Fuel sloshing noise simulation analysis method, platform and computer storage medium

Abstract

The present application discloses a fuel sloshing noise simulation analysis method, platform and computer storage medium. The method includes: establishing a noise simulation model according to the input fuel tank data of a vehicle; wherein the fuel tank data at least includes strap data, shock pad data and anti-surge plate data; obtaining the vibration data of the fuel tank housing surface and the nodal reactions of the shock pad surface and the strap mounting points corresponding to the output of the noise simulation model according to the input boundary conditions; wherein the boundary conditions include the fuel tank liquid level and the driving conditions; and obtaining the fuel sloshing noise value based on a pre-designed calculation rule according to the vibration data of the fuel tank housing surface and the nodal reactions of the shock pad surface and the strap mounting points. The fuel sloshing noise simulation analysis method, platform and computer storage medium provided by the present application can quickly and accurately predict the fuel sloshing noise without the need for vehicle data, improving the vehicle R & D efficiency and reducing the vehicle R & D cost.

Description

Technical Field

[0001] The present invention relates to the field of computer-aided design, and particularly to a method, platform and computer storage medium for simulating and analyzing fuel sloshing noise. Background Art

[0002] In the automotive field, the objectionable sounds generated by a vehicle during conditions such as braking, turning, and creeping are generally collectively referred to as fuel sloshing noise. In the prior art, for fuel sloshing noise, a method of single-product verification combined with subjective evaluation is generally used for monitoring. If there is fuel sloshing noise, iterative optimization is achieved by continuously changing the structure, but this is often time-consuming and laborious, and the effect is not ideal. In existing fuel sloshing noise simulation analysis methods, some use the radiation sound of the fuel tank shell as the evaluation criterion, which does not match the generation mechanism of fuel sloshing noise and the reliability of the calculation results is poor; while some require complete vehicle data to complete the calculation, but in the early stage of actual vehicle development, it is often difficult to obtain complete vehicle data, which affects the vehicle development efficiency. Summary of the Invention

[0003] The purpose of the present invention is to provide a method, platform and computer storage medium for simulating and analyzing fuel sloshing noise, which can quickly and accurately predict fuel sloshing noise without vehicle data, improve vehicle development efficiency and reduce vehicle development costs.

[0004] To achieve the above object, the technical solution of the present invention is realized as follows:

[0005] In a first aspect, an embodiment of the present invention provides a method for simulating and analyzing fuel sloshing noise, the method comprising:

[0006] Establishing a noise simulation model according to the input fuel tank data of the vehicle; wherein, the fuel tank data at least includes strap data, shock pad data and anti-sloshing plate data;

[0007] Obtaining the surface vibration data of the fuel tank shell and the nodal reactions at the surfaces of the shock pads and the strap mounting points corresponding to the output of the noise simulation model according to the input boundary conditions; wherein, the boundary conditions include the fuel tank liquid level and the driving conditions;

[0008] Obtaining the fuel sloshing noise value based on a pre-designed calculation rule according to the surface vibration data of the fuel tank shell and the nodal reactions at the surfaces of the shock pads and the strap mounting points.

[0009] As one implementation manner, the obtaining the fuel sloshing noise value based on a pre-designed calculation rule according to the surface vibration data of the fuel tank shell and the nodal reactions at the surfaces of the shock pads and the strap mounting points includes:

[0010] Obtain the radiated noise value of the fuel tank housing based on the surface vibration data of the fuel tank housing;

[0011] Calculate the fuel sloshing noise value P according to the formula P = A*X + B*2*Y, where A and B are preset weighting coefficients, X is the radiated noise value of the fuel tank housing, and Y is the maximum value between the nodal reaction force value on the surface of the shock pad and the nodal reaction force value at the strap mounting point.

[0012] As one implementation, A is 0.2 and B is 0.8.

[0013] As one implementation, it further includes:

[0014] When the fuel sloshing noise value meets the preset conditions, determine that the fuel sloshing noise is qualified; and / or,

[0015] When the fuel sloshing noise value does not meet the preset conditions, determine that the fuel sloshing noise is unqualified.

[0016] As one implementation, the preset condition is that the radiated noise value of the fuel tank housing is less than or equal to a preset noise threshold.

[0017] As one implementation, before establishing the noise simulation model based on the input fuel tank data of the vehicle, it further includes:

[0018] Perform mesh division on the input fuel tank data of the vehicle to establish a noise simulation model based on the fuel tank data after mesh division.

[0019] As one implementation, before performing mesh division on the input fuel tank data of the vehicle, it further includes:

[0020] Perform preset geometric processing on the input fuel tank data.

[0021] As one implementation, the preset geometric processing at least includes coincident surface processing and interface processing.

[0022] In a second aspect, an embodiment of the present invention provides a fuel sloshing noise simulation analysis platform, which includes a processor and a memory for storing a program; when the program is executed by the processor, the processor implements the fuel sloshing noise simulation analysis method described in the first aspect.

[0023] In a third aspect, an embodiment of the present invention provides a computer storage medium storing a computer program, which when executed by a processor, implements the fuel sloshing noise simulation analysis method described in the first aspect.

[0024] The fuel sloshing noise simulation analysis method, platform and computer storage medium provided by the embodiments of the present invention, the method comprising: establishing a noise simulation model according to the input fuel tank data of a vehicle; wherein the fuel tank data at least includes strap data, shock pad data and anti-sloshing plate data; obtaining the vibration data of the fuel tank housing surface and the nodal reactions at the shock pad surface and the strap mounting points corresponding to the output of the noise simulation model according to the input boundary conditions; wherein the boundary conditions include the fuel tank liquid level and the driving conditions; obtaining the fuel sloshing noise value based on a pre-designed calculation rule according to the vibration data of the fuel tank housing surface and the nodal reactions at the shock pad surface and the strap mounting points. In this way, the fuel sloshing noise value can be directly calculated according to the fuel tank data of the vehicle and the input boundary conditions, that is, the two major transmission paths of fuel sloshing noise are included and without the need for vehicle data, the fuel sloshing noise can be predicted quickly and accurately, improving the vehicle R & D efficiency, shortening the vehicle R & D cycle and reducing the vehicle R & D cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic flow chart of the fuel sloshing noise simulation analysis method provided by the embodiments of the present invention;

[0026] Figure 2 is a schematic structural diagram of the fuel sloshing noise simulation analysis platform provided by the embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0028] It should be noted that, in this document, the terms "include", "comprise" or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article or device including a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "including a..." does not exclude the presence of additional identical elements in the process, method, article or device including the element. In addition, components, features, elements with the same name in different embodiments of the present application may have the same meaning or different meanings, and their specific meanings need to be determined by their explanations in the specific embodiments or further combined with the context in the specific embodiments.

[0029] It should be understood that although the terms first, second, third, etc. may be used herein to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this document, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "when" or "while" or "in response to determining". Furthermore, as used in this document, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context indicates otherwise. It should be further understood that the terms "comprising", "including" indicate the presence of the stated features, steps, operations, elements, components, items, kinds, and / or groups, but do not preclude the presence, occurrence, or addition of one or more other features, steps, operations, elements, components, items, kinds, and / or groups. The terms "or" and "and / or" as used herein are interpreted as inclusive, meaning any one or any combination. Thus, "A, B, or C" or "A, B, and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B, and C". An exception to this definition occurs only when the combination of elements, functions, steps, or operations is inherently mutually exclusive in some way.

[0030] It should be understood that although the steps in the flowchart in the embodiments of this application are shown sequentially according to the indication of the arrows, these steps are not necessarily executed sequentially in the order indicated by the arrows. Unless there is a clear indication in this document, the execution of these steps has no strict order limitation, and they can be executed in other orders. Moreover, at least a part of the steps in the figure may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed alternately or in turn with at least a part of other steps or sub-steps or stages of other steps.

[0031] It should be noted that in this document, step codes such as S101, S102, etc. are used. The purpose is to more clearly and briefly express the corresponding content and do not constitute a substantial limitation in terms of order. Those skilled in the art may execute S102 first and then S101, etc. during specific implementation, but these should all be within the protection scope of this application.

[0032] It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0033] In the following description, suffixes such as "module", "component", or "unit" used to represent elements are only for facilitating the description of the present application, and have no specific meaning in themselves. Therefore, "module", "component", or "unit" can be used interchangeably.

[0034] See Figure 1 , which is a schematic flowchart of the fuel sloshing noise simulation analysis method provided by an embodiment of the present invention. This fuel sloshing noise simulation analysis method can be executed by a fuel sloshing noise simulation analysis platform provided by an embodiment of the present invention. This platform can be implemented in software and / or hardware. The fuel sloshing noise simulation analysis method includes the following steps:

[0035] Step S101: Establish a noise simulation model based on the input fuel tank data of the vehicle; wherein, the fuel tank data at least includes strap data, shock pad data, and anti-sloshing plate data;

[0036] In this embodiment, taking the establishment of a noise simulation model based on the simulation analysis software Intesim as an example, after opening the Intesim software, the fuel tank data of the vehicle is input into the Intesim software to establish a noise simulation model. Here, the fuel tank data of the vehicle is 3D data.

[0037] In one embodiment, before establishing the noise simulation model based on the input fuel tank data of the vehicle, it may further include: performing mesh division on the input fuel tank data of the vehicle to establish a noise simulation model based on the fuel tank data after mesh division. Here, the user can input the mesh size as needed to perform mesh division on the fuel tank data of the vehicle, thereby improving the efficiency and accuracy of subsequent calculations. In this embodiment, taking the mesh division based on the simulation analysis software Hypermesh as an example, after Hypermesh software performs mesh division on the fuel tank data of the vehicle, the fuel tank data after mesh division is sent to the Intesim software to establish a noise simulation model. In addition, before performing mesh division on the input fuel tank data of the vehicle, it may further include: performing preset geometric processing on the input fuel tank data. Here, the Hypermesh software can be used to perform preset geometric processing on the input fuel tank data to improve the quality of the fuel tank data, thereby improving the efficiency of subsequent calculations. Among them, the preset geometric processing includes but is not limited to coincidence surface processing and interface processing, etc.

[0038] Step S102: Obtain the vibration data of the fuel tank shell surface and the nodal reactions at the shock pad surface and the strap mounting points corresponding to the output of the noise simulation model according to the input boundary conditions; wherein, the boundary conditions include the fuel tank liquid level and the driving conditions;

[0039] Here, the fuel tank liquid level and the driving conditions can be set according to actual needs. The fuel tank liquid level can be a specific value such as 10 L, 30 L, etc., or a relative value such as one-fifth, three-fourths of the total height of the fuel tank. The driving conditions can be left turn, right turn, braking, high-speed driving, low-speed driving and other conditions. In this embodiment, taking the vibration data on the surface of the fuel tank housing and the nodal reactions at the surface of the shock pad and the strap mounting points based on the simulation analysis software Intesim as an example, after inputting the boundary conditions into the Intesim software, the Intesim software obtains the vibration data on the surface of the fuel tank housing and the nodal reactions at the surface of the shock pad and the strap mounting points corresponding to the output of the noise simulation model. It should be noted that the nodal reactions at the surface of the shock pad and the nodal reactions at the strap mounting points both vary with time and have maximum and minimum values respectively.

[0040] Step S103: Based on a pre-designed calculation rule, obtain the fuel sloshing noise value according to the vibration data on the surface of the fuel tank housing and the nodal reactions at the surface of the shock pad and the strap mounting points.

[0041] Specifically, the obtaining of the fuel sloshing noise value based on a pre-designed calculation rule according to the vibration data on the surface of the fuel tank housing and the nodal reactions at the surface of the shock pad and the strap mounting points includes: obtaining the radiation noise value of the fuel tank housing according to the vibration data on the surface of the fuel tank housing; calculating the fuel sloshing noise value P according to the formula P = A*X + B*2*Y, where A and B are preset weighting coefficients, X is the radiation noise value of the fuel tank housing, and Y is the maximum value between the nodal reaction value at the surface of the shock pad and the nodal reaction value at the strap mounting point.

[0042] It should be noted that the radiation noise value of the fuel tank housing refers to the numerical part of the radiation noise of the fuel tank housing, without including the unit dB. Correspondingly, the nodal reaction value at the surface of the shock pad and the nodal reaction value at the strap mounting point also refer to the numerical parts of the corresponding nodal reactions, without including the unit N. And Y is actually the maximum value between the maximum nodal reaction value at the surface of the shock pad and the maximum nodal reaction value at the strap mounting point. Among them, the values of the preset weighting coefficients A and B can be set according to actual needs. In this embodiment, A is taken as 0.2 and B is taken as 0.8 as an example. In this embodiment, taking the obtaining of the radiation noise value of the fuel tank housing according to the vibration data on the surface of the fuel tank housing based on the simulation analysis software Virtual Lab as an example, and calculating the fuel sloshing noise value based on the simulation analysis software Python.

[0043] Optionally, the method may further include: determining that the fuel sloshing noise is qualified when the fuel sloshing noise value meets a preset condition; and / or determining that the fuel sloshing noise is unqualified when the fuel sloshing noise value does not meet the preset condition. Specifically, after obtaining the fuel sloshing noise value, it is determined whether the fuel sloshing noise value meets the preset condition. If the fuel sloshing noise value meets the preset condition, it is determined that the fuel sloshing noise is qualified; if the fuel sloshing noise value does not meet the preset condition, it is determined that the fuel sloshing noise is unqualified. Among them, the preset condition can be set according to actual needs. For example, the preset condition is that the fuel sloshing noise value is less than or equal to a preset noise threshold, and the preset noise threshold can be equal to or greater than 50, etc.

[0044] In summary, in the fuel sloshing noise simulation analysis method provided in the above embodiments, without the need for vehicle data, only a noise simulation model needs to be established based on the fuel tank data of the vehicle, and then the fuel sloshing noise under different fuel tank liquid levels and different driving conditions can be obtained based on the noise simulation model. That is, without the need for vehicle data and covering the two major transmission paths of fuel sloshing noise, the fuel sloshing noise can be predicted quickly and accurately, improving the vehicle R & D efficiency, shortening the vehicle R & D cycle and reducing the vehicle R & D cost.

[0045] Based on the same inventive concept as the foregoing embodiments, this embodiment details the technical solutions of the foregoing embodiments through specific examples. The specific process of the fuel sloshing noise simulation analysis method provided in the embodiments of the present invention mainly includes:

[0046] 1) Import the fuel tank data (including straps, shock pads, anti-surge plates, etc.) into the simulation analysis pre-processing software Hypermesh to complete geometric processing and mesh generation;

[0047] 2) Import the mesh processed by the simulation analysis pre-processing software Hypermesh into the simulation analysis software Intesim to establish a simulation model, and after completing the boundary settings, calculate the vibration data on the surface of the fuel tank shell and the nodal reactions on the strap mounting points and the surfaces of the shock pads;

[0048] 3) Use the simulation analysis software Virtual Lab to calculate the radiated noise of the fuel tank shell based on the vibration data on the surface of the fuel tank shell;

[0049] 4) Use the simulation analysis software Python to calculate the fuel sloshing noise P based on the set fitting formula P = A*X + B*2*Y, where A and B are preset weighting coefficients with A = 0.2 and B = 0.8, X is the radiation noise of the fuel tank shell, and Y is the maximum value between the node reaction force on the surface of the shock pad and the node reaction force at the strap mounting point; here, X is generally 40 dB to 60 dB, and Y is generally 20 N to 70 N. Only the numerical part is taken during the calculation.

[0050] 4) If the fuel sloshing noise P is greater than 50, it is considered unqualified; if the fuel sloshing noise P is less than or equal to 50, it is considered qualified.

[0051] In summary, in the fuel sloshing noise simulation analysis method provided by this embodiment, complete vehicle body data is not required, and still includes the two major transmission paths of fuel sloshing noise. It can accurately evaluate the fuel sloshing noise at the stage of incomplete vehicle body data, saving laboratory resources and reducing test costs, and meeting the engineering mechanism; secondly, it improves the optimization efficiency of key components of fuel sloshing noise and reduces the development cost; in addition, it advances the evaluation time of the fuel sloshing noise risk level in the whole vehicle development process, shortens the development cycle, and improves the iteration efficiency.

[0052] Based on the same inventive concept as the foregoing embodiment, an embodiment of the present invention provides a fuel sloshing noise simulation analysis platform, as Figure 2 shown. The platform includes: a processor 110 and a memory 111 for storing a computer program that can run on the processor 110; wherein, Figure 2 The processor 110 shown does not refer to the number of processors 110 being one, but only refers to the positional relationship of the processor 110 relative to other devices. In actual applications, the number of processors 110 can be one or more; similarly, Figure 2 The memory 111 shown has the same meaning, that is, it only refers to the positional relationship of the memory 111 relative to other devices. In actual applications, the number of memories 111 can be one or more. When the processor 110 is used to run the computer program, the fuel sloshing noise simulation analysis method is implemented.

[0053] The platform may further include: at least one network interface 112. Each component in the platform is coupled together through a bus system 113. It can be understood that the bus system 113 is used to realize the connection and communication between these components. The bus system 113 includes not only a data bus, but also a power bus, a control bus, and a status signal bus. However, for the sake of clear illustration, in Figure 2 all kinds of buses are labeled as the bus system 113.

[0054] Among them, the memory 111 can be a volatile memory or a non-volatile memory, or can include both volatile and non-volatile memories. Among them, the non-volatile memory can be a read-only memory (ROM, Read Only Memory), a programmable read-only memory (PROM, Programmable Read-Only Memory), an erasable programmable read-only memory (EPROM, Erasable Programmable Read-Only Memory), an electrically erasable programmable read-only memory (EEPROM, Electrically Erasable Programmable Read-Only Memory), a ferromagnetic random access memory (FRAM, ferromagnetic random access memory), a flash memory (Flash Memory), a magnetic surface memory, an optical disc, or a compact disc read-only memory (CD-ROM, Compact Disc Read-Only Memory); the magnetic surface memory can be a disk memory or a tape memory. The volatile memory can be a random access memory (RAM, Random Access Memory), which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as a static random access memory (SRAM, Static Random Access Memory), a synchronous static random access memory (SSRAM, Synchronous Static Random Access Memory), a dynamic random access memory (DRAM, Dynamic Random Access Memory), a synchronous dynamic random access memory (SDRAM, Synchronous Dynamic Random Access Memory), a double data rate synchronous dynamic random access memory (DDR SDRAM, Double Data Rate Synchronous Dynamic Random Access Memory), an enhanced synchronous dynamic random access memory (ESDRAM, Enhanced Synchronous Dynamic Random Access Memory), a sync link dynamic random access memory (SLDRAM, SyncLink Dynamic Random Access Memory), a direct rambus random access memory (DRRAM, Direct Rambus Random Access Memory).The memory 111 described in the embodiments of the present invention is intended to include, but is not limited to, these and any other suitable types of memory.

[0055] The memory 111 in the embodiments of the present invention is used to store various types of data to support the operation of the platform. Examples of such data include: any computer programs for operating on the platform, such as operating systems and application programs; contact data; phone book data; messages; pictures; videos, etc. Among them, the operating system contains various system programs, such as the framework layer, the core library layer, the driver layer, etc., for implementing various basic services and processing hardware-based tasks. The application programs can include various application programs, such as a Media Player, a Browser, etc., for implementing various application services. Here, the program for implementing the method of the embodiments of the present invention can be included in the application programs.

[0056] Based on the same inventive concept as the foregoing embodiments, this embodiment also provides a computer storage medium. The computer storage medium stores a computer program. The computer storage medium can be a ferromagnetic random access memory (FRAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory, a magnetic surface memory, an optical disc, or a compact disc read-only memory (CD-ROM), etc.; it can also be various devices including one or any combination of the above memories, such as a mobile phone, a computer, a tablet device, a personal digital assistant, etc. When the computer program stored in the computer storage medium is run by a processor, the above-mentioned fuel sloshing noise simulation analysis method is implemented. For the specific step flow implemented when the computer program is executed by the processor, please refer to Figure 1 the description of the illustrated embodiments, which will not be repeated here.

[0057] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0058] In this text, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion. In addition to the elements listed, it may also include other elements not specifically listed.

[0059] As described above, it is only a specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claimed rights.

Claims

1. A simulation analysis method for fuel sloshing noise, characterized in that, The method includes: Establishing a noise simulation model based on the input fuel tank data of the vehicle; wherein, the fuel tank data at least includes strap data, shock pad data, and anti-surge plate data; Obtaining the vibration data of the fuel tank shell surface and the nodal reaction forces of the shock pad surface and the strap mounting points corresponding to the output of the noise simulation model according to the input boundary conditions; wherein, the boundary conditions include fuel tank liquid level and driving conditions; Obtaining the fuel sloshing noise value based on a pre-designed calculation rule according to the vibration data of the fuel tank shell surface and the nodal reaction forces of the shock pad surface and the strap mounting points; The obtaining the fuel sloshing noise value based on a pre-designed calculation rule according to the vibration data of the fuel tank shell surface and the nodal reaction forces of the shock pad surface and the strap mounting points includes: Obtaining the radiated noise value of the fuel tank shell according to the vibration data of the fuel tank shell surface; Calculating the fuel sloshing noise value P according to the formula P = A * X + B * 2 * Y, where A and B are preset weighting coefficients, X is the radiated noise value of the fuel tank shell, and Y is the maximum value between the nodal reaction force value of the shock pad surface and the nodal reaction force value of the strap mounting point.

2. The method according to claim 1, characterized in that A is 0.2 and B is 0.

8.

3. The method according to claim 1, wherein It further includes: When the fuel sloshing noise value meets the preset condition, determining that the fuel sloshing noise is qualified; And / or, When the fuel sloshing noise value does not meet the preset condition, determining that the fuel sloshing noise is unqualified.

4. The method according to claim 3, characterized in that, The preset condition is that the fuel sloshing noise value is less than or equal to a preset noise threshold.

5. The method according to claim 1, characterized in that Before establishing the noise simulation model based on the input fuel tank data of the vehicle, it further includes: Performing mesh division on the input fuel tank data of the vehicle to establish a noise simulation model according to the fuel tank data after mesh division.

6. The method according to claim 5, wherein Before performing mesh division on the input fuel tank data of the vehicle, it further includes: Performing preset geometric processing on the input fuel tank data.

7. The method according to claim 6, characterized in that, The preset geometric processing at least includes coincident surface processing and interface processing.

8. A fuel sloshing noise simulation and analysis platform, characterized in that, The platform includes a processor and a memory for storing programs; when the program is executed by the processor, the processor implements the fuel sloshing noise simulation analysis method as described in any one of claims 1 to 7.

9. A computer storage medium, characterized in that, A computer program is stored, and when the computer program is executed by a processor, it implements the fuel sloshing noise simulation analysis method as described in any one of claims 1 to 7.

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