A LIFTING VEHICLE CONFIGURED FOR ATTACHING HIGH-POWER HYDRAULIC IMPLEMENTS

Abstract

 A lifting vehicle comprising:
- a frame (12) carrying a pair of front wheels (14) and a pair of rear wheels (16),
- a lifting arm (18) articulated to the frame (12), having a distal end equipped with an attachment for an implement (24) comprising a high-power hydraulic actuator (40),
- a thermal engine-hydraulic pump assembly (30, 32), wherein the hydraulic pump (32) sends hydraulic fluid into a hydraulic power line (34),
- a traction hydraulic motor (38) connected through a gearbox (42) to a mechanical transmission (44) that drives the wheels of the vehicle,
- a hydraulic diverter (36) that selectively connects the hydraulic power line (34) to said traction hydraulic motor (38) or to said hydraulic actuator of the implement (40),
wherein said hydraulic diverter (36) is controlled by an electronic control unit (46) that sets said hydraulic diverter (36) to an implement use mode when an operating mode selector (48) is in the implement use mode and a travel-direction selector (50) is in neutral mode.

Description

TEXT OF THE DESCRIPTION

Field of the invention

[0001] The present invention relates to a lifting vehicle provided with a lifting arm configured for attaching an implement that requires high hydraulic power, such as vibrating heads for shaking olive trees or other fruit plants.

Description of the prior art

[0002] Lifting vehicles with telescopic lifting arms are usually equipped with a hydrostatic transmission, with a thermal engine that drives a hydraulic pump. The hydraulic pump is connected to a hydraulic power line that drives a traction hydraulic motor, connected through a gearbox to a mechanical transmission that drives the wheels of the vehicle.

[0003] In the case of vehicles configured to operate implements connected to the end of the telescopic arm that require high hydraulic power, a hydraulic diverter is assembled on the hydraulic power line, which connects the hydraulic pump to the traction hydraulic motor. The hydraulic diverter has two operative positions selectable by the operator. Depending on the position of the hydraulic diverter, the vehicle is placed into a traction mode in which the hydraulic diverter connects the hydraulic power line to the traction hydraulic motor, or into an implement operating mode in which the hydraulic diverter connects the hydraulic power line to the hydraulic actuator of the implement.

[0004] In vehicles according to the prior art configured to operate with high-power hydraulic implements, in the implement operating mode, the implement is controlled by the same controls that -in the traction mode- are used to control the traction of the vehicle. In particular, for controlling the drive direction of the hydraulic actuator of the implement, the same three-position selector is used to set the forward travel-direction, reverse travel-direction or neutral mode, when the hydraulic diverter is set to traction mode, and to adjust the hydraulic power of the implement, the vehicle accelerator is used.

[0005] In the event of operator error or malfunction of the hydraulic diverter, vehicles of this type are affected by safety issues. For example, if the operator believes that the hydraulic diverter has been set to the implement control mode, while in fact the hydraulic diverter has remained in the traction mode, when the operator drives the commands, believing that the implement is being moved, he actually causes an involuntary movement of the vehicle. Conversely, the operator may inadvertently cause the movement of the implement instead of controlling the vehicle movements.

[0006] In the solutions according to the prior art, the risk of mismanagement derives from the fact that the same commands used to control the traction of the vehicle are used to command the implement. The hydraulic diverter selects the destination utility of the hydraulic power (vehicle traction system or implement actuator) but the commands for the two operating modes are the same.

[0007] Another limit of the less recent solutions according to the prior art is that the operator can also control the implement without being seated in the driving position. This worsens the risk of incorrect selection of the operating mode.

Object and summary of the invention

[0008] The object of the present invention is to provide a lifting vehicle configured to operate with high-power hydraulic implements, which overcomes the problems of the prior art.

[0009] According to the present invention, this object is achieved by a lifting vehicle having the characteristics forming the subject of claim 1.

[0010] The claims form an integral part of the disclosure provided here in relation to the invention.

Brief description of the drawings

[0011] The present invention will now be described in detail with reference to the attached drawings, given purely by way of non-limiting example, wherein:

• Figure 1 is a perspective view of a lifting vehicle configured to operate with a high-power hydraulic implement, and
• Figure 2 is a simplified diagram illustrating the hydraulic circuit and the electric circuit for controlling the operation mode of the vehicle.

Detailed description

[0012] Referring to Figure 1, numeral 10 indicates a lifting vehicle comprising a frame 12, a pair of front wheels 14, and a pair of rear wheels 16. The vehicle 10 comprises a telescopic lifting arm 18 articulated to the frame 12 and controlled by a lifting cylinder 20. The arm 18 is provided at its distal end with an attachment 22 through which various types of implements can be connected to the arm 18. In particular, the vehicle 10 is configured to be able to operate with implements 24 that absorbs high hydraulic power, such as vibrating heads for shaking olive trees or other fruit plants.

[0013] With reference to Figure 2, the vehicle 10 comprises a thermal engine 30 that operates a hydraulic pump 32. The hydraulic pump 32 is connected to a hydraulic power line 34. The vehicle 10 comprises a hydraulic diverter 36 that selectively connects the hydraulic power line 34 to a traction hydraulic motor 38 or to a hydraulic actuator of the implement 40. The traction hydraulic motor 38 is connected, through a gearbox 42, to a mechanical transmission 44 that drives the wheels of the vehicle. The hydraulic actuator of the implement 40 can be a rotary actuator (hydraulic motor) or a linear actuator (hydraulic cylinder). The hydraulic diverter 36 has two operating positions relative to two operating modes of the vehicle:

• a traction mode in which the hydraulic actuator of the implement 40 is not powered, and all the hydraulic power generated by the hydraulic pump 32 is sent to the traction hydraulic motor 38;
• an implement operating mode in which the vehicle transmission is deactivated and all the hydraulic power generated by the hydraulic pump 32 is sent to the hydraulic actuator of the implement 40.

[0014] The operating modes of the hydraulic diverter 36 are set by an electronic control unit 46. The electronic control unit 46 receives a signal from an operating mode selector 48, operated by the operator to switch the operating mode of the vehicle between the traction mode and the implement use mode. The electronic control unit 46 also receives control signals coming from a travel-direction selector 50. The travel-direction selector 50 is a three-position selector that -in traction mode- allows selection between forward travel-direction, reverse travel-direction, or neutral mode. The electronic control unit receives a control signal for the accelerator 52 by means of which the user controls the rotational speed of the thermal engine 30. The electronic control unit 46 receives signals from a control device of the implement 54, by means of which the operator controls the hydraulic actuator of the implement 40 in the implement use mode. The electronic control unit 46 also receives a signal from a sensor 56 in the seat, which indicates the presence of the operator at the control station and a signal coming from a speed sensor 58 of the vehicle arranged on the gearbox 42. The electronic control unit 46 receives a signal from an operating mode sensor 60, which controls the position of the hydraulic diverter 36 and the signal of a selector 62, which sets the parking brake of the vehicle. The electronic control unit 46 also receives signals from pressure sensors 64 that detect the pressure in the hydraulic power line 34.

[0015] The electronic control unit 46 controls the hydraulic pump 32 as a function of the signals coming from the accelerator control 52. The electronic control unit 46 controls warning lights 66 located on the instrument panel of the vehicle, to indicate the operating mode that has been set to the operator.

[0016] The electronic control unit 46 sets the operating mode of the vehicle between the traction mode and the implement use mode by selecting the operative status of the diverter 36. The electronic control unit 46 sets the hydraulic diverter 36 to the implement operating mode when:

• the operating mode selector 48 is in the implement control mode,
• the travel-direction selector 50 is in the neutral mode,
• the operator presence sensor 56 indicates the presence of the operator at the command post,
• the parking brake selector 52 is in the inserted parking brake mode, and
• the speed sensor 58 indicates that the vehicle is stationary.

[0017] When all these conditions are verified, the electronic control unit 46 sets the hydraulic diverter 36 to the implement operating mode. When one or more of the aforesaid conditions are not verified, the high-power hydraulic power supply is stopped.

[0018] When the vehicle is set to the implement use mode, the operator controls the implement actuator 40 via the control device 54 of the implement, which is separate and independent from the travel-direction selector 50 that controls the travel-direction of the vehicle in traction mode.

[0019] To use the high-power hydraulic implement, the operator must, therefore, stop the vehicle and, while remaining seated on the seat so that the electronic control unit 46 recognizes his presence, he controls the activation of the implement use mode by means of the operating mode selector 48. At this point, the operator can control the activation of the implement by means of the dedicated control device 54, and accelerate the thermal engine by means of the accelerator 52 to provide the required power. The electronic control unit 46, during this step, controls the functionality of the system by means of the sensors and, in the event of anomalies or controls that are not allowed by the operator, immediately stops the oil flow. In particular, in addition to the presence of the on-board operator, the electronic control unit 46 verifies that all the controls are consistent and that no unwanted movements of the vehicle wheels occur during the activation of the implement.

[0020] When, on the other hand, the operator wishes to control the movement of the machine, it is sufficient that, while still sitting on the seat, he selects the direction of travel by means of the travel-direction selector 50 and accelerates the thermal engine by means of the accelerator 52 until the required speed is reached. In this condition, the electronic control unit 46 configures the system into the traction operating mode and inhibits the high-power hydraulic power supply of the implement 40.

[0021] Of course, without prejudice to the principle of the invention, the details of construction and the embodiments can be widely varied with respect to those described and illustrated, without thereby departing from the scope of the invention as defined by the claims that follow.

Claims

1. A lifting vehicle comprising:

- a frame (12) carrying a pair of front wheels (14) and a pair of rear wheels (16),

- a lifting arm (18) articulated to the frame (12) and having a distal end equipped with an attachment for an implement (24) comprising a high-power hydraulic actuator (40),

- a thermal engine-hydraulic pump assembly (30, 32), wherein the hydraulic pump (32) sends hydraulic fluid into a hydraulic power line (34),

- a traction hydraulic motor (38) connected through a gearbox (42) to a mechanical transmission (44) that drives the wheels of the vehicle,

- a hydraulic diverter (36) selectively settable to a traction mode in which it connects the hydraulic power line (34) to said traction hydraulic motor (38) or to an implement use mode in which it connects the hydraulic power line (34) to said hydraulic actuator of the implement (40),

characterized in that said hydraulic diverter (36) is controlled by an electronic control unit (46), which receives signals from:

- an operating mode selector (48) settable by the operator into a traction mode or into an implement use mode,

- a travel-direction selector (50) settable by the operator to a forward-drive mode, a reverse-drive mode or a neutral mode, and

- an implement control device (54) operable by the operator to control the implement actuator (40),

wherein said control unit (46) sets said hydraulic diverter (36) to said implement use mode when said operating mode selector (48) is in the implement use mode and said travel-direction selector (50) is in neutral mode.

2. A vehicle according to claim 1, wherein said electronic control unit (46) receives a signal from a sensor (56) that signals the presence of the operator at the controls and inhibits setting the hydraulic diverter (36) to the implement use mode when the operator presence sensor (56) does not detect the presence of the operator at the controls.

3. A vehicle according to claim 1, wherein said electronic control unit (46) receives a signal of a parking brake selector (62) and inhibits setting the hydraulic diverter (36) to the implement use mode when the parking brake is disengaged.

4. A vehicle according to claim 1, wherein said electronic control unit (46) receives a signal from a speed sensor (58) and inhibits setting the hydraulic diverter (36) to the implement use mode when the speed detected by said sensor (58) is different from zero.

Drawing