Auxiliary Drive Unit

Abstract

To provide an auxiliary drive device which restrains brake force from being generated by lack of oil quantity and at the same time can prevent a motor from being damaged even if a vehicle is towed by a traction vehicle at speed exceeding speed that is considered as limit of use of an auxiliary drive motor in the auxiliary drive device.SOLUTION: A hydraulic circuit 6 includes a hydraulic drain passage 64 which communicates a storage tank 69 which stores working fluid with a hydraulic drain port 43 and a pilot valve 67 which cuts off the hydraulic drain passage 64 by the hydraulic force applied from a gauge port 44 and at the same time opens the hydraulic drain passage 64 by spring force urged by hydraulic force when the hydraulic force is lost.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an auxiliary drive device for a towed vehicle that is towed by a towing vehicle having running performance. [Background technology]

[0002] Tractors are vehicles used primarily for agricultural work, and are used as towing vehicles to tow implements such as boom sprayers and potato harvesters. The operator of the tractor changes direction using the steering wheel and adjusts speed using the accelerator, brake, etc. The operator also operates the implement at the same time. For example, when the towed vehicle is a boom sprayer, the operator adjusts the boom height, inclination, amount of spray, and spray range so that the spray liquid is evenly applied to the crops.

[0003] Incidentally, in recent years, as working machines have become larger and travel faster, inventions have been proposed that install an auxiliary drive device that generates driving force on the working machine side to supplement the driving force of a towing vehicle such as a tractor. For example, JP2018-524237A discloses an invention relating to a combination vehicle that has a second axle that can be driven electrically or hydraulically and can be connected to a tractor or the like (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2018-524237 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the invention described in Patent Document 1, when the towed vehicle is towed by the towing vehicle at a speed exceeding the usage limit of the auxiliary drive motor in the auxiliary drive device, the amount of hydraulic oil supplied to the auxiliary drive motor becomes insufficient, causing the brakes to be applied. Furthermore, if this condition continues or the speed increases further, the piston inside the motor will interfere with the cam profile, causing a problem of damage to the motor.

[0006] The present invention has been made to meet the above-mentioned needs, and has as its object to provide an auxiliary drive device that can suppress the generation of braking force due to insufficient oil and prevent damage to the motor, even when the auxiliary drive device is towed by a towing vehicle at a speed that exceeds the operating limit of the auxiliary drive motor in the auxiliary drive device. [Means for solving the problem]

[0007] The auxiliary drive device of the present invention is an auxiliary drive device for a towed vehicle towed by a towing vehicle having running performance, in order to solve the problem of suppressing the generation of braking force due to a lack of oil even when the towed vehicle is towed by the towing vehicle at a speed exceeding the usage limit of the auxiliary drive motor, and includes a variable hydraulic pump that generates oil pressure that is continuously variable using power obtained from the towing vehicle, an auxiliary drive motor in which forward driving force, reverse driving force and braking force transmitted to the towed vehicle are switched by the variable hydraulic pump, and a hydraulic circuit that circulates hydraulic oil between the variable hydraulic pump and the auxiliary drive motor, and the variable hydraulic pump operates to drive the auxiliary drive motor forward. The hydraulic circuit has a forward port that sends out hydraulic oil and returns the hydraulic oil that passes through the auxiliary drive motor when driving in reverse, and a reverse port that sends out hydraulic oil when driving the auxiliary drive motor in reverse, and returns the hydraulic oil that passes through the auxiliary drive motor when driving it forward. The hydraulic circuit is configured as a closed circuit with a forward path that communicates with the forward port and the auxiliary drive motor, a reverse path that communicates with the reverse port and the auxiliary drive motor, and a bypass path that communicates between the forward path and the reverse path, and the bypass path is provided with a bypass valve that blocks the flow of hydraulic oil during forward driving, reverse driving and braking, and opens the flow of hydraulic oil in neutral.

[0008] The auxiliary drive device of the present invention is an auxiliary drive device for a towed vehicle that is towed by a towing vehicle having running performance, in order to solve the problem of preventing damage to the auxiliary drive motor even when the vehicle is towed by the towing vehicle at a speed exceeding the usage limit of the auxiliary drive motor in the auxiliary drive device, and the auxiliary drive device has a variable hydraulic pump that generates a continuously variable hydraulic pressure using power obtained from the towing vehicle, an auxiliary drive motor in which the forward driving force, reverse driving force and braking force transmitted to the towed vehicle are switched by the variable hydraulic pump, and a hydraulic circuit for circulating hydraulic oil between the variable hydraulic pump and the auxiliary drive motor, the variable hydraulic pump having a hydraulic relief port capable of draining the hydraulic pressure of the hydraulic oil before being supplied to the auxiliary drive motor, and a gauge port capable of measuring the generated hydraulic pressure, and the hydraulic circuit has a hydraulic relief path that communicates between the hydraulic relief port and a storage tank that stores the hydraulic oil, and a pilot valve that closes the hydraulic relief path using hydraulic pressure received from the gauge port and opens the hydraulic relief path using a spring force biased by the hydraulic pressure when the hydraulic pressure is lost.

[0009] In addition, as one aspect of the present invention, in order to solve the problem of returning hydraulic oil leaking due to internal leakage that occurs when preventing damage to the motor to a storage tank, the auxiliary drive motor is configured as a radial piston motor, and the hydraulic circuit has an internal leakage oil return path that returns hydraulic oil leaking due to internal leakage of the auxiliary drive motor to the storage tank, and a pressurizing motor that pressurizes the hydraulic oil inside the auxiliary drive motor, and when the pilot valve blocks the hydraulic pressure relief path by hydraulic pressure received from the gauge port, the internal leakage oil return path is opened, and when the pilot valve opens the hydraulic pressure relief path by spring force, the internal leakage oil return path is blocked, and the pressurizing motor increases the internal pressure of the auxiliary drive motor to compress a plurality of pistons arranged in the radial direction. Effect of the Invention

[0010] According to the present invention, even if the auxiliary drive device is towed by a towing vehicle at a speed exceeding the limit of use of the auxiliary drive motor, the generation of braking force due to insufficient oil can be suppressed and damage to the motor can be prevented. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram showing an auxiliary driving device according to an embodiment of the present invention in a state of use; [Diagram 2] FIG. 2 is a configuration diagram showing an auxiliary driving device according to the present embodiment. [Diagram 3] 1 is a hydraulic circuit diagram showing an auxiliary drive device according to an embodiment of the present invention. [Figure 4] FIG. 2 is a schematic diagram showing the internal structure of an auxiliary drive motor in the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an auxiliary driving device according to the present invention will now be described with reference to the drawings.

[0013] As shown in Fig. 1, the auxiliary drive device 1 is provided on a towed vehicle 3 towed by a towing vehicle 2 having running performance, and provides driving performance to the towed vehicle 3 to assist in running. As shown in Fig. 2, the auxiliary drive device 1 of this embodiment has a variable hydraulic pump 4, an auxiliary drive motor 5 that generates auxiliary driving force for the towed vehicle 3, and a hydraulic circuit 6 that circulates hydraulic oil between the variable hydraulic pump 4 and the auxiliary drive motor 5. Each component will be described in detail below.

[0014] The variable hydraulic pump 4 is a pump that can generate a continuously variable hydraulic pressure using the power obtained from the towing vehicle 2. This variable hydraulic pump 4 is configured to extract engine power from the towing vehicle 2 by a power take-off (PTO) and generate hydraulic pressure in the working oil using this extracted power. There are no particular limitations on the type of variable hydraulic pump 4, but in this embodiment, a piston pump is used.

[0015] As shown in Figures 2 and 3, the variable hydraulic pump 4 in this embodiment has a forward port 41 from which hydraulic oil is delivered when the auxiliary drive motor 5 is driven forward, a reverse port 42 from which hydraulic oil is delivered when the auxiliary drive motor 5 is driven reverse, a hydraulic pressure relief port 43 which relieves the hydraulic pressure of the hydraulic oil before it is supplied to the auxiliary drive motor 5, and a gauge port 44 which enables the generated hydraulic pressure to be measured.

[0016] The forward port 41 is an inlet / outlet for sending and returning hydraulic oil to the auxiliary drive motor 5 via the hydraulic circuit 6, and is configured as an inlet / outlet for sending out hydraulic oil when the auxiliary drive motor 5 is driven forward, and for returning the hydraulic oil returning via the auxiliary drive motor 5 when the auxiliary drive motor 5 is driven reverse.

[0017] The reverse port 42, like the forward port 41, is an inlet / outlet for sending and returning hydraulic oil to the auxiliary drive motor 5 via the hydraulic circuit 6, and is configured as an inlet / outlet for sending out hydraulic oil when the auxiliary drive motor 5 is driven in reverse, and for returning hydraulic oil returning via the auxiliary drive motor 5 when the auxiliary drive motor 5 is driven in forward.

[0018] The hydraulic pressure relief port 43 is an outlet for releasing the hydraulic pressure generated within the variable hydraulic pump 4 to the outside, and is used to relieve the hydraulic pressure of the working oil before it is supplied to the auxiliary drive motor 5.

[0019] The gauge port 44 is an outlet for hydraulic oil that allows the generated hydraulic pressure to be measured. The gauge port 44 in this embodiment is configured as an outlet for hydraulic oil that supplies hydraulic pressure for operating the pilot valve 67.

[0020] The auxiliary drive motor 5 is a motor that exerts an auxiliary drive force by hydraulic oil delivered from the variable hydraulic pump 4 via the hydraulic circuit 6. As shown in FIG. 4, the auxiliary drive motor 5 in this embodiment is a radial piston motor, and is configured to rotate a cylinder block 514 connected to a tire axle by sequentially pushing a cam profile 52 having a star-shaped inner circumference shape by a plurality of pistons 51 arranged in the radial direction. The piston 51 in this embodiment has a cylinder 511 into which hydraulic oil flows, a piston head 512 that slides in the cylinder 511, and a roller 513 provided at the tip of the piston head 512. In addition, the auxiliary drive motor 5 has a leak discharge port 53 that discharges internal leaks leaking into the inside from a gap between the cylinder 511 and the piston head 512, as shown in FIGS. 2 and 3.

[0021] The auxiliary drive motor 5 can switch the driving force from the forward direction to the reverse direction and vice versa by switching the inflow and outflow direction of the hydraulic oil, and can exert a braking force by stopping reverse rotation and the inflow and outflow of the hydraulic oil. The auxiliary drive device 1 of this embodiment includes two auxiliary drive motors 5, 5, as shown in Fig. 3.

[0022] The hydraulic circuit 6 is a circuit consisting of passages for circulating hydraulic oil between the variable hydraulic pump 4 and the auxiliary drive motor 5, valves for opening and closing the passages, etc., and in this embodiment, is configured as a closed hydraulic circuit (closed circuit).

[0023] As shown in Figures 2 and 3, the hydraulic circuit 6 in this embodiment has a forward path 61 that connects the forward port 41 and the auxiliary drive motor 5, a reverse path 62 that connects the reverse port 42 and the auxiliary drive motor 5, a bypass path 63 that connects the forward path 61 and the reverse path 62, a hydraulic pressure relief path 64 that connects the hydraulic pressure relief port 43 and a storage tank 69 that stores hydraulic oil, an internal leakage oil return path 65 that returns hydraulic oil leaking due to an internal leak of the auxiliary drive motor 5 to the storage tank 69, a bypass valve 66 that opens and closes the bypass path 63, a pilot valve 67 that opens and closes the hydraulic pressure relief path 64, and a pressurizing motor 68 that increases the internal pressure of the auxiliary drive motor 5.

[0024] As shown in FIG. 3, the forward path 61 is a passage for hydraulic oil that communicates between the forward port 41 of the variable type hydraulic pump 4 and the auxiliary drive motor 5, and allows hydraulic oil to flow from the variable type hydraulic pump 4 to the auxiliary drive motor 5 during forward drive, and from the auxiliary drive motor 5 to the variable type hydraulic pump 4 during reverse drive.

[0025] Further, the reverse path 62 is a passage for hydraulic oil that communicates between the reverse port 42 of the variable type hydraulic pump 4 and the auxiliary drive motor 5. During reverse drive, the hydraulic oil flows from the variable type hydraulic pump 4 to the auxiliary drive motor 5, and during forward drive, the hydraulic oil flows from the auxiliary drive motor 5 to the variable type hydraulic pump 4.

[0026] The bypass passage 63 is a passage for hydraulic oil that connects the forward passage 61 and the reverse passage 62, and is provided with a bypass valve 66 in the middle thereof that can open and close the passage.

[0027] The hydraulic pressure relief passage 64 is a passage for hydraulic oil that connects the hydraulic pressure relief port 43 with a storage tank 69 that stores hydraulic oil, and is provided with a pilot valve 67 in the middle of the passage that can open and close the passage.

[0028] The internal leak oil return path 65 is a hydraulic oil passage that connects the auxiliary drive motor 5 and the storage tank 69, and is a passage used for returning hydraulic oil leaking as an internal leak from a gap between the cylinder 511 and the piston head 512 of the piston 51 of the auxiliary drive motor 5 between the piston 51 and the cam profile 52 to the storage tank 69. The internal leak oil return path 65 in this embodiment is configured as a passage that connects the leak discharge port 53 of the auxiliary drive motor 5 and the storage tank 69, and a pilot valve 67 that can open and close the passage is provided midway.

[0029] The bypass valve 66 is a valve for opening and closing the bypass passage 63. The bypass valve 66 in this embodiment is configured to block the flow of hydraulic oil in the bypass passage 63 during forward drive, reverse drive, and braking, and to open the flow of hydraulic oil in neutral.

[0030] The pilot valve 67 is a valve that automatically opens and closes the hydraulic pressure relief passage 64 and the internal leak oil return passage 65 in response to the PTO. The pilot valve 67 in this embodiment is configured to be able to switch passages using hydraulic pressure and spring force, and is connected to receive hydraulic pressure from the gauge port 44 of the variable-speed hydraulic pump 4. With this configuration, when the pilot valve 67 receives hydraulic pressure from the gauge port 44, it operates the valve to block the hydraulic pressure relief passage 64 against the spring force and open the internal leak oil return passage 65, and when it is released from the hydraulic pressure from the gauge port 44, it opens the hydraulic pressure relief passage 64 by the biased spring force and operates the valve to block the internal leak oil return passage 65.

[0031] The pressurizing motor 68 is a motor for increasing the internal pressure of the auxiliary drive motor 5 in order to compress the piston 51 of the auxiliary drive motor 5. The pressurizing motor 68 in this embodiment is configured by a DC motor, and is connected to the internal leak oil return path 65 between the auxiliary drive motor 5 and the pilot valve 67.

[0032] Next, the operation of each component in the auxiliary driving device 1 of this embodiment will be described.

[0033] When exerting forward driving force, reverse driving force, and braking force, the variable hydraulic pump 4 receives power from the towing vehicle 2 via the PTO to generate hydraulic pressure.

[0034] The pressurized hydraulic oil is sent to the auxiliary drive motor 5 by the variable hydraulic pump 4 via the forward path 61 or the reverse path 62. When the auxiliary drive device 1 exerts a forward driving force, the hydraulic oil is sent to the auxiliary drive motor 5 via the forward path 61. The auxiliary drive motor 5 exerts a forward driving force by the hydraulic pressure of the sent hydraulic oil. Specifically, the multiple pistons 51 arranged in a star shape are appropriately expanded and contracted by the hydraulic pressure, and the rollers 513 at the tips push the cam profile 52, causing the cylinder block 514 connected to the tire shaft to rotate and exert a driving force. At this time, the bypass valve 66 blocks the bypass path 63, so that the hydraulic pressure applied to the forward path 62 does not escape to the reverse path 63 side, and the rollers 513 can push without floating up from the cam profile 52. This enables the auxiliary drive motor 5 to travel at the maximum speed of its performance. The hydraulic oil used to exert a forward driving force in the auxiliary drive motor 5 is returned to the variable hydraulic pump from the reverse port 42 via the reverse path 62.

[0035] When a reverse drive force is generated in the auxiliary drive device 1, hydraulic pressure is applied in the opposite direction to that in the case of a forward drive force. Specifically, hydraulic oil is sent from the variable hydraulic pump 4 to the auxiliary drive motor 5 via the reverse path 62, a reverse drive force is generated by the hydraulic pressure of the sent hydraulic oil, and the hydraulic oil is returned to the variable hydraulic pump 4 via the forward path 61.

[0036] In addition, the auxiliary drive device 1 exerts a braking force by causing the auxiliary drive motor 5 to exert a driving force in a direction opposite to the traveling direction.

[0037] When the auxiliary drive motor 5 is exerting a forward drive force, a reverse drive force, and a braking force, the pilot valve 67 receives hydraulic pressure from the gauge port 44. The pilot valve 67 receives this hydraulic pressure and operates against the spring force to block the hydraulic pressure relief passage 64 and open the internal leak oil return passage 65. By blocking the hydraulic pressure relief passage 64, the hydraulic pressure generated by the variable hydraulic pump 4 is transmitted to the auxiliary drive motor 5. In addition, because the internal leak oil return passage 65 is open, the leaked hydraulic oil is returned to the storage tank 69, and the amount of hydraulic oil in the entire device is not reduced.

[0038] Next, the neutral state will be described. The bypass valve 66 opens the bypass path 63, allowing hydraulic oil to flow between the forward path 61 and the reverse path 62. As a result, even if the amount of oil in the auxiliary drive motor 5 becomes low on the forward path 61 side or the reverse path 62 side, hydraulic oil is replenished via the bypass path 63 due to the difference in oil pressure caused by the lack of oil, so the amount of oil in the auxiliary drive motor 5 will not be insufficient. Therefore, even if the auxiliary drive device 1 is towed by the towing vehicle 2 and exceeds the speed that is considered to be the usage limit of the auxiliary drive motor 5, the amount of oil in the auxiliary drive motor 5 will not be insufficient, and braking force due to the lack of oil will not be generated.

[0039] Next, a case will be described in which the variable hydraulic pump 4 cannot obtain driving force from the PTO due to some factor, such as an incorrect operation by the operator of the towing vehicle 2 or an unintended malfunction by the operator. The hydraulic pressure at the gauge port 44 of the variable hydraulic pump 4 becomes zero. In response to this, the pilot valve 67 operates by spring force to open the hydraulic relief passage 64 and block the internal leak oil return passage 65. In addition, the pressurizing motor 68 starts to drive in order to increase the internal pressure of the auxiliary drive motor 5.

[0040] The auxiliary drive motor 5 is released from hydraulic pressure and goes into neutral when the hydraulic relief passage 64 is opened. Therefore, even if driving force from the PTO cannot be obtained while the towed vehicle 3 is being towed by the towing vehicle 2, the auxiliary drive motor 5 automatically goes into neutral, preventing damage to the auxiliary drive motor 5.

[0041] In addition, the auxiliary drive motor 5 is pressurized by the pressurizing motor 68, and the internal pressure rises. At this time, the pilot valve 67 blocks the flow of the internal leak oil return path 65, so the pressure applied by the pressurizing motor 68 does not leak out to the storage tank 69 through the internal leak oil return path 65. In the auxiliary drive motor 5, the multiple pistons 5 arranged in the radial direction are compressed by being pressurized. As a result, the cam profile 52 is raised above the pistons 61, and damage to the auxiliary drive motor 5 due to cam strike can be prevented.

[0042] According to the auxiliary driving device 1 of this embodiment as described above, the following effects can be achieved. 1. When in neutral, hydraulic oil is automatically circulated between the forward path 61 and the reverse path 62 due to the hydraulic pressure difference through the bypass valve 66, so that the amount of hydraulic oil supplied to the auxiliary drive motor 5 does not become insufficient, and it is possible to prevent the brakes from being applied even if the auxiliary drive motor 5 is towed by the towing vehicle 2 at a speed exceeding the operating limit of the auxiliary drive motor 5. 2. Even if the variable hydraulic pump 4 is unable to obtain driving force from the PTO due to some factor, such as incorrect operation by the driver of the towing vehicle 2 or an unintentional malfunction by the driver, the pilot valve 67 automatically opens the hydraulic relief path 64 and the auxiliary drive motor 5 switches to a neutral state, thereby preventing damage to the auxiliary drive motor 5. 3. When the variable hydraulic pump 4 is unable to obtain driving force from the PTO due to some factor, such as incorrect operation by the driver of the towing vehicle 2 or an unintentional malfunction by the driver, the internal leak oil return path 65 is blocked and the internal pressure of the auxiliary drive motor 5 is increased by the pressure motor 68, so that the multiple pistons 51 arranged in the radial direction are compressed to lift the cam profile 52, thereby preventing damage due to cam striking, etc.

[0043] The auxiliary drive device according to the present invention is not limited to the above-mentioned embodiment, and can be modified as appropriate. For example, the pressure motor 68 may be started based on a detection signal obtained by detecting the driving of the PTO using a sensor or the like, or may be linked to the output of the gauge port 44 in the same manner as the pilot valve 67. [Explanation of symbols]

[0044] 1 Auxiliary drive unit 2 Towing vehicle 3 Towed vehicle 4 Variable Hydraulic Pump 5 Auxiliary drive motor 6 Hydraulic Circuit 41 Advance port 42 Reverse port 43 Hydraulic relief port 44 Gauge port 51 Piston 52 Cam Profile 53 Leak exhaust port 61 Forward path 62 Backward path 63 Bypass Road 64 Hydraulic drain 65 Internal leak oil return path 66 Bypass valve 67 Pilot valve 68 Pressure motor 69 Storage Tank 511 Cylinder 512 Piston head 513 Lola 514 Cylinder block

Claims

1. An auxiliary drive device for a towed vehicle towed by a towing vehicle having running performance, comprising: A variable hydraulic pump that generates a continuously variable hydraulic pressure using the power obtained from the towing vehicle; an auxiliary drive motor that can switch between a forward drive force, a reverse drive force, and a braking force transmitted to the towed vehicle by the variable hydraulic pump; a hydraulic circuit for circulating hydraulic oil between the variable hydraulic pump and the auxiliary drive motor, The variable hydraulic pump comprises: a forward port for delivering hydraulic oil to the auxiliary drive motor when driving the auxiliary drive motor forward; a reverse port for sending hydraulic oil to the auxiliary drive motor when driving the vehicle in reverse; a hydraulic pressure relief port capable of releasing hydraulic pressure of the hydraulic oil before it is supplied to the auxiliary drive motor; and a gauge port capable of measuring the generated hydraulic force. The hydraulic circuit includes: a forward passage communicating the forward port with the auxiliary drive motor; a reverse passage communicating the reverse port with the auxiliary drive motor; a hydraulic pressure relief passage communicating the hydraulic pressure relief port with a storage tank that stores the hydraulic oil; a pilot valve that blocks the hydraulic pressure relief passage by the hydraulic pressure received from the gauge port and opens the hydraulic pressure relief passage by the spring force biased by the hydraulic pressure when the hydraulic pressure is lost; The auxiliary drive device.

2. the auxiliary drive motor is configured by a radial piston motor, and the hydraulic circuit has an internal leakage oil return path that returns hydraulic oil leaking due to an internal leak of the auxiliary drive motor to the storage tank, and a pressurizing motor that pressurizes the hydraulic oil inside the auxiliary drive motor, When the pilot valve blocks the hydraulic pressure relief passage due to hydraulic pressure received from the gauge port, the internal leak oil return passage is opened, 2. The auxiliary drive device according to claim 1, wherein when the pilot valve opens the hydraulic relief passage by a spring force, the internal leak oil return passage is blocked, and the pressurizing motor increases the internal pressure of the auxiliary drive motor to compress a plurality of pistons arranged in a radial direction.

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