JP2011251657A - Hydraulic circuit for four-wheel drive vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a large-capacity hydraulic pump, and to reduce kinds of components required for two hydraulic pumps.SOLUTION: Individual hydraulic motors 3L, 3R, 4L, 4R are mounted to right and left front wheels 1L, 1R provided on a front vehicle body, and right and left crawler type rear wheels 2L, 2R provided on a rear vehicle body in an articulate type four-wheel drive vehicle. The hydraulic motor 3L for the left front wheel and the hydraulic motor 4R for the right rear wheel are connected in parallel to a first hydraulic pump 13. The hydraulic motor 3R for the right front wheel and the hydraulic motor 4L for the left rear wheel are connected in parallel to a second hydraulic pump 14. The capacity of the hydraulic pump 13 is set to be the same as that of the hydraulic pump 14 by feeding working fluids 17 to the hydraulic motors 3L and 4R and the hydraulic motors 3R and 4L for the front and rear wheels, respectively, from the hydraulic pumps 13, 14 in advance or reverse drive.

Description

  The present invention relates to a hydraulic circuit for a four-wheel drive vehicle of a type in which four hydraulic motors individually attached to left and right drive wheels provided at the front and rear of the vehicle are driven by two hydraulic pumps. It is.

  As shown in FIG. 3, a vehicle for running on rough terrain used when working or carrying loads on rough terrain includes a pair of front wheels 1L and 1R provided on the front of a vehicle body (not shown) and a rear vehicle body. A vehicle using a four-wheel drive system with hydraulic motors 3L, 3R and 4L, 4R for traveling individually attached to rear wheels 2L, 2R provided as a pair of left and right may be used.

  In the four-wheel drive type vehicle as described above, two hydraulic pumps 5 and 6 may be used. In this case, usually, one hydraulic pump 5 is a front-wheel hydraulic pump for driving the front wheels 1L and 1R. 5, a front wheel hydraulic circuit 7 is formed by connecting the left and right front wheel hydraulic motors 3L and 3R attached to the left and right front wheels 1L and 1R in parallel to the front wheel hydraulic pump 5. The other hydraulic pump 6 is used as a rear wheel hydraulic pump 6 for driving the rear wheels 2L and 2R, and the rear wheel hydraulic pump 6 is used for the left and right rear wheels attached to the left and right rear wheels 2L and 2R. A hydraulic circuit configuration in which a rear wheel hydraulic circuit 8 is formed by connecting hydraulic motors 4L and 4R in parallel is employed. Reference numeral 9 denotes an engine for operating the two hydraulic pumps 5 and 6 (see, for example, Patent Document 1).

  By the way, in a work vehicle, a type using wheels of different diameters for the front wheels and the rear wheels, or a type called a so-called half truck in which a crawler type drive mechanism is provided in place of the wheels in the rear wheel part. There exists a thing (for example, refer patent document 2).

  In addition, as a steering method of the work vehicle, there are a type in which the front wheels and the rear wheels are steered with respect to the vehicle body, and an articulate type in which the vehicle body is bent halfway.

Japanese Patent Laid-Open No. 2000-198363 (left column on page 2, FIG. 2 (B)) Japanese Patent Laid-Open No. 10-44856

  However, in the hydraulic circuit configuration shown in FIG. 3, the left and right front wheel hydraulic motors 3L and 3R are connected in parallel to one front wheel hydraulic pump 5, so that when the vehicle turns, the left and right front wheels 1L And 1R inner and outer wheel path differences can be absorbed by the difference in flow rate of hydraulic fluid supplied from the front wheel hydraulic pump 5 to the left and right front wheel hydraulic motors 3L and 3R. Since the left and right rear wheel hydraulic motors 4L and 4R are connected in parallel to one rear wheel hydraulic pump 6, the difference in the path between the inner and outer wheels of the left and right rear wheels 2L and 2R generated when the vehicle turns. Is effective in that it can be absorbed by a difference in flow rate of hydraulic oil supplied from the rear wheel hydraulic pump 6 to the left and right rear wheel hydraulic motors 4L and 4R.

  However, as described above, the front wheels and the rear wheels in the work vehicle have different diameters, or the front and rear wheels have different types of driving as in the half-track type work vehicle disclosed in Patent Document 2. When equipped with a mechanism, the hydraulic motors 3L, 3R and 4L, 4R for individually driving front wheels and rear wheels (including drive mechanisms other than wheels such as crawlers) are equipped with hydraulic motors having different rotational speeds. In this case, since it is necessary to change the capacities of the front wheel hydraulic pump 5 and the rear wheel hydraulic pump 6, the capacity of one of the pumps is increased.

  Therefore, there is a problem that the cost required for a hydraulic pump having a large pump capacity increases.

  Furthermore, if hydraulic pumps with different capacities for front wheels and rear wheels are used, the parts used for each hydraulic pump with different capacities increase, resulting in an increase in the number of types of parts, thus increasing the cost required for manufacturing and maintenance. There is also a problem.

  Therefore, the present invention provides a four-wheel drive vehicle in which two hydraulic pumps are used to drive hydraulic motors individually attached to left and right front wheels and left and right rear wheels. Even when the rear wheel hydraulic motor is installed with different rotational motors, the capacity of the two hydraulic pumps can be made equal, making it unnecessary to use a large capacity hydraulic pump and the types of parts. It is an object of the present invention to provide a hydraulic circuit for a four-wheel drive vehicle that can reduce the cost required for manufacturing and maintenance.

  In order to solve the above-mentioned problem, the present invention, corresponding to claim 1, attaches separate hydraulic motors to the left and right front wheels and the left and right rear wheels, and attaches the left front wheel hydraulic motor and the right hydraulic motor to the first hydraulic pump. The rear wheel hydraulic motor is connected in parallel, and the right front wheel hydraulic motor and the left rear wheel hydraulic motor are connected in parallel to the second hydraulic pump.

  Corresponding to claim 2, the left and right front wheels provided on the front vehicle body in an articulated four-wheel drive vehicle in which a front vehicle body and a rear vehicle body are connected via a joint, and the rear vehicle body Separate hydraulic motors are attached to the left and right rear wheels provided on the left, the left front wheel hydraulic motor and the right rear wheel hydraulic motor are connected in parallel to the first hydraulic pump, and the second hydraulic pump is connected to the right The front wheel hydraulic motor and the left rear wheel hydraulic motor are connected in parallel.

According to the hydraulic circuit for a four-wheel drive vehicle of the present invention, the following excellent effects are exhibited.
(1) Separate hydraulic motors are attached to the left and right front wheels and the left and right rear wheels, the left front wheel hydraulic motor and the right rear wheel hydraulic motor are connected in parallel to the first hydraulic pump, and the second hydraulic pump In addition, since the right front wheel hydraulic motor and the left rear wheel hydraulic motor are connected in parallel, when the four-wheel drive vehicle travels forward or backward, the first and second hydraulic pumps are In either case, the hydraulic oil can be supplied to one hydraulic motor for the front wheel and one for the rear wheel. For this reason, even if there is a difference in the capacity and rotational speed of each front wheel hydraulic motor and each rear wheel hydraulic motor due to the difference in the diameter of the front wheel and the rear wheel or the difference in the type of drive mechanism, The capacities of the first and second hydraulic pumps can be made equal.
(2) For this reason, a hydraulic pump with a large capacity can be eliminated. Furthermore, since the components of the two hydraulic pumps can be shared, the types of components can be reduced, and the cost required for manufacturing and maintenance can be reduced.
(3) Left and right front wheels provided on the front vehicle body and left and right rear wheels provided on the rear vehicle body in an articulated four-wheel drive vehicle in which the front vehicle body and the rear vehicle body are connected via a joint. In addition, a separate hydraulic motor is attached, a left front wheel hydraulic motor and a right rear wheel hydraulic motor are connected in parallel to the first hydraulic pump, and a right front wheel hydraulic motor and a left rear are connected to the second hydraulic pump. By adopting a configuration in which wheel hydraulic motors are connected in parallel, the capacities of the first and second hydraulic pumps can be made equal even when turning an articulated four-wheel drive vehicle. . Therefore, the same effects as the above (1) and (2) can be obtained in an articulated four-wheel drive vehicle.

1 is a schematic diagram showing an embodiment of a hydraulic circuit for a four-wheel drive vehicle according to the present invention. FIG. 2 is a schematic plan view showing a turning state of an articulated four-wheel drive vehicle to which the hydraulic circuit of FIG. 1 is applied. It is a figure which shows the hydraulic circuit structure in the vehicle of the conventional four-wheel drive system.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIGS. 1 and 2 show an example of application to an articulated four-wheel drive vehicle as shown in FIG. 2 as one embodiment of the hydraulic circuit for a four-wheel drive vehicle of the present invention. It is as a structure.

  First, an outline of the articulated four-wheel drive vehicle shown in FIG. 2 will be described. The articulated four-wheel drive vehicle includes a front vehicle body 10 and a rear vehicle body 11 via joints 12. , And connected so as to be rotatable in the horizontal direction relative to the vertical axis. The joint portion 12 preferably includes a mechanism and a structure capable of allowing a relative angle change in a twisting direction around the horizontal axis between the front vehicle body 10 and the rear vehicle body 11.

  Furthermore, a pair of left and right front wheels 1L and 1R are provided on the left and right sides of the front vehicle body 10, and a pair of left and right crawler drive mechanisms are provided on the left and right sides of the rear vehicle body 11 as rear wheels 2L and 2R. As a configuration.

  As shown in FIG. 1, the hydraulic circuit for a four-wheel drive vehicle according to the present invention applied to an articulated four-wheel drive vehicle having the above-described configuration is provided with left and right front wheels 1L and 1R on the left and right front wheels 1L and 1R. The front wheel hydraulic motors 3L and 3R are individually attached, and the left and right rear wheel hydraulic motors 4L and 4R are individually attached to the left and right rear wheels 2L and 2R.

  Furthermore, first and second hydraulic pumps 13 and 14 operated by the engine 9 are provided.

  Pressure oil pipelines 15 and 16 are connected to one and the other of the pressure oil discharge ports of the first hydraulic pump 13, respectively. One of the two pressure oil lines 15 and 16 is used to guide hydraulic oil (pressure oil) 17 discharged from the first hydraulic pump 13 when the first hydraulic pump 13 is driven forward. The pressure oil pipeline 15 branches its tip side into two branch pipelines 15a and 15b via a divider 18, and each of the branch pipelines 15a and 15b is connected to the left front wheel hydraulic motor 3L and the right rear wheel. The hydraulic oil motor 4R is connected to a pressure oil inlet / outlet on the pressure oil supply side during forward drive.

  Further, when the first hydraulic pump 13 is operated for reverse travel, the other pressure oil conduit 16 for guiding the hydraulic oil (pressure oil) 17 discharged from the first hydraulic pump 13 is connected to the tip side. Branching into two branch pipes 16a and 16b via a divider 19, and supply of the pressure oil to the branch pipes 16a and 16b when the left front wheel hydraulic motor 3L and the right rear wheel hydraulic motor 4R are driven backward. Connect to the pressure oil inlet / outlet on the side. Accordingly, the left front wheel hydraulic motor 3L and the right rear wheel hydraulic motor 4R are connected in parallel to the first hydraulic pump 13, and the first hydraulic pump 13 and the left front wheel hydraulic motor 3L are connected in parallel. The hydraulic oil 17 is bidirectionally circulated between the pressure oil pipe 15 and the branch pipes 15a and 15b, and the pressure oil pipe 16 and the branch pipes 16a and 16b. Form a possible hydraulic circuit.

  Furthermore, pressure oil pipes 20 and 21 are connected to one and the other of the pressure oil discharge ports of the second hydraulic pump 14, respectively. One of the two pressure oil pipes 20 and 21 that guides hydraulic oil (pressure oil) 17 discharged from the second hydraulic pump 14 when the second hydraulic pump 14 is operated for forward movement. The pressure oil pipe 20 is branched at its distal end into two branch pipes 20a and 20b via a divider 22, and each of the branch pipes 20a and 20b is connected to the right front wheel hydraulic motor 3R and the left rear wheel. The hydraulic oil motor 4L is connected to the pressure oil inlet / outlet on the pressure oil supply side during forward drive.

  In addition, when the second hydraulic pump 14 is operated for reverse travel, the other pressure oil conduit 21 for guiding the hydraulic oil (pressure oil) 17 discharged from the second hydraulic pump 14 is connected to the tip end side thereof. Branching into two branch pipes 21a and 21b via a divider 23, and supply of pressure oil to the branch pipes 21a and 21b when the right front wheel hydraulic motor 3R and the left rear wheel hydraulic motor 4L are driven backward. Connect to the pressure oil inlet / outlet on the side. Thus, the right front wheel hydraulic motor 3R and the left rear wheel hydraulic motor 4L are connected in parallel to the second hydraulic pump 14, and the second hydraulic pump 14 and the right front wheel hydraulic motor 3R are connected in parallel. The hydraulic oil 17 is bidirectionally circulated between the hydraulic motor 4L and the left rear wheel hydraulic motor 4L via the pressure oil pipe 20 and the branch pipes 20a and 20b, the pressure oil pipe 21 and the branch pipes 21a and 21b. The configuration is such that a possible hydraulic circuit is formed.

  When the four-wheel drive vehicle hydraulic circuit of the present invention having the above-described configuration is used, when both the first hydraulic pump 13 and the second hydraulic pump 14 are operated for forward movement, the first hydraulic pump 13 is used. The hydraulic oil 17 discharged from the hydraulic oil is supplied to the left front wheel hydraulic motor 3L and the right rear wheel hydraulic motor 4R through the pressure oil pipe 15 and the branch pipes 15a and 15b, and the left front wheel hydraulic motor 3L. The right rear wheel hydraulic motor 4R is driven forward. For this reason, the forward driving force is exerted on the left front wheel 1L and the right rear wheel 2R.

  At the same time, the hydraulic oil 17 discharged from the second hydraulic pump 14 is supplied to the right front wheel hydraulic motor 3R and the left rear wheel hydraulic motor 4L via the pressure oil pipe 20 and the branch pipes 20a and 20b. Thus, the right front wheel hydraulic motor 3R and the left rear wheel hydraulic motor 4L are driven forward. For this reason, the forward driving force is also exerted on the right front wheel 1R and the left rear wheel 2L.

  Therefore, in the four-wheel drive vehicle equipped with the hydraulic circuit for a four-wheel drive vehicle of the present invention, the vehicle moves forward in a state where the forward drive force is exerted on all the left and right front wheels 1L and 1R and the left and right rear wheels 2L and 2R. Driving will be performed.

  On the other hand, when both the first hydraulic pump 13 and the second hydraulic pump 14 are operated for reverse travel, the hydraulic oil 17 discharged from the first hydraulic pump 13 is supplied to the pressure oil pipeline 16 and the branch pipeline 16a, The left front wheel hydraulic motor 3L and the right rear wheel hydraulic motor 4R are supplied to the left front wheel hydraulic motor 3L and the right rear wheel hydraulic motor 4R via the motor 16b, and the left front wheel hydraulic motor 3L and the right rear wheel hydraulic motor 4R are driven backward. For this reason, the reverse drive force is exerted on the left front wheel 1L and the right rear wheel 2R.

  Simultaneously, the hydraulic oil 17 discharged from the second hydraulic pump 14 is supplied to the right front wheel hydraulic motor 3R and the left rear wheel hydraulic motor 4L via the pressure oil pipe 21 and the branch pipes 21a and 21b. Thus, the right front wheel hydraulic motor 3R and the left rear wheel hydraulic motor 4L are driven backward. For this reason, the reverse drive force is also exerted on the right front wheel 1R and the left rear wheel 2L.

  Therefore, in the four-wheel drive vehicle equipped with the hydraulic circuit for a four-wheel drive vehicle of the present invention, the reverse drive is performed with the reverse drive force exerted on all the left and right front wheels 1L and 1R and the left and right rear wheels 2L and 2R. Driving will be performed.

  When the four-wheel drive vehicle travels forward or backward as described above, if a constant load is applied to the front wheels 1L and 1R and the rear wheels 2L and 2R, the first hydraulic pump 13 The hydraulic oil 17 for the left front wheel hydraulic motor 3L and the right rear wheel hydraulic motor 4R is left to drive the left front wheel 1L according to the differential action of the left front wheel 1L and the right rear wheel 2R. The flow rate of the hydraulic oil 17 required by the front wheel hydraulic motor 3L and the flow rate of the hydraulic oil 17 required by the right rear wheel hydraulic motor 4R for driving the right rear wheel 2R are appropriately distributed and supplied. Will come to be. Similarly, from the second hydraulic pump 14, hydraulic oil 17 acts on the differential action of the right front wheel 1R and the left rear wheel 2L with respect to the right front wheel hydraulic motor 3R and the left rear wheel hydraulic motor 4L. Accordingly, the flow rate of the hydraulic oil 17 required for the right front wheel hydraulic motor 3R to drive the right front wheel 1R, and the left rear wheel hydraulic motor 4L required to drive the left rear wheel 2L. The flow rate of the hydraulic oil 17 is appropriately distributed and supplied.

  Therefore, each of the first and second hydraulic pumps 13 and 14 may supply the hydraulic oil 17 to the hydraulic motors 3L and 4R for the front wheels and the hydraulic motors 3R and 4R for the rear wheels. Therefore, as described above, the front wheels 1L and 1R of the four-wheel drive vehicle are wheels, and the rear wheels 2L and 2R are crawler-type drive mechanisms. Even when there is a difference in the capacity and rotation speed of the wheel hydraulic motors 4L, 4R, the capacity required for the first and second hydraulic pumps 13 and 14 is averaged.

Further, as the four-wheel drive vehicle equipped with the hydraulic circuit for a four-wheel drive vehicle according to the present invention is an articulate type, the four-wheel drive vehicle is turned in the left-right direction, for example, as shown in FIG. In the state where the front vehicle body 10 and the rear vehicle body 11 are bent around the joint portion 12 and the four-wheel drive vehicle is turned leftward, the parameters are set as follows:
Front wheel 1L, 1R tread: C
Rear wheel 2L, 2R tread: D
Turning radius at the center of the front wheel axle (not shown): X
Center turning radius of rear wheel axle (not shown): Y
Turning radius of left front wheel 1L: Rfl (Rfl = X- (C / 2))
Turning radius of right front wheel 1R: Rfr (Rfr = X + (C / 2))
Turning radius of left rear wheel 2L: Rrl (Rrl = Y− (D / 2))
Turning radius of right rear wheel 2R: Rrr (Rrr = Y + (D / 2))
The sum Z1 of the movement trajectory (path length) of the left front wheel 1L and the movement trajectory (path length) of the right rear wheel 2R is:
Z1 = 2π (Rfl + Rrr) = 2π (X + Y + (D−C) / 2)
It becomes.

On the other hand, the sum Z2 of the movement trajectory (path length) of the right front wheel 1R and the movement trajectory (path length) of the left rear wheel 2L is:
Z2 = 2π (Rfr + Rrl) = 2π (X + Y + (C−D) / 2)
It becomes.

  Therefore, if the tread (C) of the front wheels 1L and 1R and the tread (D) of the rear wheels 2L and 2R are set to be substantially equal (C≈D), the movement locus of the left front wheel 1L ( The sum Z1 of the movement path (path length) of the right rear wheel 2R and the movement path (path length) of the right front wheel 1R and the movement path (path length) of the left rear wheel 2L is approximately Equally (Z1≈Z2).

  For this reason, in the articulated four-wheel drive vehicle, hydraulic oil is supplied to the left front wheel hydraulic motor 3L and the right rear wheel hydraulic motor 4R corresponding to the left front wheel 1L and the right rear wheel 2R even during turning. The hydraulic oil 17 is supplied to the right front wheel hydraulic motor 3R and the left rear wheel hydraulic motor 4L corresponding to the right front wheel 1R and the left rear wheel 2L, and the flow rate required for the first hydraulic pump 13 for supply. Therefore, the flow rate required for the second hydraulic pump 14 can be equalized.

  Thus, according to the hydraulic circuit for a four-wheel drive vehicle of the present invention, the hydraulic motors 3L, 3R individually attached to the left and right front wheels 1L, 1R and the left and right rear wheels 2L, 2R by the two hydraulic pumps 13 and 14. 4L, 4R, a first hydraulic pump 13 for driving hydraulic motors 3L and 4R corresponding to left front wheel 1L and right rear wheel 2R, right front wheel 1R, The capacity of the second hydraulic pump 14 for driving the hydraulic motors 3R and 4L corresponding to the left rear wheel 2L can be made equal.

  For this reason, even when the rotational speeds of the front wheel hydraulic motors 3L, 3R and the rear wheel hydraulic motors 4L, 4R are different, a hydraulic pump having a large capacity can be dispensed with.

  Further, since the parts of the two hydraulic pumps 13 and 14 can be made common, the types of parts can be reduced, and the cost required for manufacturing and maintenance can be reduced.

  It should be noted that the present invention is not limited to the above-described embodiment, and for a four-wheel drive vehicle, the front wheel hydraulic pressure for the front wheels 1L, 1R and the rear wheels 2L, 2R are different from each other in size (size). Different types of motors 3L, 3R and rear wheel hydraulic motors 4L, 4R have different rotational speeds, and front wheels 1L, 1R and rear wheels 2L, 2R have different types of driving mechanisms such as wheels, crawlers and other driving mechanisms. As a result, the front wheel hydraulic motors 3L, 3R and the rear wheel hydraulic motors 4L, 4R have different rotational speeds. Also good.

  Furthermore, the front wheels 1L and 1R and the rear wheels 2L and 2R may be applied to a four-wheel drive vehicle having a drive mechanism of the same type and size.

  The connection order of the first hydraulic pump 13 and the second hydraulic pump 14 to the engine 9 in FIG. 1 may be reversed.

  Of course, various modifications can be made without departing from the scope of the present invention.

1L Left front wheel 1R Right front wheel 2L Left rear wheel 2R Right rear wheel 3L Left front wheel hydraulic motor 3R Right front wheel hydraulic motor 4L Left rear wheel hydraulic motor 4R Right rear wheel hydraulic motor 10 Front car body 11 Rear car body 12 Joint part 13 First hydraulic pump 14 Second hydraulic pump

Claims (2)

  Separate hydraulic motors are attached to the left and right front wheels and the left and right rear wheels, the left front wheel hydraulic motor and the right rear wheel hydraulic motor are connected in parallel to the first hydraulic pump, and the second hydraulic pump is connected to the right A hydraulic circuit for a four-wheel drive vehicle, characterized in that a front wheel hydraulic motor and a left rear wheel hydraulic motor are connected in parallel.   Separately for the left and right front wheels provided on the front vehicle body and the left and right rear wheels provided on the rear vehicle body in an articulated four-wheel drive vehicle in which the front vehicle body and the rear vehicle body are connected via a joint. The left front wheel hydraulic motor and the right rear wheel hydraulic motor are connected in parallel to the first hydraulic pump, and the right front wheel hydraulic motor and the left rear wheel hydraulic motor are connected to the second hydraulic pump. A hydraulic circuit for a four-wheel drive vehicle, characterized by having a configuration in which a motor is connected in parallel.

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