CN112311640A

CN112311640A - Vehicle-mounted CAN bus communication network and vehicle

Info

Publication number: CN112311640A
Application number: CN202011154288.XA
Authority: CN
Inventors: 黄榆彬; 韦仁; 何晔; 胡耀
Original assignee: Baoneng Guangzhou Automobile Research Institute Co Ltd
Current assignee: Baoneng Guangzhou Automobile Research Institute Co Ltd
Priority date: 2020-10-26
Filing date: 2020-10-26
Publication date: 2021-02-02

Abstract

The invention discloses a vehicle-mounted CAN bus communication network and a vehicle, wherein the vehicle-mounted CAN bus communication network comprises a first terminal node, a second terminal node and at least one secondary terminal node, the first terminal node, the second terminal node and the at least one secondary terminal node are communicated through a CAN bus network, and a first resistor and a second resistor with equal resistance values are respectively connected in parallel between a CAN _ H and a CAN _ L which are connected with the first terminal node and the second terminal node; and a third resistor is connected in parallel between the CAN _ H and the CAN _ L of each secondary terminal node, wherein the resistance value and the number of the third resistor are determined according to the resistance value of the first resistor or the second resistor and the number of the secondary terminal nodes, so that the resistance value after the first resistor, the second resistor and the third resistor are connected in parallel is equal to a preset value. Therefore, the vehicle-mounted CAN bus communication network CAN lead the wiring of the whole vehicle wire harness to be free from constraint, and simultaneously improve the transmission quality of CAN bus signals.

Description

Vehicle-mounted CAN bus communication network and vehicle

Technical Field

The invention relates to the technical field of vehicle control, in particular to a vehicle-mounted CAN bus communication network and a vehicle.

Background

At present, a Controller Area Network (CAN) bus is generally used in a vehicle on the market as a main Network for communication between electronic control units of the vehicle, and in order to match characteristic impedance of a twisted pair used for signal transmission of a CAN bus signal, resistance between CAN _ H and CAN _ L of the CAN bus is about 60 ohms.

In the related technology, the terminal electronic control unit of the adopted bus type network is selected as the two farthest electronic control units on the network, the terminal electronic control units are connected in parallel with resistors with the resistance value of about 120 ohms on the CAN _ H and the CAN _ L of the CAN bus interface circuit, other non-terminal electronic control units are not connected in parallel with resistors with any resistance value, and the two resistors with the resistance value of about 120 ohms are connected in parallel on the CAN bus, namely the resistor between the CANH and the CANL of the CAN bus is about 60 ohms. Designed according to the requirement, the distance from the non-terminal electronic control unit to the trunk network cannot exceed 1.7 meters, the requirement of meeting the SAE J2283-3 standard is met, and if the length of the non-terminal electronic control unit exceeds 1.7 meters, signal reflection can affect the quality of bus signals, thereby affecting the communication of the electronic control unit.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, an object of the present invention is to provide a vehicle-mounted CAN bus communication network, which CAN allow wiring of a complete vehicle harness to be unconstrained and improve transmission quality of CAN bus signals.

A second object of the invention is to propose a vehicle.

In order to achieve the above object, a first aspect of the present invention provides a vehicle-mounted CAN bus communication network, which includes a first terminal node, a second terminal node, and at least one secondary terminal node, where the first terminal node, the second terminal node, and the at least one secondary terminal node communicate with each other through a CAN bus network, and a first resistor and a second resistor with equal resistance values are connected in parallel between a CAN _ H and a CAN _ L connecting the first terminal node and the second terminal node, respectively; and a third resistor is connected in parallel between the CAN _ H and the CAN _ L of each secondary terminal node, wherein the resistance value and the number of the third resistor are determined according to the resistance value of the first resistor or the second resistor and the number of the secondary terminal nodes, so that the resistance value after the first resistor, the second resistor and the third resistor are connected in parallel is equal to a preset value.

The vehicle-mounted CAN bus communication network comprises a first terminal node, a second terminal node and at least one secondary terminal node, wherein the first terminal node, the second terminal node and the at least one secondary terminal node are communicated through a CAN bus network, a first resistor and a second resistor which are equal in resistance value are respectively connected in parallel between CAN _ H and CAN _ L which are connected with the first terminal node and the second terminal node, a third resistor is connected in parallel between CAN _ H and CAN _ L of each secondary terminal node, and the resistance value of the third resistor needs to be determined according to the resistance value of the first resistor or the second resistor and the number of the secondary terminal nodes, so that the resistance value of the first resistor, the second resistor and the third resistor which are connected in parallel is equal to a preset value. Therefore, the vehicle-mounted CAN bus communication network CAN lead the wiring of the whole vehicle wire harness to be free from constraint, and simultaneously improve the transmission quality of CAN bus signals.

In some examples of the present invention, the resistance value of the third resistor is calculated according to the following formula:

wherein n is the total number of nodes in the CAN bus communication network, n is more than 2, R is the resistance value of the third resistor, and R is the resistance value of the first resistor or the second resistor.

In some examples of the invention, the first resistor, the second resistor and the third resistor are all designed following a separation principle.

In some examples of the present invention, the first resistor, the second resistor, and the third resistor are each formed by connecting two resistors in series.

In some examples of the invention, the third resistor is composed of two resistors connected in series, and a first node is arranged between the two resistors connected in series and is connected to the ground through a first capacitor.

In some examples of the invention, the first resistor and the second resistor are each formed by two resistors in series, with a second node between the two resistors in series, the second node being connected to ground through a second capacitor, and the second node being connected to a split pin of a CAN transceiver in a respective terminal node.

In some examples of the invention, the CAN bus comprises a CAN _ H bus and a CAN _ L bus.

To achieve the above object, an embodiment of a second aspect of the present invention provides a vehicle including an on-vehicle CAN bus communication network as described in the above embodiments.

According to the vehicle provided by the embodiment of the invention, the wiring of the whole vehicle wire harness is not restricted through the vehicle-mounted CAN bus communication network in the embodiment, and the transmission quality of CAN bus signals is improved.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

FIG. 1 is a schematic diagram of an on-board CAN bus communication network in accordance with one embodiment of the present invention;

FIG. 2 is a schematic diagram of a CAN bus structure and a first resistor structure in accordance with one embodiment of the present invention;

FIG. 3 is a schematic diagram of a third resistor structure in accordance with one embodiment of the present invention;

fig. 4 is a schematic diagram of the first resistor and second resistor structure in accordance with one embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

An in-vehicle CAN bus communication network and a vehicle of an embodiment of the present invention are described below with reference to the drawings.

Fig. 1 is a schematic diagram of an on-board CAN bus communication network according to an embodiment of the present invention.

In this embodiment, the in-vehicle CAN bus communication network comprises a first end node 01, a second end node n and at least one secondary end node, in particular, as shown in fig. 1, the secondary end node may comprise a secondary end node 02, a secondary end node 03, …, a secondary end node n-1. The first terminal node 01, the second terminal node n and the at least one secondary terminal node communicate via a CAN bus network, and it should be noted that fig. 1 only shows a single connection line, but it CAN be understood that the connection line includes a CAN _ H bus and a CAN _ L bus of the CAN bus.

It should be noted that the design structure of the vehicle-mounted CAN bus communication network in this embodiment may also be designed as a star network structure, a daisy network structure, or the like.

In this embodiment, referring to fig. 1, a first resistor R1 and a second resistor Rn with equal resistance values are respectively connected in parallel between CAN _ H and CAN _ L connected to the first terminal node 01 and the second terminal node n, and as CAN be understood from fig. 2 by taking the first resistor R1 as an example, the first resistor R1 is connected between CAN _ H and CAN _ L, and the second resistor Rn is also connected between CAN _ H and CAN _ L in the same manner.

In each secondary terminal node, a third resistor R3 is connected in parallel between CAN _ H and CAN _ L as shown in fig. 1, it being understood that a third resistor R3 is also connected between CAN _ H and CAN _ L in the same manner as shown in fig. 2. It should be noted that the resistance of the third resistor R3 is determined according to the resistance of the first resistor R1 or the second resistor Rn and the number of the secondary terminal nodes, so that the resistance of the first resistor R1, the second resistor Rn and the third resistor R3 after being connected in parallel is equal to a preset value.

Specifically, during the transmission of the CAN bus signal, after the signal is transmitted to the node, the signal may be reflected on the node due to impedance discontinuity, so that corresponding resistors need to be connected to the first CAN bus and the second CAN bus, so that the CAN bus CAN solve the impedance discontinuity after the resistors are connected. Since the twisted pair characteristic impedance of the CAN bus signal is 60 ohms, in this embodiment, the resistance values of the first resistor R1, the second resistor Rn, and the third resistor R3 after being connected in parallel may be infinitely close to 60 ohms, that is, the preset value in this embodiment is 60 ohms.

In this embodiment, the resistance value of the third resistor R3 is calculated according to the following formula

Specifically, since the characteristic impedance of the twisted pair for transmitting the CAN bus signal is 60 ohms, the resistance value of the first resistor R1, the second resistor Rn and the third resistor R3 after being connected in parallel is set to be 60 ohms, as CAN be seen from fig. 1 and 2, the first resistor R1, the second resistor Rn and the third resistor R3 are connected in parallel, and the resistance values of the first resistor R1, the second resistor Rn and the third resistor R3 after being connected in parallel are calculated according to a resistor parallel formula

Wherein, R is the resistance of the first resistor R1 and the second resistor Rn, R is the resistance of the third resistor R3, and the resistance of the third resistor can be obtained after simplification

It should be noted that when n is 2, the resistance value of the third resistor R3 is 0, that is, the secondary terminal node is not provided in this example, and only the first terminal node and the second terminal node are provided.

In some examples of the invention, the first resistor and the second resistor have a resistance of 129.8 ohms, and the first resistor, the second resistor and the third resistor have a resistance of 60.5 ohms after being connected in parallel.

Specifically, for example, the above embodiment is further described by taking the node number in the CAN bus communication network as 12, in this embodiment, n is 12, R is 129.8 ohms, and after the calculation is performed by the above formula, the resistance R of the third resistor R3 is obtained to be approximately equal to 7947 ohms, so as long as the third resistor R3 with a resistance of 7947 ohms is provided at each secondary terminal node, the resistance of the CAN bus CAN be finally maintained at about 60 ohms, and in this embodiment, the resistance of the first resistor, the second resistor, and the third resistor connected in parallel is 60.5 ohms, which is close to the characteristic impedance of the twisted pair for transmitting the CAN bus signal, and is 60 ohms.

In addition, it should be noted that, in an ideal state, the parallel resistances of the first CAN bus and the second CAN bus at the two nodes of the first terminal node R1 and the second terminal node Rn are 120 ohms, but in practical applications, since the resistances have errors due to process problems, it is necessary to select a resistance greater than 120 ohms in order to further improve accuracy. In this embodiment, the first resistor R1 and the second resistor Rn are both selected to have a resistance of 129.8 ohms.

In some examples of the invention, the first resistor, the second resistor and the third resistor are all designed following the principle of separation. In this embodiment, the first resistor, the second resistor and the third resistor are all connected in series.

Because the resistance of the resistor manufactured in the existing industrial level is generally not fixed, the resistances of the first resistor, the second resistor and the third resistor can be matched in a separation mode, so that the resistances of the first resistor, the second resistor and the third resistor can reach the values obtained by the formula, and the resistor precision is improved. Taking the first resistor as an example, as shown in fig. 2, the first resistor R1 is designed according to the principle of separation, and the first resistor R1 is set as two resistors R0 with the same resistance value in series. For example, the resistance R of the third resistor R3 is 7947 ohms in the above embodiment, but since the resistor with the resistance of 7947 ohms is not available in the existing industrial manufacturing resistors, two resistors with the resistance of 4020 ohms can be connected in series to obtain an 8040 ohms resistor which is not much different from 7947 ohms.

In this embodiment, as shown in fig. 3, the third resistor is composed of two resistors connected in series, and a first node is provided between the two resistors connected in series, and the first node is connected to ground through the first capacitor. As shown in fig. 4, the first resistor and the second resistor are both composed of two resistors connected in series, a second node is arranged between the two resistors connected in series, the second node is connected to ground through a second capacitor, and the second node is connected to a split pin of the CAN transceiver in the corresponding terminal node.

Specifically, in this embodiment, as can be seen from fig. 3, a first node is disposed between two resistors R0 forming the third resistor R3, and the first node is connected to the first capacitor C1 and then grounded, wherein the capacitor C1 can be made to perform a filtering function by utilizing the characteristics of the capacitor for conducting alternating current and blocking direct current. In fig. 4, a first resistor R1 is taken as an example, wherein a second node is disposed between two resistors R0 constituting the first resistor R1, and the second node is connected to a second capacitor C2 and then grounded, and CAN also play a role of filtering, and CAN also be connected to a split pin of the CAN transceiver through the second node.

In summary, the vehicle-mounted CAN bus communication network of the embodiment of the invention CAN lead the wiring of the whole vehicle wire harness to be free from restriction, and simultaneously improve the transmission quality of CAN bus signals.

Further, the present invention proposes a vehicle including the in-vehicle CAN bus communication network in the above embodiment.

According to the vehicle provided by the embodiment of the invention, the wiring of the whole vehicle wire harness CAN be free from constraint through the vehicle-mounted CAN bus communication network in the embodiment, and the transmission quality of CAN bus signals is improved.

In addition, other configurations and functions of the vehicle according to the embodiment of the present invention are known to those skilled in the art, and are not described herein in detail to reduce redundancy.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. An in-vehicle CAN bus communication network comprising a first terminal node, a second terminal node and at least one secondary terminal node, the first terminal node, the second terminal node and the at least one secondary terminal node communicating over a CAN bus network, wherein,

a first resistor and a second resistor with equal resistance values are respectively connected in parallel between the CAN _ H and the CAN _ L which are connected with the first terminal node and the second terminal node;

and a third resistor is connected in parallel between the CAN _ H and the CAN _ L of each secondary terminal node, wherein the resistance value and the number of the third resistor are determined according to the resistance value of the first resistor or the second resistor and the number of the secondary terminal nodes, so that the resistance value after the first resistor, the second resistor and the third resistor are connected in parallel is equal to a preset value.

2. The on-board CAN bus communication network of claim 1, wherein the third resistor has a resistance value calculated according to the following formula:

3. The on-board CAN bus communication network of claim 1 or 2, wherein the first, second and third resistors are all designed following a split principle.

4. The on-board CAN bus communication network of claim 3, wherein the first resistor, the second resistor, and the third resistor are each formed by two resistors connected in series.

5. The on-board CAN bus communication network of claim 4, wherein the third resistor is comprised of two resistors connected in series with a first node therebetween, the first node being connected to ground through a first capacitor.

6. The on-board CAN bus communication network of claim 4, wherein the first resistor and the second resistor are each comprised of two resistors in series with a second node between the two resistors in series, the second node connected to ground through a second capacitor, and the second node connected to a split pin of a CAN transceiver in a respective end node.

7. The in-vehicle CAN bus communication network of claim 1, wherein the CAN bus comprises a CAN _ H bus and a CAN _ L bus.

8. A vehicle comprising an onboard CAN bus communication network according to any one of claims 1-7.