Method system for controlling gear selection in a vehicle

Abstract

A method of controlling gear selection in a vehicle transmission includes detecting a change in a direction control signal (DCS) from a neutral signal state. If a current TOS is less than or equal to a predetermined neutral shift threshold TOS, the transmission selects one of a plurality of first direction gears when the DCS changes to a first direction signal state or one of a plurality of second direction gears when the DCS changes to a second direction signal state. If the current TOS is greater than the predetermined neutral shift threshold TOS, the transmission selects one of the plurality of first direction gears when a machine motion direction parameter indicates that the vehicle is moving in a first direction or one of the plurality of second direction gears when the machine motion direction parameter indicates that the vehicle is moving in a second direction.

Description

Technical Field

[0001] This disclosure relates to a method for controlling gear selection in a vehicle's transmission in response to an operator's request to shift the vehicle's transmission into neutral, and a control system for controlling gear selection when shifting into neutral in a vehicle. Background Technology

[0002] Many vehicles, such as working machines, mining equipment, and other working vehicles, may include power-shift transmissions coupled to a power source such as an internal combustion engine or an electric motor to provide greater flexibility in using the power source's output. Transmissions for such vehicles typically include multiple speed and direction-changing clutches and multiple transmission gears, where combinations of the various pairs of direction and speed-changing clutches effectively complement the transmission gears to provide multiple transmission gear ratios. The transmission not only provides multiple gears with gear ratios, enabling the working machine to travel at a relatively wide speed range or under conditions that might be impractical without a transmission, but also serves to change the vehicle's direction between forward and reverse. Some transmissions are configured to automatically change gears to improve the ease of operation of the vehicle across its speed range.

[0003] The vehicle's direction of travel can be selected by the operator via a suitable control device, such as a joystick. Operator selection of direction switching to change the direction of travel while the vehicle is moving is common, especially for vehicles such as backhoe loaders and forklifts. The operator can also select a control setting to place the transmission in neutral during vehicle operation. This can occur, for example, during the transition of the control device from a forward position through a neutral position to a reverse position. Alternatively, an additional neutral control can be provided that overrides the control device's position to place the transmission in neutral. With the transmission in neutral, the vehicle can accelerate or decelerate, for example, while coasting downhill.

[0004] When requesting to shift out of neutral, the operator can request a direction that matches or opposes the machine's current direction of motion. During transmission shifts, energy is transferred to the clutch plates, and the amount of energy is proportional to the speed difference between the clutch plates. In high-speed directional shifts, the clutch plates rotate in opposite directions at a high speed difference before engaging. Therefore, during the time required for the clutch to fully engage, a significant amount of energy can be transferred to the clutch plates, converting from kinetic energy to heat due to friction. The increased energy demand during speed changes can lead to increased heat generation at the transmission clutches, and premature clutch failure can occur when the clutch temperature repeatedly exceeds the material durability limits of the clutch components. Similar problems can occur when the vehicle accelerates or decelerates in neutral and then engages the forward or reverse gear. Similar problems can also occur when the vehicle accelerates and the clutch upshifts, and when the vehicle decelerates and the clutch holds the current gear or downshifts for engine braking. In some power shift transmissions, the impending directional change clutch is often the most vulnerable to failure because a large portion of the vehicle's energy is effectively absorbed by the directional change clutch.

[0005] If the vehicle speed has increased while in neutral, there is a risk of the vehicle's power unit overspeeding when shifting out of neutral.

[0006] One option to mitigate this behavior is to issue a warning, but this can still cause potential damage. Another option when requesting a high-speed directional change is to suppress the directional change. Suppressing the directional change involves holding the original gear but limiting engine speed to slow the machine or selecting neutral to slow the vehicle. Suppressing the directional change can be problematic because the vehicle's behavior may not be as the operator expects. If only moderate deceleration is achieved or no deceleration is achieved when the operator expects rapid deceleration, this can lead to degraded control or the need to use inconvenient stopping mechanisms, such as unloading work tools or applying the parking brake. Suppressing the directional change out of neutral can be detrimental because it can lead to coasting and an unnecessary increase in speed. Suppressing the directional change may involve holding the original gear or selecting neutral.

[0007] US9689490B2 describes a method for selecting and switching the speed-changing gears on an automatic grader, including a method for controlling the selection of the direction-changing gear. When the speed of the transmission output shaft exceeds a predetermined limit, the transmission is prevented from directly switching to the reverse gear. Instead, the transmission initially downshifts to the lower forward gear (e.g., from 4F to 3F) and applies a delaying force to slow the machine until the speed of the transmission output shaft is below a predetermined maximum speed limit. When the speed is below the predetermined limit, the direction change is completed by switching the transmission to the lower reverse gear (e.g., from 3F to 1R). This is a combined direction change, i.e., there is a change in both direction and gear number. In some cases, direction changing is prohibited until the operator slows the machine down to below a predetermined speed.

[0008] A control strategy is needed to select the appropriate gear when shifting out of neutral, thus maintaining vehicle control while preventing transmission damage. Summary of the Invention

[0009] Therefore, this disclosure provides a method for controlling gear selection in a transmission of a vehicle having a power unit and an automatic transmission, the transmission having a plurality of first direction gears configured to move the vehicle in a first direction and a plurality of second direction gears configured to move the vehicle in a second direction opposite to the first direction;

[0010] It receives directional control signals from one or more input devices controlled by the operator of the vehicle; and

[0011] The vehicle's control system determines the machine's motion direction parameters;

[0012] The method includes the following steps:

[0013] i) Detect the change of the direction control signal from the neutral signal state to the first direction signal state or the second direction signal state;

[0014] ii) Determine the current transmission output speed;

[0015] iii) Compare the current transmission output speed with a predetermined neutral shift threshold transmission output speed; and any one of the following

[0016] iv a) If the current transmission output speed is less than or equal to the predetermined neutral shift threshold transmission output speed, then the transmission selects a gear from the plurality of first direction gears when the direction control signal becomes the first direction signal state, or selects a gear from the plurality of second direction gears when the direction control signal becomes the second direction signal state; or

[0017] iv b) If the current transmission output speed is greater than the predetermined neutral shift threshold transmission output speed, then the transmission selects a gear from the plurality of first direction gears when the machine motion direction parameter indicates that the vehicle is moving in the first direction, or selects a gear from the plurality of second direction gears when the machine motion direction parameter indicates that the vehicle is moving in the second direction.

[0018] This disclosure also provides a control system for controlling gear selection in a transmission of a vehicle, the vehicle having a power unit and an indirect-drive automatic transmission, the transmission having a plurality of first-direction gears configured to move the vehicle in a first direction and a plurality of second-direction gears configured to move the vehicle in a second direction opposite to the first direction, the control system being configured to;

[0019] Evaluate the direction control signals from one or more input devices controlled by the operator of the vehicle; and

[0020] Determine the parameters of the machine's direction of motion;

[0021] i) The control system is further configured to detect changes in the directional control signal from a neutral signal state to a first directional signal state or a second directional signal state;

[0022] ii) Determine the current transmission output speed;

[0023] iii) Compare the current transmission output speed with a predetermined neutral shift threshold transmission output speed; and any one of the following

[0024] iv a) If the current transmission output speed is less than or equal to the predetermined neutral shift threshold transmission output speed, then the transmission selects a gear from the plurality of first direction gears when the direction control signal becomes the first direction signal state, or selects a gear from the plurality of second direction gears when the direction control signal becomes the second direction signal state; or

[0025] iv b) If the current transmission output speed is greater than the predetermined neutral shift threshold transmission output speed, then the transmission selects a gear from the plurality of first direction gears when the machine motion direction parameter indicates that the vehicle is moving in the first direction, or selects a gear from the plurality of second direction gears when the machine motion direction parameter indicates that the vehicle is moving in the second direction.

[0026] This disclosure also provides vehicles, including:

[0027] Power unit;

[0028] An indirect-drive automatic transmission having a plurality of first-direction gears configured to move the vehicle in a first direction and a plurality of second-direction gears configured to move the vehicle in a second direction opposite to the first direction;

[0029] An operator-actuated input direction control, the operator-actuated input direction control being configured to generate a direction control signal;

[0030] At least one transmission output speed sensor, the at least one transmission output speed sensor being configured to measure the current speed of the transmission output and generate a transmission output speed signal; and

[0031] According to the control system disclosed herein, the control system is operatively connected to the power unit, transmission, input direction control, and at least one transmission output speed sensor. Attached Figure Description

[0032] Some aspects of this disclosure will be described below by way of example only, with reference to the following figures, in which:

[0033] Figure 1 A side view of a backhoe loader as a vehicle, suitable for implementing the methods and control systems of this disclosure;

[0034] Figure 2 It is a schematic diagram of a powertrain including a transmission control system for implementing the methods of this disclosure;

[0035] Figure 3 yes Figure 1 A diagram of the vehicle's transmission system;

[0036] Figure 4 yes Figure 3 The cross-section of the transmission system is represented;

[0037] Figure 5 It includes Figure 2 A schematic diagram of the machine control system, including the transmission control system and associated control components;

[0038] Figure 6 This is a flowchart illustrating the method according to this disclosure;

[0039] Figure 7 This is a flowchart illustrating a gear selection routine according to the method of this disclosure;

[0040] Figure 8 This is a flowchart illustrating the process for defining machine motion direction parameters according to the method of this disclosure;

[0041] Figure 9 This is a flowchart illustrating another gear selection routine according to the method of this disclosure;

[0042] Figure 10 It is by Figure 2 A data table of exemplary direction switching control logic implemented in a transmission control system. Detailed Implementation

[0043] Figure 1An example of vehicle 10 is shown, in which case the vehicle is a backhoe loader, suitable for implementing the methods and control systems of this disclosure. However, vehicle 10 can be another type of vehicle or working machine. Vehicle 10 may include a main unit 13 having an operator's cab 14 for an operator and a power unit 19 for providing power to ground engagement devices 15 (e.g., tracks or wheels). Figure 1 (Not shown in the image), such as an internal combustion engine. Vehicle 10 may include: a first implement 11, in this example, a bucket; and a first boom arrangement 16 (backhoe), the first implement 11 being connectable to the first boom arrangement via a known coupling arrangement 17. Vehicle 10 may also include a second implement 12, in this example, also a bucket, attached to the main unit 13 via a second boom arrangement 18. The first boom arrangement 16 and the second boom arrangement 18, as well as the first implement 11 and the second implement 12, may be operated by a suitable hydraulic system known in the art. Depending on the intended use and function of vehicle 10, vehicle 10 suitable for implementing the methods of this disclosure may have any alternative configuration, including or excluding some boom, implement, and / or attachments.

[0044] Ground engagement device 15 may be made of an automatic transmission 21 operably connected between power unit 19 and ground engagement device 15 (see...). Figures 2 to 4The power unit 19 provides power. A rotary power unit output shaft (not shown) can extend from the power unit 19 and can be directly connected to the transmission input shaft 22 by a torque converter or by another indirect drive connection known in the art. Alternatively, the transmission 21 can be a direct drive system, which may require a different calibration system than an indirect drive system. The transmission output shaft 23 can be connected to the ground engagement device 15 via a final drive or the like (not shown). The transmission 21 can be a constant-mesh transmission as shown or another type of transmission. As known in the art, the transmission 21 may include a series of gears that are selectively engaged by a combination of clutches 26 and brakes. Clutches 26 may include multiple speed-changing clutches and direction-changing clutches. Although not described in detail, the combination of direction and speed-changing clutches effectively provides multiple transmission gears for controlling the power transmission between the power unit 19 and the ground engagement device 15. Transmission gears can be provided to move the vehicle 10 in a first (usually) forward direction and a second (usually reverse) direction. Therefore, the transmission 21 may have multiple first-direction transmission gears, which may be forward transmission gears (e.g., 1F, 2F, 3F, 4F), and second-direction transmission gears, which may be reverse transmission gears (e.g., 1R, 2R, 3R). A suitable shift control 20, such as a joystick or shift arrangement, may be provided in the operator's cab 14 to allow the operator to select the desired driving direction of the vehicle 10, i.e., forward, neutral, or reverse, and thereby act as an input direction control 31. The input direction control 31 may also include a neutralizer control 20a, such as a switch or trigger, which may be configured to select neutral without moving the shift control 20. The neutralizer control 20a may be located on the shift control 20 or at any other suitable location. The shift control 20 may also allow the operator to request a gear to shift up or down, thereby acting as an input gear control 32. However, the latter function may be provided by a separate device (e.g., a switch). A suitable input speed control 30, such as a gas pedal or accelerator, may also be provided in the operator's cab 14 to allow the operator to adjust the speed of the vehicle 10. The control device, including the switching control 20 and the neutralizer control 20a, can generate a directional control signal to the transmission control system 24 indicating the direction (forward, reverse, or neutral) requested by the vehicle operator.

[0045] The transmission 21 can be electronically coupled to a transmission control system 24, which can electronically control the operation of the transmission 21 at least by controlling the engagement and disengagement of clutches 26. Clutches 26 can be hydraulically actuated clutches, disposed in a hydraulic circuit and each operable to engage in a known manner in response to actuating pressurized hydraulic fluid flowing thereto. The transmission control system 24 may include an on / off clutch control system that controls the desired speed and direction of the clutches 26 during each gear shift. Clutches 26 can be controlled by means of a solenoid valve arrangement comprising a solenoid corresponding to each clutch 26. For example, actuation of the solenoid upon receiving a suitable control signal can cause the solenoid to direct an actuating flow of pressurized hydraulic fluid to its corresponding clutch 26.

[0046] When a request is made to upshift or downshift in the forward / reverse direction, the engagement / disengagement control mechanism engages the upcoming clutch 26 by engaging the associated solenoid and disengages the corresponding speed clutch 26 by disengaging the associated solenoid. When a direction change is selected, the corresponding speed and direction clutches 26 engage and disengage in a similar manner. Such engagement / disengagement control mechanisms are known in the art. Alternatively, the transmission system may have other types of clutch control, such as electronic clutch pressure control.

[0047] Although the physical configuration of the transmission control system 24 is not illustrated, it may include a number of conventional electronic components, analog-to-digital converters, input-output devices, solenoid drivers, electronic circuitry, and one or more processors. It should be understood that the one or more processors may include one or more microprocessors, controllers, or any other suitable computing devices, resources, hardware, software, or embedded logic. The transmission control system 24 may include memory, main memory, and / or hard disk drives in the processors carrying a set of non-transitory machine-readable instructions or software / code that, when executed by one or more processors, cause the transmission control system 24 to operate gear selection routines 45, 145 in the manner described herein.

[0048] The transmission control system 24 may include multiple components or modules corresponding to functional tasks to be performed by it. In this regard, the term "module" in the specification should be understood as including identifiable portions of code, computations or executable instructions, data, or computational objects to implement a particular function, operation, process, or program. Therefore, modules do not need to be implemented in software; modules may be implemented in software, optionally in hardware, or a combination of software and hardware. Furthermore, modules do not necessarily need to be integrated into a single system, but may be distributed across multiple other devices and systems to provide the functionality described herein. In one exemplary embodiment, one or more processors executing the aforementioned machine-readable instructions or software / code can effectively provide the modules or their functionality as described herein.

[0049] As an alternative, the transmission control system 24 can be an analog or electromechanical device.

[0050] The transmission control system 24 can be a host control system 25 that controls other functions of the vehicle 10 (such as...). Figure 5 (As shown) part of the machine control system 25. The machine control system 25 can be any suitable known type and may include an engine control unit (ECU), etc. The machine control system 25 may include a memory capable of storing instructions or algorithms in data form and a processing unit configurable to perform operations based on those instructions. The memory may include any suitable computer-accessible or non-transitory storage medium for storing computer program instructions, such as RAM, SDRAM, DDR SDRAM, RDRAM, SRAM, ROM, magnetic media, optical media, etc. The processing unit may include any suitable processor capable of executing the instructions stored in the memory, such as a microprocessor, single-processor, multiprocessor, etc. Alternatively, the transmission control system 24 may be a separate control unit electronically connected to the machine control system 25.

[0051] The machine control system 25 can be electronically connected to the control elements of the vehicle 10 and various input devices for commanding the operation of the vehicle 10 and monitoring its performance. The machine control system 25 can be connected to multiple input devices that detect operator input providing demand signals to the machine control system 25. These multiple input devices may include: -

[0052] - Input speed control 30, which generates a speed control signal;

[0053] - Input direction control 31, which generates direction control signals; and

[0054] - Input gear control 32, which generates a gear selection signal.

[0055] The machine control system 25 can also be electronically connected to multiple sensing devices that provide sensor signals having values ​​indicating the real-time operating conditions of the vehicle 10. The sensors may include: -

[0056] - At least one transmission output speed sensor 33, connected to an output shaft 23, which transmits a transmission output speed signal and can transmit a value indicating the rotational transmission output speed (TOS) of the transmission output shaft 23; and

[0057] - An oil temperature sensor 36, such as a thermocouple disposed within the transmission housing or other drivetrain components, transmits an oil temperature sensor signal corresponding to a value of oil temperature. Although the control strategies described herein may not utilize oil temperature values, temperature has a significant impact on transmission fluid and can prevent or allow certain operating modes. Therefore, they can be used in modified versions of the strategy.

[0058] The machine control system 25 can also be electrically connected to an output device, to which control signals are transmitted, and from which the machine control system 25 can receive control signals. The output device may include: -

[0059] - An engine throttle valve 37 that can control the speed of the power unit 19;

[0060] - One or more clutch actuators 38, which can control the transmission clutch 26 (via the transmission control system 24) to switch between available gears;

[0061] - A brake actuator or actuator 39, which allows hydraulic fluid to flow to the braking device to engage and reduce the speed of the vehicle 10; and

[0062] - Other optional delay devices actuator 40 that can be operated to reduce TOS. Although the examples of control strategies described herein may not use braking and delay systems, they may be used in modified strategies.

[0063] refer to Figure 6 and Figure 7The transmission control system 24 is programmable to execute a gear selection routine 145 in response to an operator's request to shift out of neutral via input direction control 31. Gear selection routine 145 may include logic based on a control strategy designed to prevent engine / transmission damage and assist the operator in controlling the vehicle 10. The logic uses a current TOS, such as that measured by the transmission output speed sensor 33, and compares it to a predetermined neutral shift threshold TOS programmed into the transmission control system 24. The neutral shift threshold TOS may be a speed below which it is considered safe to allow the transmission to shift out of neutral in the opposite direction of travel, making damage unlikely. If the current TOS exceeds the neutral shift threshold, the logic matches the transmission gear direction to the machine's direction of motion and matches the selected gear to the current TOS. Therefore, if the current TOS exceeds the neutral shift threshold and the machine's direction of motion parameters do not indicate the same direction as the direction control signal, the logic can suppress the shift.

[0064] The neutral shift threshold TOS of vehicle 10 can be based on the maximum amount of energy consumed to shift into neutral without exceeding the operational limitations of components of vehicle 10, such as transmission unit 21 and transmission clutch 26. The neutral shift threshold TOS can be pre-programmed into the transmission control system 24. The neutral shift threshold TOS can be empirically derived from test data of vehicle 10 and can be derived using power and energy analysis to determine the TOS limit that clutch 26 can achieve without damage. Different configurations of vehicle 10 and transmission 21 can have different neutral shift threshold TOS. The neutral shift threshold TOS can be a fixed value. For example, the neutral shift TOS threshold could be 1000 rpm. The neutral shift threshold TOS of any vehicle can depend on any of many parameters, including gear ratio, tire size, vehicle weight, and transmission design.

[0065] Figure 6 An embodiment of control logic for a gear selection routine 145 in a vehicle 10 described herein, according to the method of this disclosure, is shown. The gear selection routine 145 may begin at block 146 when the operator issues a switching request from neutral to forward or reverse.

[0066] If the request to shift out of neutral is determined by the change in the direction control signal from the neutral signal state to the forward or reverse signal state, then control can be passed to block 147.

[0067] At box 147, the transmission control system 24 can determine the current TOS based on measurements taken by the transmission output speed sensor 33.

[0068] At box 148, the transmission control system 24 can compare the current TOS with the neutral shift threshold TOS for which a shift is requested.

[0069] If the current TOS is equal to or less than the neutral shift threshold TOS, control can be passed to block 149, where a signal can be generated to transmission 21 that enables transmission to select a gear from a plurality of forward gears when the direction control signal becomes a forward direction control signal, or to select a gear from a plurality of reverse gears when the direction control signal becomes a reverse signal.

[0070] If the current TOS is greater than the neutral shift threshold TOS, control can be passed to block 150. At block 150, if the machine motion direction parameter indicates forward motion, gear selection routine 145 can cause transmission 21 to select a gear from a plurality of forward gears; or if the machine motion direction parameter indicates reverse motion, it can select a gear from a plurality of reverse gears.

[0071] The machine's motion direction parameters can be determined by the transmission control system 24 based on, for example... Figure 8 The parameter setting method is as shown. When the current transmission output speed is below the direction detection threshold, the machine motion direction parameter is zero. The direction detection threshold is a speed above which the machine's movement can be accurately determined. When the transmission output speed increases to or above the direction detection threshold, if one of the multiple forward gears is currently engaged, the machine motion direction parameter is set to the forward direction; or if one of the multiple reverse gears is currently engaged, the machine motion direction parameter is set to the reverse direction. The machine motion direction parameter remains fixed until the current transmission output speed changes below the direction detection threshold. Therefore, the machine motion direction parameter does not change directly from forward to reverse, and only changes when the transmission output speed is below the direction detection threshold.

[0072] Alternatively, the machine's motion direction parameters can be determined by other suitable means, such as by a direction detection sensor attached to the transmission output.

[0073] Each of the multiple forward gears and multiple reverse gears has a gear selection threshold transmission output speed. In blocks 149 and 150, a specific gear is selected from the multiple forward gears or multiple reverse gears by comparing the current transmission output speed with the gear selection threshold transmission output speed.

[0074] A gear selection threshold TOS can be set for each gear, representing the maximum TOS required to switch to that particular gear. This threshold can be based on a calculable or sensed speed that is directly related to the power and energy that the transmission must absorb or redirect. This threshold can be stored or calculated in real time.

[0075] The gear selected for a specific current TOS can be the lowest gear whose current TOS is less than or equal to the gear selection threshold TOS. If the current TOS exceeds the gear selection threshold of the highest gear in a specific direction, then the highest gear in that direction can be selected.

[0076] For example, the gear selection threshold TOS can be shown in the table below.

[0077] 1F (i.e., 1 forward) 475 2F 1283 3F 1644 4F 3837 5F 3837 6F 3837 1R (i.e., 1 in reverse) 475 2R 1283 3R 1644

[0078] As another example, the gear selection threshold TOS can be shown in the table below.

[0079]

[0080] After selecting a gear in boxes 149 or 150, another gear selection routine or control method can be used to determine subsequent gear changes. For example, if the direction selected by the operator differs from the actual machine direction, reducing engine speed can be used to slow the machine to a suitable speed before selecting the operator's requested direction. If the engagement direction matches the operator's requested direction, other gear switching routines can select further modifications to the gears and direction in response to changes in vehicle speed or operator requests.

[0081] Therefore, gear selection routine 145 can form part of gear control method 155, such as Figure 7 As shown. From box 149 or 150, control can be passed to the start of gear control method 155.

[0082] like Figure 7 As shown, the transmission control system 24 can continuously evaluate the value of the direction control signal from the input direction control 31. Therefore, the gear selection routine 145 can form part of the continuous cyclic gear control method 155.

[0083] Gear control method 155 includes steps (blocks 156 to 159) in which a direction control signal is detected to change from a neutral signal state to a forward signal state or a reverse signal state. For example... Figure 7As shown, if the shift control 20 is in the neutral position, or if the neutralizer switch 20a is activated by the operator, the direction control signal can be in the neutral state. In gear control method 155, in block 156, the transmission control system 24 detects whether the shift control 20 is in the forward or reverse position. If the shift control 20 is not in the forward or reverse position (i.e., in the neutral position), or if the neutralizer switch 20a is pressed, as checked in block 158, then as shown in block 157, the transmission is placed in neutral (in the neutral state), after which gear control method cycle 155 restarts.

[0084] At box 159, if the switching control 20 is in the forward or reverse position and the neutralizer switch is not pressed, the transmission control system 24 compares the current direction control signal with the direction control signal detected in the previous cycle of method 155.

[0085] If the direction control signal was previously in neutral, and it has been identified that the direction control signal has changed from neutral to forward or reverse (see box 146), then gear selection routine 145 can be performed as follows: Figure 6 Execute as shown.

[0086] As shown in box 160, if the direction control signal in the previous control cycle was in a forward or reverse state (i.e., the direction control signal was not in neutral), the transmission control system 24 can determine whether a direction change from forward to reverse (or vice versa) has been requested. If a direction change has been requested, another gear selection routine 45 can be executed (e.g., Figure 9 (As shown and described below). If no direction switch is requested (i.e., the direction control signal in the previous loop is the same as the current loop of the routine), the routine may return to the beginning of method 155 to detect whether the toggle control 20 is forward or reverse.

[0087] By way of example, the positions of the switching control 20 and the neutralizer switch 20a are mentioned in this specification. Those skilled in the art will understand that the direction input control 31 may take another physical form, or may take a form other than a device with a different physical location, such as a touch screen control, in which case the “position” of the control refers to different states of the control (e.g., neutral state, forward state, and reverse state), and “pressing the neutralizer switch” may include any activation form of the neutralizer control.

[0088] like Figure 9As shown, the transmission control system 24 is programmable to execute a gear selection routine 45 in response to a direction change requested by the operator via input direction control 31. The gear selection routine 45 may include logic based on a control strategy designed to prevent engine / transmission damage and assist the operator in controlling the vehicle 10. This logic can ensure that the vehicle 10 is moving at an appropriate speed before a direction change is performed. Therefore, the gear selection routine 45 can initially suppress the requested direction change. When the requested direction change is not immediately performed, the gear selection routine 45 can be designed to perform one or more sequential downshifts in the same direction of vehicle travel from the initial gear (i.e., the gear at the time of the requested direction change) to the secondary gear to assist in decelerating the vehicle 10. Under certain conditions, the gear selection routine 45 can also maintain the initial gear and can execute an engine deceleration command that also contributes to the deceleration of the vehicle 10. A direction change can then be performed only when the vehicle 10 is moving at an appropriate speed, and the selected opposite-direction gear can be a gear that matches the current vehicle speed. Therefore, the same opposite-direction gear can be selected as either the initial gear or the secondary gear. The logic uses the current TOS, such as that measured by the transmission output speed sensor 33, and compares it with a predetermined direction switching threshold TOS programmed into the transmission control system 24.

[0089] The direction switching threshold TOS of vehicle 10 can be based on the maximum amount of energy consumed to change the direction of vehicle 10 without exceeding the operational limitations of components of vehicle 10 (e.g., transmission 21 and transmission clutch 26). The direction switching threshold TOS can be pre-programmed into the transmission control system 24. The direction switching threshold TOS can be empirically derived from test data of vehicle 10 and can be derived using power and energy analysis to determine the possible direction switching TOS limit that clutch 26 can achieve without causing damage. Different configurations of vehicle 10 and transmission 21 can have different direction switching threshold TOS.

[0090] The machine control system 25 and / or the transmission control system 24 are also programmable with predetermined downshift suppression thresholds TOS for each downshift (i.e., to a gear in the same direction). These prevent the transmission 21 from downshifting to a lower gear, which would risk overspeeding of the power unit 19.

[0091] Figure 9An embodiment of control logic for another gear selection routine 45 in the vehicle 10 described herein, according to the method of this disclosure, is shown. Gear selection routine 45 may begin at block 46, where the operator makes a direction change request from forward to reverse or from reverse to forward. The transmission control system 24 may continuously evaluate the value of the direction control signal from the input direction control 31 and determine that a direction change request has been issued when the direction control signal value changes from the current driving direction (first direction) of the vehicle 10 to the opposite direction (second direction). If a direction change request is determined by the change in the direction control signal, control may be passed to block 47.

[0092] At box 47, the transmission control system 24 can determine the current TOS based on measurements taken by the transmission output speed sensor 33.

[0093] At box 48, the transmission control system 24 can compare the current TOS with the direction switching threshold TOS of the requested direction switching.

[0094] If the current TOS is equal to or less than the direction switching threshold TOS, control can be passed to block 49, where a transmission direction switching signal can be generated to transmission 21, which can cause the transmission to perform the requested direction switching of the same gear in the second direction (referred to as a straight-line direction switching). If there is no same gear in the opposite direction (e.g., if there are 4 forward gears and 3 reverse gears and the direction switching is from 4F), then upshifting to the next highest gear in the other direction (switching to 3R in the aforementioned example) is possible.

[0095] If the current TOS is greater than the direction switching threshold TOS, control can be passed to block 50. At block 50, gear selection routine 45 can suppress direction switching and can generate one or more transmission downshift signals to transmission 21 to perform one or more sequential downshifts of the first direction downshift gear (hereinafter referred to as the secondary gear), or maintain the initial gear until the current TOS decreases to or below the direction switching threshold TOS. The gear change caused by downshifting can cause engine braking, reducing the speed of vehicle 10 and thus reducing TOS. Gear selection routine 45 may alternatively or additionally issue an engine deceleration signal to reduce engine speed (i.e., the speed of power unit 19). Machine control system 25 can override engine throttle valve 37 upon receiving such an engine deceleration signal. In the case where the commanded engine speed is lower than the actual engine speed, machine control system 25 can limit the fuel supply to power unit 19 so that power unit 19 can be rotated by transmission 21. This means that transmission 21 can consume energy to rotate power unit 19, which can reduce its speed. Engine deceleration commands can be limited so that power unit 19 does not provide positive torque. The delay can also be provided by mitigating losses in the power unit 19 and parasitic loads on the power unit 19 and vehicle 10. The downshift gear (and torque converter characteristics) can act to reverse the power unit 19 to the maximum appropriate speed in response to these losses, maximizing the delay effect. Gear selection routine 45 can select the lowest gear in the first direction, which has a downshift suppression threshold TOS greater than the current TOS, and can cause the transmission 21 to sequentially downshift to that gear. This gear can then be maintained until the current TOS drops to or below the direction switching threshold TOS.

[0096] If the initial gear has a downshift suppression threshold TOS greater than the current TOS, the gear selection routine 45 can maintain the initial gear and wait for the current TOS to drop to or below the direction switching threshold TOS, thereby generating a transmission direction switching signal.

[0097] Then, control can be passed to block 49, and if the operator is still requesting a direction change, i.e., the direction change request is still valid, a transmission direction change signal can be generated to transmission 21, which can enable a direction change to be performed on the same gear in the second direction (or on the next highest gear if there is no corresponding gear in the second direction).

[0098] In any aspect of this disclosure, the neutral shift threshold is a threshold applied when shifting out of neutral, and it may be the same as the predetermined direction shift threshold. Alternatively, the neutral shift threshold and the predetermined direction shift threshold may be different values.

[0099] Industrial applicability

[0100] The methods of this disclosure, which execute gear selection routine 145 and gear selection method 155, are particularly suitable for vehicles using open / close clutch control systems, such as backhoe loaders, but can be applied to other types of vehicles operating other types of clutch control. The methods of this disclosure can effectively limit transmission damage when shifting gears out of neutral. When the transmission output speed is too high, the logic used in these methods can suppress the requested directional change and thus mitigate transmission clutch deterioration and premature failure.

[0101] According to this disclosure, a method for controlling gear selection in a vehicle transmission includes detecting changes in a direction control signal (DCS) from a neutral signal state. If the current TOS is less than or equal to a predetermined neutral shift threshold TOS, the transmission selects one of a plurality of first direction gears when the DCS becomes a first direction signal state, or selects one of a plurality of second direction gears when the DCS becomes a second direction signal state. If the current TOS is greater than the predetermined neutral shift threshold TOS, the transmission selects one of a plurality of first direction gears when a machine motion direction parameter indicates that the vehicle is moving in a first direction, or selects one of a plurality of second direction gears when a machine motion direction parameter indicates that the vehicle is moving in a second direction.

[0102] Examples of gear selection routine 145 and gear selection method 155 according to this disclosure are provided below. In the following examples, the neutral shift transmission output speed threshold can be 1000 rpm. These examples are provided to aid in understanding the methods and control systems of this disclosure and should not be considered limiting.

[0103] In the first instance, when the operator requests a direction change, switching the direction control signal from forward to neutral (immediately) and then to reverse, the machine may travel downhill in the forward direction at a transmission output speed of 1800 rpm (making the machine's direction of motion parameter forward).

[0104] Initially, before requesting a direction switch, the direction control signal remains in a forward state, starting from block 156 of the gear control method. The control sequence passes through block 158 (since the neutralizer switch is not pressed) to block 159. Since the direction control signal was in a forward state in the previous loop, control is passed to block 160, initiating gear selection routine 45. At this point, since no direction switch has been requested, the routine returns to the beginning of method 155 to detect the position of the switching control 20.

[0105] When the shift control 20 momentarily moves to neutral, the direction control signal changes to neutral, and the control system can place the transmission in neutral. Then, the routine returns to the beginning of method 155 to detect the position of the shift control 20.

[0106] When the toggle control 20 moves to the reverse direction, upon detecting the position of the toggle control 20, the control sequence passes through box 158 to box 159 (because the neutralizer switch is not pressed). Since the direction control signal in the previous cycle was in neutral, a request to switch out of neutral is detected, and control is passed to box 146, initiating gear selection routine 145.

[0107] In this example, the current transmission output speed remains above the neutral shift threshold (1800 rpm vs. 1000 rpm). Therefore, the transmission control system 24 selects a forward gear based on the machine motion direction parameters as shown in block 150. The selected forward gear (e.g., 2F, 3F, 4F) can be matched to the current transmission output speed. The routine can then return to the beginning of method 155 to detect the position of the shift control 20.

[0108] The method then continues through blocks 156, 158, and 159 (in the order stated). The direction control signal from the previous control loop is not in neutral and is therefore sequentially passed to block 160. At this stage, the operator requests a reverse direction via switching control 20, and the machine is moving forward with the transmission in the forward gear. Therefore, when the transmission is in the initial forward gear and routine 45 is applied, the transmission control system 24 determines that the vehicle operator has issued a direction switching request to move the vehicle from the forward direction to the reverse direction. If the current transmission output speed remains above a predetermined direction switching threshold, the control system can slow down the machine, downshift, and reduce the transmission output speed. If the transmission output speed is less than or equal to the predetermined direction switching threshold, and the operator is still requesting a direction switching, the system switches to the reverse direction.

[0109] In addition to the first example, if the vehicle operator presses and releases the neutral switch after moving the shift control 20 to the reverse position, the control system can detect further changes in leaving neutral. Assuming the transmission output speed remains above the threshold, the control routine can be passed back to block 149 and can follow the remaining routines as described in the first example above.

[0110] In the second example, when the operator presses and releases the neutralizer switch 20a, the machine can travel in the forward direction on a flat road at a transmission output speed of 1800 rpm (making the machine's direction of motion parameter forward).

[0111] Initially, before the neutralizer switch 20a is pressed and starting from block 156 of the gear control method, the direction control signal remains in the forward state. The control sequence passes through blocks 158 to 159 (because the neutralizer switch is not pressed). Since the direction control signal was in the forward state in the previous cycle, control is passed to block 160, and the gear selection routine 45 begins. At this point, if no direction switching is requested, the routine can return to the beginning of method 155 to detect the position of the switching control 20.

[0112] When the neutral switch 20a is pressed by the operator, the direction control signal can be switched to neutral, and the transmission control system 24 can put the transmission in neutral. Then, the routine can return to the beginning of method 155 to detect the position of the switching control 20.

[0113] When the neutralizer switch 20a is released, the control sequence moves from box 158 (when the neutralizer switch is not pressed) to box 159 upon detection of the position of the switching control 20. Since the direction control signal in the previous cycle was in neutral, a request to switch out of neutral is detected, and control is passed to box 146, initiating gear selection routine 145.

[0114] In this example, the current transmission output speed remains above the neutral shift threshold (1800 rpm vs. 1000 rpm). Therefore, the transmission control system 24 can select a forward gear based on the machine motion direction parameters as shown in block 150. The selected forward gear (e.g., 2F, 3F, 4F) can be matched to the current transmission output speed. Thus, the machine continues forward with the appropriate gear for the current transmission output speed. The routine then returns to the beginning of method 155.

[0115] In the third example, when the operator requests a direction change, switching the direction control signal from forward to neutral (immediately) and then to reverse, the machine can travel downhill in the forward direction at a transmission output speed of 700 rpm (making the machine's direction of motion parameter forward).

[0116] Initially, before a direction switch is requested, the direction control signal remains in a forward state, starting from block 156 of the gear control method. The control sequence passes through blocks 158 to 159 (because the neutralizer switch is not pressed). Since the direction control signal was in a forward state in the previous loop, control is passed to block 160, initiating gear selection routine 45. At this point, if no direction switch is requested, the routine returns to the beginning of method 155 to detect the position of the switching control 20.

[0117] When the shift control 20 momentarily moves to neutral, the direction control signal changes to neutral, and the control system can place the transmission in neutral. Then, the routine returns to the beginning of method 155 to detect the position of the shift control 20.

[0118] When the toggle control 20 moves to the reverse direction, upon detecting the position of the toggle control 20, the control sequence passes through box 158 to box 159 (because the neutralizer switch is not pressed). Since the direction control signal in the previous cycle was in neutral, a request to switch out of neutral is detected, and control is passed to box 146, initiating gear selection routine 145.

[0119] In this example, the current transmission output speed remains below the neutral shift threshold (700 rpm vs. 1000 rpm). Therefore, as shown in block 149, the transmission control system 24 selects the reverse gear based on the direction control signal. The selected reverse gear (e.g., 2R, 3R, 4R) can be matched to the current transmission output speed. Thus, the machine switches to the reverse gear as requested by the operator. The routine then returns to the beginning of method 155 to detect the position of the shift control 20.

[0120] In the fourth example, when the operator presses the neutralizer switch, the machine can travel in the forward direction on a flat road at a transmission output speed of 700 rpm (making the machine's direction of motion parameter forward), further slowing down the machine and releasing the neutralizer switch.

[0121] Initially, before requesting a direction change, starting from block 156 of gear control method 155, the direction control signal remains in a forward state. The control sequence passes through blocks 158 to 159 (because the neutralizer switch is not pressed). Since the direction control signal was in a forward state in the previous loop, control is passed to block 160, and gear selection routine 45 begins. At this point, if no direction change is requested, the routine returns to the beginning of method 155 to detect the position of the switching control 20.

[0122] When the operator presses the neutralizer switch 20a, the direction control signal can be switched to neutral, and the control system can place the transmission in neutral. The routine can then return to the beginning of method 155 to detect the position of the switching control 20.

[0123] When neutralizer switch 20a is released, the control sequence moves from box 158 to box 159 (because neutralizer switch 20a is not pressed) upon detecting the position of switch control 20. Since the direction control signal in the previous cycle was in neutral, a request to switch out of neutral is detected, and control is passed to box 146, initiating gear selection routine 145.

[0124] When the current transmission output speed remains below the neutral shift threshold, the control system selects a forward gear according to the direction control signal as shown in block 149. The selected forward gear (e.g., 2F, 3F, 4F) can be matched with the current transmission output speed. Therefore, the machine continues forward with the appropriate gear for the current transmission output speed. Gear selection routine 145 then returns to the beginning of method 155.

[0125] The method of this disclosure for executing gear selection routine 45 is also particularly suitable for vehicles using on / off clutch control systems, such as backhoe loaders, but it can be applied to other types of vehicles operating other types of clutch control. This method can effectively limit transmission damage caused by heat dissipation from high-speed direction switching to the clutch, and thus mitigate transmission clutch deterioration and premature failure. The logic used in gear selection routine 45 can control the TOS by downshifting in the same direction to slow the vehicle by 10 to a speed at which a straight-line direction switch reversing the driving direction may not cause transmission damage. The method does not attempt to impose any time constraints on direction switching, only on speed. Time-based control strategies can be affected by a lack of system feedback. By using speed, the strategy can respond faster or slower according to the system, and can provide better performance and protection.

[0126] Figure 10 The table provides an example of the logical steps executed by the transmission control system 24 in the gear selection routine 45. This will now be described in more detail based on an exemplary transmission 21 with four forward transmission gears 1F, 2F, 3F, 4F and three reverse transmission gears 1R, 2R, 3R, and a 1000rpm direction switching threshold TOS. The downshift suppression threshold TOS for this example is shown in the table below.

[0127] 4F-3F 1345 3F-2F 1020 2F-1F 717 2R-1R 717 3R-2R 1345

[0128] It should be noted that Figure 10 The table shown does not indicate 1F or 1R as the initial gear for direction switching. This is likely because, in this embodiment, the current TOS may not have reached the damage speed in these gears. Furthermore, 1F or 1R can be avoided in the downshift strategy of gear selection routine 45 to prevent excessive torque from passing through the transmission, which could be greater than the operator expects. Alternatively, the vehicle 10 may be traveling too fast, which could damage 1R / 1F in the event of a sudden gear reduction. This could be a separate control strategy to prevent the power unit 19 from overspeeding.

[0129] The control strategies disclosed herein can be designed to interact with other control strategies programmed to be implemented by the transmission control system 24 and / or the machine control system 25.

[0130] If the initial gear (i.e., the gear when a direction change is requested) is 3F, and the current TOS is equal to or below the 1000 rpm direction change threshold TOS, then gear selection routine 45 can generate a transmission direction change signal that causes transmission 21 to immediately perform a direction change to 3R (i.e., perform a direction change on the same gear in another direction). However, if the current TOS exceeds 1000 rpm, for example, 1010 rpm, then gear selection routine 45 can initially suppress the direction change (by not generating a transmission direction change signal) and can generate a transmission downshift signal to cause transmission 21 to perform a downshift to the next lowest gear 2F (i.e., the secondary gear) in the same direction. Gear selection routine 45 can also generate an engine deceleration signal to reduce engine speed. Engine speed reduction and / or downshifting may delay the speed of vehicle 10 and reduce the current TOS. Adverse gradients, payload, friction effects, and lack of engine power can also be variables that help vehicle 10 decelerate naturally. When the current TOS drops to 1000 rpm or below, and the operator is still requesting a direction change, the gear selection routine 45 can generate a transmission direction change signal so that the transmission 21 performs a direction change to 2R (i.e., performs a direction change on the same gear in the second direction).

[0131] Gear selection routine 45 can omit 1F as the secondary gear for further downshifting because, in this example, the downshift suppression threshold TOS for the 2F-1F downshift is 717 rpm, which is lower than the 1000 rpm direction switching threshold TOS for the 2F-2R direction switch. The same applies to the reverse (i.e., selecting 1R). This applies to each of the following examples.

[0132] If the initial gear is 2F and the current TOS is equal to or below the 1000 rpm direction switching threshold TOS, gear selection routine 45 can generate a transmission direction switching signal that immediately causes transmission 21 to perform a direction switch to 2R (i.e., perform a direction switch on the same gear in the second direction). However, if the current TOS is above 1000 rpm, gear selection routine 45 can initially suppress direction changes by maintaining the initial gear 2F, thereby generating an engine deceleration signal to reduce engine speed. When the current TOS drops to 1000 rpm or below, gear selection routine 45 can generate a transmission direction switching signal that causes transmission 21 to perform a direction switch to 2R (i.e., perform a direction switch on the same gear in the second direction).

[0133] If the initial gear is 4F and the current TOS is equal to or below the 1000 rpm direction switching threshold TOS, gear selection routine 45 can generate a transmission direction switching signal to cause transmission 21 to immediately perform a direction switch to 3R (i.e., the next highest reverse gear, since 4R does not exist in this instance). However, if the current TOS exceeds 1000 rpm, for example at 1010 rpm, gear selection routine 45 can initially suppress the direction switching and can generate a transmission direction switching signal to cause transmission 21 to perform a first downshift to 3F as the first primary gear in the same direction, and then perform a second downshift to 2F as the second primary gear. Gear selection routine 45 can also generate an engine deceleration signal to reduce engine speed. When the current TOS subsequently decreases to 1000 rpm or below, gear selection routine 45 can generate a transmission direction switching signal to cause transmission 21 to perform a direction switch to 2R (i.e., a direction switch on the same gear in the second direction).

[0134] If a direction change is requested when the initial gear is 4F and the current TOS is, for example, 1050 rpm, only the first downshift from 4F to 3F can be performed because the current TOS is higher than the downshift threshold TOS for 3F to 2F (i.e., 1020 rpm). Therefore, 3F can be the secondary gear that remains selected until the current TOS subsequently drops to 1000 rpm or below. At this point, gear selection routine 45 can generate a transmission direction change signal to cause transmission 21 to perform a direction change to 3R (i.e., perform a direction change for the same gear in the other direction). In this case, when the current TOS is between 1000 rpm and 1020 rpm, 2F may or may not be selected, depending on calibration.

[0135] If the initial gear is 3R and the current TOS is equal to or below the 1000 rpm direction switching threshold TOS, gear selection routine 45 can generate a transmission direction switching signal to cause transmission 21 to perform a direction switch to 3F (i.e., perform a direction switch on the same gear in another direction). However, if the current TOS exceeds 1000 rpm, for example at 1010 rpm, gear selection routine 45 can initially suppress the direction switch and can generate a transmission direction switching signal to cause transmission 21 to downshift to 2R, which is the secondary gear in the same direction. Gear selection routine 45 can also cause the generation of an engine deceleration signal to reduce engine speed. When the current TOS drops to 1000 rpm or below, gear selection routine 45 can generate a transmission direction switching signal to cause transmission 21 to perform a direction switch to 2F (i.e., perform a direction switch on the same gear in a second direction).

[0136] If the initial gear is 2R and the current TOS is equal to or lower than the 1000 rpm direction switching threshold TOS, the gear selection routine 45 can generate a transmission direction switching signal to cause the transmission 21 to perform a direction switch to 2F (i.e., perform a direction switch on the same gear in another direction). However, if the current TOS exceeds 1000 rpm, the gear selection routine 45 can initially suppress the direction switch and maintain the initial gear 2R, and generate an engine deceleration signal to reduce the engine speed. When the current TOS decreases to 1000 rpm or below, the transmission control system 24 can generate a transmission direction switching signal to cause the transmission 21 to perform a direction switch to 2F (i.e., perform a direction switch on the same gear in a second direction).

[0137] In any aspect of this disclosure, the “current TOS” in a subsequent control loop or method can be an updated current TOS of said loop or method. Similarly, the direction control signal in a subsequent control loop or method can be an updated direction control signal of said loop or method.

[0138] In any aspect of this disclosure, the first direction may be one of a forward direction or a reverse direction, and the second direction may be the other of a forward direction or a reverse direction.

Claims

1. A method for controlling gear selection in a transmission of a vehicle, the vehicle having a power unit and an automatic transmission, the transmission having a plurality of first direction gears configured to move the vehicle in a first direction and a plurality of second direction gears configured to move the vehicle in a second direction opposite to the first direction; Direction control signals are received from one or more input devices controlled by the operator of the vehicle; as well as The vehicle's control system determines the machine's motion direction parameters according to a parameter setting method, wherein: When the transmission output speed is below the direction detection threshold, the machine motion direction parameter is set to zero; and When the transmission output speed increases to or above the direction detection threshold, if one of the multiple first direction gears is currently engaged, the machine motion direction parameter corresponds to the first direction; or if one of the multiple second direction gears is currently engaged, the machine motion direction parameter corresponds to the second direction; and The machine's motion direction parameters remain fixed until the transmission output speed changes to below the direction detection threshold. The method includes the following steps: i) Detect the change of the direction control signal from the neutral signal state to the first direction signal state or the second direction signal state; ii) Determine the current transmission output speed; iii) Compare the current transmission output speed with a predetermined neutral shift threshold transmission output speed; and any one of the following iv a) If the current transmission output speed is less than or equal to the predetermined neutral shift threshold transmission output speed, then the transmission selects a gear from the plurality of first direction gears when the direction control signal becomes the first direction signal state, or selects a gear from the plurality of second direction gears when the direction control signal becomes the second direction signal state; or iv b) If the current transmission output speed is greater than the predetermined neutral shift threshold transmission output speed, then the transmission selects a gear from the plurality of first direction gears when the machine motion direction parameter indicates that the vehicle is moving in the first direction, or selects a gear from the plurality of second direction gears when the machine motion direction parameter indicates that the vehicle is moving in the second direction.

2. The method of claim 1, wherein each of the plurality of first directional gears and the plurality of second directional gears has a gear selection threshold transmission output speed; and A gear is selected from the plurality of first directional gears or the plurality of second directional gears by comparing the current transmission output speed with the gear selection threshold transmission output speed.

3. The method of claim 1, further comprising detecting an updated direction control signal after step iv a) or iv b), and any one of the following: If the updated direction control signal is in the neutral signal state, then the transmission is placed in neutral; or If the updated direction control signal is in the first direction signal state or the second direction signal state, then another gear selection method is applied.

4. The method according to claim 3, wherein the other gear selection method comprises: When the transmission is in the initial first direction gear, determine whether the vehicle operator has requested a direction change to move the vehicle from the first direction to the second direction; And if requested, Determine the updated current transmission output speed; The updated current transmission output speed is compared with the predetermined direction switching threshold transmission output speed; as well as If the updated current transmission output speed is less than or equal to the predetermined direction switching threshold transmission output speed, then the transmission performs a direction switch from the initial first direction gear to the same second direction gear; or if there is no second direction gear corresponding to the initial first direction gear, then a direction switch is performed to the next highest second direction gear. If the updated current transmission output speed is greater than the predetermined direction switching threshold transmission output speed, the direction switching is suppressed until the updated current transmission output speed slows down to less than or equal to the predetermined direction switching threshold transmission output speed.

5. The method according to claim 4, wherein: If the updated current transmission output speed is greater than the predetermined direction switching threshold transmission output speed, the transmission performs one or more downshifts from the initial first direction gear to a secondary first direction gear, the secondary first direction gear being the lowest gear having a predetermined downshift suppression threshold greater than the updated current transmission output speed, each downshift sequentially to the next highest first direction gear, and... When the updated current transmission output speed slows down to less than or equal to the predetermined direction switching threshold transmission output speed, and if the direction switching request is still valid, the transmission performs a direction switch from the secondary first direction gear to the same second direction gear, or if there is no second direction gear corresponding to the secondary first direction gear, it performs a direction switch to the next highest second direction gear.

6. The method according to claim 4, wherein: If the initial first direction gear is the lowest gear having a predetermined downshift suppression threshold greater than the updated current transmission output speed, then the initial first direction gear is maintained, and When the updated current transmission output speed slows down to less than or equal to the predetermined direction switching threshold transmission output speed, and if the direction switching request is still valid, the transmission performs a direction switch from the initial first direction gear to the same second direction gear, or if there is no second direction gear corresponding to the initial first direction gear, it performs a direction switch to the next highest second direction gear.

7. The method of claim 1, further comprising the step of executing an engine deceleration signal to reduce the speed of the power unit.

8. A control system for controlling gear selection in a transmission of a vehicle, the vehicle having a power unit and an indirect-drive automatic transmission, the transmission having a plurality of first-direction gears configured to move the vehicle in a first direction and a plurality of second-direction gears configured to move the vehicle in a second direction opposite to the first direction, the control system being configured to; Evaluate directional control signals from one or more input devices controlled by the operator of the vehicle; as well as The machine motion direction parameters are determined according to the parameter setting method, where: When the transmission output speed is below the direction detection threshold, the machine motion direction parameter is set to zero; and When the transmission output speed increases to or above the direction detection threshold, if one of the multiple first direction gears is currently engaged, the machine motion direction parameter corresponds to the first direction; or if one of the multiple second direction gears is currently engaged, the machine motion direction parameter corresponds to the second direction; and The machine's motion direction parameters remain fixed until the transmission output speed changes to below the direction detection threshold. i) The control system is further configured to detect changes in the directional control signal from a neutral signal state to a first directional signal state or a second directional signal state; ii) Determine the current transmission output speed; iii) Compare the current transmission output speed with a predetermined neutral shift threshold transmission output speed; and any one of the following iv a) If the current transmission output speed is less than or equal to the predetermined neutral shift threshold transmission output speed, then the transmission selects a gear from the plurality of first direction gears when the direction control signal becomes the first direction signal state, or selects a gear from the plurality of second direction gears when the direction control signal becomes the second direction signal state; or iv b) If the current transmission output speed is greater than the predetermined neutral shift threshold transmission output speed, then the transmission selects a gear from the plurality of first direction gears when the machine motion direction parameter indicates that the vehicle is moving in the first direction, or selects a gear from the plurality of second direction gears when the machine motion direction parameter indicates that the vehicle is moving in the second direction.

9. The control system of claim 8, wherein each of the plurality of first directional gears or the plurality of second directional gears has a gear selection threshold transmission output speed; and Gears are selected from the plurality of first-direction gears and the plurality of second-direction gears by comparing the current transmission output speed with the gear selection threshold transmission output speed.

10. The control system of claim 8, further configured to detect an updated direction control signal after step iv a) or iv b), and any one of the following: If the updated direction control signal is in the neutral signal state, then the transmission is placed in neutral; or If the updated direction control signal is in the first direction signal state or the second direction signal state, then another gear selection method is applied.

11. The control system of claim 10, wherein during the other gear selection method, the control system is configured to: The direction control signal is evaluated to determine whether the vehicle operator has made a direction switching request to move the vehicle from the first direction to the second direction when the transmission is in the initial first direction gear; and if so, Determine the updated current transmission output speed; The updated current transmission output speed is compared with the predetermined direction switching threshold transmission output speed; as well as If the updated current transmission output speed is less than or equal to the predetermined direction switching threshold transmission output speed, a transmission direction switching signal is generated to cause the transmission to perform a direction switch from the initial first direction gear to the same second direction gear; or, if there is no second direction gear corresponding to the initial first direction gear, a direction switch to the next highest second direction gear is performed. If the updated current transmission output speed is greater than the predetermined direction switching threshold transmission output speed, the direction switching is suppressed until the updated current transmission output speed slows down to less than or equal to the predetermined direction switching threshold transmission output speed.

12. The control system according to claim 11, wherein: If the updated current transmission output speed is greater than the predetermined direction switching threshold transmission output speed, the control system is further configured to generate a downshift signal to cause the transmission to perform one or more downshifts from the initial first direction gear to a secondary first direction gear, the secondary first direction gear being the lowest gear having a predetermined downshift suppression threshold greater than the updated current transmission output speed, each downshift sequentially to the next highest first direction gear, and... When the updated current transmission output speed slows down to less than or equal to the predetermined direction switching threshold transmission output speed, if the direction switching request is still valid, a direction switching signal is generated. The direction switching signal causes the transmission to perform a direction switch from the secondary first direction gear to the same second direction gear, or if there is no second direction gear corresponding to the secondary first direction gear, to perform a direction switch to the next highest second direction gear.

13. The control system according to claim 11, wherein: If the initial first directional gear is the lowest gear having a predetermined downshift suppression threshold greater than the updated current transmission output speed, then the control system is configured to maintain the initial first directional gear, and When the updated current transmission output speed slows down to less than or equal to the predetermined direction switching threshold transmission output speed, if the direction switching request is still valid, a direction switching signal is generated. The direction switching signal causes the transmission to perform a direction switch from the initial first direction gear to the same second direction gear, or if there is no second direction gear corresponding to the initial first direction gear, to perform a direction switch to the next highest second direction gear.

14. The control system of claim 11, wherein the control system is configured to generate an engine deceleration signal.

15. A vehicle comprising: Power unit; An indirect-drive automatic transmission having a plurality of first-direction gears configured to move the vehicle in a first direction and a plurality of second-direction gears configured to move the vehicle in a second direction opposite to the first direction; An operator-actuated input direction control, the operator-actuated input direction control being configured to generate a direction control signal; At least one transmission output speed sensor, the at least one transmission output speed sensor being configured to measure the current speed of the transmission output and generate a transmission output speed signal; as well as The control system according to claim 9 is operatively connected to the power unit, transmission, input direction control, and at least one transmission output speed sensor.

Images