JP3904630B2 - Four-wheel drive vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a four-wheel drive vehicle in which the rotational driving force of a main prime mover is transmitted to front wheels and rear wheels, and more particularly to a four-wheel drive vehicle in which drive force is transmitted by working fluid pressure.
[0002]
[Prior art]
In this type of four-wheel drive vehicle, in the case of a four-wheel drive vehicle in which the mechanical connection between the two-wheel drive and the four-wheel drive is manually switched as in the part time type, the switching operation is troublesome. It is not suitable for passenger cars due to problems such as tight corner braking. In contrast, a full-time four-wheel drive vehicle can eliminate the tight corner braking phenomenon, but requires a differential limiting device at the center differential, which complicates the device. In addition, because the drive system used in current passenger cars regardless of part-time type and full-time type has a propeller shaft, this increases the weight of the front-wheel drive vehicle, adversely affects the interior space, deteriorates fuel consumption, Noise and vibration will be worsened, and even in the case of rear-wheel drive vehicles, weight increases and fuel consumption will be unavoidable.
[0003]
Therefore, conventionally, for the purpose of reducing the weight of components, for example, as described in Japanese Patent Laid-Open No. 3-224830 (hereinafter referred to as a first conventional example), a front wheel directly driven by a prime mover and A power transmission device for a four-wheel drive vehicle having a rear wheel driven through a clutch operated by fluid pressure, the first fluid pressure pump driven in conjunction with the front wheel, and the rear wheel A second fluid pressure pump that is driven in conjunction, a connecting oil passage that connects a discharge port of the first fluid pressure pump and a suction port of the second fluid pressure pump, and the connecting oil passage and the fluid pressure A hydraulic supply oil passage that communicates with the hydraulic pressure chamber of the clutch, and responds to a flow rate difference between the first fluid pressure pump and the second fluid pressure pump due to a difference in rotational speed between the front wheel side and the rear wheel side. Control of the clutch Four-wheel drive vehicle has been proposed which is adapted to control.
[0004]
In order to transmit a driving force from a driving axle to a driven axle only when a main drive wheel slips on a low friction coefficient road or the like by using a hydraulic power transmission instead of a propeller shaft, for example, Japanese Patent Laid-Open No. 1-223030 No. 1 (hereinafter referred to as a second conventional example), a first hydraulic pump composed of, for example, a vane pump that rotates in conjunction with a drive axle and generates hydraulic pressure in accordance with the rotational speed, and a follower A second hydraulic pump similarly configured by a vane pump that rotates in conjunction with the axle and generates hydraulic pressure according to the rotation speed, and one discharge port and the other suction port of the first and second hydraulic pumps The thing provided with the structure provided with the oil path which each communicates is proposed.
[0005]
However, in the four-wheel drive vehicle of the first conventional example, it is possible to reduce the weight of the propeller shaft by limiting the transmission torque, but the propeller shaft cannot be omitted. There is a certain limit, and there is an unresolved problem that it cannot be improved at all against the adverse effect on the vehicle interior space.
[0006]
Further, the four-wheel drive vehicle of the second conventional example uses a hydraulic power transmission device, so the propeller shaft is omitted to reduce the weight, secure a vehicle interior space, improve fuel consumption, and reduce noise and vibration. However, in order to cope with reversal of the flow direction of the hydraulic oil due to the difference in the rotation direction of the axle between the forward movement and the reverse movement, the first hydraulic pump and the second hydraulic pump Both of the pair of hydraulic pipes communicating with each other must be expensive high-pressure pipes, and when applying hydraulic elements such as valves in the hydraulic power transmission, it is necessary to cope with both high and low pressures. There is an unsolved problem that the configuration of the system becomes complicated.
[0007]
Accordingly, the present applicant has simplified the overall configuration by reducing the number of high-pressure piping portions of the hydraulic transmission device, and has almost eliminated transmission of driving force to the driven axle when the rotational speed difference between the driving axle and the driven axle is small. For the purpose of maintaining the two-wheel drive state and maintaining the four-wheel drive state by increasing the transmission of the driving force to the driven axle as the rotational speed difference increases, for example, Japanese Patent Application No. 6-049146 (hereinafter referred to as the third conventional art). As described, the driving axle driven by the main prime mover, and rotating in conjunction with the driving axle and discharging the working fluid in a constant direction regardless of the direction of rotation of the driving axle, for example, suction A fluid pressure pump composed of a throttle-type piston pump, a fluid pressure pump motor composed of, for example, a swash plate type variable displacement pump motor rotating in conjunction with a driven axle, and the fluid pressure pump motor A forward / reverse switching means comprising, for example, a two-position, four-port electromagnetic directional switching valve connected to the high pressure flow path communicating the discharge port of the fluid pressure pump and the suction port of the forward / backward switching means; It is composed of a low-pressure channel that communicates the discharge port of the forward / reverse switching means and the suction port of the fluid pressure pump, and a relief valve that defines the upper limit of the transmission torque between the fluid pressure pump and the forward / reverse switching means, for example. Proposed having a configuration comprising torque limiting means, and a check valve that allows fluid flow from the low-pressure flow path to the high-pressure flow path side inserted in the communication passage communicating the high-pressure flow path and the low-pressure flow path is doing.
[0008]
[Problems to be solved by the invention]
By the way, in the four-wheel drive vehicle of the third conventional example, a countermeasure against contamination of the working fluid (contamination is performed so that a clean working fluid circulates between the fluid pressure pump and the fluid pressure pump motor and normal driving force is transmitted. (Measures) must be taken. In the four-wheel drive vehicle of the third conventional example, it is conceivable that a fluid filter is interposed in a part of the low-pressure channel through which a relatively low-pressure working fluid flows.
[0009]
However, the fluid filter must be set to a filter capacity corresponding to the maximum flow rate of the low-pressure flow path in order to suppress pressure loss in the low-pressure flow path. There is a problem in terms of weight reduction, and the resulting low fuel consumption is also adversely affected. In addition, the layout of the large fluid filter reduces the degree of freedom in layout and further increases the cost of the apparatus.
[0010]
On the other hand, if the viscosity of the working fluid increases at low temperatures, the pressure loss in the low-pressure flow path increases, which may affect the fuel economy and driving force performance of a four-wheel drive vehicle. In this case, the filter is further enlarged.
[0011]
Therefore, the present invention has been made paying attention to the above-mentioned unsolved problems of the conventional example, and does not lower the degree of freedom of layout while reducing weight and improving fuel consumption. An object of the present invention is to provide a four-wheel drive vehicle capable of taking measures against contamination of working fluid while suppressing pressure loss at the time.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 is directed to a drive axle driven by a main prime mover, fluid pressure supply means for rotating in conjunction with the drive axle and discharging working fluid, and interlocking with a driven axle. Fluid pressure driving means that rotates, a high-pressure channel that communicates the discharge port of the fluid pressure supply means and the suction port of the fluid pressure drive means, the discharge port of the fluid pressure drive means, and the fluid pressure supply means The flow of the working fluid between the high-pressure flow path and the low-pressure flow path interposed between the low-pressure flow path communicating with the suction port of the gas and the communication flow path connected between the high-pressure flow path and the low-pressure flow path In a four-wheel drive vehicle equipped with a control valve for adjusting the control valve, the control valve is disposed between the high-pressure channel and the low-pressure channel. Communicating when in a two-wheel drive state and not communicating when in a four-wheel drive state In addition to the open / close switching valve, a fluid filter was inserted into the communication flow path on the low pressure flow path side from the open / close switching valve.
[0018]
【The invention's effect】
According to the four-wheel drive vehicle of the first aspect, when the working fluid passes through the fluid filter inserted in the communication flow path, impurities mixed in the working fluid are removed by the filtering action of the fluid filter. It is possible to provide a four-wheel drive vehicle equipped with a countermeasure against fluid contamination. In addition, the fluid filter of the present invention is inserted in a communication channel through which a low flow rate working fluid flows, and is not inserted in a main channel, that is, a high pressure channel or a low pressure channel. It does not affect the fuel consumption and driving force performance of the driving vehicle. Moreover, even if the viscosity of the working fluid increases at low temperatures, even if pressure loss occurs on the upstream side of the fluid filter, there is no problem in the performance of the four-wheel drive vehicle.
[0019]
Since only a low flow rate of working fluid flows into the fluid filter inserted in series with the control valve, a small filter corresponding to the low flow rate can be obtained.
As a result, a small fluid filter can be inserted in the communication flow path, so that the problems of weight reduction of the vehicle body, fuel consumption, and increase of the apparatus can be solved. Further, since a small fluid filter may be connected in series with the control valve, there is no layout restriction.
[0020]
According to the four-wheel drive vehicle of claim 1, the high-pressure working fluid flows in the high-pressure channel. Four-wheel drive state If the on / off switching valve is in a non-communication state at this time, the fluid filter inserted in the communication channel on the low pressure channel side from the on / off switching valve is not affected by the pressure of the working fluid.
[0023]
Therefore, since the fluid filter of the present invention does not need to have a pressure-resistant structure, an inexpensive fluid filter can be obtained. Further, the same effect as that of the first aspect of the invention can be obtained.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic diagram showing a first embodiment when the present invention is applied to a four-wheel drive vehicle based on a front-wheel drive vehicle.
[0031]
Reference numeral 1 in the figure denotes an engine as a main prime mover, and the rotational driving force of the engine 1 is input to the front wheel side differential 3 via the transmission 2, and a drive axle is provided on the output side of the differential 3. A front wheel 5 is connected via a front axle 4.
[0032]
In the front wheel side differential 3, a ring gear 3b formed in the differential gear case 3a meshes with a gear 2a connected to the output side of the transmission 2 and is driven to rotate. A pair of gears 3a formed in the differential gear case 3a. A pinion 3d is attached to the pinion shaft 3c, a pair of side gears 3e mesh with the pinion 3d, and a front axle 4 is connected to the side gears 3e.
[0033]
Further, a suction throttle type piston pump 6 (hereinafter referred to as a piston pump 6) as a fluid pressure pump constituting a fluid pressure supply means through a gear 3g meshed with a ring gear 3f formed in parallel with the ring gear 3b in the differential gear case 3a. Is abbreviated as “”).
[0034]
The piston pump 6 has a suction port 6b connected to a strainer 7a disposed in the reservoir tank 7 via a suction pipe 8S, and serves as a forward / reverse switching means through a low pressure pipe 8L as a low pressure flow path. The discharge port 6c is connected to a pump port P serving as a suction port of the electromagnetic direction switching valve 9 through a high pressure pipe 8H as a high pressure flow path. Here, in the piston pump 6, the suction port and the discharge port are not interchanged depending on the rotation direction of the rotating shaft 6a, and the discharge flow rate is represented by the characteristic curve L in FIG. ₁ As shown by, the rotational speed is from “0” to a predetermined value V ₁ Until the rotation speed reaches the predetermined value V ₁ Above, maximum discharge flow rate Q _1MAX Is set to saturate.
[0035]
The electromagnetic direction switching valve 9 communicates the pump port P serving as a suction port with the output port A and the tank port T serving as a discharge port to the output port B in a normal position where the solenoid 9a is in a non-energized state. Further, at the offset position where the solenoid 9a is energized, the pump port P communicates with the output port B, the tank port T communicates with the output port A, and the output ports A and B are swash plate type variable capacities as a fluid pressure pump motor. It is connected to suction / discharge ports 10a and 10b of a pump motor 10 (hereinafter abbreviated as pump motor 10), and the high pressure hydraulic oil (high pressure operation) of the high pressure pipe 8H is in a normal position where the solenoid 9a is not energized. Fluid) is connected to the suction / discharge port 10a of the pump motor 10 and the low-pressure pipe 8L is connected to the suction / discharge port 10b, so that the rotary shaft 10c is driven to rotate in the clockwise direction when viewed from the left side, for example. At the offset position, the high pressure hydraulic fluid in the high pressure pipe 8H is communicated with the suction / discharge port 10b of the pump motor 10 and the low pressure pipe 8L is communicated with the suction / discharge port 10a. The rotation shaft 10c as viewed from the rotational direction, for example left side during forward travel is driven to rotate in a counterclockwise direction.
[0036]
The electromagnetic direction switching valve 9 is built in the pump motor 10, and the output ports A and B are connected to the suction / discharge ports 10a and 10b of the pump motor 10 without any piping. In addition, the solenoid 9a of the electromagnetic direction switching valve 9 is not energized during forward travel by being connected to the DC power source 9c via the detection switch 9b which is turned on when reverse is selected with a select lever (not shown). In the energized state, the energized state is controlled during reverse travel.
[0037]
The flow rate of the pump motor 10 includes a hydraulic cylinder 12a with a differential pressure generated at both ends of a differential pressure detecting orifice 11 inserted in a low pressure pipe 8L in the vicinity of the tank port T of the electromagnetic direction switching valve 9. By controlling the swash plate variable mechanism 12, the characteristic curve L in FIG. ₂ As shown in FIG. ₁ Until the rotation speed reaches V, the rotation speed increases in proportion to the increase in the rotation speed. ₁ Reaches the maximum discharge flow rate Q of the piston pump 6 _1MAX More discharge flow rate Q ₂ And then increases relatively slowly as the rotational speed increases. Here, the discharge flow rate of the pump motor 10 and the discharge flow rate of the piston pump 6 are such that the discharge flow rate of the pump motor 10 is greater than the discharge flow rate of the piston pump 6 for the same wheel speed, as shown in FIG. The inherent discharge flow rate and the gear ratio of the gear connected to the rotating shaft are set.
[0038]
Further, as shown in FIG. 1, a relief valve 13 as a torque limiting means is inserted in the communication pipe 14A that communicates between the high-pressure pipe 8H and the low-pressure pipe 8L, and is arranged in parallel with the communication pipe 14A. A check valve 15 that permits only a fluid flow from the low pressure pipe 8L side to the high pressure pipe 8H side and a fixed orifice 16 are connected to each of the communication pipes 14B and 14C in parallel with the relief valve 13. Yes.
[0039]
Further, a communication pipe 20 is connected between the high-pressure pipe 8H and the low-pressure pipe 8L near the suction port 6b side, and the communication pipe 20 has a high pressure during normal running (during running on a high friction coefficient road). An electromagnetic switching valve 22 communicating with the pipe 8H and the suction pipe 8S is inserted.
[0040]
The electromagnetic switching valve 22 is configured as a spring offset type two-position two-port, and includes a solenoid a, an input port 22b connected to the high-pressure pipe 8H on the discharge port 6c side, an output port 22c connected to the suction pipe 8S, The return spring 22d has a spool that switches the input port 22b and the output port 22c to a communication state or a non-communication state. When the solenoid 22a is in a non-energized state, the spool moves to a normal position where the input port 22b and the output port 22c are communicated. Further, when the solenoid 22a is energized, the spool moves to an offset position where the input port 22b and the output port 22c are disconnected. The solenoid 22a is energized with an exciting current i from a controller 24 described later.
[0041]
Here, in the communication pipe 20, a fluid filter 40 is inserted on the low pressure pipe 8 L side from the electromagnetic switching valve 22. The fluid filter 40 removes impurities mixed with hydraulic oil passing through the inside by filtration.
[0042]
On the other hand, a gear 10d is attached to the rotary shaft 10c of the pump motor 10, and a ring gear 17b formed in a differential gear case 17a of the rear wheel side differential 17 is meshed with the gear 10d. The rear wheel differential 17 has substantially the same configuration as the front wheel differential 3, and a pinion 17d is attached to a pair of pinion shafts 17c formed in the differential gear case 17a. A pair of side gears 17e mesh with each other, a rear axle 18 is connected to these side gears 17e, and a rear wheel 19 is connected to the rear axle 18.
[0043]
Further, the front axle 4 is provided with a front axle rotational speed sensor 26 for detecting the rotational speed, and the rear axle 18 is provided with a rear axle rotational speed sensor 28 for detecting the rotational speed. ing. Front axle rotational speed detection value N output from these front axle rotational speed sensor 26 and rear axle rotational speed sensor 28 _F , Rear axle rotation speed detection value N _R Is input to the controller 24.
[0044]
The controller 24 outputs and stops the excitation current i to the electromagnetic switching valve 22 based on detection signals from the front axle rotational speed sensor 26 and the rear axle rotational speed sensor 28.
[0045]
That is, the controller 24 includes a microcomputer 30 and a drive circuit 32 that outputs an excitation current i corresponding to the control signal CS output from the microcomputer 30 as shown in FIG.
[0046]
The microcomputer 30 includes an input interface circuit 30a having an A / D conversion function for reading detection signals from the front axle rotational speed sensor 26 and the rear axle rotational speed sensor 28, and an electromagnetic switching valve 22 according to a predetermined program. An arithmetic processing device 30b that performs arithmetic processing for the switching operation, a storage device 30c such as a ROM and a RAM, and an output interface circuit 30d that outputs a control signal CS are provided.
[0047]
Here, in the storage device 30c, a program and fixed data necessary for execution of the arithmetic processing of the arithmetic processing device 30b are stored in advance, and the processing result can be temporarily stored. Among these, as the fixed data, the front and rear axles 4, 18 generated when traveling with the diameter changed due to the difference in the rotational speeds of the front and rear axles 4, 18 generated when the tires of different diameters travel, that is, tire wear or the like. Reference speed difference ΔN set higher than the speed difference by a predetermined value _F Is remembered. Note that since the rotational speed difference ΔN increases as the vehicle speed increases, the reference rotational speed difference ΔN _F Changes according to the vehicle speed. That is, the reference rotational speed difference ΔN _F Is a function of vehicle speed.
[0048]
In the arithmetic treatment device 30b, the front axle rotation speed detection value N _F To rear axle rotation speed detection value N _R The rotation speed difference ΔN (= N _F -N _R ) Is calculated, and this rotational speed difference ΔN and the reference rotational speed difference ΔN _F The comparison judgment is performed. The arithmetic processing device 30b is configured such that the current rotational speed difference ΔN is equal to the reference rotational speed difference ΔN _F (ΔN <ΔN _F ) Since the control signal CS is not output from the output interface circuit 30d to the drive circuit 32 and the exciting current i is not output to the solenoid 22a, the solenoid 22a maintains the non-energized state. On the other hand, the rotational speed difference ΔN is equal to the reference rotational speed difference ΔN. _F When it is determined that the above is true (ΔN ≧ ΔN _F ), The control signal CS is output from the output interface circuit 30d to the drive circuit 32. Thereby, the solenoid 22a maintains an energized state.
[0049]
Next, the operation and action of the four-wheel drive vehicle having the above configuration will be described.
Now, when the vehicle stops on a road with a high coefficient of friction such as a dry road surface and the engine 1 starts traveling in a braking state where the engine 1 is in an idling state, the vehicle enters a starting state by switching the shift lever to the forward traveling side. At this time, the detection switch 9b on the reverse travel side maintains the OFF state, so the solenoid 9a of the electromagnetic direction switching valve 9 maintains the non-energized state, and the switching position continues at the normal position shown in FIG. In this state, when the brake pedal is released and the accelerator pedal is depressed, the rotational force of the engine 1 is transmitted to the front wheel side differential 3 via the transmission 2, and the front wheel 5 actuates the front wheel 5. Advancement is started by rotationally driving in the forward direction.
[0050]
At this time, the discharge flow rates of the piston pump 6 and the pump motor 10 are set so that the discharge flow rate of the pump motor 10 is larger than that of the piston pump 6 at the same rotational speed Vr, as shown in FIG. Therefore, the high-pressure hydraulic oil discharged from the piston pump 6 is sucked by the pump motor 10 and the pressure of the high-pressure pipe 8H does not increase.
[0051]
Then, from the front axle rotational speed sensor 26 and the rear axle rotational speed sensor 28, the rotational speed detection value N _F , N _R Is inputted to the controller 24, the rotational speed difference ΔN (= N _F -N _R ) And the reference speed difference ΔN _F And comparison operation. In this high friction coefficient road, the rotational speed difference ΔN becomes almost zero, and the reference rotational speed difference ΔN _F Since it becomes a lower value (ΔN <ΔN _F ), The solenoid 22a of the electromagnetic switching valve 22 is maintained in a non-energized state, and the switching position is set to the normal position shown in FIG. As a result, the electromagnetic switching valve 22 communicates with the input port 22b and the output port 22c, so that low-flowing hydraulic oil that is not sucked in by the pump motor 10 passes through the electromagnetic switching valve 22 and the fluid filter 40 to the low-pressure pipe 8L side. The vehicle is returned and the vehicle is forcibly driven in a two-wheel drive state.
[0052]
Next, when starting on a low friction coefficient road such as an icy road or a snowy road, the front wheel 5 is first driven to rotate. However, since the road is a low friction coefficient road, the front wheel 5 slips and the front wheel 5 and the rear wheel 19 are driven. A rotational speed difference that causes the front wheel 5 to have a high rotational speed.
[0053]
At this time, the controller 24 determines that the rotation speed difference ΔN is equal to the reference rotation speed difference ΔN. _F (ΔN ≧ ΔN) _F ), The solenoid 22a of the electromagnetic switching valve 22 is energized, and the input port 22b and the output port 22c are switched to the offset position where they are not connected. Thereby, since the electromagnetic switching valve 22 is shut off, the hydraulic oil does not flow into the fluid filter 40, but the hydraulic oil flows from the piston pump 6 to the pump motor 10, and the discharge flow rate of the piston pump 6 is equal to the discharge flow rate of the pump motor 10. If it exceeds, the resistance of the pump motor 10 becomes a load and the hydraulic pressure of the high-pressure pipe 8H increases, so that the pump motor 10 operates as a hydraulic motor.
[0054]
Thereby, the driving force according to the pressure inside the high-pressure pipe 8H is transmitted to the rear wheel 19 via the rear wheel side differential device 17, and the state shifts to the four-wheel driving state. That is, as shown in FIG. 4, the torque transmitted to the rear wheel 19 increases rapidly with an increase in the rotational speed difference, and the maximum torque T due to the pressure restriction by the relief valve 13. _MAX Will be regulated.
[0055]
Further, the rise of the transmission torque in FIG. 4 is managed by controlling the amount of leakage from the high pressure pipe 8H to the low pressure pipe 8L by the fixed orifice 16 inserted in the communication pipe 14C communicating the high pressure pipe 8H and the low pressure pipe 8L. The characteristics can be set arbitrarily by changing the rising edge. And, due to the temperature characteristics accompanying the change in the viscosity of the hydraulic oil in the orifice, the leakage amount of the fixed orifice 16 is reduced and the driving force is more likely to be generated at low temperatures than at high temperatures, so a function as a four-wheel drive vehicle is required. It becomes easy to become four-wheel drive in the winter when there are many opportunities to be done.
[0056]
Next, when the vehicle is moved backward, the detection switch 9b is turned on by switching the select lever to the reverse position, so that the solenoid 9a of the electromagnetic direction switching valve 9 is energized and the switching position is changed from the normal position. Switch to the offset position. As a result, the hydraulic oil inside the high-pressure pipe 8H is supplied to the suction / discharge port 10b of the pump motor 10, and the hydraulic oil discharged from the suction / discharge port 10a is returned to the low-pressure pipe 8L side. The rear wheel 19 is rotated in the reverse direction by reversing the shaft 10c during forward travel.
[0057]
At this time, the rotational speed difference ΔN is equal to the reference rotational speed difference ΔN. _F When a lower value is indicated (ΔN <ΔN _F ), The solenoid 22a is maintained in a non-energized state, the switching position of the electromagnetic switching valve 22 is set to the normal position, and the working fluid flows into the low pressure pipe 8L via the electromagnetic switching valve 22 and the fluid filter 40. Further, the rotational speed difference ΔN is equal to the reference rotational speed difference ΔN. _F (ΔN ≧ ΔN _F ), The solenoid 22a is maintained in the energized state, and the switching position of the electromagnetic switching valve 22 is set as the offset position. For this reason, even when the vehicle is traveling backward, the transmission of the driving force is exactly the same as when traveling forward, and the front wheel 5 slips and the front and rear axles 4 and 18 have a reference rotational speed difference ΔN. _F Only when the above rotational speed difference occurs, pressure is generated inside the high-pressure pipe 8H, and the driving force is transmitted to the rear wheel 19.
[0058]
Next, the effect of the fluid filter 40 inserted in the communication pipe 20 will be described. The hydraulic oil passes through the fluid filter 40 when the vehicle is stopped with the engine 1 idling as described above, and when the vehicle is traveling forward on a high friction coefficient road in a two-wheel drive state. Or, when the vehicle is traveling backward, the electromagnetic switching valve 22 is in the normal position (the input port 22b and the output port 22c are in communication), and the hydraulic oil on the high-pressure pipe 8H side passes through the fluid filter 40. Thus, the impurities that flow into the low pressure pipe 8L and are mixed into the hydraulic oil are sequentially removed by the filtering action of the fluid filter 40.
[0059]
Here, when the vehicle travels, the hydraulic fluid that passes through the fluid filter 40 has a maximum flow rate when the vehicle travels forward in a two-wheel drive state. When the vehicle travels, the hydraulic fluid discharged from the piston pump 6 is discharged. Most of the applied hydraulic oil is sucked into the pump motor 10, and the hydraulic oil flowing into the fluid filter 40 from the high-pressure pipe 8H via the electromagnetic switching valve 22 has a low flow rate. Thereby, even if this fluid filter 40 is a small filter having a filter capacity corresponding to the low flow rate, pressure loss (pressure loss at normal temperature) is unlikely to occur.
[0060]
As a result, the small fluid filter 40 can be inserted into the communication pipe 20, so that the problems of weight reduction of the vehicle body, fuel consumption, and a rise in the device can be solved. Moreover, since the small fluid filter 40 should just be connected in series with the electromagnetic switching valve 22, there is no layout restriction.
[0061]
In addition, since the fluid filter 40 is inserted on the low pressure pipe 8L side, that is, on the downstream side with respect to the electromagnetic switching valve 22, it is not necessary to have a structure that can withstand high pressure, and an inexpensive fluid filter can be obtained. . In addition, since the fluid filter 40 of the present embodiment is not disposed at a position where a large amount of hydraulic fluid circulates, even if the viscosity of the hydraulic fluid increases at low temperatures, The pressure loss due to the presence of the filter 40 is not generated, and the fuel efficiency and driving force performance of the four-wheel drive vehicle are not adversely affected.
[0062]
Therefore, a four-wheel drive vehicle with hydraulic oil contamination countermeasures (contamination countermeasures) while reducing the freedom of layout while reducing weight, improving fuel economy, and reducing costs, and also suppressing pressure loss at low temperatures. Can be provided.
[0063]
Next, what is shown in FIG. Similar to 2nd Embodiment is shown. In addition, the same code | symbol is attached | subjected to the same component as 1st Embodiment shown in FIGS. 1-4, and the description is abbreviate | omitted.
[0064]
In this embodiment, instead of the fluid filter 40 inserted in the communication pipe 20 of the first embodiment, the fluid filter 50 is connected to the communication pipe 14B provided with the check valve 15 on the low pressure pipe 8L side of the check valve 15. Is inserted.
[0065]
When the vehicle travels forward on the high friction coefficient road, when the suction flow rate of the pump motor 10 exceeds the discharge flow rate of the piston pump 6, the pressure on the low pressure pipe 8L side of the communication pipe 14B is higher than that on the high pressure pipe 8H side. Therefore, the check valve 15 is opened, and the insufficient hydraulic oil is replenished from the low pressure pipe 8L side to the high pressure pipe 8H side. At that time, the hydraulic oil passes through the fluid filter 50 of the present embodiment, and impurities mixed in the fluid filter 50 are sequentially removed by the filtering action of the fluid filter 50.
[0066]
At this time, since only a low flow amount of hydraulic fluid for replenishment passes through the fluid filter 50, pressure loss (pressure loss at normal temperature) hardly occurs even with the small filter 50 having a filter capacity corresponding to the low flow rate. As a result, the small fluid filter 50 can be inserted into the communication pipe 14B, so that the problems of weight reduction of the vehicle body, fuel consumption, and increase of the apparatus can be solved. In addition, since a small fluid filter 50 may be connected in series with the check valve 15, there is no layout restriction. Moreover, since the fluid filter 50 of the present embodiment is not disposed at a position where a large amount of hydraulic fluid circulates, even if the viscosity of the hydraulic fluid increases at a low temperature, the fluid filter 50 is provided in the hydraulic fluid passage. There is no pressure loss due to the presence of 50, and the performance of the four-wheel drive vehicle is not adversely affected.
[0067]
Therefore, as in the first embodiment, it is possible to provide a four-wheel drive vehicle in which hydraulic oil contamination countermeasures (contamination countermeasures) are taken without reducing the degree of freedom in layout while reducing weight and improving fuel efficiency.
[0068]
Next, what is shown in FIG. Similar to 3rd Embodiment is shown. In this embodiment, the same components as those in the first embodiment shown in FIGS. 1 to 4 are denoted by the same reference numerals, and the description thereof is omitted.
[0069]
In this embodiment, instead of the fluid filter 40 inserted in the communication pipe 20 of the first embodiment, a fluid filter 60 is provided on the communication pipe 14A provided with the relief valve 13 on the low pressure pipe 8L side from the relief valve 13. It is inserted.
[0070]
The vehicle starts on a low friction coefficient road such as a freezing road, a snowfall road, etc., and a difference in rotational speed is generated between the front wheel 5 and the rear wheel 19 due to slip of the front wheel 5, and the discharge flow rate of the piston pump 6 is discharged from the pump motor 10 When the flow rate is exceeded and the resistance of the pump motor 10 becomes a load and the hydraulic pressure of the high-pressure pipe 8H increases, the relief valve 13 is opened at a predetermined opening, so that the hydraulic oil on the high-pressure pipe 8H side becomes the relief valve 13, The maximum torque T by flowing into the low pressure pipe 8L side through the fluid filter 60 of the embodiment _MAX Is regulated. When the hydraulic oil passes through the fluid filter 60, impurities mixed in the fluid filter 60 are sequentially removed by the filtering action of the fluid filter 60.
[0071]
At this time, the fluid filter 60 has a maximum torque T _MAX Since only a low flow rate hydraulic oil for regulating the flow rate passes, even a small filter 60 having a filter capacity corresponding to the low flow rate is less likely to cause pressure loss (pressure loss at normal temperature).
[0072]
As a result, the small fluid filter 60 can be inserted into the communication pipe 14A, so that the problems of weight reduction of the vehicle body, fuel consumption, and increase of the apparatus can be solved. Further, since a small fluid filter 60 may be connected in series with the relief valve 13, there is no layout restriction.
[0073]
Further, since the fluid filter 60 is inserted on the low pressure pipe 8L side, that is, on the downstream side with respect to the relief valve 13, it is not necessary to have a structure that can withstand high pressure, and an inexpensive fluid filter can be obtained. Therefore, the same effect as that of the first embodiment can be obtained.
[0074]
Next, what is shown in FIG. Similar to A 4th embodiment is shown. In the present embodiment, instead of the fluid filter 40 inserted in the communication pipe 20 of the first embodiment, a fluid filter 70 is provided on the communication pipe 14C provided with the fixed orifice 16 on the low pressure pipe 8L side from the fixed orifice 16. It is inserted.
[0075]
This fluid filter 70 is also inserted downstream of the fixed orifice 16 for managing the amount of leakage from the high pressure pipe 8H to the low pressure pipe 8L in order to set the rising of the transmission torque, and the inside of the fluid filter 70 is operated from the fixed orifice 16. When the oil passes, the impurities mixed inside are sequentially removed by the filtering action of the fluid filter 70.
[0076]
For this reason, since only a low flow rate of hydraulic oil flowing from the fixed orifice 16 passes through the fluid filter 70, the pressure loss (pressure loss at normal temperature) is small even with a small filter 70 having a filter capacity corresponding to the low flow rate. Hard to occur. As a result, the small fluid filter 70 can be inserted into the communication pipe 14C, so that the problems of weight reduction of the vehicle body, fuel consumption, and increase of the apparatus can be solved. Further, since a small fluid filter 70 may be connected in series with the fixed orifice 16, there is no layout restriction.
[0077]
Furthermore, since the fluid filter 70 is inserted downstream of the fixed orifice 16 on the low pressure pipe 8L side, it is not necessary to have a structure that can withstand high pressure, and an inexpensive fluid filter can be obtained. Therefore, the same effect as that of the first embodiment can be obtained.
[0078]
Next, what is shown in FIG. Similar to 5th Embodiment is shown. In this embodiment, one end of a communication pipe (filter flow path) 82 with a fluid filter 80 interposed is connected to the high-pressure pipe 8H. The other end of the communication pipe 82 is connected to one end of four communication pipes (control valve flow paths) 84A, 84B, 84C, 84D arranged in parallel to each other, and these four communication pipes. The other ends of 84A, 84B, 84C, and 84D are connected to the low-pressure pipe 8L, respectively. The electromagnetic switching valve 22 is inserted in the communication pipe 84A, the fixed orifice 16 is inserted in the communication pipe 84B, the relief valve 13 is inserted in the communication pipe 84C, and the check valve 15 is inserted in the communication pipe 84D.
[0079]
According to the configuration of the present embodiment, when the input port 22b and the output port 22c of the electromagnetic switching valve 22 communicate with each other, the suction flow rate of the pump motor 10 exceeds the discharge flow rate of the piston pump 6, and the check valve 15 is opened. When the discharge flow rate of the piston pump 6 exceeds the discharge flow rate of the pump motor 10 and the relief valve 13 is opened at a predetermined opening, or leaks from the high pressure pipe 8H through the fixed orifice 16 to the low pressure pipe 8L. In any case when the hydraulic oil flows out, the hydraulic oil on the high-pressure pipe 8H side passes through the fluid filter 80 and flows into the low-pressure pipe 8L side, and impurities mixed in the hydraulic oil are mixed in the fluid filter 80. It is removed sequentially by filtration.
[0080]
Therefore, in this embodiment, since the opportunity for the hydraulic oil to pass through the fluid filter 80 increases, the filtration performance of the hydraulic oil can be improved. As in the other embodiments described above, only a low flow rate of hydraulic fluid passes through the fluid filter 80, so that the fluid filter 80 can be made small, and the layout can be freely achieved while reducing weight and improving fuel consumption. Degradation can be prevented.
[0081]
In each of the above embodiments, the configuration in which the fluid filter is connected in series to the electromagnetic switching valve 22, the relief valve 13, the check valve 15, or the fixed orifice 16 is shown, but the gist of the present invention is limited to this. However, even if a fluid filter is built in the valves, the same effect can be obtained.
[0082]
In addition, the controller 24 used in each embodiment performs the opening / closing operation of the electromagnetic switching valve 22 based on the detection signals from the front axle rotation speed sensor 26 and the rear axle rotation speed sensor 28, but is not limited thereto. Even if the controller 24 is configured to receive a detection signal from a pressure switch connected to the high-pressure pipe 8H, for example, the same operation and effect can be obtained even when the electromagnetic switching valve 22 is opened and closed.
[0083]
Further, in each of the above embodiments, the case where the rear wheel side differential device 17 is provided has been described. However, the present invention is not limited to this, and the rear wheel differential device 17 is omitted. The pump motors 10L and 10R may be individually provided on the left and right axles 18L and 18R of the 19L and 19R. In this case, when different loads are applied to the left and right wheels at the time of turning, each pump motor Since the discharge flow rate difference corresponding to the difference is naturally generated by 10L and 10R, the differential function equivalent to the differential device can be exhibited.
[0084]
In each of the above embodiments, the case where the forward / reverse switching electromagnetic direction switching valve 9 is built in the pump motor 10 has been described. However, the present invention is not limited to this, and is provided separately outside the pump motor 10. You may do it.
[0085]
Further, in the above-described embodiment, the embodiment based on the front wheel drive vehicle has been described. However, the present invention is not limited to this, and the piston pump 6 is arranged on the rear wheel side and the pump motor 10 when the rear wheel drive vehicle is used as the base. By arranging on the front wheel side, it is possible to obtain the same effect as the above embodiment.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a four-wheel drive vehicle showing a first embodiment of the present invention.
FIG. 2 is a characteristic diagram showing discharge flow rate characteristics of a fluid pressure pump and a fluid pressure pump motor according to the present invention.
FIG. 3 is a block diagram showing control means according to the present invention.
FIG. 4 is a characteristic diagram showing the relationship between front and rear axle rotation speed difference and transmission torque.
FIG. 5 shows the present invention. Similar to It is a schematic block diagram of the four-wheel drive vehicle which shows 2nd Embodiment.
FIG. 6 Similar to It is a schematic block diagram of the four-wheel drive vehicle which shows 3rd Embodiment.
FIG. 7 Similar to It is a schematic block diagram of the four-wheel drive vehicle which shows 4th Embodiment.
FIG. 8 shows the present invention. Similar to It is a schematic block diagram of the four-wheel drive vehicle which shows 5th Embodiment.
[Explanation of symbols]
1 Engine (main prime mover)
4 Front axle (drive axle)
6 Piston pump (fluid pressure supply means)
6b Piston pump suction port
6c Piston pump outlet
8H high pressure piping (high pressure flow path)
8L low pressure piping (low pressure flow path)
10 Pump motor (fluid pressure drive means)
10a Pump motor inlet
10b Pump motor outlet
13 Relief valve
14A, 14B, 14C Communication piping (communication flow path)
15 Check valve
16 Fixed orifice (orifice)
18 Rear axle (driven axle)
20 Communication piping (communication flow path)
22 Electromagnetic switching valve (open / close switching valve)
24 controller
40, 50, 60, 70, 80 Fluid filter
82 Communication piping (filter flow path)
84A, 84B, 84C, 84D Communication piping (control valve flow path)

Claims (1)

A driving axle driven by the main prime mover, a fluid pressure supplying means that rotates in conjunction with the driving axle and discharges the working fluid, a fluid pressure driving means that rotates in conjunction with the driven axle, and the fluid pressure supplying means A high-pressure channel that communicates the discharge port of the fluid pressure driving means with the suction port of the fluid pressure driving means, a low-pressure channel that communicates the discharge port of the fluid pressure driving means and the suction port of the fluid pressure supply means, and the high-pressure flow In a four-wheel drive vehicle comprising a control valve that is inserted in a communication channel connected between a road and the low-pressure channel and adjusts the flow of the working fluid between the high-pressure channel and the low-pressure channel, The control valve is constituted by an open / close switching valve between the high pressure flow path and the low pressure flow path that is in a communication state when in a two-wheel drive state and a non-communication state when in a four-wheel drive state. A fluid filter is connected to the communication channel on the low-pressure channel side. Four-wheel drive vehicle, characterized in that the.

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