Method and arrangement for selecting a starting gear and a vehicle comprising this arrangement

SWEDEN (₁₂₎ PATENT WRITING (13) C2 (11) 525 482

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(19) SE (₅₁)

International class ⁷F16H 61/02, 59/50

PATENT AND REGISTRATION (45) (41) (22) (24) (62) (86) (83)

Patent issued 2005-03-01

Application generally available 2005-01-04 The patent application was filed on 03/07/2003

Running day 2003-07-03

Tribal application number

International filing day

Filing date for European patent application

Deposit of microorganism (21) Patent Application Number Q301982-5

Application received as:

Γ5Π Swedish patent application completed international patent application with number □ converted European patent application with number (30) Priority information (73) (72) (74) (54) (56) (57)

PATIENTS Volvo Trucks AB, 405 08 Gothenburg SE

INNOVATOR Sixten Berglund, Torslanda SE Anders Eriksson, Gothenburg SE

Marcus Steen, Angered'S OMBUD Volvo Technology Corp

NAME Method and arrangement for starter gear selection and a vehicle comprising this arrangement

CALLED PUBLICATIONS: - SUMMARY:

The invention relates to a method for selecting a starter gear for a vehicle comprising an engine (3), a transmission with an automated gearbox (5), and a power take-off (9) for operating at least one body mounting device on the vehicle. The method comprises the following steps:

- generating a first signal upon actuation of the power take-off (9) for operating at least one attachment device mounted on the vehicle;

controlling the gearbox strategy (5) of the gear selection strategy for selecting a predetermined starting gear in response to at least said first signal;

- retaining the predetermined starting gear as long as at least one predetermined condition is met.

The invention also relates to an arrangement for selecting a starter gear and a vehicle comprising such an arrangement.

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The numbers in parentheses indicate the INID code.

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SUMMARY

The invention relates to a method for selecting a starter gear for a vehicle comprising an engine (3), a transmission with an automated gearbox (5), and a power take-off (9) for operating at least one body mounting device on the vehicle. The method comprises the following steps:

- generating a first signal upon actuation of the power take-off (9) for operating at least one attachment device mounted on the vehicle;

controlling the gear selection strategy of the gearbox (5) for selecting a predetermined starting gear in response to at least said first signal;

- retaining the predetermined starting gear as long as at least one predetermined condition is met.

The invention also relates to an arrangement for selecting a starter gear and a vehicle comprising such an arrangement.

(Figure 1)

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TECHNICAL FIELD

The invention relates to a method and arrangement for selecting star gear when a vehicle is operated at a low speed while at the same time some body arrangement on the vehicle is used.

The invention also relates to a computer program for causing a computer to perform such a process.

BACKGROUND OF THE ART

Today automated mechanical gearboxes, known as "Automated Mechanical Transmissions" or AMT, are becoming more common in heavy vehicles. In order to determine the gear selection strategy for vehicles with AMT, an estimate or calculation of the current travel resistance is usually made. On the basis of the input signals from a number of sensors, the current travel resistance is determined, after which an electronic control unit determines an appropriate gear selection strategy.

For starting gear selection, this usually means that the control unit only takes into account the weight of the vehicle and the slope of the vehicle, choosing a starting gear that provides optimum starting characteristics. This usually means that a relatively high starting gear is selected, and that the gearbox changes up as soon as the gear selection strategy permits. The intention is that the vehicle should be able to start and reach the marching speed as quickly as possible.

This gear selection is not optimal at all times. For example, when tipping a load from a flat, grading in conjunction with tipping or operating at low speed while using any attachment device on the vehicle, a starter gear selected according to the above mentioned method may be directly inappropriate.

For example, EP 1 103 742 shows an AMT system where the driver can manually select a pre-selected starting gear, provided that this choice

525 482 is accepted by the gearbox controller. If a power take-off is activated, said controller will temporarily switch from automatic to manual shift mode. This system requires the driver to make certain settings regarding the starting gear. When changing the driver, problems can also occur if a previous driver has made a pre-selection of the starter gear that is not suitable for the maneuver to be performed.

US 5,455,767 describes a way to control the transmission if the vehicle is in motion when the PTO is activated. By sensing the current power consumption of the PTO, it is possible for the gearbox controller to move the gear selection strategy's change points. The method does not apply to the selection and / or locking of a starter gear under certain conditions. In addition, the method requires the control unit to switch to a manual transmission mode, so that the driver can select the starting gear.

The invention thus aims to solve the above-mentioned problems by providing a method in which the gearbox controller detects that a power take-off is active at start from stationary or near stationary, whereby a pre-programmed starting gear is selected and maintained until at least a predetermined condition is met, for example that the PTO is deactivated. This is done without disconnecting the vehicle's automatic shift mode and without the driver having to intervene.

DISCLOSURE OF THE INVENTION

The above object is achieved by the method of selecting a starter gear whose characteristic feature is apparent from the following claim 1, with an arrangement according to claim 8, and with a vehicle comprising said arrangement according to claim 14.

According to a preferred embodiment, the invention relates to a method for selecting a starter gear for a vehicle comprising a motor, a transmission with an automated gearbox, and a power take-off for operating at least one body mounting device on the vehicle. The method includes the following steps:

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- generating a first signal when activating the power take-off for operating at least one attachment device mounted on the vehicle;

controlling the gearbox selection strategy for selecting a predetermined starting gear in response to at least said first signal;

- retaining the predetermined starting gear as long as at least one predetermined condition is met.

Said condition for maintaining the predetermined starting gear can be a number of different parameters. One condition may be that a power take-off in the form of a compressor, hydraulic pump, or the like, is activated.

Other conditions may be that the movement of the vehicle should exceed a predetermined distance, or that the speed of the vehicle has exceeded a certain speed for a predetermined period of time. Appropriate distances and / or speeds are selected with respect to the main area of ​​use of the vehicle. This may be relevant for certain types of vehicles, such as cement mixers, where a PTO must be active both at take-off and while traveling for a vehicle with full load.

According to a further embodiment, the predetermined starting gear is preferably, but not necessarily, the lowest gearbox. Selection of starter gear can be pre-programmed with a recommended selection from the factory or at the request of the user. Of course, the starting gear selection can be changed at a later date, if, for example, the vehicle's use area is changed.

Control of the gearbox's choice of take-off gear is preferably independent of the actual measured weight of the vehicle. However, it is possible to program the gearbox controller to select the starting gear from a train weight dependent table stored in the controller unit memory.

According to a further embodiment, the controller selects an automated transmission mode with a gear selection strategy comprising the predetermined starting gear. As a result, the driver does not need to intervene to select the starting gear, which would be the case if the controller has conventionally chosen a manual transmission mode.

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The invention also includes an arrangement for selecting a star gear for a vehicle comprising an engine, a transmission with an automated gearbox, and a power take-off for operating at least one attachment device on the vehicle. In addition, the arrangement comprises at least one sensor for generating a first signal upon actuation of the power take-off for actuating at least one attachment device mounted on the vehicle and an electronic control unit for controlling the gearbox selection strategy in response to at least said first signal, thereby maintaining a predetermined starting gear a predetermined condition is met.

The electronic control unit is preferably arranged to maintain the predetermined starting gear as long as the PTO is activated.

In an alternative embodiment, the predetermined take-off gear is maintained until the vehicle's displacement has exceeded a predetermined distance, or until the vehicle's speed has exceeded a certain speed for a predetermined period of time. This allows the electronic control unit to select a different gear even though a power take-off is active. According to a further embodiment, the arrangement can be controlled so that switching is allowed if a first PTO is active, but is prohibited if a second PTO is active.

The predetermined starting gear is preferably, but not necessarily, the lowest gearbox. Alternatively, the starter gear can be selected from a train weight dependent table stored in the electronic control unit.

The invention also relates to a vehicle provided with an arrangement according to the above, which vehicle comprises an engine, a transmission with an automated gearbox, and a power take-off for operating at least one body mounting device on the vehicle. As described above, the arrangement includes at least one sensor for generating a first signal upon actuation of the power take-off for operating at least one vehicle mounting device and an electronic control unit for controlling the gearbox selection strategy in response to at least said first

525 482 signal, maintaining a predetermined starting gear as long as at least one predetermined condition is met.

The invention thus permits an automated transmission mode with a gear selection strategy comprising a predetermined starting gear. As a result, the driver does not need to intervene to select the starting gear, which would be the case if the controller has conventionally chosen a manual transmission mode.

DESCRIPTION

The invention will now be described in more detail with an exemplary embodiment with reference to the accompanying schematic drawing figures, wherein;

Figure 1 is a schematic illustration of an automatic arrangement for selecting the starting gear according to the invention;

Figure 2 shows a schematic illustration of a flow chart for controlling an arrangement according to the invention;

Figure 3 shows a schematic illustration of a flow chart for controlling an alternative arrangement according to the invention

PREFERRED EMBODIMENTS

Figure 1 shows a schematic illustration of an automatic arrangement for selecting the starting gear according to the invention. The arrangement comprises a central electronic control unit (ECU) 1 which is connected to a motor control unit 2 for a motor 3 and a transmission control unit 4 for an automated gearbox (AMT) 5. The motor control unit 2 receives signals from a number of sensors (not shown) for engine speed, motor torque. , road speed, train weight, road slope, etc. The central electronic control unit 1 receives signals from a driver-controlled accelerator pedal 6, a gear selector 7 and data from the motor control unit

2 including a number of engine-related operating parameters. With guidance from these received signals, the central electronic control unit 1 selects a suitable switching strategy from a number of strategies stored in a memory integrated in the control unit 1. Signals related to gear selection are then sent to the transmission control unit 4 of the automated gearbox 5, which performs shifting

525 482 to the requested exchange. At the same time, signals are sent to the motor controller 2 with the desired speed request. Gearboxes of this type are generally known from, for example, EP 1,103,742, US 5,816,100, US 5,390,561, US 4,754,665 and US 4,735,109, and will not be described in further detail.

A signal representing the choice of gear is also sent to a display 8, giving the driver a confirmation of which gear is currently selected.

In addition to the above signals, the central electronic control unit 1 receives an additional signal from a power take-off (PTO) 9 whenever this is activated. The power take-off can consist of a compressor, hydraulic pump, or the like, and is used to drive an attachment unit on the vehicle. The PTO can also be mounted to be driven directly by the vehicle engine.

Figure 2 shows a schematic illustration of a flow chart for controlling an arrangement according to the invention. The control is started S1 when the driver activates the gear selector S2 for a stationary vehicle. The central electronic control unit, hereafter referred to as the vehicle's ECU, then checks whether a PTO is active S3. If this is not the case, the vehicle's ECU selects an appropriate starting gear based on a gear selection strategy based on the vehicle's train weight and the current slope of the road. If a PTO is active, a so-called PTO mode is activated, where the vehicle's ECU selects and locks the transmission at a predetermined starting gear. Thereafter, the vehicle ECU will continuously monitor if the current PTO is active S6 and keep the selected starting gear S7 until the PTO is deactivated. When that happens, the said PTO mode S8 is deactivated and the vehicle's ECU returns to selecting gear S4 based on a gear selection strategy based on the vehicle's train weight, the slope of the road and the required torque from the driver.

The regulation of the vehicle start is thus completed S9.

Figure 3 shows a schematic illustration of a flow chart for controlling an alternative arrangement according to the invention. The control of the vehicle is initially done in the same way as described in Figure 2. After a PTO mode has been activated S5, the vehicle's ECU will start monitoring the current PTO S6 and retain the selected starting gear S7. Monitoring

525 However, 482 includes an additional step, where the vehicle ECU checks whether an additional condition is met S10. As long as this condition is not met, monitoring of the PTO will continue. If, on the other hand, the condition proves to be fulfilled, the said PTO mode S8 is terminated and the vehicle's ECU returns to select gear

S4 according to Figure 2 above. An example of such a condition may be that the vehicle's movement has exceeded a predetermined distance, or that the speed of the vehicle has exceeded a certain speed for a predetermined period of time.

The invention is not limited to the above examples and embodiments shown in the drawings but can be varied within the scope of the following claims.

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