A gear shifting system, control method and engineering vehicle

Abstract

This invention relates to the field of agricultural machinery technology, and discloses a gear shifting system, control method, and engineering vehicle. The gear shifting system includes an input shaft, an output shaft, a hydraulic motor, a first sensor, a second sensor, and a controller. The controller is adapted to adjust the displacement of the hydraulic motor and control the speed of the input shaft. When the speeds of the input shaft and the output shaft are the same, the controller is adapted to control the gear shifting mechanism to change the engagement gear of the input shaft and the output shaft. This invention uses the first and second sensors to feed back the speeds of the input shaft and the output shaft to the controller. Gear shifting only occurs when the speeds of the input shaft and the output shaft are the same, eliminating the need for a clutch and avoiding the problems of clutch wear and failure due to long-term use. It enables gear shifting without stopping, ensuring continuous operation and improving the operating efficiency of the engineering vehicle. Before shifting, the input shaft speed is adjusted by adjusting the displacement of the hydraulic motor to match the speeds of the input and output shafts, avoiding shifting shock, gear wear, and gear grinding.

Description

Technical Field

[0001] This invention relates to the field of agricultural machinery technology, specifically to a gear shifting system, control method, and engineering vehicle. Background Technology

[0002] Medium and large UTVs (Universal Televisions) have high requirements for the reliability and operability of their power transmission systems. Related technologies typically use clutches for gear shifting. While this can meet the need for shifting while driving to some extent, the clutch itself has a complex structure, with numerous operating mechanisms, hydraulic lines, and actuators. This not only complicates the assembly process of the entire vehicle's transmission system but also significantly increases overall manufacturing and maintenance costs. Simplifying the structure and reducing costs by using physical and mechanical transmission solutions would result in vehicles that cannot shift smoothly while driving, requiring gear changes only when stationary. This not only makes the operation cumbersome but also affects the continuity of vehicle movement. Summary of the Invention

[0003] This invention provides a gear shifting system, control method, and engineering vehicle to solve the problems in related technologies where the use of a clutch structure in engineering vehicles is complex and costly, and where engineering vehicles without a clutch can only shift gears while stopped, making operation more complicated.

[0004] In a first aspect, the present invention provides a gear shifting system, comprising: The input shaft and output shaft, and the output shaft and input shaft, can be connected in an on / off manner through a shifting mechanism; A hydraulic motor is connected to the input shaft and is suitable for driving the input shaft to rotate. A first drive element, the first drive element being adapted to provide power to a hydraulic motor; The first sensor is located on the input shaft and is suitable for monitoring the rotational speed of the input shaft; The second sensor is located on the output shaft and is suitable for monitoring the rotational speed of the output shaft; The controller is electrically connected to the first sensor and the second sensor. The controller is adapted to control the shift mechanism to disconnect the output shaft and the input shaft based on the shift command and to adjust the displacement of the first drive member to control the speed of the input shaft. When the speeds of the input shaft and the output shaft are the same, the controller is adapted to control the shift mechanism to change the engagement gear of the input shaft and the output shaft.

[0005] Beneficial effects: The shifting system in this invention eliminates the need for a clutch, which not only reduces the installation space for the clutch and its associated transmission structure and simplifies the overall structure, but also avoids the problems of easy wear and failure of the clutch during long-term use, effectively reducing manufacturing costs and subsequent maintenance costs.

[0006] Meanwhile, the gear shifting system of the present invention can achieve gear shifting without stopping the vehicle, and can switch gears without interrupting the vehicle's operation, which significantly improves work efficiency and avoids the work interruption problem caused by stopping to shift gears. It is especially suitable for continuous operation scenarios of engineering vehicles, which can improve the work efficiency of engineering vehicles, reduce work loss time, and ensure the continuity and smoothness of the work process.

[0007] Before shifting gears, the hydraulic motor displacement is adjusted by the controller to change the input shaft speed, making the input shaft speed the same as the output shaft speed. Then, the gear shift is performed. This avoids impact and gear wear during the shifting process, prevents gear grinding, extends gear life, ensures smoothness during shifting, and improves the overall operational stability and service life of the shifting system. It is suitable for the high-intensity and long-term operation requirements of engineering vehicles.

[0008] In one optional embodiment, the hydraulic motor includes a motor inlet end and a motor outlet end, and the first driving component includes an oil outlet and an oil inlet. The oil outlet is connected to the motor inlet end through a first pipeline, and the oil inlet is connected to the motor outlet end through a second pipeline. The shifting system also includes: The directional valve is connected to the first pipeline and the second pipeline. The directional valve has a blocking position suitable for blocking the passage of hydraulic oil and a conducting position suitable for allowing hydraulic oil to pass through to connect the first pipeline and the second pipeline. When the input shaft and the output shaft rotate at the same speed, the controller controls the directional valve to be in the conducting position.

[0009] Beneficial effects: The reversing valve cuts off the power of the hydraulic motor, preventing the hydraulic motor from continuously acting on the input shaft, reducing the impact during gear shifting, and avoiding problems such as gear wear and gear shifting jamming caused by the failure to cut off the power.

[0010] In one optional implementation, the reversing valve is a hydraulically controlled reversing valve, and the shifting system further includes: The first valve body is connected to the control port of the directional valve. The first valve body includes a first connecting position adapted to put the directional valve in the open position and a first cutting-off position adapted to put the directional valve in the blocking position. The second drive unit is connected to the first valve body and is adapted to provide hydraulic oil to the first valve body; Alternatively, the directional valve can be a solenoid directional valve.

[0011] In one alternative embodiment, the input shaft is connected to a first gear and a third gear with different numbers of teeth, the first gear and the third gear being adapted to rotate synchronously with the input shaft; The output shaft is coaxially fitted with a second gear and a fourth gear with different numbers of teeth. The second gear meshes with the first gear, and the fourth gear meshes with the third gear. The shifting mechanism is a shift fork assembly, which is adapted to selectively connect the second gear and the fourth gear to the input shaft; or to disengage both the second gear and the fourth gear from the input shaft.

[0012] In one alternative embodiment, the shifting mechanism further includes: A first-gear control valve includes a third connecting position adapted to drive the shift fork assembly to drive the fourth gear to the input shaft, and a third disconnecting position adapted to disconnect the fourth gear from the output shaft.

[0013] The two-position control valve includes a fourth connecting position adapted to drive the shift fork assembly to drive the second gear to the output shaft, and a fourth disconnecting position adapted to disconnect the second gear from the output shaft. The second drive unit is connected to the first-gear control valve and the second-gear control valve, and is suitable for providing hydraulic oil to the first-gear control valve and the second-gear control valve.

[0014] In one alternative embodiment, the shifting mechanism further includes: The second valve body includes a second connecting position adapted to cause hydraulic oil to drive the swashplate to rotate so that the hydraulic motor is in a first displacement state, and a second disconnecting position adapted to reset the swashplate so that the hydraulic motor is in a second displacement state. The second drive unit, connected to the second valve body, is adapted to supply hydraulic oil to the second valve body.

[0015] Secondly, the present invention also provides a control method applicable to the shifting system described above, the control method comprising: Obtain the rotational speeds of the input and output shafts; Based on the shift command, the shift mechanism is controlled to disconnect the output shaft and the input shaft; the displacement of the first drive component is adjusted to control the speed of the input shaft; when the speeds of the input shaft and the output shaft are the same, the shift mechanism is controlled to change the engagement gear of the input shaft and the output shaft.

[0016] By adjusting the displacement of the first drive component to change the speed of the input shaft, the speed of the input shaft and the speed of the output shaft are made the same before gear shifting. This avoids gear meshing impact caused by excessive speed difference, reduces the occurrence of gear grinding, and ensures the smoothness of the shifting process. At the same time, the load on the motor is released during the shifting process, which can reduce the impact of power transmission and make gear shifting more smooth.

[0017] In one optional implementation, the rotational speed of the input shaft is defined as n1, the rotational speed of the output shaft is defined as n2, the shifting mechanism has a disconnect position that disconnects the output shaft and the input shaft, and a first engagement position and a second engagement position that drively connects the output shaft and the input shaft, when the shifting system includes a reversing valve; When the shift command is an upshift command, the control methods include: S11, control the shifting mechanism to switch from the first engaged position to the disengaged position; reduce the displacement of the first driving component to reduce the displacement of the hydraulic motor and reduce n1; S12. When n1 and n2 are the same, control the directional valve to switch to the on position, so that the hydraulic motor runs idle; control the shifting mechanism to switch to the second engagement position. S13, control the directional valve to switch to the blocking position, and the hydraulic motor obtains power; When the shift command is a downshift command, the control methods include: S21. Control the shifting mechanism to switch from the second engaged position to the disengaged position; increase the displacement of the first drive component to increase the displacement of the hydraulic motor and raise n1; S22. When n1 and n2 are the same, control the directional valve to switch to the on position so that the hydraulic motor can run freely; control the shifting mechanism to switch to the first engagement position. S23, control the directional valve to switch to the blocking position, and the hydraulic motor obtains power.

[0018] In one alternative implementation, the shifting system includes a first gear control valve, a second gear control valve, and a first valve body; In S11, the first gear control valve is switched to the third cut-off position so that the gear shifting mechanism is switched from the first engaged position to the disengaged position; In S12, the first valve body is controlled to switch to the first connected position so that the directional valve switches to the open position; the second gear control valve is controlled to switch to the fourth connected position so that the shifting mechanism switches to the second engaged position. In S13, the first valve body is switched to the first shut-off position so that the directional valve is switched to the blocking position; In S21, the second gear control valve is switched to the fourth cut-off position so that the shifting mechanism is switched from the second engaged position to the disengaged position; In S22, the second valve body is controlled to switch to the second connected position so that the directional valve switches to the open position; the first gear control valve is controlled to switch to the third connected position so that the shifting mechanism switches to the first engaged position. In S23, the first valve body is switched to the first shut-off position so that the directional valve is switched to the blocking position.

[0019] Thirdly, the present invention also provides an engineering vehicle, including a vehicle body and a gear shifting system as described above disposed on the vehicle body.

[0020] Beneficial effects: By equipping engineering vehicles with the aforementioned gear shifting system, smooth gear shifting can be achieved without the need for a clutch or stopping, significantly improving work efficiency, avoiding gear shifting jams and component wear, adapting to various engineering operation scenarios, being easy to operate, and ensuring stable operation of the vehicle during continuous work. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of a gear shifting system according to an embodiment of the present invention; Figure 2 for Figure 1 The diagram shows a partial structural schematic of the gear shifting system. Figure 3 This is a schematic diagram of the shifting system of this invention when it is in neutral. Figure 4 This is a schematic diagram of the shifting system in first gear according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the shifting system in second gear according to an embodiment of the present invention.

[0023] Explanation of reference numerals in the attached figures: 1. Input shaft; 101. First sensor; 2. Output shaft; 201. Second sensor; 3. Shift fork assembly; 4. Hydraulic motor; 41. Swashplate; 5. First drive component; 6. Reversing valve; 61. Blocking position; 62. Open position; 71. First valve body; 711. First connecting position; 712. First shut-off position; 72. Second valve body; 721. Second connecting position; 722. Second shut-off position; 73. First-position control valve; 731. Third connecting position; 732. Third shut-off position; 74. Second-position control valve; 741. Fourth connecting position; 742. Fourth shut-off position; 100, First Pipeline; 200, Second Pipeline; 300, Third Pipeline; 400, Fourth Pipeline; 500, Fifth Pipeline; 600, Sixth Pipeline; 700, Seventh Pipeline; 8. Second driving component; Z1, first gear; Z2, second gear; Z3, third gear; Z4, fourth gear. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Medium and large UTV farm vehicles have high requirements for the reliability and operability of their power transmission systems. Related technologies typically use clutches for gear shifting. While this can meet the need for shifting while driving to some extent, the clutch itself has a complex structure, with numerous operating mechanisms, hydraulic lines, and actuators. This not only complicates the assembly process of the entire vehicle's transmission system but also significantly increases overall manufacturing and maintenance costs. Simplifying the structure and reducing costs by adopting a clutchless transmission solution would result in vehicles unable to shift smoothly while driving, requiring gear changes only when stationary. This not only makes the operation cumbersome but also affects the continuity of driving and the driving experience, leading to lower driver acceptance and making it difficult to adapt to the complex operating conditions of medium and large UTV farm vehicles in agricultural and forestry operations and site transportation.

[0026] The following is combined with Figures 1 to 5 The following describes embodiments of the present invention.

[0027] According to an embodiment of the present invention, in one aspect, a shifting system is provided, comprising: Input shaft 1 and output shaft 2, and output shaft 2 and input shaft 1 can be connected in an on / off manner through a shifting mechanism; Hydraulic motor 4 is connected to the input shaft and is suitable for driving the input shaft 1 to rotate. First drive element 5, first drive element 5 is adapted to provide power to hydraulic motor 4; The first sensor 101 is disposed on the input shaft 1 and is suitable for monitoring the rotational speed of the input shaft 1; The second sensor 201 is disposed on the output shaft 2 and is suitable for monitoring the rotational speed of the output shaft 2; The controller is electrically connected to the first sensor 101 and the second sensor 201. The controller is adapted to control the shift mechanism to disconnect the output shaft 2 and the input shaft 1 based on the shift command and to adjust the displacement of the first drive member 5 to control the speed of the input shaft 1. When the speeds of the input shaft 1 and the output shaft 2 are the same, the controller is adapted to control the shift mechanism to change the engagement gear of the input shaft 1 and the output shaft 2.

[0028] Reference Figure 3The second gear Z2 and the fourth gear Z4 on the output shaft 2 are mounted on the output shaft 2 in the form of empty sleeves. The positions of the second gear Z2 and the fourth gear Z4 are fixed by means of shaft shoulder positioning and retaining ring limiting, so that the second gear Z2 and the fourth gear Z4 cannot slide along the axial direction of the output shaft 2. The shifting mechanism is a shift fork assembly 3, which includes a sleeve, a connecting rod and a drive structure. The sleeve is sleeved on the output shaft 2 and can rotate synchronously with the output shaft 2. Both ends of the sleeve include spline structures. The ends of the second gear Z2 and the fourth gear Z4 opposite to the sleeve also include spline structures. After the sleeve can move, it engages with the second gear Z2 or the fourth gear Z4 through the splines, thereby making the second gear Z2 or the fourth gear Z4 rotate synchronously with the output shaft 2. The drive structure includes a piston and a piston cylinder. The piston can slide back and forth in the piston cylinder. Hydraulic oil can be supplied to both end c and end d of the piston cylinder. When oil is supplied to end c, it pushes the piston to move towards end d; when oil is supplied to end d, it pushes the piston to move towards end c. The connecting rod is used to connect the piston and the sleeve. When the piston reciprocates in the piston cylinder, the connecting rod drives the sleeve to move axially in the same direction on the output shaft 2, thereby engaging or disengaging the sleeve with the corresponding gear. When power transmission between the second gear Z2 and the output shaft 2 needs to be connected, oil is supplied to end d of the piston cylinder. The pressure of the hydraulic oil pushes the piston to end c, which in turn pulls the sleeve towards the second gear Z2 via the connecting rod. This causes the spline structure at the end of the sleeve to mesh with the spline structure of the second gear Z2. At this time, the second gear Z2 will rotate synchronously with the sleeve and the output shaft 2, realizing power output. When power transmission between the second gear Z2 needs to be disconnected, oil is supplied to end c of the piston cylinder, pushing the piston to end d. This pushes the sleeve to reset in the opposite direction via the connecting rod, disengaging the sleeve spline from the second gear Z2 spline, and the second gear Z2 returns to its idling state. Similarly, when power transmission between the fourth gear Z4 and the output shaft 2 needs to be connected or disconnected, the controller controls the oil supply status at ends c and d of the piston cylinder, driving the piston to reciprocate. This drives the sleeve to move or reset towards the fourth gear Z4 via the connecting rod, causing the sleeve to engage or disengage with the fourth gear Z4 spline, thus completing the power switching of the corresponding gear.

[0029] For example, the hydraulic motor 4 in this embodiment includes a first displacement mode and a second displacement mode, wherein the displacement of the first displacement mode is greater than that of the second displacement mode.

[0030] The shifting system in this invention eliminates the need for a clutch, which not only reduces the installation space for the clutch and its associated transmission structure and simplifies the overall structure, but also avoids the problems of easy wear and failure of the clutch during long-term use, effectively reducing manufacturing costs and subsequent maintenance costs.

[0031] Meanwhile, the gear shifting system of the present invention can achieve gear shifting without stopping the vehicle, and can switch gears without interrupting the vehicle's operation, which significantly improves work efficiency and avoids the work interruption problem caused by stopping to shift gears. It is especially suitable for continuous operation scenarios of engineering vehicles, which can improve the work efficiency of engineering vehicles, reduce work loss time, and ensure the continuity and smoothness of the work process.

[0032] Before shifting gears, the displacement of the hydraulic motor 4 is adjusted by regulating the displacement of the first drive component 5, thereby changing the speed of the input shaft 1 to make the speed of the input shaft 1 equal to that of the output shaft 2. Then, the gear shift is performed. This avoids impact and gear wear during the shifting process, prevents gear grinding, extends the service life of the gears, ensures the smoothness of the shifting process, and improves the overall operational stability and service life of the shifting system. It is suitable for the high-intensity and long-term operation requirements of engineering vehicles.

[0033] In one embodiment, the hydraulic motor 4 includes a motor inlet end and a motor outlet end, and the first driving component 5 includes an oil outlet and an oil inlet. The oil outlet is connected to the motor inlet end through a first pipeline 100, and the oil inlet is connected to the motor outlet end through a second pipeline 200. The shifting system also includes: The reversing valve 6 is connected to the first pipeline 100 and the second pipeline 200. The reversing valve 6 has a blocking position 61 suitable for blocking the passage of hydraulic oil, and a conducting position 62 suitable for allowing hydraulic oil to pass through to connect the first pipeline 100 and the second pipeline 200. When the input shaft 1 and the output shaft 2 rotate at the same speed, the controller controls the reversing valve 6 to be in the conducting position 62.

[0034] It also includes a fourth pipeline 400, one end of which is connected to the b1 end of the reversing valve 6, and the other end is connected to the first valve body 71; the third pipeline 300 and the fourth pipeline 400 are connected through the first valve body 71. When the first valve body 71 is in the first connected position 711, it can supply oil from the third pipeline 300 to the fourth pipeline 400. When the first valve body is in the first cut-off position 712, it can cut off the oil supply from the third pipeline 300 to the fourth pipeline 400.

[0035] For example, in this embodiment, the first valve body 71 is a solenoid valve and the reversing valve 6 is a hydraulically controlled reversing valve. After the second drive unit 8 is started, it continuously supplies hydraulic oil to the third pipeline 300. When the hydraulic motor 4 needs to idle, the solenoid valve of the first valve body 71 is energized. After the first valve body 71 is energized, it switches to the first connected position 711. At this time, the third pipeline 300 and the fourth pipeline 400 are connected. The hydraulic oil output by the second drive unit 8 flows through the third pipeline 300 and the first valve body 71 to the fourth pipeline 400, and finally to the b1 end of the reversing valve 6, which pushes the valve core of the reversing valve 6 to move, so that the reversing valve 6 switches to the conducting position 62. At this time, the first pipeline 100 and the second pipeline 200 are connected through the hydraulically controlled reversing valve. The hydraulic oil output by the first drive unit 5 to the inlet end of the hydraulic motor 4 can flow directly through the hydraulically controlled reversing valve through the second pipeline 200 back to the oil inlet of the first drive unit 5. There is no longer a pressure difference between the inlet end and the outlet end of the hydraulic motor 4. This causes the hydraulic motor 4 to idle without power, unable to drive the input shaft 1 to rotate. After the gear shift is completed, the controller de-energizes the solenoid valve, which is the first valve body 71. After the solenoid valve is de-energized, it resets to the first cut-off position 712, cutting off the connection between the third pipeline 300 and the fourth pipeline 400, and no longer supplies control oil to the b1 end of the hydraulic directional valve. The hydraulic directional valve resets to the blocking position 61 under the action of its own reset structure, cutting off the connection between the first pipeline 100 and the second pipeline 200. At this time, the hydraulic oil output by the first drive unit 5 enters the inlet end of the hydraulic motor 4 through the first pipeline 100, and flows out from the outlet end after the hydraulic motor 4 performs work. It then flows back to the oil inlet of the first drive unit 5 through the second pipeline 200. Under the action of the hydraulic pressure difference between the first pipeline 100 and the second pipeline 200, the hydraulic motor 4 resumes power output, driving the input shaft 1 to rotate normally, completing the entire power on / off control process.

[0036] The reversing valve 6 cuts off the power of the hydraulic motor 4, thus preventing the hydraulic motor 4 from continuously acting on the input shaft 1, reducing the impact during gear shifting, and avoiding problems such as gear wear and gear shifting jamming caused by the failure to cut off the power.

[0037] It is understood that, in another embodiment, the reversing valve 6 is an electromagnetic reversing valve, and the working position of the electromagnetic reversing valve is controlled by the energization or de-energization of the electromagnetic coil of the electromagnetic reversing valve.

[0038] In one embodiment, the reversing valve 6 is a hydraulically controlled reversing valve, and the shifting system further includes: The first valve body 71 is connected to the control port of the directional valve 6. The first valve body 71 includes a first connecting position 711 adapted to put the directional valve 6 into the conducting position 62, and a first cutting-off position 712 adapted to put the directional valve 6 into the blocking position 61. The second drive component 8 is connected to the first valve body 71 and is adapted to provide hydraulic oil to the first valve body 71; Alternatively, directional valve 6 can be a solenoid directional valve.

[0039] In one embodiment, a second drive element 8 is also included. The second drive element 8 is adapted to provide hydraulic oil to the first valve body 71. The oil outlet of the second drive element 8 is connected to a third pipeline 300. The third pipeline 300 is provided with a filter. The hydraulic oil output by the second drive element 8 is filtered by the filter and flows to the accumulator through a one-way valve on the third pipeline 300.

[0040] For example, in this embodiment, the first drive component 5 is a piston pump, and the second drive component 8 is a gear pump. The piston pump is used to provide hydraulic oil to the hydraulic motor 4. The piston pump is connected to an electro-proportional controller to control the forward or reverse rotation of the piston pump and to control the flow rate of the piston pump. The first pipeline 100 and the second pipeline 200 are also connected to relief valves, which are used to control the working pressure of the piston pump's outlet and inlet.

[0041] In one embodiment, the input shaft 1 is connected to a first gear Z1 and a third gear Z3 with different numbers of teeth, and the first gear Z1 and the third gear Z3 are adapted to rotate synchronously with the input shaft 1. The output shaft 2 is coaxially fitted with a second gear Z2 and a fourth gear Z4 with different numbers of teeth. The second gear Z2 meshes with the first gear Z1, and the fourth gear Z4 meshes with the third gear Z3. The shifting mechanism is a shift fork assembly 3, which is adapted to selectively connect the second gear Z2 and the fourth gear Z4 to the input shaft 1; or to disengage both the second gear Z2 and the fourth gear Z4 from the input shaft 1.

[0042] For example, this embodiment is not limited to a gear transmission configuration where the input shaft 1 has only two gears and the output shaft 2 has two corresponding gears. In practical applications, three, four, or more transmission gears with the same number of teeth can be arranged on the input shaft 1 according to the gear shifting requirements. At the same time, an equal number of driven gears are matched and arranged on the output shaft 2. This allows each transmission gear on the input shaft 1 and each driven gear on the output shaft 2 to form multiple independent meshing transmissions. The shift fork assembly 3 can enable any one of the multiple gears to establish a transmission connection with the output shaft 2, or it can put the shifting system in neutral.

[0043] In one embodiment, the shifting mechanism further includes: The first gear control valve 73 includes a third connecting position 731 adapted to drive the shift fork assembly 3 to drive the fourth gear Z4 to the output shaft 2, and a third disconnecting position 732 adapted to disconnect the fourth gear Z4 from the output shaft 2.

[0044] The second-gear control valve 74 includes a fourth communication position 741 adapted to drive the second gear Z2 and the output shaft 2 through the shift fork assembly 3, and a fourth disconnect position 742 adapted to disconnect the second gear Z2 and the output shaft 2.

[0045] The second drive unit 8 is connected to the first gear control valve 73 and the second gear control valve 74, and is suitable for providing hydraulic oil to the first gear control valve 73 and the second gear control valve 74.

[0046] For example, refer to Figure 1 The first gear control valve 73 and the c end of the shift fork assembly 3 are connected through the sixth pipe 600, and the second gear control valve 74 is connected to the d end of the shift fork assembly through the seventh pipe 700.

[0047] Reference Figure 3 When the first gear control valve 73 is in the third cut-off position 732 and the second gear control valve 74 is in the fourth cut-off position 742, the shifting system is in neutral. When the first gear control valve 73 is in the third connected position 731 and the second gear control valve 74 is in the fourth cut-off position 742, the shifting system is in first gear. When the first gear control valve 73 is in the third cut-off position 732 and the second gear control valve 74 is in the fourth connected position 741, the shifting system is in second gear.

[0048] When gear shifting is required, the controller controls the displacement of the piston pump according to the current gear and the target gear requirement, thereby changing the displacement of the hydraulic motor 4 to control the speed of the input shaft 1, gradually making the speed of the input shaft 1 the same as the speed of the output shaft 2; when the first sensor 101 and the second sensor 201 report that the speed of the input shaft 1 and the speed of the output shaft 2 are the same, the reversing valve 6 switches to the open position 62, and the hydraulic oil in the first pipeline 100 flows to the second pipeline 200 through the reversing valve 6. At this time, there is no pressure difference between the inlet and outlet of the hydraulic motor 4, and the hydraulic motor 4... In the idling state, the hydraulic motor 4 cannot drive the input shaft 1 to rotate; at this time, the first gear control valve 73 is in the third connection position 731, or the second gear control valve 74 is in the fourth connection position 741, the shift fork assembly 3 is activated, pushing the second gear Z2 or the fourth gear Z4 to drive the output shaft 2 to complete the gear switching; then the first valve body 71 is switched to the first connection position 711, so that the reversing valve 6 is switched to the blocking position 61, cutting off the connection between the first pipeline 100 and the second pipeline 200, so that the hydraulic motor 4 resumes power output, and the power is transmitted to the output shaft 2 through the input shaft 1.

[0049] For example, in this embodiment, the first gear control valve 73 is a solenoid valve. After the second drive unit 8 is started, it supplies hydraulic oil to the third pipeline 300. When it is necessary to switch to the first gear and establish a transmission connection between the fourth gear Z4 and the output shaft 2, the first gear control valve 73 is energized and switches to the third connection position 731. At this time, the third pipeline 300 is connected to the sixth pipeline 600. The hydraulic oil is controlled to be delivered to the c end of the shift fork assembly 3 through the sixth pipeline 600, which pushes the shift fork assembly 3 to move, thereby driving the fourth gear Z4 to drive the transmission connection between the fourth gear Z4 and the output shaft 2, completing the shift of the first gear. When it is necessary to cancel the transmission connection between the fourth gear Z4 and the output shaft 2, the first gear control valve 73 is de-energized and switches to the third cut-off position 732, cutting off the connection between the third pipeline 300 and the sixth pipeline 600. The shift fork assembly 3 is reset, and the fourth gear Z4 is disconnected from the transmission connection between the output shaft 2.

[0050] For example, in this embodiment, the second-gear control valve 74 is a solenoid valve. When it is necessary to switch to the first gear and establish a transmission connection between the second gear Z2 and the output shaft 2, the second-gear control valve 74 is energized and switches to the fourth connection position 741. At this time, the third pipeline 300 and the seventh pipeline 700 are connected, and the control hydraulic oil is delivered to the d end of the shift fork assembly 3 through the seventh pipeline 700, pushing the shift fork assembly 3 to move, thereby driving the second gear Z2 to drive the transmission connection between the output shaft 2 and complete the switching of the second gear. When it is necessary to cancel the transmission connection between the second gear Z2 and the output shaft 2, the second-gear control valve 74 is de-energized and switches to the fourth cut-off position 742, cutting off the connection between the third pipeline 300 and the seventh pipeline 700, the shift fork assembly 3 is reset, and the transmission connection between the second gear Z2 and the output shaft 2 is released.

[0051] In one embodiment, an energy storage device is also included, which is disposed in the third pipeline 300.

[0052] The accumulator can stably maintain the pressure of the hydraulic oil in the third pipeline 300, effectively mitigating the instantaneous fluctuations in the output pressure of the second drive component 8 and avoiding the problem of control oil pressure fluctuations caused by the unstable pressure of the second drive component 8. Since the action of the shift fork assembly 3 depends on stable hydraulic oil pressure, the accumulator can store excess hydraulic oil and release the oil in time to replenish the pressure when the output pressure of the second drive component 8 fluctuates, ensuring that the hydraulic oil in the third pipeline 300 always maintains a stable pressure value, providing stable power for the control action of the shifting system.

[0053] In one embodiment, it also includes: The second valve body 72 includes a second connecting position 721 adapted to cause hydraulic oil to drive the swashplate 41 to rotate so that the hydraulic motor 4 is in a first displacement state, and a second disconnecting position 722 adapted to reset the swashplate 41 so that the hydraulic motor 4 is in a second displacement state.

[0054] The fifth pipe 500 is adapted to connect the swashplate 41 of the hydraulic motor 4 and the second valve body 72. For example, in this instance, the second valve body 72 is a solenoid valve. When the hydraulic motor 4 needs to be in the first displacement state, the controller controls the second valve body 72 to be in the second connection position 721. At this time, the third pipeline 300 and the fifth pipeline 500 are connected. The hydraulic oil output by the second drive unit 8 is delivered to the swashplate 41 through the third pipeline 300, the second connection position 721 and the fifth pipeline 500, pushing the swashplate 41 to rotate so that the hydraulic motor 4 is in the first displacement state. When the hydraulic motor 4 needs to be in the second displacement state, the controller controls the second valve body 72 to be in the second cut-off position. At this time, the connection between the third pipeline 300 and the fifth pipeline 500 is cut off, the swashplate 41 is reset, and the hydraulic motor 4 is in the second displacement state.

[0055] The shifting system in this invention includes four speed modes, each corresponding to different operational requirements. The first speed mode corresponds to the first displacement state of the hydraulic motor 4 in first gear; the second speed mode corresponds to the second displacement state of the hydraulic motor 4 in first gear; the third speed mode corresponds to the first displacement state of the hydraulic motor 4 in second gear; and the fourth speed mode corresponds to the second displacement state of the hydraulic motor 4 in second gear.

[0056] All four speed modes support switching between manual and automatic modes. In manual mode, the operator can manually control the switching between first and second gear modes and adjust the displacement according to the work requirements to adapt to different work loads and road conditions. In automatic mode, the system can automatically switch to the corresponding speed mode according to changes in the load and driving speed requirements of the work scenario, without the need for manual intervention.

[0057] For example, in addition to the first displacement state and the second displacement state, the hydraulic motor 4 may also include other displacements. For example, according to the load size and speed requirements of the actual working scenario of the engineering vehicle, different displacement levels such as the third displacement state and the fourth displacement state may be added to give the engineering vehicle more speed modes.

[0058] The second valve body 72 can change the displacement of the hydraulic motor 4 according to actual operating requirements, thereby changing the vehicle speed to meet the operating needs of engineering vehicles in different operating scenarios. At the same time, it can also adjust the displacement of the hydraulic motor 4 to make the speed of the input shaft 1 close to the speed of the output shaft 2, ensuring the smoothness of the shifting process, avoiding shifting shock and component wear caused by speed mismatch, and ensuring the smoothness of power transmission.

[0059] According to an embodiment of the present invention, in another aspect, a control method is also provided, applicable to the shifting system as described above, the control method comprising: Obtain the rotational speeds of input shaft 1 and output shaft 2; Based on the shift command, the shift mechanism is controlled to disconnect the output shaft 2 and the input shaft 1; the displacement of the first drive component 5 is adjusted to control the speed of the input shaft 1; when the speeds of the input shaft 1 and the output shaft 2 are the same, the shift mechanism is controlled to change the engagement gear of the input shaft 1 and the output shaft 2.

[0060] The controller is the Vehicle Electronic Control Unit (VECU). The VECU monitors n1 and n2 and regulates the on / off states of the first valve body 71, the second valve body 72, the first gear control valve 73, and the second gear control valve 74 to achieve gear switching of the gear shifting system and control the displacement of the hydraulic motor 4.

[0061] By monitoring n1 and n2 in real time with the controller, n1 is first reduced by decreasing the displacement of the hydraulic motor 4, so that n1 and n2 gradually approach each other before shifting gears. This avoids gear meshing impact caused by excessive speed difference, reduces the occurrence of gear grinding, and ensures the smoothness of the shifting process. At the same time, the load on the motor is released during the shifting process, which can reduce the impact of power transmission and make the gear shifting process smoother.

[0062] In one embodiment, the rotational speed of the input shaft 1 is defined as n1, the rotational speed of the output shaft 2 is defined as n2, and the shifting mechanism has a disconnect position that disconnects the output shaft 2 from the input shaft 1, and a first engagement position and a second engagement position that drive the output shaft 2 and the input shaft 1 together. The shifting system includes a reversing valve 6. When the shift command is an upshift command, the control methods include: S11, control the shifting mechanism to switch from the first engaged position to the disengaged position; reduce the displacement of the first drive component 5 so that the displacement of the hydraulic motor 4 is reduced, thereby reducing n1; S12. When n1 and n2 are the same, control the reversing valve 6 to switch to the on position 62, so that the hydraulic motor 4 can run freely; control the shifting mechanism to switch to the second engagement position. S13, control the directional valve 6 to switch to the blocking position 61, and the hydraulic motor 4 obtains power; When the shift command is a downshift command, the control methods include: S21, control the shifting mechanism to switch from the second engaged position to the disengaged position; increase the displacement of the first drive component 5 so that the displacement of the hydraulic motor 4 increases and n1 rises; S22. When n1 and n2 are the same, control the reversing valve 6 to switch to the on position 62 so that the hydraulic motor 4 can run freely; control the shifting mechanism to switch to the first engagement position. S23, control the directional valve 6 to switch to the blocking position 61, and the hydraulic motor 4 obtains power.

[0063] When shifting from first gear to second gear, the gear ratio of first gear (n1 / n2 = Z4 / Z3) needs to be satisfied, which requires n1 / n2 = Z2 / Z1. Therefore, the speeds of n1 and n2 need to be matched. n2 is determined by the load and cannot be adjusted, but the synchronization of the two gears can be achieved by adjusting n1. When shifting from first gear to second gear, n1 needs to be reduced, therefore the displacement of the hydraulic motor 4 needs to be reduced to achieve effective matching.

[0064] When the gear shifting system includes a first gear control valve 73, a second gear control valve 74, and a first valve body 71; In S11, the first gear control valve 73 is switched to the third cut-off position 732 so that the gear shifting mechanism is switched from the first engaged position to the disengaged position; In S12, the first valve body 71 is switched to the first connecting position 711 so that the reversing valve 6 is switched to the conducting position 62; the second gear control valve 74 is switched to the fourth connecting position 741 so that the shifting mechanism is switched to the second engaging position. In S13, the first valve body 71 is switched to the first shut-off position 712 so that the reversing valve 6 is switched to the blocking position 61; In S21, the second gear control valve 74 is switched to the fourth cut-off position 742 so that the shifting mechanism is switched from the second engaged position to the disengaged position; In S22, the second valve body 72 is switched to the second connecting position 721 so that the reversing valve 6 is switched to the conducting position 62; the first gear control valve 73 is switched to the third connecting position 731 so that the shifting mechanism is switched to the first engaging position. In S23, the first valve body 71 is switched to the first shut-off position 712 so that the directional valve 6 is switched to the blocking position 61.

[0065] When shifting from second gear to first gear, the gear ratio (n1 / n2 = Z2 / Z1) in second gear needs to satisfy n1 / n2 = Z4 / Z3. Here, n2 is determined by the load and cannot be adjusted. Synchronization of the two gears can be achieved by adjusting n1. Shifting from second to first gear requires increasing n1, thus necessitating an increase in the displacement of the hydraulic motor 4 for effective matching.

[0066] According to an embodiment of the present invention, in another aspect, an engineering vehicle is also provided, including a vehicle body and a gear shifting system as described above disposed on the vehicle body.

[0067] By equipping engineering vehicles with the aforementioned gear shifting system, smooth gear shifting can be achieved without the need for a clutch or stopping, significantly improving work efficiency, avoiding gear shifting jams and component wear, adapting to various engineering operation scenarios, being easy to operate, and ensuring stable operation of the vehicle during continuous work.

[0068] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A gear shifting system, characterized in that, include: An input shaft (1) and an output shaft (2) are connected in an on / off manner via a shifting mechanism. A hydraulic motor (4) is connected to the input shaft (1) and is adapted to drive the input shaft (1) to rotate; A first drive element (5) is adapted to provide power to the hydraulic motor (4); A first sensor (101) is disposed on the input shaft (1) and is adapted to monitor the rotational speed of the input shaft (1); The second sensor (201) is disposed on the output shaft (2) and is adapted to monitor the rotational speed of the output shaft (2); The controller is electrically connected to the first sensor (101) and the second sensor (201). The controller is adapted to control the shift mechanism to disconnect the output shaft (2) and the input shaft (1) based on the shift command and to adjust the displacement of the first drive (5) to control the speed of the input shaft (1). When the speeds of the input shaft (1) and the output shaft (2) are the same, the controller is adapted to control the shift mechanism to change the engagement gear of the input shaft (1) and the output shaft (2).

2. The shifting system according to claim 1, characterized in that, The hydraulic motor (4) includes a motor inlet end and a motor outlet end. The first drive component (5) includes an oil outlet and an oil inlet. The oil outlet is connected to the motor inlet end through a first pipeline (100), and the oil inlet is connected to the motor outlet end through a second pipeline (200). The shifting system also includes: A reversing valve (6) is connected to a first pipeline (100) and a second pipeline (200). The reversing valve (6) has a blocking position (61) suitable for blocking the passage of hydraulic oil, and a conducting position (62) suitable for allowing hydraulic oil to pass through to connect the first pipeline (100) and the second pipeline (200). When the input shaft (1) and the output shaft (2) rotate at the same speed, the controller controls the reversing valve (6) to be in the conducting position (62).

3. The shifting system according to claim 2, characterized in that, The reversing valve (6) is a hydraulically controlled reversing valve. The shifting system further includes: a first valve body (71) connected to the control port of the reversing valve (6). The first valve body (71) includes a first connecting position (711) adapted to put the reversing valve (6) into the conducting position (62), and a first cutting-off position (712) adapted to put the reversing valve (6) into the blocking position (61). The second drive unit (8) is connected to the first valve body (71) and is adapted to provide hydraulic oil to the first valve body (71); Alternatively, the reversing valve (6) may be an electromagnetic reversing valve.

4. The shifting system according to any one of claims 1 to 3, characterized in that, The input shaft (1) is connected to a first gear (Z1) and a third gear (Z3) with different numbers of teeth. The first gear (Z1) and the third gear (Z3) are adapted to rotate synchronously with the input shaft (1). The output shaft (2) is coaxially fitted with a second gear (Z2) and a fourth gear (Z4) with different numbers of teeth. The second gear (Z2) meshes with the first gear (Z1), and the fourth gear (Z4) meshes with the third gear (Z3). The shifting mechanism is a shift fork assembly (3), which is adapted to selectively connect the second gear (Z2) and the fourth gear (Z4) to the output shaft (2); or to disengage both the second gear (Z2) and the fourth gear (Z4) from the output shaft (2).

5. The shifting system according to claim 4, characterized in that, The shifting system also includes: A first-gear control valve (73) includes a third communication position (731) adapted to drive the shift fork assembly (3) to drive the fourth gear (Z4) to drive the output shaft (2), and a third disconnect position (732) adapted to disconnect the fourth gear (Z4) from the output shaft (2). The two-position control valve (74) includes a fourth communication position (741) adapted to drive the shift fork assembly (3) to drive the second gear (Z2) to the output shaft (2), and a fourth disconnect position (742) adapted to disconnect the second gear (Z2) from the output shaft (2). The second drive unit (8) is connected to the first gear control valve (73) and the second gear control valve (74) and is adapted to provide hydraulic oil to the first gear control valve (73) and the second gear control valve (74).

6. The shifting system according to claim 1, characterized in that, Also includes: The second valve body (72) includes a second connecting position (721) adapted to cause hydraulic oil to drive the swashplate (41) to rotate so that the hydraulic motor (4) is in a first displacement state, and a second disconnecting position (722) adapted to reset the swashplate (41) so that the hydraulic motor (4) is in a second displacement state. The second drive element (8) is connected to the second valve body (72) and is adapted to supply hydraulic oil to the second valve body (72).

7. A control method, characterized in that, The control method, applicable to any one of claims 1 to 6, comprises: Obtain the rotational speeds of the input shaft (1) and the output shaft (2); Based on the shift command, control the shift mechanism to disconnect the output shaft (2) and the input shaft (1); adjust the displacement of the first drive (5) to control the speed of the input shaft (1); when the speeds of the input shaft (1) and the output shaft (2) are the same, control the shift mechanism to change the engagement gear of the input shaft (1) and the output shaft (2).

8. The control method according to claim 7, characterized in that, The rotational speed of the input shaft (1) is defined as n1, and the rotational speed of the output shaft (2) is defined as n2. The shifting mechanism has a disconnection position that disconnects the output shaft (2) and the input shaft (1), and a first engagement position and a second engagement position that connects the output shaft (2) and the input shaft (1) in a transmission manner. The shifting system includes a reversing valve (6). When the shift command is an upshift command, the control method includes: S11. Control the shifting mechanism to switch from the first engaged position to the disengaged position; reduce the displacement of the first drive member (5) so that the displacement of the hydraulic motor (4) is reduced, thereby reducing n1; S12. When n1 and n2 are the same, control the reversing valve (6) to switch to the conducting position (62) so that the hydraulic motor (4) can run idle; control the shifting mechanism to switch to the second engagement position; S13, control the reversing valve (6) to switch to the blocking position (61), and the hydraulic motor (4) obtains power; When the shift command is a downshift command, the control method includes: S21. Control the shifting mechanism to switch from the second engaged position to the disengaged position; increase the displacement of the first drive member (5) so that the displacement of the hydraulic motor (4) increases and the n1 is raised; S22. When n1 and n2 are the same, control the reversing valve (6) to switch to the conducting position (62) so that the hydraulic motor (4) can run idle; control the shifting mechanism to switch to the first engagement position; S23. Control the reversing valve (6) to switch to the blocking position (61), and the hydraulic motor (4) obtains power.

9. The control method according to claim 8, characterized in that, When the shifting system includes a first gear control valve (73), a second gear control valve (74), and a first valve body (71); In S11, the first gear control valve (73) is switched to the third cut-off position (732) so that the gear shifting mechanism is switched from the first engaged position to the disengaged position; In S12, the first valve body (71) is switched to the first connecting position (711) so that the reversing valve (6) is switched to the conducting position (62); the second gear control valve (74) is switched to the fourth connecting position (741) so that the shifting mechanism is switched to the second engaging position; In S13, the first valve body (71) is controlled to switch to the first shut-off position (712) so that the reversing valve (6) switches to the blocking position (61). In S21, the second gear control valve (74) is switched to the fourth cut-off position (742) so that the shifting mechanism is switched from the second engaged position to the disengaged position; In S22, the second valve body (72) is switched to the second connecting position (721) so that the reversing valve (6) is switched to the conducting position (62); the first gear control valve (73) is switched to the third connecting position (731) so that the gear shifting mechanism is switched to the first engaging position; In S23, the first valve body (71) is switched to the first shut-off position (712) so that the directional valve (6) is switched to the blocking position (61).

10. An engineering vehicle, characterized in that, It includes a vehicle body and a shifting system as described in any one of claims 1 to 6 disposed on the vehicle body.

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