Gear shifting system and construction vehicle

Abstract

A gear shifting system and a vehicle. The gear shifting system comprises a directional control lever, a hydraulic system, and an electronic control system. A first directional control valve, a forward clutch, and a reverse clutch are provided on a directional control branch of the hydraulic system; and the first directional control valve realizes the switching between the forward clutch and the reverse clutch by means of the movement of the directional control lever. An electric control valve, a first-gear clutch, and a second-gear clutch are provided on a gear shifting branch; and in an initial state, an oil passage from the electric control valve to the second-gear clutch remains open, so that the second-gear clutch is engaged when a vehicle is started. A controller of the electronic control system controls the switching between the first-gear clutch and the second-gear clutch on the basis of a speed signal measured by a speed sensor assembly.

Description

Gear shifting system and engineering vehicle

[0001] This application claims priority to Chinese patent application No. 202410013850.9 filed on January 2, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application relates to the technical field of engineering machinery, and in particular to a gear shifting system and a vehicle. Background Art

[0003] Construction machinery such as loaders, forklifts, and tractors typically shift gears manually, requiring at least two levers: a directional lever and a gear lever. This makes shifting less convenient. Loaders, for example, require frequent direction changes during operation, and the operator must also adjust gears based on the operating conditions, making the operation complex and demanding. Configuring fully automatic shifting systems for construction machinery is expensive. Technical issues

[0004] In view of this, the embodiments of the present application are dedicated to providing a semi-automatic gear shifting system, which can achieve directional shifting and gear changing by operating only one operating lever, reducing the complexity of the gear shifting operation. It is used in engineering machinery that requires frequent directional shifting and gear changing, which can reduce the driver's operating intensity. Compared with the fully automatic gear shifting system, it has a simple structure and low cost. Technical Solutions

[0005] On one hand, the present application provides a shifting system, including a reversing operating lever, a hydraulic system, and an electronic control system. The hydraulic system includes a reversing branch and a shifting branch, both connected to a hydraulic pump and arranged in parallel. The reversing branch is provided with a first reversing valve, a forward clutch, and a reverse clutch. The first reversing valve realizes the switching of the forward clutch and the reverse clutch by moving the reversing operating lever.

[0006] The shift branch is provided with an electronically controlled valve, a first-gear clutch, and a second-gear clutch, and in an initial state, the oil passage from the electronically controlled valve to the second-gear clutch is in a conducting state, so that the second-gear clutch is engaged when the vehicle starts;

[0007] The electronic control system includes a controller and a speed sensor assembly. The controller controls the switching of the first-gear clutch and the second-gear clutch according to a speed signal measured by the speed sensor assembly.

[0008] In one possible embodiment, the speed sensor assembly includes a first speed sensor for measuring the engine output speed and a second speed sensor for measuring the transmission output speed, and the controller of the electronic control system controls the electronically controlled valve based on the detection information of the first speed sensor and the detection information of the second speed sensor.

[0009] In one possible implementation, when the output speed of the transmission shows a continuous downward trend and is lower than a first preset value, the controller regulates the electronically controlled valve to engage the first-gear clutch; when the output speed of the engine is within a preset range and the output speed of the transmission shows a continuous increasing trend and is higher than a second preset value, the controller re-engages the second-gear clutch; wherein the first preset value is greater than the second preset value.

[0010] In a possible implementation, the controller of the electronic control system controls the electronically controlled valve according to a speed value of the output speed of the engine, a speed value of the output speed of the transmission, and an acceleration of the output speed of the transmission.

[0011] In one possible embodiment, the electrically controlled valve is an electro-hydraulic reversing valve, comprising a normally closed solenoid valve body and a hydraulically controlled reversing valve body connected to the normally closed solenoid valve body. The normally open oil circuit of the hydraulically controlled reversing valve body is connected to the second-gear clutch. When the normally closed solenoid valve body is turned on, the oil circuit of the hydraulically controlled reversing valve body is switched, so that the first-gear clutch is engaged and the second-gear clutch is disconnected.

[0012] In a possible implementation manner, accumulators are provided on the oil circuits connecting the first reversing valve and the forward clutch and the reverse clutch.

[0013] In one possible embodiment, the output port of the hydraulic pump is provided with a first oil circuit and a second oil circuit in parallel, the first oil circuit is provided with a brake assembly and the reversing branch and the shifting branch connected in parallel at the output end of the brake assembly, and the second oil circuit is provided with a first pressure regulating valve, a torque converter, a second pressure regulating valve and a cooler in sequence.

[0014] The present application also provides an engineering vehicle, comprising a gear shifting system as described in any one of the above items.

[0015] On the other hand, the present application further provides a shifting method for an engineering vehicle, which is applicable to the above-mentioned shifting system. The shifting method includes the following contents:

[0016] Control the vehicle to start at the second gear speed position;

[0017] The controller collects a speed signal and adjusts the speed gear according to the speed signal, wherein the speed signal at least includes output speed information of the engine and output speed information of the gearbox.

[0018] In a possible implementation, the following contents are also included:

[0019] The speed signal also includes acceleration information of the transmission output speed. Beneficial effects

[0020] The shifting system provided by the present application switches the driving direction via a first reversing valve, which is directly implemented by a manually operated reversing lever, forming a mechanical control structure. The speed gear shifting is automatically controlled by an electronic control system measuring a speed signal, without the need for driver involvement. This is the automatic control portion, requiring only a single joystick to achieve directional shifting operations. This makes operation simple, time-saving, and error-free. Furthermore, the semi-automatic combination structure is less expensive, more durable, and easier to maintain than a fully automatic shifting system. It also has high adaptability to adverse operating conditions and is highly suitable for engineering vehicles that require frequent directional shifting. Furthermore, in the present application, the vehicle is started directly in second gear. For engineering vehicles, the engine power is sufficient to support second-gear starting, so starting directly in second gear eliminates the need to start in first gear and then switch to second gear, further simplifying the shifting operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a diagram showing the components of a shift system according to an embodiment of the present application;

[0022] FIG2 is a diagram showing the relationship between traction and vehicle speed in an embodiment of the present application.

[0023] Description of Figure Numbers:

[0024] 6. Hydraulic pump; 7. First pressure-regulating valve; 8. Torque converter; 9. Second pressure-regulating valve; 10. Cooler; 11. Fuel tank; 12. Air compressor; 13. Brake valve; 14. Second reversing valve; 15. First reversing valve; 18. Reverse clutch; 19. Forward clutch; 20. Second gear clutch; 21. First gear clutch; 22. Hydraulically controlled reversing valve body; 23. First speed sensor; 24. Controller; 25. Second speed sensor; 26. Normally closed solenoid valve body. Modes for Carrying Out the Invention

[0025] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0026] First, it's important to note that spatially relative terms, such as "horizontal," are intended to correspond to the product's actual orientation in use and to accommodate the orientation of the accompanying drawings for ease of description. When the orientation of the drawings changes, or the product's actual orientation in use changes, these spatially relative terms should be interpreted accordingly and are not intended to be limited to a single orientation.

[0027] Referring to FIG1 , an embodiment of the present application provides a shifting system comprising a reversing operating lever, a hydraulic system, and an electronic control system. The hydraulic system comprises a hydraulic pump 6 , a first reversing valve 15 , an electronically controlled valve, a forward clutch 19 , a reverse clutch 18 , a first-gear clutch 21 , and a second-gear clutch 20 . The first reversing valve 15 and the electronically controlled valve are connected in parallel at the output end of the hydraulic pump 6 , forming a reversing branch and a shifting branch connected to the hydraulic pump 6 and arranged in parallel. The forward clutch 19 and the reverse clutch 18 are arranged in the reversing branch, both connected to the first reversing valve 15 and connected to two different oil channels of the first reversing valve 15 . Switching the oil channel of the first reversing valve 15 can switch the forward clutch 19 and the reverse clutch 18 , thereby switching the driving direction. The reversing operating lever is connected to the valve core of the first reversing valve 15 . By moving the reversing operating lever, the oil channel of the first reversing valve 15 is switched to switch the forward clutch 19 or the reverse clutch 18 , thereby switching the driving direction. In this application, the driving direction is switched by manual operation without the involvement of an automatic control system. It is a mechanical control structure with low cost and only two options: forward and reverse. It is easy to operate, highly reliable, and will not cause misoperation.

[0028] The first-gear clutch 21 and the second-gear clutch 20 are located on the shift branch and are both connected to an electronically controlled valve and to two different oil passages in the electronically controlled valve. The electronic control system includes a controller 24 and a speed sensor assembly. Based on the measured speed signal, it switches the oil passages of the electronically controlled valve to open or close the first-gear clutch 21 or the second-gear clutch 20. The speed shift is automatically controlled by the electronic control system, measuring the speed signal, without driver intervention, thus forming the automatic control portion. Shifting gears requires only a single joystick, making operation simple, time-saving, and error-free. This makes it ideal for engineering vehicles that require frequent shifting. Furthermore, the semi-automatic combination structure is less expensive, more durable, and easier to maintain than a fully automatic shifting system. It also offers high adaptability to adverse operating conditions, making it highly suitable for engineering vehicles.

[0029] In the initial state, the oil passageway of the electronically controlled valve leading to the second-gear clutch 20 is in a conducting state, allowing the second-gear clutch 20 to engage when the vehicle starts. That is, the oil passageway of the electronically controlled valve connecting to the second-gear clutch 20 is in a normally open state. When the vehicle starts, whether moving forward or backward, it starts directly in the second gear speed range, rapidly increasing the engine output speed, shortening the starting time, and eliminating the need to switch from first gear to second gear. After starting, depending on the operating conditions, if the vehicle speed slows, the electronic control system automatically switches to the first gear speed range, and then switches back to the second gear speed range after the speed increases. Specifically, when the measured speed signal meets a first preset condition, the electronic control system switches the oil passageway of the electronically controlled valve to engage the first-gear clutch 21, and re-engages the second-gear clutch 20 when the speed signal meets a second preset condition.

[0030] It can be seen that the shifting system provided by the present application has a simple structure and is easy to use. Compared with the manual operating system, it is easy to operate, has high reliability, low operating errors, and reduces the driver's operating intensity. Compared with the fully automatic shifting system, the control system is simple, low in cost, easy to maintain, has high resistance and adaptability to adverse working conditions, and high durability. The shifting system provided by the present application is very suitable for engineering vehicles that require frequent direction and gear shifting, such as loaders, forklifts, etc.

[0031] The speed gears may be only two speed gears, namely, first gear and second gear, forming a low speed gear and a high speed gear, or may have multiple speed gears. In some embodiments of the present application, as shown in the accompanying drawings, the speed gears may be only first gear and second gear. With a small number of speed gears, the control system does not need to set up complex algorithm logic, thus reducing costs. Moreover, for engineering vehicles, two speed gears can also meet the driving speed requirements of the engineering vehicles, without the need to set up too many speed gears.

[0032] Therefore, in some embodiments of the present application, the speed sensor assembly includes a first speed sensor 23 for measuring the engine output speed and a second speed sensor 25 for measuring the transmission output speed. The electronic control system controller 24 can control the electronically controlled valve based on the detection information from the first speed sensor 23 and the detection information from the second speed sensor 25. Speed ​​gear switching is controlled by the logical relationship between the engine output speed information and the transmission output speed information (the transmission output speed also represents the vehicle's driving speed). The algorithm logic is simple, eliminating the need for complex signal acquisition and logic processing, and the need for multiple sensors, which can reduce costs. For shifts with a small number of speed gears, simple judgment logic is sufficient to meet the speed switching requirements of engineering vehicles.

[0033] Specifically, as shown in Figure 2, in the traction force P-vehicle speed n (transmission output speed) diagram, the intersection of high and low gears is set at (n0, P0), the downshifting point from second gear to first gear is n1, and the upshifting point from first gear to second gear is n2. When controller 24 detects, via second speed sensor 25, that the transmission output speed is continuously decreasing and falls below a first preset value, i.e., below n1, the electronic control system regulates the electronically controlled valve to engage first gear clutch 21. When controller 24 detects, via first speed sensor 23, that the transmission output speed is continuously increasing and exceeds a second preset value, i.e., above n2, and the engine output speed is within a preset range, the second gear clutch 20 is reengaged; the first preset value is greater than the second preset value. For example, when the vehicle is traveling in second gear, or high gear, and the speed decreases to a first preset value, the solenoid valve opens, shifting the vehicle into low gear. When the vehicle is traveling in first gear, or low gear, and the speed increases, and the engine speed is near its rated speed, and the vehicle speed reaches the upper limit of the low gear speed, the solenoid valve closes, shifting the vehicle into high gear. If the first preset value is greater than the second preset value, changing speed gears in a timely manner is safer.

[0034] If the shift system is applied to other types of vehicles, or if a large number of speed gears are set, such as three, four, or more, acceleration information can be incorporated into the algorithm logic for determining whether to switch speed gears. That is, the controller 24 of the electronic control system controls the switching of the oil passages of the electronically controlled valve to switch speed gears based on at least three signal parameters: the speed value information of the engine output speed, the speed value information of the transmission output speed, and the acceleration information of the transmission output speed. This makes the control logic more precise and allows for precise switching of multiple speed gears.

[0035] In some embodiments, the electrically controlled valve is an electro-hydraulic directional control valve, comprising a normally closed solenoid valve body 26 and a hydraulically controlled directional control valve body 22 connected to the normally closed solenoid valve body 26. The normally closed solenoid valve body 26 is initially in an off state. When it is on, it switches the oil path of the hydraulically controlled directional control valve body 22. A controller 24 controls the on / off state of the normally closed solenoid valve body 26 based on a speed signal. The normally open oil path of the hydraulically controlled directional control valve body 22 is connected to the second-speed clutch 20. When the normally closed solenoid valve body 26 is off, the normally open oil path of the hydraulically controlled directional control valve body 22 is on. Consequently, the vehicle starts in second gear, regardless of whether it is in forward or reverse gear. When the normally closed solenoid valve body 26 is on, it pushes the valve core of the hydraulically controlled directional control valve body 22 to move, switching the oil path of the hydraulically controlled directional control valve body 22, disengaging the second-speed clutch 20 and engaging the first-speed clutch 21.

[0036] With this arrangement, the electric control valve has a simple composition, is easy to set up, has low cost, and is highly reliable, durable, and easy to maintain compared to a complex valve body.

[0037] As shown in Figure 1, the output port of hydraulic pump 6 is connected in parallel to a first oil circuit and a second oil circuit. The first oil circuit houses a brake assembly, as well as a direction-changing branch and a gear-shifting branch connected in parallel to the brake assembly's output. Specifically, the input port of the brake assembly's valve body is connected to the output port of hydraulic pump 6, while the electronically controlled valve and first reversing valve 15 are connected in parallel to the brake assembly's valve body output port. When braking is required, the valve body shuts off the first oil circuit, disengaging all clutches and braking the vehicle. When the brake is released, the valve body connects to the first oil circuit, allowing direction-changing and gear-shifting to resume.

[0038] The second oil circuit is provided with a first pressure regulating valve 7, a torque converter 8, a second pressure regulating valve 9 and a cooler 10 in sequence. The output port of the cooler 10 is connected to the oil return port of the oil tank 11.

[0039] In some embodiments, the brake assembly includes a brake valve 13 and a second reversing valve 14. The second reversing valve 14 is normally open by default, or in other words, initially. Its normally open path connects the reversing branch and the shifting branch. The brake valve 13 is used to shut off the second reversing valve 14 to achieve braking. This arrangement results in a simple valve assembly and easy operation.

[0040] The brake assembly further includes an air compressor 12 , and the brake valve 13 is an air brake valve 13 and is connected to the air compressor 12 .

[0041] Accumulators are provided on the oil paths connecting the first reversing valve 15 and the forward clutch 19 and the reverse clutch 18 .

[0042] The present application also provides an engineering vehicle including a shifting system as described in any of the above embodiments. The engineering vehicle can easily shift gears, requiring only a single operating lever to achieve shifting, thereby reducing driver fatigue and operating effort. Furthermore, the shifting system has a simple structure, is less expensive, and is more practical than fully automatic shifting.

[0043] The embodiments of the present application further provide a shifting method for an engineering vehicle, which is applicable to the above-mentioned shifting system. The shifting method includes the following contents:

[0044] Control the vehicle to start at the second gear speed position;

[0045] The controller 24 collects speed signals and adjusts the speed gear according to the speed signals. The speed signals at least include output speed information of the engine and output speed information of the gearbox.

[0046] In this way, when driving the vehicle, the driver can start the vehicle in the second gear after determining the driving direction through the manual operating lever.

[0047] In some embodiments, the gear shifting method for an engineering vehicle further includes the following: the speed signal further includes acceleration information of the output speed of the transmission.

[0048] The basic principles of the present application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in this application are merely illustrative and not restrictive, and it should not be assumed that these advantages, strengths, and effects are required of each embodiment of this application. In addition, the specific details disclosed above are merely illustrative and facilitating understanding, and are not restrictive. The above details do not limit this application to necessarily being implemented using the above specific details.

[0049] The components and devices involved in this application are only illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the accompanying drawings. As will be appreciated by those skilled in the art, these components and devices can be connected, arranged, or configured in any manner. Words such as "including," "comprising," "having," and the like are open-ended words that mean "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or" and can be used interchangeably therewith unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0050] It should also be noted that in the apparatus and method of the present application, each component or each step can be decomposed and / or recombined, and such decomposition and / or recombination should be regarded as equivalent solutions of the present application.

[0051] 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 be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0052] The above description has been provided for the purpose of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

[0053] The above description is merely an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A shift system, wherein, The shift system includes a reversing operating lever, a hydraulic system, and an electronic control system. The hydraulic system includes a reversing branch and a shifting branch that are both connected to a hydraulic pump and arranged in parallel. A first reversing valve, a forward clutch, and a reverse clutch are provided on the reversing branch. The first reversing valve realizes the switching between the forward clutch and the reverse clutch through the movement of the reversing operating lever. An electronic control valve, a first-gear clutch, and a second-gear clutch are provided on the shifting branch. And in the initial state, the oil passage of the electronic control valve leading to the second-gear clutch is in a conducting state, so that the second-gear clutch engages when the vehicle starts. The electronic control system includes a controller and a speed sensor assembly. The controller controls the switching between the first-gear clutch and the second-gear clutch according to the speed signal measured by the speed sensor assembly.

2. The shift system according to claim 1, wherein, The speed sensor assembly includes a first speed sensor for measuring the output speed of the engine and a second speed sensor for measuring the output speed of the transmission. The controller of the electronic control system controls the electronic control valve according to the detection information of the first speed sensor and the detection information of the second speed sensor.

3. The shift system according to claim 2, wherein, When the output speed of the transmission shows a continuous downward trend and is lower than a first preset value, the controller adjusts the electronic control valve to engage the first-gear clutch; when the output speed of the engine is within a preset range, the output speed of the transmission shows a continuous upward trend and is higher than a second preset value, the controller re-engages the second-gear clutch; wherein, the first preset value is greater than the second preset value.

4. The shift system according to any one of claims 1-3, wherein, The controller of the electronic control system controls the electronic control valve according to the speed value of the output speed of the engine, the speed value of the output speed of the transmission, and the acceleration of the output speed of the transmission.

5. The shift system according to any one of claims 1-4, wherein, The electronic control valve is an electro-hydraulic reversing valve, which includes a normally closed solenoid valve body and a hydraulic control reversing valve body connected to the normally closed solenoid valve body. The normally open oil passage of the hydraulic control reversing valve body is connected to the second-gear clutch. When the normally closed solenoid valve body is conducting, the oil passage of the hydraulic control reversing valve body is switched, so that the first-gear clutch engages and the second-gear clutch disengages.

6. The shift system according to any one of claims 1-5, wherein, Accumulators are provided on the connection oil passages between the first reversing valve and the forward clutch and the reverse clutch.

7. The shift system according to any one of claims 1-6, wherein, A first oil passage and a second oil passage are arranged in parallel at the output port of the hydraulic pump. A braking assembly is provided on the first oil passage, and the reversing branch and the shifting branch are arranged in parallel at the output end of the braking assembly. A first pressure regulating valve, a torque converter, a second pressure regulating valve, and a cooler are arranged in sequence on the second oil passage.

8. An engineering vehicle, wherein, The engineering vehicle includes the shift system according to any one of claims 1-7.

9. A gear shifting method for an engineering vehicle, wherein, Applicable to the shift system according to claims 1-7, the shift method includes the following: Control the vehicle to start in the second-gear speed gear. The controller collects speed signals and adjusts the speed gear according to the speed signals. The speed signals at least include the output speed information of the engine and the output speed information of the transmission.

10. The shifting method of the engineering vehicle according to claim 9, wherein, The shift method of the engineering vehicle further includes the following: The speed signals further include the acceleration information of the output speed of the transmission.

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