JP2001146951A - Dual type pump unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dual type pump unit capable of effectively suppressing the rise of temperature of a hydraulic oil refilled to a pair of oil pressure lines leading between a hydraulic motor and a hydraulic pump. SOLUTION: The dual type pump unit is equipped with a first and a second hydraulic pump connected with a first and a second hydraulic motor through each pair of oil pressure lines, the first and second, a center section to support the first and second hydraulic pumps, a housing storing the first and second hydraulic pumps and used as an oil tank, and an oil circulating mechanism to take out the oil from the tank and return the oil into it, wherein the oil circulating mechanism is arranged so as to cool the oil circulating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump unit for use in a vehicle in which first and second hydraulic motors are respectively connected to left and right drive wheels, wherein the first and second hydraulic motors are respectively connected to the first and second hydraulic motors. The present invention relates to a pump unit including first and second hydraulic motors that cooperate.

[0002]

2. Description of the Related Art In a vehicle in which first and second hydraulic motors are respectively connected to left and right drive wheels, the first
And a second hydraulic motor and first and second hydraulic pumps respectively connected by a pair of first hydraulic lines and a pair of second hydraulic lines, and the suction / discharge oil amount of the first and second hydraulic pumps is By operating to change the output of the first and second hydraulic motors and thereby control the rotational speed and rotational direction of the left and right drive wheels, for example, US Pat. No. 4,920,733 It is publicly known as described in the gazette.

[0003] However, in the vehicle described in the above-mentioned US Patent Publication, a first hydraulic pump cooperating with the first hydraulic motor and a second hydraulic pump cooperating with the second hydraulic motor are separated. Therefore, there have been various inconveniences such as a complicated hydraulic oil supply pipe from the oil tank storing the HST hydraulic oil to the pair of first hydraulic lines and the pair of second hydraulic lines. Further, the temperature of the HST hydraulic oil increases due to an external load. Such an increase in the temperature of the hydraulic oil causes inconveniences such as a decrease in volumetric efficiency (a decrease in axle rotation speed) and a decrease in durability. However, those described in this publication are considered in terms of suppressing the temperature of the HST hydraulic oil. Was not.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and is a dual pump used in a vehicle having first and second hydraulic motors connected to left and right driving wheels, respectively. An object of the present invention is to provide a dual pump unit which is a unit and can effectively suppress a rise in temperature of hydraulic oil supplied to a pair of hydraulic lines between a hydraulic motor and a hydraulic pump.

[0005]

According to the present invention, there is provided a dual pump unit for use in a vehicle in which first and second hydraulic motors are connected to left and right drive wheels, respectively. A first hydraulic pump and a second hydraulic pump connected to the first and second hydraulic motors by a pair of first hydraulic lines and a pair of second hydraulic lines, respectively;
A center section for supporting the first and second hydraulic pumps, a housing for accommodating the first and second hydraulic pumps and a housing used as an oil tank, and taking out oil from the oil tank; An oil circulation mechanism for returning the oil into the oil tank. The oil circulation mechanism provides a dual pump unit configured to cool the oil to be circulated.

Preferably, the oil circulation mechanism has a circulation line having at least a part thereof connected to the oil tank at one end and another end at the other end to the oil tank. At least a part of the pipe may be provided with a cooling fin.

In one aspect, the center section is a single member that supports the first and second hydraulic pumps in a parallel state, and the housing has the first and second hydraulic pumps on one side wall. An opening through which a pump can be inserted is formed, and the single center section and the housing are liquid-tightly closed at the opening of the housing by the single center section supporting the first and second hydraulic pumps. Thus, the single center section is integrally connected to form a single unit, and the single center section has one end communicating with the first hydraulic pump and the other end opening outward. A pair of first oil passages forming a connection port with the pair of first hydraulic lines, and a pair of second oil passages each having one end communicating with the second hydraulic pump and the other end being opened outward.
A pair of second oil passages forming a connection port with a line, and a charging suction port having one end communicating with the oil tank and serving as an inlet of the replenishing oil; An oil passage and a charge oil passage communicated via a check valve to each of the pair of second oil passages are formed, and the dual pump unit sucks up oil stored in the oil tank to charge the oil. A charge pump that discharges to the suction port, and a pressure regulation line that has one end connected to the charging oil passage through a relief valve and the other end forming a drain port for drain oil discharged from the relief valve. ,
A pipe may be provided for connecting the other end of the pressure regulating line to an oil tank, and the pipe may constitute the piping, and the charge pump may constitute a part of the oil circulation mechanism. .

In another aspect, the center section has first and second center sections for supporting the first and second hydraulic pumps, respectively, and the housing has one and the other side walls facing each other. First and second openings through which first and second hydraulic pumps can be inserted are formed, and the first and second center sections and the housing are connected to the first and second openings of the housing, respectively. The first and second center sections supporting the first and second hydraulic pumps are integrally connected to form a single unit so as to be liquid-tightly closed by the first and second center sections, and the first center section includes: One end communicates with the first hydraulic pump and the other end opens outwardly to form a pair of first oil passages forming a connection port with the pair of first hydraulic lines. The second center section includes a pair of second oils, one end of which communicates with the second hydraulic pump and the other end of which opens outward to form a connection port with the pair of second lines. A passage is formed, and one end of one of the first and second center sections is communicated with the oil tank to form a charging suction port serving as an inlet for the replenishing oil. A charging oil passage whose end is connected to each of the pair of first oil passages and the pair of second oil passages via a check valve is formed, and further, the dual pump unit includes the oil tank. A charge pump that sucks up the stored oil inside and discharges it to the charging suction port, and a drain pump that has one end connected to the charging oil passage through a relief valve and the other end discharged from the relief valve. Discharge port A pressure regulating line to be formed, and a pipe connecting the other end of the pressure regulating line to the oil tank, the pipe constituting the piping, and the charge pump forming part of the oil circulation mechanism. Can be configured.

Preferably, the apparatus further includes a reserve tank connected and supported by the single unit, and the reserve tank is configured to be able to circulate oil with the housing via an oil flow passage so as to form an oil tank with the housing. The charging suction port may be configured to communicate with the reserve tank via an oil supply path.

[0010] More preferably, the oil supply path and the oil communication path may be provided with cooling fins.

A cooling fan driven in synchronization with the first and second hydraulic pumps is provided in the vicinity of the single unit, and the reserve tank is provided between the single unit and the cooling fan. And the oil flow passage and the oil supply passage may be arranged so as to cross the gap.

[0012] Preferably, a wind guide plate for guiding cooling air from the cooling fan to the gap can be provided.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, a first preferred embodiment of a pump unit according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a hydraulic circuit diagram of a vehicle to which a pump unit 1 according to the present embodiment is applied, and FIG. 2 is a vertical sectional side view near the pump unit. 3 to FIG. 6, respectively.
FIG. 3 is a sectional view taken along line A, line BB, line CC, and line DD.

As shown in FIGS. 1 to 3, the pump unit 1 is used for a vehicle in which first and second hydraulic motors 120a and 120b are connected to left and right drive wheels 130a and 130b, respectively. A first hydraulic pump 10a and a second hydraulic pump 10b connected to the first and second hydraulic motors 120a and 120b by a first and second pair of hydraulic lines 140a and 140b, respectively.
And a housing 20 for accommodating the hydraulic pumps 10a and 10b.

The left and right drive wheels 130a, 130b
That the first and second hydraulic motors 120a and 120b are connected to each other means that each hydraulic motor is directly connected to each drive wheel, and that each hydraulic motor is connected via an appropriate power transmission mechanism. A mode in which the driving wheels are operatively connected is also included. 1, reference numeral 100 denotes a drive source, reference numeral 110 denotes a cooling fan, and reference numeral 160 denotes a filter.

As shown in FIGS. 2 and 3, the first
Each of the hydraulic pump 10a and the second hydraulic pump 10b is a variable displacement axial piston pump, and a first pump shaft 11a extending in the vertical direction and arranged in the housing 20 in parallel with each other in the vehicle width direction.
And a second pump shaft 11b, a first piston unit 12a and a second piston unit 12b that reciprocate with the rotation of the pump shaft, and a first cylinder block 13a and a second piston unit 13 that reciprocally support the piston unit. A two-cylinder block 13b, a first movable swash plate 14a and a second movable swash plate 14b for regulating the stroke length of the piston unit by the inclination angle and changing the suction / discharge oil amount of the piston unit, It has a first control shaft 15a and a second control shaft 15b for controlling the inclination angle of the plate.

In the present embodiment, the pump unit 1 is a vertical type in which the first and second pump shafts 11a and 11b are arranged to extend in the vertical direction.
However, the present invention is not limited to such a form, and a horizontal type (horizontal) in which the first and second pump shafts 11a and 11b are arranged to extend in the horizontal direction.
type).

As shown in FIG. 3, in the present embodiment, the first and second movable swash plates 14a, 14a
A cradle-type movable swash plate is used as b.

As shown in FIGS. 2 and 6, the first
Each of the control shaft 15a and the second control shaft 15b has an inner end protruding into the housing 20 and has an arm 16a,
It is connected to the first movable swash plate 14a and the second movable swash plate 14b via 16b. The outer ends of the first control shaft 15a and the second control shaft 15b extend rearward in the longitudinal direction of the vehicle.

It should be noted that the first control shaft 15a and the second control shaft 15b can be arranged along the vehicle width direction such that their outer ends are separated from each other. By arranging the first control shaft 15a and the second control shaft 15b in this manner, when the pump unit 1 is installed on a vehicle body having a push-pull type operation lever, the first control shaft 15a and the second The rotation axis of the control shaft 15b can be arranged parallel to the rotation fulcrum of the operation lever,
The structure of the link mechanism that connects the first control shaft 15a and the second control shaft 15b to the operation lever can be simplified. In such a case, more preferably, the first control shaft 15a and the second control shaft 15b can be located at substantially the same position in the vehicle longitudinal direction. With this configuration, the first control shaft 15a and the second control shaft 15b can be aligned with the operation lever in the vehicle longitudinal direction, and the structure of the link mechanism can be further simplified.

The pump unit 1 is further housed in the housing 20 and a common center section 30 for supporting the first and second hydraulic pumps 10a and 10b, and is provided with the first and second hydraulic pump shafts 11a and 11b. And a power transmission mechanism 40 for operatively connecting the power transmission mechanism 11b.

By providing the power transmission mechanism 40, the drive source and one of the first and second pump shafts 11a and 11b (in this embodiment, the first pump shaft 11
a), the pump shafts 11a, 11
b can be driven at the same time, whereby the transmission structure from the drive source to the pump unit 1 can be simplified. In the present embodiment, as the power transmission mechanism 40, a first gear 40a that is supported below the first pump shaft 11a so as to be relatively non-rotatable, and a power transmission mechanism 40 that is relatively non-rotatable below the second pump shaft 11b. Supported and the first
A gear transmission including a gear 40a and a second gear 40b that meshes is used (see FIGS. 3 and 4). In addition,
Instead of the gear transmission, an appropriate power transmission mechanism such as a chain or a belt can be used.

As shown in FIGS. 2 and 3, the housing 20 includes first and second hydraulic pumps 10a and 10b.
Housing 21 for housing the power transmission mechanism 4
And a second housing 22 for accommodating the same.

The first housing 21 is shown in FIGS.
As shown in FIG. 1, the first and second pump shafts 11a and 11b are disposed on one side in the longitudinal direction (the lower side in the present embodiment, hereinafter referred to as the lower side), and
A first side wall portion 21a formed with a bearing hole through which lower end portions of the pump shafts 11a and 11b can be inserted, and the first side wall portion 21
a having a peripheral wall portion 21b extending from the peripheral edge portion a to the other longitudinal side of the pump shafts 11a and 11b (in the present embodiment, an upper side, hereinafter referred to as an upper side), A first hydraulic pump 1 is provided on the upper end surface.
An opening into which the first hydraulic pump 0a and the second hydraulic pump 10b can be inserted is formed. The opening of the first housing 21 is closed by the center section 30 in a liquid-tight manner. That is, in the present embodiment, the center section 30 constitutes a part of the first housing 21.

The second housing 22 is disposed on the lower side, and has a bearing hole through which the lower end of the first pump shaft 11a can be inserted and a bearing portion for bearing and supporting the lower end of the second pump shaft 11b. The formed lower side wall 22a and the lower side wall 22
The power transmission mechanism 40 is formed in a box shape having a peripheral wall portion 22b extending upward from a peripheral edge of the power transmission mechanism 40, and an opening through which the power transmission mechanism 40 can be inserted is formed in an upper end surface.

The second housing 22 is connected to the first housing 21 such that the opening is closed in a liquid-tight manner by the first side wall 21a of the first housing 21. A space for accommodating the power transmission mechanism 40 is formed in cooperation with the first side wall 21a.

The housing 20 is configured as described above, and the first side wall 21a of the first housing 21 functions as a partition wall that divides the housing housing space into the hydraulic pump housing chamber and the power transmission mechanism housing chamber. ing. As described above, by separating the hydraulic pump housing chamber and the power transmission mechanism housing chamber by the partition wall, foreign matter such as iron powder generated in the power transmission mechanism 40 enters the hydraulic pump housing chamber, and the piston units 12a, 12b And cylinder block 13
a, 13b can be effectively prevented from being damaged. Further, the first and second pump shafts 11 penetrating the partition wall 21a
If a seal ring is installed on the outer peripheral surface of a, 11b,
Intrusion of the foreign matter can be reliably prevented.

Each shaft 1 in the housing 20
The insertion portions of 1a, 15a, and 15b are liquid-tightly sealed by appropriate sealing means, so that the housing 20 can be used as an oil tank.

Further, preferably, an oil flow hole (not shown) is formed in the first side wall portion 21a functioning as a partition wall so as to communicate the hydraulic pump housing chamber and the power transmission mechanism housing chamber. Can be provided with a filter for preventing the entry of foreign matter and the like. Thus, if the oil circulation hole is formed, the lubricating oil for the power transmission mechanism is not separately supplied,
The power transmission mechanism 40 can be lubricated with the oil stored in the housing, so that cost reduction and maintainability can be improved.

Further, in the present embodiment, as described above, since the first and second movable swash plates 14a and 14b are of a cradle type, as shown in FIG. 3, the hydraulic pump of the partition wall 21a is provided. If a concave arc surface 24 corresponding to the convex arc surface 19 of the movable swash plate 14a, 14b on the side (back side) away from the piston units 12a, 12b is formed on the surface facing the 10a, 10b, The movable swash plates 14a, 14b are formed by the concave arc surface 24.
Of the movable swash plate 14a, 14b can be stably set.

In the present embodiment, the first side wall portion 21a of the first housing 21 is used as a partition wall. However, various forms can be applied instead of the first side wall portion 21a as long as the above-described action is achieved. For example, the housing may be configured as a simple single box, and a partition wall may be separately attached to a middle portion of the single box.

Next, the center section 30 will be described. FIG. 7 is a sectional view taken along line EE in FIG.
As shown in FIGS. 5 and 7, the center section 30 has a pair of first oil passages 31a having one end communicating with the first piston unit and the other end opening outward.
Are formed. The other end openings of the pair of first oil passages 31a form a pair of first suction / discharge ports 32a that serve as connection ports with the pair of first hydraulic lines 140a (see FIG. 1).

As shown in FIG. 5, the center section 30 has a pair of second oil passages 31b, one end of which communicates with the second piston unit and the other end of which opens outward. Is formed. The other end opening of the pair of second oil passages 31b is connected to the pair of second hydraulic lines 14.
0b, a pair of second suction / discharge ports 32 serving as connection ports
b (see FIG. 1).

As described above, the common center section 3
0, a pair of first suction / discharge ports 32a and a pair of second suction / discharge ports 32b serving as connection ports for the pair of first hydraulic lines 140a and the pair of second hydraulic lines 140b.
Of the hydraulic pumps 10a, 10
b and the pipe connection work between the hydraulic motors 120a and 120b can be facilitated. In the present embodiment, a pair of first suction / discharge ports 32 are respectively provided on mutually facing side surfaces of the common center section 30.
a and a pair of second suction / discharge ports 32b, but instead of the suction / discharge port 32b,
The a and 32b can also be formed on the same side surface of the center section 30, so that the pipe connection operation can be further facilitated.

As shown in FIGS. 2, 4 and 5, the center section 30 further has a charging suction port 34 which opens outward at one end and serves as an inlet for supply oil. The other end is connected to each of the pair of first oil passages 31a and the pair of second oil passages 31b by a check valve 6.
An oil passage 33 for charging is formed, which communicates via 1a, 61b, 61c, 61d.

In this embodiment, as shown in FIGS. 2 and 3, the upper end of the first pump shaft 11a is extended further upward from the center section 30, and the extended portion is charged. The pump 50 is supported.
A cartridge type filter 160 is detachably provided on the upper surface of the charge pump, and the filter 16 is connected to the suction port 55 of the charge pump 50.
Oil is inhaled through the zero. The filter 160 may be provided on the discharge side of the charge pump 50.

One end of a pressure regulating line 53 in which a relief valve 52 is interposed is connected to the charging oil passage 33, and the relief valve 52 allows the charging oil passage 3 to be connected.
3 can be set (see FIGS. 1 and 2). The other end of the pressure regulation line is opened outward to form a discharge port 54 for discharging drain oil from the relief valve 52.

In this embodiment, the pressure regulating line 53 is formed in the charge pump casing 59 mounted on the upper surface of the center section 30, but the present invention is not limited to this embodiment. . That is, the pressure regulation line 53 can be formed in the center section 30. Reference numeral 51 in FIGS. 2 and 4 denotes a discharge port of the charge pump. Reference numeral 56 denotes a suction port connected to the suction port 55 of the charge pump 50 via the filter 160.

As described above, the other end of the charging oil passage 33 is connected to the pair of first oil passages 31a and the pair of second oil passages 3a.
1b and check valves 61a, 61b, 61c, 61
d, and a common charging oil passage 33
Thus, the pressure oil is supplied to the low-pressure side of both the pair of first hydraulic lines 140a and the pair of second hydraulic lines 140b, and vice versa.

Further, between at least one of the pair of first oil passages 31a and the charging oil passage 33, and between at least one of the pair of second oil passages 31b and the charging oil passage 33. , Bypass line 62 with throttle valve
a and 62b are formed (see FIGS. 1 and 5).

The bypass lines 62a and 62b are used to stably maintain the neutral state of the hydraulic pumps 10a and 10b. That is, when the movable swash plates 14a, 14b of the hydraulic pumps 10a, 10b are slightly inclined from the neutral position, a pressure difference is generated between the pair of first hydraulic lines 140a and / or between the pair of second hydraulic lines 140b. Thereby, the hydraulic motors 130a and 130b rotate. Therefore, the movable swash plates 14a, 14b
If the neutral position is slightly deviated from the set position, the hydraulic motors 130a and 130b rotate against the user's will. On the other hand, as described above, when the bypass lines 62a and 62b are provided, the hydraulic lines 140a and 140b are connected via the bypass lines 62a and 62b.
Pressure oil leaks from the first hydraulic line 140a even when the movable swash plates 14a and 14b are to be in the neutral position and inclined due to a manufacturing error or the like.
And / or a pressure difference generated between the pair of second hydraulic lines 140b is effectively suppressed, and the hydraulic motors 120a,
0b can be effectively prevented from rotating.

The leakage of the pressure oil from the pair of hydraulic lines 140a and 140b by the bypass lines 62a and 62b is caused by the hydraulic pumps 10a and 10b and the hydraulic motor 120.
a, the bypass line is connected between the charging oil passage 33 and one of the pair of first oil passages 31a and one of the pair of second oil passages 31b. Is preferably provided only for

Further, preferably, as shown in FIG.
Each of the check valves 61a, 61b, 61c, and 61d is provided with an opening means 62 so as to forcibly communicate between the pair of first oil passages 31 and between the pair of second oil passages 31b in an emergency. be able to. Such opening means 6
2, the drive source 100 and the hydraulic pump 1
When it is necessary to forcibly move the vehicle (forcibly rotate the wheels) by manual power at the time of failure of 0a, 10b or the like, the vehicle can be easily moved. That is, the pair of first oil passages 31a and / or the pair of second oil passages 3
When the wheels connected to the hydraulic motors 120a and 120b are forcibly rotated in a state where the hydraulic motor 1b is closed, the hydraulic motor 1
Due to the rotation of 20a and 120b, a pressure difference is generated between the pair of first hydraulic lines 31a and between the pair of second hydraulic lines 31b, and it becomes difficult to move the vehicle (rotate the wheels). On the other hand, if the opening means is provided, all the check valves 61a, 61b, 61c, 61d are forcibly mechanically opened, and the space between the pair of first oil passages 31a and the pair of second oil Since the roads 31b can be communicated with each other, the forcible movement of the vehicle can be easily performed.

As shown in FIG. 5, by arranging all the opening means 63 on the same side of the center section 30, a link connected to the opening means for operating the opening means 63 is provided. The mechanism can be easily configured.

As described above, the pump unit 1 according to this embodiment includes the first and second hydraulic pumps 10a, 1a.
0b, the center section 30 and the housing 20, and these members are integrally connected to form a single unit 1a. Therefore, only by attaching the single unit 1a to the vehicle, both the first hydraulic pump 10a and the second hydraulic pump 10b can be installed in the vehicle, so that the assembling work efficiency of the vehicle can be improved.

Further, as shown in FIGS. 2 to 4, the pump unit 1 according to the present embodiment includes a reserve tank 150 connected and supported by the single unit 1a. In the present embodiment, the reserve tank 150
Mounting ribs 151 are provided on the left and right side surfaces of the
The reserve tank 150 is connected to and supported by the single unit 1a via the mounting member 200 connected to the unit 1.
As shown in FIGS. 2 and 6, the reserve tank 150 is communicated with the housing 20 via an appropriate oil supply path 170 such as a pipe so as to allow oil to flow therethrough, and functions as an oil tank together with the housing 20. It is supposed to.

Preferably, the upper surface of the reserve tank 150 can be positioned higher than the upper surface of the housing 20, whereby the inside of the housing 20 is completely filled with oil, thereby effectively preventing air from being mixed into the oil. it can. In addition,
With respect to the volume change due to the temperature change of the oil in the housing 20, the reserve tank 1 connected to the housing
50 is adjustable.

The oil tank is connected to the charging suction port 34. In the present embodiment, the oil pumped up by the charge pump 50 via the oil supply path 180 from the reserve tank 150 constituting a part of the oil tank is supplied to the charging suction port 34 via the pressure regulating line 53. (See FIGS. 1 and 2).

On the other hand, one end of a cooling pipe 210 is connected to a discharge port 54 for discharging drain oil of a relief valve 52 inserted in the pressure regulating line 53. The other end of the cooling pipe 210 communicates with a reserve tank 150 that forms a part of an oil tank. As shown in FIG. 2, the cooling pipe 210 has at least a part thereof.
The oil, which is separated from the single unit 1a and the reserve tank 150 and extends into the outside air, can flow through the cooling pipe 210 to be air-cooled. Preferably, cooling fins can be attached to the outer peripheral surface of the cooling pipe 210, whereby the cooling efficiency can be improved by increasing the heat radiation area. The cooling pipe 210 is
It can be connected to the reserve tank 150 or the single unit 1a by an appropriate steadying means.

As described above, in the present embodiment, the suction port 55 of the charge pump 50 is
A part of the oil that is sucked into the discharge pipe 51 and discharged from the discharge port 51 of the charge pump 50 is
Through the oil tank. That is, a circulation line having one end communicating with the oil tank and the other end communicating with the oil tank again is formed by the oil supply path 180, a part of the pressure regulating line 53, and the cooling pipe 210. The pump 50 is configured to suck up the oil in the oil tank from one end of the circulation line and return the oil into the oil tank from the other end of the circulation line, thereby effectively suppressing the temperature rise of the stored oil, The operation efficiency of the hydraulic pump and the hydraulic motor can be prevented from deteriorating.

In this embodiment, the drain oil of the relief valve 52 inserted in the pressure regulating line 53 is returned to the oil tank via the cooling pipe 210.
This is because the oil cooling efficiency was considered. That is, the discharge oil from the charge pump 50 has a high pressure, and the drain oil from the relief valve 52 has a high temperature due to the pressure energy of the discharge oil. Therefore, if the drain oil is returned directly to the oil tank, the temperature of the oil stored in the oil tank may increase. On the other hand, in the present embodiment, since the drain oil of the relief valve 52, which is at a high temperature, is configured to be returned to the oil tank via the cooling pipe 210, the stored oil in the oil tank is Temperature rise can be suppressed efficiently.

Further, preferably, a cooling fan 110 operatively driven by a drive source 100 is provided in the vicinity of the single unit 1a and the reserve tank 150, and the reserve tank 150 is connected to the reserve tank 150 and the single unit 1a. Is connected to the single unit 1a such that there is a gap 190 into which the cooling air from the cooling fan 110 is introduced, so that the oil supply path 180 and / or the oil flow path 170 cross the gap. Can be configured.

At this time, preferably, the oil supply path 180
And a baffle plate (shroud) on the left and right sides of the oil flow passage 170
, Whereby the cooling air from the cooling fan can be efficiently guided to the gap 190.
In the present embodiment, the mounting member 200 for mounting the reserve tank 150 to the single unit 1a has a casing shape (see FIG. 8), and the cooling air from the cooling fan 110 is directed by the side wall of the mounting member 200. It is configured to efficiently lead to the gap.

With this configuration, in addition to cooling the oil when flowing through the cooling pipe 210, the oil can be cooled when flowing through the oil supply path 180 and the oil flow path 170. The temperature rise in the oil tank can be suppressed more effectively.

More preferably, the oil supply path 18
Cooling fins can also be provided on the outer circumference of the oil flow passage 170 and the oil flow passage 170, thereby improving the cooling efficiency by increasing the heat radiation area. Further, cooling fins can be provided in the reserve tank 150 itself.

The reserve tank 150 is preferably made of a translucent resin so that the amount of stored oil inside can be visually checked. Further, the reserve tank 150 may be provided with an oiling cap 152 having an air bleeding mechanism on its upper surface.

In the present embodiment, a charge pump 50 is provided to forcibly supply pressure oil to the charge suction port 34, and the charge pump 50 circulates oil through a circulation line. However, the present invention is not limited to such an embodiment.
For example, when the charge suction port 34 is directly connected to the reserve tank 150 via the oil supply path 180 without providing the charge pump, and the hydraulic pressure of the low pressure side line of the pair of hydraulic lines falls below a predetermined value. It is also possible to adopt a configuration in which the oil is naturally sucked and a pump for circulating the oil in the circulation line is additionally provided.

Furthermore, if cooling air from a cooling fan (not shown) for driving source or a radiator (not shown) is applied to the cooling pipe 210, the oil flowing through the cooling pipe 210 Can be more efficiently cooled.

Embodiment 2 Hereinafter, a second preferred embodiment of the pump unit according to the present invention will be described with reference to FIG. FIG. 9 is a vertical sectional side view of a pump unit 1 'according to the present embodiment. As shown in FIG.
The pump unit 1 'according to the present embodiment is a tandem pump unit in which a first hydraulic pump 10 and a second hydraulic pump 20 are connected in series. In the following description, the same members or corresponding members as those in the first embodiment are denoted by the same reference numerals or the same reference numerals, and the description thereof is omitted.

As shown in FIG. 9, the pump unit 1 'includes a first hydraulic pump 10a and a second hydraulic pump 1a.
0b, and a first center section 30a and a second center section 30b supporting the first hydraulic pump 10a and the second hydraulic pump 10b, respectively.

The common housing 20 'is provided with the pump shaft 1
A first hydraulic pump 10a and a second hydraulic pump 10b into which the first hydraulic pump 10a and the second hydraulic pump 10b can be inserted respectively on one side (lower side in the present embodiment) and the other side (upper side in the present embodiment) of the axial lines 1a and 11b. Opening 20a 'and second opening 2
0b 'is formed.

Further, a partition wall 20c 'is formed in the common housing 20' at a substantially central portion in the axial direction of the pump, and the partition wall 20c 'allows the first pump chamber receiving space and the second pump chamber receiving space to be formed. It is partitioned into space. The partition wall 20c 'includes a first pump shaft 11a and a second pump shaft 1a.
1b has a bearing portion for bearing-supporting the connecting portion. Specifically, a connecting member 16 is provided at the rear end (upper end) in the transmission direction of the first pump shaft 11a and the front end (lower end) in the transmission direction of the second pump shaft 11b so as to be relatively non-rotatably inserted.
A bearing hole 20d 'in which the connecting member 16 is formed in the partition wall.
Is supported so as to be relatively rotatable. The partition wall 2
A plurality of oil flow passages 20e 'that communicate the first hydraulic pump housing chamber and the second hydraulic pump housing chamber can be formed in Oc'. By forming such an oil flow passage 20e ', the entire housing can be used as an oil tank.

The first center section 30a supports the first hydraulic pump 10a on the upper surface side,
It is connected to the housing 20 'so as to close the first opening 20a' of the housing. First hydraulic pump 1
The first pump shaft 11a has a front end (lower end) in the transmission direction extending downward through the first center section 30a. Power is input from the lower extension and the cooling fan 110 can be driven.

On the other hand, the second center section 30b
Is connected to the housing 20 'so as to support the second hydraulic pump 10b on the lower surface side and close the second opening 20b' of the housing 20 '. Second
The second pump shaft 11b of the hydraulic pump 10b has a rear end (upper end) in the transmission direction extending upward through the second center section 30b, and the charge pump 50 is driven by the upward extension. Have been.

The first center section 30a includes:
As shown in FIGS. 1 and 9, one end is open on a surface (upper surface) facing the first piston unit so that the one end communicates with the suction / discharge port of the first piston unit 12a, and the other end is open outward. Pair of first oil passages 31 for the first hydraulic pump
a is formed. The other end openings of the pair of first oil passages 31a form a pair of first suction / discharge ports 32a serving as connection ports with the pair of first hydraulic lines 140a between the first hydraulic motor 120a. .

Similarly, the second center section 30
As shown in FIG. 1 and FIG. 9, one end opens to a surface (lower surface) facing the second piston unit so that one end thereof communicates with the suction / discharge port of the second piston unit 12 b and the other end thereof. A pair of first oil passages 31b for the second hydraulic pump, which are open outward, are formed. The pair of second oil passages 31
The other end opening of the second hydraulic motor 120b is connected to a pair of second hydraulic lines 140b.
The suction / discharge port 32b is formed.

Further, as in the first embodiment, the pump unit 1 'according to the present embodiment has one end opened to the outside of the unit to form the charging suction port 34 and the other. A common charging oil passage 33 whose end communicates with each of the pair of first oil passages and the pair of second oil passages is provided so as to be disposed in the pump unit.

As shown in FIG. 9, one end of the charging oil passage 33 is open to the upper surface of the second center section to form the charging suction port 34, and the other end is the check valve 61c. , 61d, and a first perforated portion 33a formed in the second center section so as to open to the second hydraulic pump accommodating chamber, and one end thereof is connected to the first oil passage 31b. A pipe portion connected to the other end of the perforated portion 33a and arranged so that the other end passes through the second hydraulic pump housing chamber, the partition wall 20c, and the first hydraulic pump housing chamber to reach the first center section 30a. 33b, the first end of which is connected to the other end of the pipe portion 33b and the other end of which is connected to the pair of first oil passages 31a via the check valves 61a, 61b.
Second perforated portion 33 formed in center section 30a
c. The pipe portion 33b is inserted into the flow hole 20e 'so that the bearing wall 20
c 'can be penetrated.

Further, one end of a pressure regulating line 53 in which a relief valve 52 is interposed is connected to the charging oil passage 33 in the same manner as in the first embodiment. It is configured so that the oil pressure of the charging oil passage 33 can be set (see FIGS. 1 and 9).
The other end of the pressure regulating line 53 is opened outward to form a discharge port 54 for discharging the drain oil from the relief valve 52.

The discharge port 54 is provided with the first embodiment.
Similarly to the above, the cooling pipe 210 is connected, and the drain oil discharged from the discharge port 54 is configured to be returned to the oil tank via the cooling pipe 210.

The same effect as in the first embodiment can be obtained in the pump unit 1 'according to the present embodiment thus configured.

Instead of the pipe portion 33b ', one end is connected to the other end of the first perforated portion 33a' and the other end is connected to one end of the second perforated portion 33c '. As described above, it is also possible to form a flow hole in the peripheral wall of the common housing 20.

[0073]

According to the dual pump unit of the present invention, there is provided a dual pump unit used for a vehicle having first and second hydraulic motors connected to left and right driving wheels, respectively. A first hydraulic pump and a second hydraulic pump connected to the first and second hydraulic motors by a pair of first hydraulic lines and a pair of second hydraulic lines, respectively, and a center supporting the first hydraulic pump and the second hydraulic pump; A housing that houses the first hydraulic pump and the second hydraulic pump and that is used as an oil tank;
An oil circulation mechanism for taking out the oil from the oil tank and returning the oil to the oil tank again. The oil circulation mechanism is configured to cool the oil to be circulated, so that the temperature of the oil stored in the oil tank rises. Therefore, it is possible to prevent the operating efficiency of the HST from deteriorating due to a rise in the temperature of the hydraulic oil.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a vehicle to which a first preferred embodiment of a pump unit according to the present invention is applied.

FIG. 2 is a vertical sectional side view of the pump unit according to the first embodiment.

FIG. 3 is a sectional view taken along line AA in FIG. 2;

FIG. 4 is a sectional view taken along line BB in FIG. 2;

FIG. 5 is a sectional view taken along line CC in FIG. 2;

FIG. 6 is a sectional view taken along line DD in FIG. 2;

FIG. 7 is a sectional view taken along line EE in FIG. 5;

FIG. 8 is a perspective view of a mounting member.

FIG. 9 is a vertical sectional side view of a second preferred embodiment of the pump unit according to the present invention.

[Explanation of symbols]

1, 1 'Pump unit 1a, 1a' Single unit 10a, 10b First hydraulic pump, second hydraulic pump 11a, 11b First pump shaft, second pump shaft 20, 20 'Housing 30 Center section 30a, 30b First Center section, second center section 31a, 32a A pair of first oil paths, a pair of second oil paths 32a, 32b A first suction / discharge port, a second suction / discharge port 33 Charge oil path 34 Charging suction port 50 Charge Pump 52 relief valve 53 pressure regulating line 54 discharge port 56 suction port 61a, 61b, check valve 61c, 61d 110 cooling fan 120a, 120b first hydraulic motor, second hydraulic motor 130a, 130b left and right drive wheels 140a, 140b first Hydraulic line, second hydraulic line 150 Reserve tank 170 Oil flow path 180 Oil supply path 190 Gap 200 Mounting member 210 Cooling pipe

Continued on the front page F term (reference) 3H089 AA71 BB21 CC08 CC12 DA03 DA06 DB03 DB33 DB86 GG02 JJ12 3J053 AA01 AB12 AB17 AB42 FB01 FB03 FB10 3J063 AA01 AB44 AC03 BA03 BA15 CA01 CB38 CD41 XH06 XH12 XH33 XH32 XH32 XH32 XH32 XH32 XH33 XH32 XH33 XH32 XH33 XH32 XH33 XH32 XH32 XH33 XH32 XH33 XH32 XH33 XH32 XH33

Claims (8)

[Claims] 1. A dual pump unit for use in a vehicle in which first and second hydraulic motors are respectively connected to left and right drive wheels, wherein the first and second hydraulic motors and a pair of first and second hydraulic motors are respectively provided. A first hydraulic pump and a second hydraulic pump connected by a hydraulic line and a pair of second hydraulic lines; a center section supporting the first hydraulic pump and the second hydraulic pump; a first hydraulic pump and a second hydraulic pressure A housing that accommodates a pump and is used as an oil tank; and an oil circulation mechanism that takes out oil from the oil tank and returns the oil back into the oil tank. The oil circulation mechanism can cool oil to be circulated. A dual pump unit characterized by being configured as described above. 2. The oil circulation mechanism has a circulation line having at least a part thereof connected at one end to the oil tank and another end at the other end to the oil tank. 2. The dual pump unit according to claim 1, wherein cooling fins are attached to at least a part of the pipe. 3. The center section is a single member that supports the first and second hydraulic pumps in parallel, and the first and second hydraulic pumps can be inserted into one side wall of the housing. The single center section and the housing are integrally formed such that the opening of the housing is liquid-tightly closed by the single center section supporting the first and second hydraulic pumps. One end of the single center section is connected to the first unit.
A pair of first oil passages communicating with the hydraulic pump and having the other end opening outward to form a connection port with the pair of first hydraulic lines, and one end communicating with the second hydraulic pump; A pair of second oil passages, the other ends of which are open outward to form a connection port with the pair of second lines, and a charge which is connected to the oil tank at one end and serves as an inlet for the replenishing oil. A charging oil passage which forms a suction port and whose other end communicates with each of the pair of first oil passages and the pair of second oil passages via a check valve; The unit includes a charge pump that sucks up oil stored in the oil tank and discharges the oil to the charging suction port. One end is connected to the charging oil passage via a relief valve, and the other end is connected to the relief valve. Form drain port for drain oil to be discharged A pressure regulating line, and a pipe connecting the other end of the pressure regulating line and an oil tank, wherein the pipe constitutes the piping, and the charge pump constitutes a part of the oil circulation mechanism. The dual pump unit according to claim 2, wherein: 4. The center section has first and second center sections supporting the first and second hydraulic pumps, respectively, and the housing has first and second side walls on one and the other side walls facing each other. 2 First hydraulic pump can be inserted
And the first and second center sections and the housing, wherein the first and second openings of the housing support the first and second hydraulic pumps, respectively. The two center sections are integrally connected to form a single unit so as to be liquid-tightly closed, and the first center section has one end communicating with the first hydraulic pump and the other. One end of the second center section is connected to the second hydraulic pump, and a pair of first oil passages is formed at the ends to open outward to form a connection port with the pair of first hydraulic lines. A pair of second oil passages communicating with each other and having the other end opening outward to form a connection port with the pair of second lines are formed, and further, any one of the first and second center sections is provided. To one end Are connected to the oil tank to form a charging suction port serving as an inlet for the replenishing oil, and the other ends are respectively connected to the pair of first oil passages and the pair of second oil passages via check valves. A communicating oil passage is formed, and the dual pump unit further includes a charge pump that sucks up oil stored in the oil tank and discharges the oil to the charging suction port. A pressure adjusting line connected to the charging oil passage and having the other end forming a drain port for drain oil discharged from the relief valve; and a pipe connecting the other end of the pressure adjusting line to an oil tank. The dual pump unit according to claim 2, wherein the pipe constitutes the pipe, and the charge pump constitutes a part of the oil circulation mechanism. 5. A reservoir tank connected to and supported by the single unit, wherein the reservoir tank is configured to allow oil to flow with the housing via an oil flow passage so as to form an oil tank together with the housing. 5. The dual pump unit according to claim 3, wherein the charging suction port is connected to the reserve tank via an oil supply path. 6. 6. The dual pump unit according to claim 5, wherein cooling fins are attached to the oil supply path and the oil communication path. 7. A cooling fan driven in synchronization with the first and second hydraulic pumps is provided in the vicinity of the single unit, and the reserve tank is provided between the single unit and the cooling fan. The oil flow passage and the oil supply passage are arranged so as to cross the gap so as to have a gap into which the cooling air is introduced. 7. The dual pump unit according to 5 or 6. 8. The dual pump unit according to claim 7, further comprising a baffle plate for guiding cooling air from the cooling fan to the gap.