passage 3.

[0051] In one possible embodiment, such as Figure 2 , Figure 4 and Figure 5 As shown, the balance valve 4 includes a first check valve 41 and a sequence valve 42. The first oil inlet 411 of the first check valve 41 is connected to the first side of the first oil circuit 1, and the first oil outlet 412 of the first check valve 41 is connected to the second side of the first oil circuit 1. The second oil inlet 421 of the sequence valve 42 is connected to the second side of the first oil circuit 1, and the second oil outlet 422 of the sequence valve 42 is connected to the first side of the first oil circuit 1. The control end 43 of the balance valve 4 is disposed on the sequence valve 42. It can be understood that, in various embodiments, the oil inlet direction of the first oil circuit 1 is from the first side of the first oil circuit 1 to the second side of the first oil circuit 1, that is, the oil inlet of the rodless chamber 21.

[0052] When oil enters the first oil circuit 1, the first check valve 41 is opened, the sequence valve 42 is closed, the balance valve 4 is opened normally, oil exits the second oil circuit 3, and the telescopic boom 200 extends normally.

[0053] When the first oil circuit 1 stops supplying oil, the first check valve 41 closes, the sequence valve 42 closes, and the hydraulic oil in the rodless chamber 21 of the telescopic cylinder 2 can keep the telescopic boom 200 stationary in that position, preventing it from falling down on its own.

[0054] When oil enters the second oil circuit 3, the first check valve 41 is closed, and the hydraulic oil flowing from the control oil circuit 7 to the control end 43 reaches the opening pressure. The sequence valve 42 is opened, which makes the first oil circuit 1 open. The opening is adjusted according to the pressure to keep the flow of the first oil circuit 1 constant and appropriately reduce the vibration.

[0055] It should be noted that if the hydraulic system includes a flow divider 8 with a second throttle port 81 and a control circuit 7 with a first throttle port 71, when oil enters the first circuit 1, the sequence valve 42 can also be opened. Specifically, part of the hydraulic oil in the first circuit 1 flows into the control circuit 7 through the flow divider 8. By adjusting the diameters of the second throttle port 81 and the first throttle port 71, the section from the first throttle port 71 to the control end 43 in the control circuit 7 reaches the opening pressure of the control end 43, thereby opening the sequence valve 42 and balancing the flow rates of the first circuit 1 and the second circuit 3.

[0056] In one possible embodiment, such as Figures 6 to 9 As shown, each boom section 100 includes a first end and a second end. In two adjacent boom sections 100, the first end of the inner boom section 100 can extend from the first end of the outer boom section 100. Each telescopic cylinder 2 is connected to the first end of the corresponding two adjacent boom sections 100. This ensures that after all telescopic cylinders 2 have retracted into place, the interconnected boom sections 100 can be arranged more compactly in the axial direction of the boom section 100, thereby reducing the overall height of the telescopic boom 100 after retraction.

[0057] To facilitate the installation of the telescopic cylinder 2, the telescopic boom also includes multiple connecting components 110, which are respectively disposed at the first end of each boom segment 100; each telescopic cylinder 2 is connected to the connecting components 110 on the corresponding two adjacent boom segments 100.

[0058] like Figures 2 to 9As shown, in two adjacent boom sections 100, the end face of the first end of the cylinder body 24 of the telescopic cylinder 2 is connected to the connecting assembly 110 on the outer boom section 100, and the first end of the piston rod 25 of the telescopic cylinder 2 is connected to the connecting assembly 110 on the inner boom section 100. This allows full utilization of the effective stroke of the piston rod 25 to drive the corresponding boom section 1 to extend and retract, while also making the connecting pipe length between each telescopic cylinder 2 shorter. The connecting pipe between the multi-stage telescopic cylinders 2 is a rigid pipe, which simplifies the pipe layout and improves the reliability of the connecting pipe.

[0059] In this embodiment, the telescopic cylinder 2 can be a hydraulic cylinder. In other embodiments, the telescopic cylinder 2 can also be a pneumatic cylinder or an electric cylinder.

[0060] In one possible embodiment, such as Figures 2 to 5 As shown, the hydraulic system includes an accumulator 9, which is installed on the second oil circuit 3 to minimize oil pressure fluctuations and ensure a more stable and reliable hydraulic system.

[0061] In one possible embodiment, such as Figure 5 As shown, the hydraulic system includes a second check valve 120, a throttle valve 130, and a third oil passage 140. The third oil passage 140 is connected between the first oil passage 1 and the second oil passage 3. Both the second check valve 120 and the throttle valve 130 are installed on the third oil passage 140. The throttle valve 130 is located on the oil outlet side of the second check valve 120. The oil in the third oil passage 140 can flow to the first oil passage 1 through the second check valve 120 to achieve flow diversion.

[0062] Specifically, when oil enters the first oil circuit 1, the second check valve 120 is closed, and oil exits normally from the second oil circuit 3. When oil enters the second oil circuit 3, oil returns from the first oil circuit 1, the second check valve 120 is opened, and part of the hydraulic oil in the second oil circuit 3 flows into the first oil circuit 1 through the throttle valve 130, thereby balancing the hydraulic oil flow between the first oil circuit 1 and the second oil circuit 3 and avoiding excessive flow difference. Combining the second check valve 120, the throttle valve 130, and the third oil circuit 140 with any of the above embodiments stabilizes the hydraulic system from multiple aspects and reduces the vibration of the hydraulic system.

[0063] In this embodiment, the throttle valve 130 is an adjustable throttle valve with an adjustable orifice.

[0064] A type of engineering vehicle, such as Figures 2 to 9 As shown, it includes a vehicle body 300 and a telescopic boom 200 in any of the above embodiments, with the telescopic boom 200 mounted on the vehicle body 300.

[0065] The various embodiments / implementations provided in this application can be combined with each other without creating contradictions.

[0066] The above description is merely a preferred embodiment of this application and is not intended to limit the application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A telescopic boom, characterized in that: It includes a multi-stage boom (100) that is nested together and a hydraulic system, the hydraulic system including a first oil circuit (1), a multi-stage telescopic cylinder (2), a second oil circuit (3), a balance valve (4), a back pressure valve (5), and a control oil circuit (7); The rodless chambers (21) of the multiple telescopic cylinders (2) are connected to the first oil circuit (1), and the rodless chambers (21) of the multiple telescopic cylinders (2) are simultaneously fed into or returned to oil through the first oil circuit (1); the rod chambers (22) of the multiple telescopic cylinders (2) are connected to the second oil circuit (3), and the rod chambers (22) of the multiple telescopic cylinders (2) are simultaneously fed into or returned to oil through the second oil circuit (3); The balance valve (4) is installed on the first oil circuit (1), and the control oil circuit (7) connects the control end (43) of the balance valve (4) with the second oil circuit (3). The back pressure valve (5) is installed on the first oil circuit (1) and the back pressure valve (5) is installed on the oil inlet side of the balance valve (4) so ​​as to generate a preset return oil back pressure on the first oil circuit (1). Two adjacent boom sections (100) are connected by at least one telescopic cylinder (2), and the telescopic cylinder (2) can drive the corresponding boom section (100) to extend or retract by extending or retracting; When the telescopic boom is in the retracted state, all the telescopic cylinders (2) are spaced apart on the outer periphery of the outermost boom section (100); The control oil circuit (7) includes a first throttle port (71); The hydraulic system includes a diversion oil passage (8) with a second throttle port (81). The first end of the diversion oil passage (8) is connected to the control oil passage (7) between the first throttle port (71) and the control end (43). The second end of the diversion oil passage (8) is connected to the first oil passage (1) located on the oil inlet side of the balance valve (4) to achieve diversion. When oil is introduced into the first oil passage (1) or the second oil passage (3), the diversion oil passage (8) connects the first oil passage (1) and the second oil passage (3). The diameter of the first throttling orifice (71) is larger than that of the second throttling orifice (81).

2. The telescopic boom according to claim 1, characterized in that: The telescopic cylinder (2) includes a piston (23), a piston rod (25), and a cylinder body (24). The piston (23) is movably disposed within the cylinder body (24) to isolate the rodless chamber (21) and the rod chamber (22). A first working oil port (241) communicating with the rodless chamber (21) is formed on the cylinder body (24). The telescopic cylinder (2) has a process flow channel (26) that penetrates the piston (23) and the piston rod (25). The first end port of the process flow channel (26) is communicating with the rodless chamber (21), and the second end port of the process flow channel (26) is disposed on a structure on which the piston rod (25) is located outside the cylinder body (24). Between two adjacent telescopic cylinders (2), the second end port of the process flow channel (26) of the upper telescopic cylinder (2) is connected to the first working oil port (241) of the cylinder body (24) of the lower telescopic cylinder (2). The first oil circuit (1) is connected to the first working oil port (241) of the first-stage telescopic cylinder (2), thereby enabling the rodless chambers (21) of multiple telescopic cylinders (2) to simultaneously receive or return oil through the first oil circuit (1).

3. The telescopic boom according to claim 1, characterized in that: The telescopic cylinder (2) includes a piston (23), a piston rod (25) and a cylinder body (24). The piston (23) is movably disposed in the cylinder body (24) to isolate the rodless chamber (21) and the rod chamber (22). The cylinder body (24) has a second working hole (242) and a third working hole (243) communicating with the rod chamber (22). Between two adjacent telescopic cylinders (2), the third working hole (243) of the cylinder body (24) of the upper telescopic cylinder (2) is connected to the second working hole (242) of the cylinder body (24) of the lower telescopic cylinder (2). The second oil passage (3) is connected to the second working hole (242) of the first-stage telescopic cylinder (2), thereby enabling the rod chambers (22) of multiple telescopic cylinders (2) to simultaneously receive or return oil through the second oil passage (3).

4. The telescopic boom according to claim 1, characterized in that: The balance valve (4) includes a first check valve (41) and a sequence valve (42). The first inlet (411) of the first check valve (41) is connected to the first side of the first oil circuit (1), the first outlet (412) of the first check valve (41) is connected to the second side of the first oil circuit (1), the second inlet (421) of the sequence valve (42) is connected to the second side of the first oil circuit (1), the second outlet (422) of the sequence valve (42) is connected to the first side of the first oil circuit (1), and the control end (43) of the balance valve (4) is disposed on the sequence valve (42).

5. The telescopic boom according to claim 1 or 4, characterized in that: The connecting pipes between the multi-stage telescopic cylinders (2) are rigid pipes.

6. The telescopic boom according to claim 1, characterized in that: The hydraulic system includes an accumulator (9) which is disposed on the second oil circuit (3).

7. The telescopic boom according to claim 1, characterized in that: The hydraulic system includes a second check valve (120), a throttle valve (130), and a third oil passage (140). The third oil passage (140) is connected between the first oil passage (1) and the second oil passage (3). The second check valve (120) and the throttle valve (130) are both located on the third oil passage (140). The throttle valve (130) is located on the oil outlet side of the second check valve (120). The oil in the third oil passage (140) can flow to the first oil passage (1) through the second check valve (120).

8. An engineering vehicle, characterized in that: It includes a vehicle body (300) and a telescopic boom (200) as described in any one of claims 1-7, the telescopic boom (200) being mounted on the vehicle body (300).

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