Hydraulic system and excavator

Abstract

The invention provides a hydraulic system which is used for the technical field of excavators, and particularly relates to a hydraulic system which comprises an executing mechanism, a sliding valve, a pressure sensor and a control unit, and the pressure sensor can detect the pressure of a rod cavity, a rodless cavity and the end of a piston rod of the executing mechanism; and the control unit can receive a pressure signal of the pressure sensor and control the differential connection oil duct to be switched between a connection state and a disconnection state, flow regulation in the connection state and / or flow regulation of the oil return oil duct. The invention further provides an excavator which comprises the hydraulic system. According to the hydraulic system and the excavator, the control unit intelligently controls on-off of differential connection according to the pressure signal of the pressure sensor, the pushing force of the oil cylinder is improved, the flow of the second oil duct is intelligently controlled, the oil return back pressure is changed, energy consumption is reduced, the working efficiency of the excavator is improved, and energy consumption is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of excavators, and in particular to a hydraulic system and an excavator. Background Art

[0002] In the prior art, when the load of the actuator is an overrunning load and the hydraulic control system works in the low-pressure regeneration mode, the inlet and outlet of the hydraulic actuator are simultaneously connected to the low-pressure oil return circuit to form a differential connection. At this time, the hydraulic actuator drives the actuator to move by overrunning the load, and no pump is required to provide flow. Although the system saves energy in this mode, when the return oil passes through the control valve and enters the low-pressure chamber of the hydraulic actuator, cavitation is easily generated due to pressure loss along the way and pressure loss at the valve port. In addition, the size of the return oil back pressure is fixed and cannot be adjusted, resulting in large pressure loss and high energy consumption. Summary of the invention

[0003] In view of this, the present application provides a hydraulic system and an excavator, which intelligently controls the on and off of the differential connection according to the pressure signal of the pressure sensor through the control unit, thereby increasing the driving force of the cylinder and intelligently controlling the flow of the second oil channel to change the return oil back pressure and reduce energy consumption, so as to improve the working efficiency of the excavator and reduce energy consumption.

[0004] In order to achieve the above objectives, this application provides the following technical solutions:

[0005] A hydraulic system comprising:

[0006] An actuator, comprising a rod chamber, a rodless chamber and a piston rod;

[0007] A slide valve; comprising an oil inlet P, an oil return port T, a working oil port A and a working oil port B; a first oil passage is provided between the oil inlet P and the working oil port A, a second oil passage is provided between the oil return port T and the working oil port B, a differential connection oil passage is provided between the first oil passage and the second oil passage, the differential connection oil passage can be switched between an on / off state and the flow rate in the on state is adjustable, and the flow rate of the second oil passage is adjustable;

[0008] The pressure sensor comprises a first pressure sensor, a second pressure sensor and a third pressure sensor, wherein the first pressure sensor is used to detect the pressure in the rodless cavity, the second pressure sensor is used to detect the pressure in the rod cavity, and the third pressure sensor is used to detect the pressure on the end of the piston rod;

[0009] A control unit can receive pressure signals fed back by the first pressure sensor, the second pressure sensor and the third pressure sensor and control the switching of the differential connection oil channel between the on / off state and the flow regulation when in the on state according to the pressure signals, and / or adjust the flow of the second oil channel.

[0010] Optionally, a proportional solenoid valve c is provided on the differential connection oil channel, and a proportional solenoid valve d is provided on the second oil channel. The proportional solenoid valve c and the proportional solenoid valve d are both electrically connected to the control unit. The control unit can control the proportional solenoid valve c to control the switching of the differential connection oil channel between on / off states and the flow regulation in the on state. The control unit can control the proportional solenoid valve d to adjust the flow of the second oil channel.

[0011] Optionally, the proportional solenoid valve d is arranged downstream of the intersection of the second oil channel and the differential connection oil channel.

[0012] Optionally, the proportional solenoid valve c includes two working positions, an upper position and a lower position. When the lower position is energized, the differential connection oil channel is connected by a throttle valve, and when the upper position is energized, the differential connection oil channel is cut off by a one-way valve.

[0013] Optionally, the proportional solenoid valve d includes two working positions, a left position and a right position. When the left position is energized, the second oil channel is always open. When the right position is energized, the second oil channel is connected by a throttle valve.

[0014] Optionally, when the first oil channel and the second oil channel are both connected, and the pressure values ​​fed back by the first pressure sensor and the second pressure sensor are greater than 0 and the pressure value fed back by the third pressure sensor is equal to 0, the control unit switches the proportional solenoid valve c to the lower energized state.

[0015] Optionally, the control unit switches the proportional solenoid valve d to the left position energized state.

[0016] Optionally, when the first oil channel and the second oil channel are both connected, and the pressure values ​​fed back by the first pressure sensor and the second pressure sensor are greater than 0 and the pressure value fed back by the third pressure sensor is greater than 0, the control unit switches the proportional solenoid valve c to the upper energized state.

[0017] Optionally, the control unit switches the proportional solenoid valve d to the right position energized state.

[0018] The present application also provides an excavator, comprising the hydraulic system.

[0019] The hydraulic system provided in the present application collects pressure signals from the rod chamber, the rodless chamber and the piston rod and sends them to a control unit. The control unit then determines the load state of the piston rod based on the pressure signals, and intelligently controls the flow rate when the differential connection is on and off and connected based on the load state to increase the driving force of the cylinder, and intelligently controls the flow rate of the second oil channel to change the return oil back pressure and reduce energy consumption.

[0020] The excavator provided in the present application uses the hydraulic system, which can improve work efficiency and reduce energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application 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 embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0022] Figure 1 A schematic diagram of the hydraulic system of the present application;

[0023] Figure 2 A schematic diagram of a slide valve of the present application;

[0024] Figure 3 for Figure 2 Enlarged schematic diagram of the oil circuit when the middle slide valve is in the right energized working position.

[0025] exist Figure 1-Figure 3 middle:

[0026] 1. Actuator; 11. Rodless chamber; 111. First pressure sensor; 12. Rod chamber; 121. Second pressure sensor; 13. Piston rod; 131. Third pressure sensor; 2. Sliding valve; 21. Working oil port A; 22. Working oil port B; 23. Oil inlet port P; 24. Oil return port T; 31. Proportional solenoid valve c; 32. Proportional solenoid valve d; 4. Control unit; 51. First oil channel 51; 52. Second oil channel; 53. Differential connection oil channel; 54. Intersection of the second oil channel and the differential connection oil channel. DETAILED DESCRIPTION

[0027] The present application provides a hydraulic system and an excavator, which improve the working efficiency of the excavator and reduce energy consumption by intelligently controlling the on-off of the differential connection according to the pressure signal of the pressure sensor through a control unit, thereby increasing the driving force of the oil cylinder and intelligently controlling the flow of the second oil channel to change the return oil back pressure.

[0028] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0029] like Figure 1-Figure 3 As shown, an embodiment of the present application provides a hydraulic system, comprising:

[0030] The actuator 1, such as a cylinder, comprises a rod chamber 12, a rodless chamber 11 and a piston rod 13, and the end of the piston rod 13 can be connected to an action mechanism such as a digging arm of an excavator;

[0031] The slide valve 2 is a three-position four-way valve in this embodiment, including an oil inlet P23, an oil return port T24, a working oil port A21 and a working oil port B22; a first oil passage 51 is provided between the oil inlet P23 and the working oil port A21, and a second oil passage 52 is provided between the oil return port T24 and the working oil port B22. The slide valve 2 includes an a end on the left and a b end on the right. When the b end of the slide valve 2 receives a pressure signal, the valve core of the slide valve 2 is in the right position. At this time, the hydraulic oil passes through the first oil passage 51, that is, passes through the oil inlet P23 and the working oil port A21 in sequence to enter the rodless chamber 11 of the oil cylinder, and at this time, the rod chamber 12 is squeezed, and the hydraulic oil passes through the second oil passage 52, that is, returns to the actuator 1 via the working oil port B22 and the oil return port T24 in sequence;

[0032] A differential connection oil passage 53 is provided between the first oil passage 51 and the second oil passage 52. The differential connection oil passage 53 can be switched between an on / off state and the flow rate can be adjusted when in the on state. The flow rate of the second oil passage 52 can be adjusted.

[0033] The pressure sensor includes a first pressure sensor 111, a second pressure sensor 121 and a third pressure sensor 131. The first pressure sensor 111 is used to detect the pressure in the rodless chamber 11, the second pressure sensor 121 is used to detect the pressure in the rod chamber 12, and the third pressure sensor 131 is used to detect the pressure on the end of the piston rod 13. When the piston rod 13 of the actuator 1 moves, the first pressure sensor 111 and the second pressure sensor 121 can detect the pressure. When the actuator 1 is loaded, the third pressure sensor 131 can detect the pressure. When the actuator 1 is unloaded, the pressure that the third pressure sensor 131 can detect is 0;

[0034] The control unit 4 can receive the pressure signals fed back by the first pressure sensor 111, the second pressure sensor 121 and the third pressure sensor 131 and control the switching of the differential connection oil channel 53 between the on / off state and the flow adjustment when in the on state according to the pressure signals, and / or adjust the flow of the second oil channel 52.

[0035] The hydraulic system of the present application collects pressure signals at the rod chamber 12, the rodless chamber 11 and the piston rod 13 and sends them to the control unit 4. The control unit 4 then determines the load state of the piston rod 13 based on the pressure signal, and intelligently controls the flow rate of the differential connection oil channel 53 when it is on and off and connected according to the load state, so as to increase the driving force of the cylinder and avoid cavitation, and can intelligently control the flow rate of the second oil channel 52 to change the return oil back pressure and reduce energy consumption.

[0036] like Figure 1-Figure 3 As shown, in a preferred embodiment, a proportional solenoid valve c31 is provided on the differential connection oil channel 53, and a proportional solenoid valve d32 is provided on the second oil channel. The proportional solenoid valve c31 and the proportional solenoid valve d32 are both electrically connected to the control unit 4. The control unit 4 can control the proportional solenoid valve c31 to control the switching of the differential connection oil channel 53 between the on / off states and the flow regulation when in the on state. The control unit 4 can control the proportional solenoid valve d32 to adjust the flow of the second oil channel 52.

[0037] In this embodiment, the control unit 4 controls the proportional solenoid valve c31 on the differential connection oil channel 53 to achieve control of the differential connection oil channel 53 switching between the on / off state and flow regulation when in the on state; similarly, the control unit 4 controls the proportional solenoid valve d32 on the second oil channel 52 to adjust the flow of the second oil channel 52; wherein, the control unit 4 controls the proportional solenoid valve c31 and the proportional solenoid valve d32 including switching of the working position of the proportional solenoid valve and adjustment of the throttle size, etc.

[0038] like Figure 3 As shown, in a preferred embodiment, the proportional solenoid valve d32 is arranged downstream of the intersection 54 of the second oil channel 52 and the differential connection oil channel 53, that is, between the intersection 54 of the second oil channel 52 and the differential connection oil channel 53 and the oil return port T24.

[0039] Since the proportional solenoid valve d32 is arranged on the second oil channel 52, if the proportional solenoid valve d32 is arranged upstream of the intersection 54 of the second oil channel 52 and the differential connection oil channel 53, that is, between the working oil port B22 and the intersection 54 of the second oil channel 52 and the differential connection oil channel 53, it will participate in the differential oil circuit, which will affect the differential oil circuit and complicate the control of the proportional solenoid valve by the control unit 4. Therefore, in this embodiment, the proportional solenoid valve d32 is arranged downstream of the intersection of the second oil channel 52 and the differential connection oil channel 53, and the return oil back pressure is adjusted by adjusting the proportional solenoid valve without affecting the differential oil circuit.

[0040] Specifically, Figure 3 As shown, in a preferred embodiment, the proportional solenoid valve c31 includes two working positions, an upper position and a lower position. When the lower position is energized, the differential connection oil channel 53 is connected by the throttle valve, and when the upper position is energized, the differential connection oil channel 53 is cut off by the one-way valve.

[0041] According to the pressure signal of the pressure sensor, the control unit 4 controls the proportional solenoid valve c31 through an electrical signal and switches its working position. When the lower position is energized, the proportional solenoid valve c31 switches to the lower working position, the differential connection oil channel 53 is connected by the throttle valve, and the flow rate of the differential connection oil channel 53 can be controlled by adjusting the throttle port of the throttle valve; when the upper position is energized, the proportional solenoid valve c31 switches to the upper working position, and the differential connection oil channel 53 is cut off by the one-way valve. In summary, the control unit 4 controls the proportional solenoid valve c31 through an electrical signal to control whether the differential connection is working and the pressure loss after the differential connection.

[0042] Similar, such as Figure 3 As shown, in a preferred embodiment, the proportional solenoid valve d32 includes two working positions, a left position and a right position. When the left position is energized, the second oil passage 52 is always open. When the right position is energized, the second oil passage 52 is connected by the throttle valve.

[0043] According to the pressure signal of the pressure sensor, the control unit 4 controls the proportional solenoid valve d32 through an electrical signal and switches its working position. When the left position is energized, the proportional solenoid valve d32 switches to the left working position, and the second oil channel 52 is always open. At this time, "zero" back pressure return oil can be achieved; when the right position is energized, the proportional solenoid valve d32 switches to the right working position, and the second oil channel 52 is connected by the throttle valve. At this time, the throttle port size of the proportional solenoid valve d32 can be controlled by the electrical signal to control the flow rate. In summary, the control unit 4 controls the proportional solenoid valve d32 through an electrical signal to control the size of the return oil back pressure.

[0044] In a preferred embodiment, when the first oil channel 51 and the second oil channel 52 are both connected, and the pressure value fed back by the first pressure sensor 111 and the second pressure sensor 121 is greater than 0 and the pressure value fed back by the third pressure sensor 131 is equal to 0, that is, when the pressure signal is obtained at the end of the sliding valve 2b, the sliding valve 2 is forced to be in the right working position, the hydraulic oil enters the rodless chamber 11 of the cylinder through the first oil channel 51, and the rod chamber 12 is squeezed at this time, and the hydraulic oil returns to the actuator 1 through the rod chamber 12, the working oil port B22, and the return oil port T24, and when the machine is in the no-load operation stage, the control unit 4 switches the proportional solenoid valve c31 to the lower energized state.

[0045] At this moment, since the proportional solenoid valve c31 is switched to the lower energized state, that is, the differential connection oil channel 53 is connected by the throttle valve, part of the hydraulic oil flowing from the working oil port B22 to the return oil port T24 flows to the working oil port A21 through the differential connection oil channel 53, replenishing the oil inlet of the rodless chamber 11 and pushing the cylinder forward. However, in order to avoid the piston rod 13 of the cylinder from advancing too fast and causing air suction, the throttle port size of the proportional solenoid valve c31 can be controlled to realize the flow rate of the hydraulic oil compensated to the rodless chamber 11 by the working oil port A21, thereby avoiding air suction.

[0046] Further, the control unit 4 switches the proportional solenoid valve d32 to the right energized state, thereby enabling the second oil channel 52 to be connected by the throttle valve.

[0047] In this way, the remaining hydraulic oil flowing from the working oil port B22 to the return oil port T24 can adjust the throttle port size of the throttle valve according to actual working conditions to establish back pressure and assist the speed of differential connection oil replenishment.

[0048] In a preferred embodiment, when the first oil channel 51 and the second oil channel 52 are both connected, and the pressure values ​​fed back by the first pressure sensor 111 and the second pressure sensor 121 are greater than 0 and the pressure value fed back by the third pressure sensor 131 is greater than 0, the control unit 4 switches the proportional solenoid valve c31 to the upper energized state.

[0049] When the piston rod 13 of the actuator 1 touches the action mechanism to be pushed and generates resistance, the control unit 4 can give a signal to the proportional solenoid valve c31, which is immediately in the upper position to block the differential connection oil channel 53. At this moment, the piston rod 13 overcomes the resistance with the maximum thrust.

[0050] Further, the control unit 4 switches the proportional solenoid valve d32 to the left energized state, thereby achieving the normal flow of the second oil channel 52.

[0051] The control unit 4 switches the proportional solenoid valve c31 to the upper energized state, that is, after the differential connection oil channel 53 is cut off by the one-way valve, in order to maximize the driving force and reduce the return pressure loss of the hydraulic oil in the rodless chamber 11 of the cylinder, the second oil channel 52 is always open to achieve "zero" back pressure return oil, thereby reducing the energy loss of the cylinder during the entire process.

[0052] Working principle of the hydraulic system of this application:

[0053] When the b end of the slide valve 2 receives a pressure signal, the slide valve 2 is forced to the right position, that is, the first oil channel 51 and the second oil channel 52 are both connected; the hydraulic oil enters the rodless chamber 11 of the cylinder from the oil inlet P23 via the working oil port A21, and the rod chamber 12 is squeezed at this time, and the hydraulic oil returns to the return oil port T24 via the working oil port B22; at this time, the pressures of the first pressure sensor 111, the second pressure sensor 121 and the third pressure sensor 131 are respectively detected. Since the piston of the cylinder is in motion, the pressure values ​​returned by the first pressure sensor 111 and the second pressure sensor 121 are greater than 0, but if there is no load assistance at the front end of the piston rod 13 of the cylinder, the pressure value detected by the third pressure sensor 131 is 0, indicating that the machine is in the no-load operation stage; in order to save energy consumption, the control unit 4 can be used to judge and give a ratio For example, the solenoid valve c31 is energized and put in the lower energized state, that is, the differential connection oil channel 53 is connected through the throttle valve. At this moment, the hydraulic oil in the rod chamber 12 of the cylinder flows through the working oil port B22, and then flows to the working oil port A21 through the proportional solenoid valve c31, replenishing the oil in the rodless chamber 11 to push the piston rod 13 of the cylinder forward. However, in order to avoid the cylinder piston rod 13 from advancing too fast and causing air suction, the throttle port size of the proportional solenoid valve c31 can be controlled to achieve the flow size of the hydraulic oil compensated to the rodless chamber 11 from the working oil port A21, thereby avoiding air suction; at the same time, part of the hydraulic oil in the rod chamber 12 passes through the working oil port B22 and the proportional solenoid valve d32 and returns to the return oil port T24. The throttle port size of the proportional solenoid valve d32 throttle valve can be adjusted according to actual working conditions to establish back pressure and assist the speed of differential connection oil replenishment.

[0054] When the piston rod 13 of the oil cylinder continues to move forward and touches the action mechanism to be pushed to generate resistance, a control signal can be sent to the proportional solenoid valve c31 through the control unit 4, so that the proportional solenoid valve c31 is in the upper energized state, blocking the differential connection oil channel 53. At this moment, the piston rod 13 overcomes the resistance with the maximum thrust; and in order to maximize the driving force and reduce the return oil pressure loss of the hydraulic oil in the rod chamber 12 of the oil cylinder, the proportional solenoid valve d32 is in the left energized state to achieve "zero" back pressure return oil, thereby reducing the energy loss of the oil cylinder during the entire process.

[0055] The present application also provides an excavator that uses the above-mentioned hydraulic system to improve work efficiency and reduce energy consumption.

[0056] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0057] The block diagrams of the devices, apparatuses, equipment, and systems involved in this application are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The words "such as" used here refer to the phrase "such as but not limited to", and can be used interchangeably with them.

[0058] It should also be noted that in the apparatus, device and method of the present application, each component or each step can be decomposed or recombined, and these decompositions or recombinations should be regarded as equivalent solutions of the present application.

[0059] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0060] It should be understood that the qualifiers "first", "second", "third", "fourth", "fifth" and "sixth" used in the description of the embodiments of the present application are only used to more clearly explain the technical solutions and cannot be used to limit the scope of protection of the present application.

[0061] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A hydraulic system, characterized in that: include: An actuator, comprising a rod chamber, a rodless chamber and a piston rod; Slide valve; Including oil inlet P, oil return port T, working oil port A and working oil port B; A first oil passage is provided between the oil inlet P and the working oil port A, a second oil passage is provided between the oil return port T and the working oil port B, a differential connection oil passage is provided between the first oil passage and the second oil passage, the differential connection oil passage can be switched between an on / off state and the flow rate can be adjusted in the on state, and the flow rate of the second oil passage can be adjusted; The pressure sensor comprises a first pressure sensor, a second pressure sensor and a third pressure sensor, wherein the first pressure sensor is used to detect the pressure in the rodless cavity, the second pressure sensor is used to detect the pressure in the rod cavity, and the third pressure sensor is used to detect the pressure on the end of the piston rod; A control unit can receive pressure signals fed back by the first pressure sensor, the second pressure sensor and the third pressure sensor and control the switching of the differential connection oil channel between the on / off state and the flow regulation when in the on state according to the pressure signals, and / or adjust the flow of the second oil channel.

2. The hydraulic system according to claim 1, characterized in that: A proportional solenoid valve c is arranged on the differential connection oil channel, and a proportional solenoid valve d is arranged on the second oil channel. The proportional solenoid valve c and the proportional solenoid valve d are both electrically connected to the control unit. The control unit can control the proportional solenoid valve c to control the switching of the differential connection oil channel between the on / off states and the flow regulation in the on state. The control unit can control the proportional solenoid valve d to regulate the flow of the second oil channel.

3. The hydraulic system according to claim 2, characterized in that: The proportional solenoid valve d is disposed downstream of the intersection of the second oil passage and the differential connection oil passage.

4. The hydraulic system according to claim 3, characterized in that: The proportional solenoid valve c includes two working positions, an upper position and a lower position. When the lower position is energized, the differential connection oil passage is connected by the throttle valve. When the upper position is energized, the differential connection oil passage is cut off by the one-way valve.

5. The hydraulic system according to claim 4, characterized in that: The proportional solenoid valve d includes two working positions, a left position and a right position. When the left position is energized, the second oil passage is always open. When the right position is energized, the second oil passage is connected by a throttle valve.

6. The hydraulic system according to claim 5, characterized in that: When the first oil channel and the second oil channel are both connected, and the pressure values ​​fed back by the first pressure sensor and the second pressure sensor are greater than 0 and the pressure value fed back by the third pressure sensor is equal to 0, the control unit switches the proportional solenoid valve c to the lower energized state.

7. The hydraulic system according to claim 6, characterized in that: The control unit switches the proportional solenoid valve d to the left-position energized state.

8. The hydraulic system according to claim 5, characterized in that: When the first oil channel and the second oil channel are both connected, and the pressure values ​​fed back by the first pressure sensor and the second pressure sensor are greater than 0 and the pressure value fed back by the third pressure sensor is greater than 0, the control unit switches the proportional solenoid valve c to the upper energized state.

9. The hydraulic system according to claim 8, characterized in that: The control unit switches the proportional solenoid valve d to the right position and the energized state.

10. An excavator, characterized in that: A hydraulic system comprising any one of claims 1-9.

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