Hydraulic circuit and kitchen truck

Abstract

The hydraulic circuit comprises a hydraulic source, a reversing valve, an opening and closing oil cylinder, a one-way pressure reducing valve and an energy accumulator, and when the reversing valve is located at a first working position, the hydraulic source is communicated with a rodless cavity of the opening and closing oil cylinder so as to drive a piston rod to stretch out; when the reversing valve is located at the second working position, the hydraulic source is communicated with the rod cavity of the opening and closing oil cylinder to drive the piston rod to retract; the energy accumulator receives backflow oil after the rear door is closed in place and supplements oil when the pressure of the rod cavity is reduced, and the one-way pressure reducing valve is closed after the pressure is increased to the preset pressure so as to close an oil passage of the rod cavity. The one-way pressure reducing valve and the energy accumulator are arranged on the hydraulic loop, on the basis of opening and closing actions of the oil cylinder, an oil passage is closed through the cut-off action of the one-way pressure reducing valve, the energy accumulator supplements oil to keep original pressure when the pressure of a rod cavity is reduced, sealing of the rear door is kept, and the closing and sealing effects of the rear door are achieved. The utility model further discloses the kitchen truck comprising the hydraulic circuit.

Description

Technical Field

[0001] The utility model relates to the technical field of vehicle equipment, in particular to a hydraulic circuit and a dining kitchen vehicle. Background Art

[0002] A food truck is a vehicle for collecting and transporting kitchen waste. When it is fully loaded with waste and is being transported, the rear door needs to be kept closed and sealed to prevent waste leakage. However, the opening and closing mechanism and the sealing and locking mechanism of the rear door of the food trucks currently on the market are relatively independent, that is, the opening and closing mechanism has an independent mechanical structure and hydraulic circuit, and the sealing and locking mechanism also has a corresponding mechanical structure and hydraulic circuit. The two independently arranged structures are not only complex in structure and more expensive to set up, but also the failure of any of the two independent systems will cause waste leakage at the rear door. When the food truck passes through a rugged road or speed bump, the rear door is at greater risk of leakage due to the vibration of the vehicle.

[0003] Therefore, how to reduce the setting cost and leakage risk of the rear door area structure of the dining kitchen cart and improve the stability of the dining kitchen cart during the garbage transfer process is a technical problem that needs to be urgently solved by technical personnel in this field. Utility Model Content

[0004] In view of this, the purpose of the utility model is to provide a hydraulic circuit to reduce the installation cost and leakage risk of the rear door area structure of the dining kitchen cart and improve the stability of the dining kitchen cart during the garbage transfer process.

[0005] Another object of the present invention is to provide a dining kitchen vehicle including the hydraulic circuit.

[0006] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0007] A hydraulic circuit comprises a hydraulic source, a reversing valve, an on-off oil cylinder, a one-way pressure reducing valve and an accumulator, wherein when the reversing valve is located at a first working position, the hydraulic source is communicated with a rodless chamber of the on-off oil cylinder to drive a piston rod to extend and drive a rear door of a vehicle to open; when the reversing valve is located at a second working position, the hydraulic source is communicated with a rod chamber of the on-off oil cylinder to drive a piston rod to retract and drive a rear door of the vehicle to close;

[0008] The accumulator is used to receive the oil refluxed in the rod chamber after the rear door is closed, and to replenish the oil into the rod chamber when the pressure in the rod chamber decreases. The one-way pressure reducing valve is closed after the pressure is increased to a preset pressure, and the oil passage in the rod chamber is closed by the one-way pressure reducing valve.

[0009] Preferably, in the above-mentioned hydraulic circuit, the reversing valve includes at least a first working position, a second working position and a third working position. When the reversing valve is located in the third working position, the oil supply of the hydraulic source is cut off, and the reversing valve switches to the third working position when the rear door seal is locked.

[0010] Preferably, in the above hydraulic circuit, a hydraulically controlled one-way valve is further included, and the hydraulically controlled one-way valve is arranged between the one-way pressure reducing valve and the opening and closing cylinder;

[0011] When the reversing valve is located in the first working position, part of the oil supplied by the hydraulic source flows to the controller port of the hydraulically controlled one-way valve to open the hydraulically controlled one-way valve; when the reversing valve is located in the third working position, the control oil in the hydraulically controlled one-way valve flows out, and the hydraulically controlled one-way valve closes the oil passage in the rod chamber.

[0012] Preferably, the above hydraulic circuit further comprises an electromagnetic reversing valve, which is opened to maintain the circuit passage when the reversing valve is located in the first working position, and is closed to maintain pressure when the reversing valve is located in the third working position.

[0013] Preferably, in the above hydraulic circuit, the reversing valve is an electromagnetic reversing valve and is connected to a switch signal in the vehicle cockpit.

[0014] Preferably, in the above hydraulic circuit, when the first end of the solenoid valve is energized, the valve core is located at the first working position, when the second end of the solenoid valve is energized, the valve core is located at the second working position, and when the solenoid valve is de-energized, the valve core is located at the third working position.

[0015] Preferably, the above hydraulic circuit further includes a pressure sensor, which is used to detect the pressure in the rod chamber and to feedback an alarm when the pressure in the rod chamber is lower than the first pressure.

[0016] Preferably, in the above hydraulic circuit, the inlet positions of the rodless chamber and the rod chamber are both provided with balancing valves for evenly allowing the oil to enter.

[0017] Preferably, in the above hydraulic circuit, the return positions of the pipelines and valves on the hydraulic circuit are connected to the oil tank.

[0018] A dining kitchen vehicle, wherein a rear door structure thereof is provided with the hydraulic circuit described in any one of the above embodiments; when the rear door of the dining kitchen vehicle needs to be opened, the reversing valve is switched to the first working position; when the rear door of the dining kitchen vehicle needs to be closed and sealed, the reversing valve is switched to the second working position.

[0019] It can be seen from the above technical scheme that the hydraulic circuit provided by the utility model is provided with a reversing valve between the hydraulic source and the opening and closing cylinder, so that the hydraulic source can supply oil to the rodless chamber and the rod chamber in the opening and closing cylinder respectively through the switching action of the two working positions of the valve core in the reversing valve, thereby driving the extension and retraction of the piston rod to realize the opening and closing action of the vehicle rear door. On this basis, a one-way pressure reducing valve and an accumulator are also provided in the hydraulic circuit. During the closing process of the rear door, that is, when the reversing valve is in the second working position, the pressure in the rod chamber continues to increase after the rear door is closed in place, and acts on the piston rod and the one-way pressure reducing valve until the one-way pressure reducing valve reaches the preset pressure, and the one-way pressure reducing valve is closed to maintain the pressure of the oil in the rod chamber, so that the piston When the rod is under preset pressure, the rear door can remain closed under pressure and maintain a tight seal under the action of the piston rod; the accumulator receives the oil driven by the rod chamber after the rear door is closed, and when the pressure in the rod chamber drops, it replenishes oil in time to maintain the original pressure, thereby maintaining the sealing and locking state of the rear door; the setting of the one-way pressure reducing valve and the accumulator enables a single hydraulic circuit to realize the opening and closing of the vehicle's rear door, as well as the pressure sealing and locking action of the rear door, without setting up two circuits to reduce the structural setting cost, and the corresponding leakage risk is also smaller, and the accumulator can also replenish oil in time when an accident occurs in the rod chamber to avoid contact with the sealing effect of the rear door, thereby improving the stability of the rear door of the dining kitchen vehicle during garbage transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of a hydraulic circuit flow chart provided for an embodiment of the utility model;

[0022] Figure 2 A schematic diagram of a hydraulic circuit flow chart provided for another embodiment;

[0023] Among them, 10-hydraulic source; 20-reversing valve; 30-opening and closing cylinder; 40-one-way pressure reducing valve; 50-accumulator; 60-hydraulic controlled one-way valve; 70-electromagnetic reversing valve; 80-pressure sensor; 90-balancing valve; 100-oil tank. DETAILED DESCRIPTION

[0024] The core of the utility model is to disclose a hydraulic circuit to reduce the setting cost and leakage risk of the rear door area structure of the dining kitchen cart and improve the stability of the dining kitchen cart during the garbage transportation process.

[0025] Another core of the utility model is to provide a dining kitchen vehicle including the hydraulic circuit.

[0026] In order to make the technical personnel in this field better understand the present invention, the embodiments of the present invention are described below with reference to the accompanying drawings. In addition, the embodiments shown below do not limit the contents of the utility model described in the claims. In addition, the entire contents of the structures represented by the following embodiments are not limited to those necessary for the solutions of the utility model described in the claims.

[0027] like Figure 1 As shown, the hydraulic circuit provided by the embodiment of the utility model includes a hydraulic source 10, a reversing valve 20, an on-off cylinder 30, a one-way pressure reducing valve 40 and an accumulator 50, wherein the hydraulic source 10 is arranged at the starting end of the circuit, which can be a hydraulic oil supply device such as a hydraulic pump, and the reversing valve 20 is arranged on the circuit, and it includes at least a first working position and a second working position. Specifically, when the reversing valve 20 is in the first working position, the hydraulic source 10 is directly connected to the rodless chamber of the on-off cylinder 30, that is, the oil supply of the hydraulic source 10 can directly reach Reaching the rodless cavity, on this basis, the oil supply from the hydraulic source 10 will drive the piston rod to extend, and in conjunction with the mechanical structure of the rear door area, it can drive the vehicle's rear door to open, allowing the operator to perform loading and unloading actions; and when the reversing valve 20 is in the second working position, the reversing valve 20 reverses the oil supply and return pipeline of the hydraulic circuit at its rear end, thereby connecting the hydraulic source 10 with the rod cavity of the opening and closing cylinder 30. At this time, the oil supply from the hydraulic source 10 can drive the piston rod to retract, and in conjunction with the mechanical structure of the rear door area, it can drive the vehicle's rear door to close.

[0028] The cooperation between the hydraulic source 10 and the reversing valve 20 can smoothly realize the extension and retraction of the piston rod in the opening and closing cylinder 30, thereby driving the opening and closing of the rear door. On this basis, a one-way pressure reducing valve 40 is also provided in the hydraulic circuit. When the reversing valve 20 is in the second working position, the one-way pressure reducing valve 40 is arranged on the upper position of the opening and closing cylinder 30 on the oil supply path; specifically, the one-way pressure reducing valve 40 maintains a passage during the extension and retraction of the piston rod, so that the oil in the hydraulic circuit circulates normally, and its valve core is pre- It will close when the set pressure is reached. On this basis, when the hydraulic source 10 drives the piston rod to retract and the rear door of the vehicle is closed, the rod chamber will gradually increase in pressure under the action of the oil and act on the one-way pressure reducing valve 40. After the one-way pressure reducing valve 40 increases in pressure to the preset pressure, the valve core will be closed, and the oil passage in the rod chamber will be closed by the one-way pressure reducing valve 40 so that the pressure in the rod chamber will no longer rise. At the same time, under the action of the one-way pressure reducing valve 40, the rod chamber of the opening and closing cylinder 30 enters a pressure maintaining state and is in a locked state after the rear door is closed.

[0029] It should be noted that a one-way pressure reducing valve 40 with a preset pressure is selected according to the locking pressure requirement of the rear door, so that the rear door can be in a pressure-maintaining state under the preset pressure and maintain its locked and sealed state under the action of the preset pressure.

[0030] On the basis of the above structure, the embodiment of the utility model is also provided with an accumulator 50, which is specifically connected to the rod chamber of the opening and closing cylinder 30. After the rear door is closed, the oil pressure in the rod chamber in the opening and closing cylinder 30 will gradually increase, and the oil will flow to the accumulator 50 under the action of pressure to flush the accumulator 50; the one-way pressure reducing valve 40 will close the oil passage of the rod chamber after reaching the preset pressure, and make the rod chamber in a pressure-maintaining locked and sealed state with the preset pressure. At this time, when the rod chamber produces pressure oil leakage under the situation of bumps and collisions, or when the one-way pressure reducing valve 40 has certain leakage problems, the pressure in the rod chamber of the opening and closing cylinder 30 will be reduced. At this time, the accumulator 50 can replenish oil to maintain the original pressure from decreasing, so as to achieve the sealing state of the rear door when the pressure oil leaks.

[0031] The hydraulic circuit provided by the embodiment of the utility model is provided with a reversing valve 20 between the hydraulic source 10 and the opening and closing cylinder 30, so that the hydraulic source 10 supplies oil to the rodless chamber and the rod chamber in the opening and closing cylinder 30 respectively through the switching action of the valve core of the reversing valve 20 between the two working positions, thereby driving the extension and retraction of the piston rod to realize the opening and closing action of the rear door of the vehicle. On this basis, a one-way pressure reducing valve 40 and an accumulator 50 are also provided in the hydraulic circuit. During the closing process of the rear door, that is, when the reversing valve 20 is located in the second working position, the pressure in the rod chamber continues to increase after the rear door is closed, and acts on the piston rod and the one-way pressure reducing valve 40, until the one-way pressure reducing valve 40 reaches the preset pressure, and the one-way pressure reducing valve 40 is closed to maintain the pressure of the oil in the rod chamber, so that The piston rod is under the preset pressure, and the rear door can remain closed under the pressure and maintain a tight seal under the action of the piston rod; the accumulator 50 receives the oil driven in the rod chamber after the rear door is closed, and when the pressure in the rod chamber decreases, the oil is replenished in time to maintain the original pressure, thereby maintaining the sealing and locking state of the rear door; the setting of the one-way pressure reducing valve 40 and the accumulator 50 enables a single hydraulic circuit to realize the opening and closing action of the vehicle's rear door, as well as the pressure sealing and locking action of the rear door, without setting up two circuits to reduce the structural setting cost, and the corresponding leakage risk is also smaller, and the accumulator 50 can also replenish oil in time when an accident occurs in the rod chamber to avoid contact with the sealing effect of the rear door, thereby improving the stability of the rear door of the dining kitchen vehicle during garbage transportation.

[0032] In order to further optimize the above technical scheme, in the hydraulic circuit provided in the embodiment of the utility model, the reversing valve 20 includes at least a third working position on the basis of the first working position and the second working position, and when the reversing valve 20 is in the third working position, the oil supply of the hydraulic source 10 is cut off, and hydraulic oil is no longer supplied in the hydraulic circuit. Specifically, the reversing valve 20 switches to the third working position when the rear door seal is locked, that is, after the one-way pressure reducing valve 40 is closed and the accumulator 50 is flushed, the oil supply of the hydraulic source 10 is cut off to avoid the impact of the hydraulic source 10 on the pressure maintaining state of the circuit, so that the rod chamber maintains a stable pressure maintaining state, ensuring the safety of the system and preventing the rear door from accidentally opening due to misoperation after the rear door is locked.

[0033] On the basis of the above embodiment, a hydraulically controlled one-way valve 60 is further provided in the hydraulic circuit. The hydraulically controlled one-way valve 60 is a valve whose switching state is controlled by hydraulic oil, and is arranged between the one-way pressure reducing valve 40 and the opening and closing cylinder 30. At the same time, the controller port of the hydraulically controlled one-way valve 60 is connected to the hydraulic source 10. When the reversing valve 20 is in the first working position, part of the oil supplied to the circuit by the hydraulic source 10 will flow to the controller port of the hydraulically controlled one-way valve 60 to open the hydraulically controlled one-way valve 60, so that the hydraulic circuit maintains a passage and allows the oil to flow to the opening and closing cylinder 30. At the same time, it should be noted that when the reversing valve 20 is in the second working position, the hydraulically controlled one-way valve 60 still maintains its open state, and when the reversing valve 20 is in the third working position, the supply and return oil of the hydraulic circuit are reversed. At this time, the hydraulically controlled one-way valve 60 The control oil in the valve 60 will flow out, and the valve core of the hydraulically controlled one-way valve 60 will be closed and the oil passage of the rod chamber will be closed at the same time. It should be noted that the reversing valve 20 is switched to the third working position when the rear door is in a sealed and locked state. Therefore, after the hydraulically controlled one-way valve 60 closes the oil passage of the rod chamber, it can cooperate with the one-way pressure reducing valve 40 to keep the rod chamber in a stable pressure maintaining state. The hydraulically controlled one-way valve 60 cooperates with the working state of the reversing valve 20, and is directly driven by the hydraulic source 10 to achieve pressure maintenance in the rod chamber. Therefore, its control accuracy of the hydraulic circuit is higher, and its complementary cooperation with the one-way pressure reducing valve 40 can maintain the pressure of the system in both pressure and flow directions. The two serve as backup for each other and can significantly improve the pressure maintaining state of the rod chamber, thereby improving the stability of the locking and sealing state of the rear door.

[0034] And as Figure 2As shown, in another embodiment of the utility model, the pressure maintaining effect of the hydraulic circuit does not rely on the hydraulically controlled one-way valve 60 in the above-mentioned embodiment, but is provided with an electromagnetic reversing valve 70. It should be noted that the setting position of the electromagnetic reversing valve 70 can be the same as the setting position of the hydraulically controlled one-way valve 60 in the above-mentioned embodiment in the circuit. Specifically, the electromagnetic reversing valve 70 is opened when the reversing valve 20 is in the first working position to maintain the circuit passage, and is closed when the reversing valve 20 is in the third working position to maintain the pressure of the oil in the rod chamber and maintain the locking seal of the rear door. The electromagnetic reversing valve 70 can be adjusted separately or in conjunction with the reversing valve 20, that is, the electromagnetic reversing valve 70 is synchronously adjusted to the open state by the signal only when the reversing valve 20 is switched to the third working position, and when the reversing valve 20 is in other working positions, the electromagnetic reversing valve 70 remains open; the electromagnetic reversing valve 70 can improve the response speed and control accuracy of the system by signal adjustment.

[0035] Furthermore, in the hydraulic circuit provided in the embodiment of the utility model, the reversing valve 20 can be a manually adjusted rotary valve or a signal-driven valve. Preferably, the reversing valve 20 is an electromagnetic reversing valve, and the electromagnetic reversing valve is connected to the switch signal in the vehicle cockpit. The operator can directly switch the working position of the electromagnetic reversing valve in the cockpit. The use of the electromagnetic reversing valve can realize remote control of the opening and closing of the rear door, thereby improving the convenience and safety of operation.

[0036] Based on the above embodiment, the control logic of the electromagnetic reversing valve is as follows: the first end of the electromagnetic valve, i.e. Figure 1 When DT1 in is energized, the valve core moves to the first working position, allowing the hydraulic oil to flow to the rodless chamber of the opening and closing cylinder 30 to open the rear door; the second end of the solenoid valve, i.e. Figure 1 When DT2 in is energized, the valve core moves to the second working position, allowing hydraulic oil to flow to the rod chamber of the opening and closing cylinder 30 to close the rear door; when the solenoid valve loses power, the valve core automatically moves to the third working position under the action of a spring, etc., cutting off the oil supply of the hydraulic source 10 to ensure system safety. The precise control of the electromagnetic reversing valve can ensure the accuracy and reliability of opening and closing the rear door. At the same time, its design of automatically returning to the third working position after power failure improves the safety of the system and prevents accidental movement of the rear door during power failure.

[0037] In order to further optimize the above technical scheme, the hydraulic circuit provided in the embodiment of the utility model also includes a pressure sensor 80, and the pressure sensor 80 is used to monitor the pressure in the rod chamber in real time. At the same time, the pressure sensor 80 is preferably connected to the vehicle control system signal, so that when the pressure sensor 80 detects that the pressure in the rod chamber is lower than the preset first pressure, the feedback control system will issue an alarm signal to prompt the operator that the system pressure is abnormal; the real-time monitoring function of the pressure sensor 80 improves the monitoring capability of the hydraulic system, so that the operator can quickly respond to abnormal system pressure and prevent potential safety risks. At the same time, the alarm signal is preferably one or both of easy-to-observe sound and light signals.

[0038] Furthermore, in the hydraulic circuit provided by the embodiment of the utility model, balancing valves 90 are respectively provided at the entrance positions of the rodless chamber and the rod chamber. The design of the balancing valve 90 ensures the uniformity of the oil when entering the opening and closing cylinder 30, reduces the hydraulic shock and system noise caused by uneven oil flow, and at the same time can make the extension and retraction process of the piston rod more uniform, and can also avoid the risk of rear door shaking caused by sudden changes in the movement of the piston rod, thereby improving the stability of the system.

[0039] In addition, it should be noted that in the hydraulic circuit provided by the embodiment of the utility model, the return positions of the pipelines and valves are connected to the oil tank 100 through the oil return pipe to collect the oil and realize the recycling of the oil, avoid the waste and pollution of the oil, and improve the economy of the system.

[0040] The embodiment of the utility model further provides a dining kitchen cart, the rear door structure of the dining kitchen cart is provided with the hydraulic circuit provided by any of the above embodiments, when the rear door of the dining kitchen cart needs to be opened, the reversing valve 20 is switched to the first working position, and when the rear door of the dining kitchen cart needs to be closed and sealed, the reversing valve 20 is switched to the second working position. The application of the above hydraulic circuit enables a single set of hydraulic circuits to meet the requirements of opening, closing and sealing of the rear door of the dining kitchen cart, reduces the setting cost and leakage risk of the rear door area structure of the dining kitchen cart, and since the hydraulic circuit has the technical effects provided by the above embodiments, the dining kitchen cart also has the above technical effects, and the embodiments of the utility model are not repeated here.

[0041] The terms "first", "second", "third", "left side" and "right side" in the specification and claims of the utility model and the above drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not set to the listed steps or units, but may include steps or units that are not listed.

[0042] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A hydraulic circuit, characterized in that: It includes a hydraulic source, a reversing valve, an opening and closing oil cylinder, a one-way pressure reducing valve and an accumulator. When the reversing valve is located at a first working position, the hydraulic source is connected to the rodless chamber of the opening and closing oil cylinder to drive the piston rod to extend and drive the rear door of the vehicle to open; When the reversing valve is in the second working position, the hydraulic source is connected to the rod chamber of the opening and closing oil cylinder to drive the piston rod to retract and drive the rear door of the vehicle to close; The accumulator is used to receive the oil refluxed in the rod chamber after the rear door is closed, and to replenish the oil into the rod chamber when the pressure in the rod chamber decreases. The one-way pressure reducing valve is closed after the pressure is increased to a preset pressure, and the oil passage in the rod chamber is closed by the one-way pressure reducing valve.

2. The hydraulic circuit according to claim 1, characterized in that The reversing valve includes at least a first working position, a second working position and a third working position. When the reversing valve is located at the third working position, the oil supply of the hydraulic source is cut off. The reversing valve switches to the third working position when the rear door seal is locked.

3. The hydraulic circuit according to claim 2, characterized in that: It also includes a hydraulically controlled one-way valve, which is arranged between the one-way pressure reducing valve and the opening and closing oil cylinder; When the reversing valve is located in the first working position, part of the oil supplied by the hydraulic source flows to the controller port of the hydraulically controlled one-way valve to open the hydraulically controlled one-way valve; when the reversing valve is located in the third working position, the control oil in the hydraulically controlled one-way valve flows out, and the hydraulically controlled one-way valve closes the oil passage in the rod chamber.

4. The hydraulic circuit according to claim 2, characterized in that: It also includes an electromagnetic reversing valve, which opens to maintain a circuit passage when the reversing valve is located in a first working position, and closes to maintain pressure when the reversing valve is located in a third working position.

5. The hydraulic circuit according to claim 2, characterized in that: The reversing valve is a solenoid valve and is connected to a switch signal in the vehicle cockpit.

6. The hydraulic circuit according to claim 5, characterized in that When the first end of the solenoid valve is energized, the valve core is located at the first working position, when the second end of the solenoid valve is energized, the valve core is located at the second working position, and when the solenoid valve is de-energized, the valve core is located at the third working position.

7. The hydraulic circuit according to claim 1, characterized in that It also includes a pressure sensor, which is used to detect the pressure in the rod cavity and feedback an alarm when the pressure in the rod cavity is lower than a first pressure.

8. The hydraulic circuit according to claim 1, characterized in that The inlet positions of the rodless chamber and the rod chamber are both provided with a balancing valve for allowing the oil to enter evenly.

9. The hydraulic circuit according to claim 1, characterized in that: The pipelines and return flow positions of the valves on the hydraulic circuit are all connected to the oil tank.

10. A dining kitchen vehicle, characterized in that: Its rear door structure is provided with the hydraulic circuit described in any one of claims 1-9. When the rear door of the dining kitchen cart needs to be opened, the reversing valve is switched to the first working position. When the rear door of the dining kitchen cart needs to be closed and sealed, the reversing valve is switched to the second working position.

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