KR20000048245A - The transmission for construction machine - Google Patents

Abstract

PURPOSE: A transmission for oil pressure operation is provided to simplify structure and to reduce a cost by using a small motor of variable capacity. CONSTITUTION: A transmission for oil pressure operation comprises: a gears power transmission device (5) to connect a variable-capacity motor(3) with high speed - low torque and a variable-capacity motor(4) with low speed - high torque with a common output shaft(2); a clutch device(7) to detach and connect the variable-capacity motor with low speed - high torque with the output shaft; a control pump(10) to be operated by the variable-capacity motor with high speed - low torque and to generate detachable oil pressure of the clutch device; where the gears power transmission device comprises a first input shaft(6), a driven shaft, a second input shaft(9) and the output shaft.

Description

Hydraulic Drive Transmission {THE TRANSMISSION FOR CONSTRUCTION MACHINE}

The present invention relates to a hydraulic drive transmission used in construction machinery.

Conventionally, this type of hydraulic drive transmission includes two variable displacement motors, that is, a high speed and low torque variable displacement hydraulic motor, and a low speed and high torque variable displacement hydraulic motor (zero light motor). One two-motor system is known. In such a system, a clutch is inserted between a low speed motor and a gearbox to improve efficiency, and the clutch is cut when the low speed motor is no longer needed. International Publication No. 97/29308 Is proposed.

Next, the hydraulic drive control system described in the above publication will be described with reference to FIG. In this conventional system, an output shaft 50 connected to a load is provided, a primary input shaft 52 connected to a low speed and high torque variable displacement motor (zero light motor) 51 at an end thereof, and the output shaft 50. The secondary input shaft 55 is fixed to the second gear 54 that is engaged with the first gear 53 is fixed to the secondary gear shaft 55, and the high speed, low torque variable displacement motor (at the end of the secondary input shaft 55) 56 is connected, and the primary input shaft 52 and the secondary input shaft 55 can be connected and disconnected by the clutch means 57. In addition, a third gear 58 is fixedly attached to the secondary input shaft 55, and the third gear 58 is fixed to the third shaft 60 connected to the control pump 59. Meshed with (61). The low speed and high torque variable displacement motor 51 and the high speed and low torque variable displacement motor 56 are driven by discharge oil from an unshown hydraulic pump driven by a prime mover.

The clutch means 57 is always engaged by the additional force of the spring 62, and the hydraulic pressure is supplied from the hydraulic source through the flow path 63 and the two-position switching valve 64 fitted to the flow path 63. When cut, it is to be cut. In the discharge passage 65 of the control pump 59, an orifice 66, a check valve 67 and a relief valve 68 arranged in parallel with the orifice 66 are provided. When the oil pressure of 65 exceeds the set hydraulic pressure, the pilot pressure is supplied to the two-position switching valve 64 so that the two-position switching valve 64 is opened.

In this manner, in the low speed mode, the driving force of both the high speed and low torque variable displacement motor 56 and the low speed and high torque variable displacement motor 51 in the state where the clutch means 57 is connected, It is transmitted to the output shaft 50 through the gear train consisting of the first gear 53 and the second gear 54 to drive the load. On the other hand, when the rotational speed of the high speed / low torque variable displacement motor 56 increases and reaches the set value, that is, in the high speed mode, the discharge hydraulic pressure of the control pump 59 reaches the set value so that the two-position switching valve 64 is opened and the clutch means 57 is cut in response to the additional force of the spring 62. As a result, power transmission from the low speed and high torque variable displacement motor 51 is cut off, and only the high speed and low torque variable displacement motor 56 is connected to the load, thereby preventing the occurrence of energy loss.

However, in the conventional system described in FIG. 4, the reduction ratio when the power is transmitted from the high speed and low torque variable displacement motor 56 to the output shaft 50 and the power is supplied from the low speed and high torque variable displacement motor 51. When the transmission ratio is transmitted to the output shaft 50 is the same, in order to ensure the traction force at low speed, there is a problem that the capacity of the low-speed, high-torque variable displacement motor 51 is increased, resulting in high cost. In addition, if the motor capacity is large in this way, the clutch passage torque is increased, and the clutch means 57 is also enlarged, which is also one factor of high cost.

In this conventional system, since the control pump 59 is attached to a shaft different from the motor driving shaft (third shaft 60), the gear pump driving gear pair (third gear 58, fourth gear) is provided. (61)), and there is also a problem that the structure is complicated by that.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and as a low speed motor, a small variable displacement motor can be used, so that the clutch transmission torque can be reduced, and the control pump driving gear pair is also unnecessary, thereby simplifying the structure. It is an object of the present invention to provide a transmission for a hydraulic drive that can achieve a reduction in the overall cost.

In order to achieve the above object, the hydraulic drive transmission according to the present invention includes a gear power transmission mechanism for connecting a high speed, low torque variable displacement motor and a low speed, high torque variable displacement motor to a common output shaft. And a clutch means for selectively connecting or disconnecting the low speed and high torque variable displacement motor and the output shaft, and a control pump driven by the high speed and low torque variable displacement motor to generate separation hydraulic pressure of the clutch means. A transmission for hydraulic drive, wherein the gear power transmission mechanism has a four-axis configuration of a primary input shaft, a driven shaft, a secondary input shaft, and an output shaft, and an interlocking gear of a first reduction gear ratio between the secondary input shaft and the output shaft. Engaging gears of a second reduction gear ratio that is configured to engage with and be electrically transmitted; and further, between the driven shaft and the output shaft, being larger than the first reduction gear ratio. And the low speed and high torque variable displacement motor are attached to the primary input shaft, and the high speed and low torque variable displacement motor and the control pump are attached to the secondary input shaft. And a means for connecting and disconnecting coaxially between the primary input shaft and the driven shaft.

According to the present invention, a gear power transmission mechanism for connecting a high speed, low torque variable displacement motor and a low speed, high torque variable displacement motor to a common output shaft, includes a primary input shaft, a driven shaft, a secondary input shaft, A four-axis configuration of the output shaft, coupled between the secondary input shaft and the output shaft to the meshing gear of the first reduction gear ratio, and coupled to the meshing gear of the second reduction gear ratio larger than the first reduction gear ratio between the driven shaft and the output shaft. The motor capacity of the low-speed, high-torque variable displacement motor can be reduced, and the motor size can be reduced. In addition, since the low speed and high torque variable displacement motor can be made small, the passage torque of the clutch means fitted to the primary input shaft to which the low speed and high torque variable displacement motor can be reduced can be made small. You can do it. In addition, since the control pump can be arranged at the shaft end of the secondary input shaft, the gear train for driving the control pump becomes unnecessary, and the structure can be simplified. As a result, cost reduction of the whole apparatus can be aimed at.

In the present invention, the clutch means includes a clutch plate for connecting the primary input shaft and the driven shaft which are rotatable to each other with a frictional force, and a frictional pressure force applied to the clutch plate by applying the frictional force to the clutch plate. And a spring member arranged in the middle of the clutch plate and the spring member to axially slide along the inner surface of the housing, and release the applied force by the spring member to separate the connection state of the clutch plate. An annular piston for freely rotating the coaxial shaft and rotationally fixing the primary input shaft together with the spring member is provided, and the clutch means includes a housing on the clutch plate side and the spring member side located on both sides of the annular piston. Lubrication oil enclosed in the housing within the space has a circulating communication path. Is recommended. In this way, the lubricating oil stirred by the drum in the clutch chamber can be circulated in the front and rear spaces of the annular piston through the communication path, and thus there is an effect of preventing overheating at high speeds.

Here, the communication path includes a through hole formed in the housing wall facing the outer peripheral portion of the clutch plate, and a through hole formed in the housing wall facing the outer peripheral portion of the spring member across the annular piston to the housing outer surface side. It is preferable to set it as the passage connected to the.

1 is a skeleton diagram showing a hydraulic drive transmission according to the first embodiment of the present invention.

2 is a cross-sectional view showing the detailed structure of the clutch, (a) is a cross-sectional view, (b) is a cross-sectional view taken along the line A-A of (a).

Fig. 3A is a graph showing the relationship between the vehicle speed and the motor speed, and Fig. 3B is a graph showing the relationship between the vehicle speed and the motor capacity.

Figure 4 is a skeleton diagram showing a conventional hydraulic drive transmission.

(Explanation of the sign)

One… Transmission 2... Output shaft

3,4... Motor 5... Gear power transmission mechanism

6... Primary input shaft 7.. Clutch means

8… Driven shaft 9.. Secondary input shaft

10... Control pump 11.. First gear

12... Second gear 13... 3rd gear

Next, a specific embodiment of the hydraulic drive transmission according to the present invention will be described with reference to the drawings.

1 is a skeleton view showing a hydraulic drive transmission according to a first embodiment of the present invention, Figure 2 is a cross-sectional view showing a detailed structure of the clutch, (a) is a cross-sectional view, (b) is a line AA of (a) It is a cross section.

In the hydraulic drive transmission 1 of this embodiment, as shown in Fig. 1, an output shaft 2 connected to a load is provided, and at the same time, a high-speed, low knock variable displacement motor 3 for driving the output shaft 2 is provided. And a low speed, high torque variable displacement motor (zero light motor) 4, and a gear power transmission mechanism 5 for connecting each of these motors 3 and 4 to the output shaft 2 so as to be connectable thereto. ) Is installed. The gear power transmission mechanism 5 includes a primary input shaft 6 connected to the low speed and high torque variable displacement motor 4, and a type in which the gear power transmission mechanism is disconnected from the primary input shaft 6 via a clutch means 7. The coaxial shaft 8, the secondary input shaft 9 to which the high speed and low torque variable displacement motor 3 is connected to one end, and the output shaft 2 have a four-axis configuration. The control pump 10 is connected to the other end is configured. In addition, the gear power transmission mechanism 5 includes a first gear 11 fixed to the output shaft 2 and a second fixed attachment to the secondary input shaft 9 so as to mesh with the first gear 11. A gear 12 and a third gear 13 fixedly attached to the driven shaft 8 so as to mesh with the second gear 12, thereby providing a gap between the secondary input shaft 9 and the output shaft 2; It is configured to couple and transfer the meshing gear of the first reduction gear ratio, and the coupling gear of the second reduction gear ratio larger than the first reduction gear ratio between the driven shaft (8) and the output shaft (2). have. Further, the high speed, low torque variable displacement motor 3 and the low speed, high torque variable displacement motor 4 are connected to a constant capacity hydraulic pub not shown, which is driven by a prime mover, via a hydraulic parallel circuit. Driven by.

The clutch means 7 is always engaged by the additional force of the spring member 14 constituted by the disc spring. The hydraulic pressure is supplied to the clutch means 7 from the hydraulic pressure source through the oil passage 15, and the clutch means 7 is cut at the time of the hydraulic pressure supply. In addition, a two-position switching valve 16 is fitted in the flow path 15 so that the supply or shutoff of hydraulic pressure to the clutch means 7 is controlled. On the other hand, the discharge passage 17 of the control pump 10 is provided with an orifice 18, a check valve 19 and a relief valve 20 arranged in parallel to the orifice 18, the orifice 18 When the hydraulic pressure of the discharge flow path 17 detected by the < RTI ID = 0.0 > (1) < / RTI > It is intended to be cut.

The hydraulic drive transmission 1 of this embodiment operates as follows. 3, the characteristics of the high speed and low torque variable displacement motor 3 and the low speed and high torque variable displacement motor 4 are shown.

First, in the low speed mode, the high speed, low torque variable displacement motor 3 and the low speed, high torque variable displacement motor 4 are connected in a state where the clutch means 7 is connected by an additional force of the spring member 14. The driving force of both) is transmitted to the output shaft 2 through the gear train consisting of the third gear 13, the second gear 12 and the first gear 11 to drive the load. On the other hand, when the rotational speed of the high speed and low torque variable displacement motor 3 increases and reaches the set value (vehicle speed = V ₂ ), that is, in the high speed mode, the discharge hydraulic pressure of the control pump 10 reaches the set value. As a result, the two-position switching valve 16 is opened, and the clutch means 7 is cut off in response to the additional force of the spring member 14. As a result, power transmission from the low speed and high torque variable displacement motor 4 is cut off, and only the high speed and low torque variable displacement motor 3 is connected to the load, thereby preventing the occurrence of energy loss. The vehicle speed V ₂ is set such that the tilt angle of the swash plate of the low speed and high torque variable displacement motor 4 is slightly larger than the vehicle speed at which zero is obtained.

In addition, when switching from the high speed mode to the low speed mode, when the rotational speed of the high speed / low torque variable displacement motor 3 decreases and reaches a set value corresponding to the vehicle speed V ₁ smaller than the vehicle speed V ₂ , The two-position switching valve 16 is opened to engage the clutch means 7 by the additional force of the spring member 14. In this way, both the high speed and low torque variable displacement motor 3 and the low speed and high torque variable displacement motor 4 are connected to the load while only the high speed and low torque variable displacement motor 3 is connected to the load. The connection state is changed.

According to the transmission structure of this embodiment, the gear structure which reaches the output shaft 2 from the motors 3 and 4 is the three gear structure of the 1st gear 11, the 2nd gear 12, and the 3rd gear 13. Since the high speed and low torque variable displacement motor 3 transmits power to the output shaft 2, the low speed and high torque variable displacement motor 4 outputs power to the output shaft 2. ), The second reduction gear ratio can be set to a large value. Therefore, the motor capacity of the low speed, high torque variable displacement motor 4 can be made smaller than in the conventional structure, and the miniaturization of the motor can simplify the device configuration and reduce the cost. In addition, since the low speed and high torque variable displacement motor 4 can be made compact, the torque of the clutch means 7 fitted to the driven shaft 8 can be reduced. It becomes possible to miniaturize. And since the control pump 10 can be arrange | positioned at the shaft end of the secondary input shaft 9, this control pump drive gear train becomes unnecessary, and this also contributes to the simplification of a structure.

2, the clutch means 7 according to the present embodiment includes a clutch plate for connecting the primary input shaft 6 and the driven shaft 8 rotatable with each other to the inside surrounded by the housing 21 ( 22, a spring member 14 which rotates together with the primary input shaft 6 to apply frictional pressure to the clutch plate 22, and is disposed between the clutch plate 22 and the spring member 14 in the middle. And an annular piston 23 sliding along the inner surface of the housing 21 in the axial direction, and releasing the added force by the spring member 14 to disconnect the clutch plate 22 from the connection state. The driven shaft 8 is free to rotate, and the primary input shaft 6 is configured to be fixed to rotate together with the spring member 14. In this case, in the conventional structure, since the clutch chamber is partitioned into the front space on the drum side and the rear space on the spring member side by the annular piston 23, when the drum 24 rotates at high speed during high-speed driving, the dip The oil in the brazing state was agitated in the narrow front space and became overheated. In order to cope with this, in the clutch chamber of the present embodiment, a through hole is formed in the housing wall facing the outer peripheral part of the clutch plate 22, and a through hole is also formed in the housing wall facing the outer peripheral part of the spring member 14. A communication path 25 is provided so that these through holes are connected across the annular piston 23 from the outer surface side of the housing 21.

By adopting the same clutch chamber configuration as in the present embodiment, the front space 26 and the rear space 27 of the annular piston 23 are successively passed through the communication path 25, so that in the front space 26 The oil stirred by the drum 24 can also be circulated to the rear subspace 27 of the annular piston 23 via the communication passage 25 as shown by arrows B, C, and E in FIG. 2. Therefore, the total amount of oil circulated is exceeded, so that overheating can be prevented even when the drum 24 rotates at high speed during high speed driving.

According to the present invention, the motor capacity of a low speed, high torque variable displacement motor can be reduced and miniaturized. In addition, since the low speed and high torque variable displacement motor can be made small, the passage torque of the clutch means fitted to the primary input shaft to which the low speed and high torque variable displacement motor can be reduced can be made small. You can do it. In addition, since the control pump can be disposed at the shaft end of the secondary input shaft, the gear train for driving the control pump becomes unnecessary, and the structure can be simplified. As a result, cost reduction of the whole apparatus can be aimed at. In addition, since the lubricating oil stirred by the drum in the clutch chamber can be circulated in the front and rear spaces of the annular piston through the communication path, there is an effect of preventing overheating at high speeds.

Claims (3)

A gear power transmission mechanism that connects the high speed, low torque variable displacement motor and the low speed, high torque variable displacement motor to a common output shaft, and selectively connects the low speed, high torque variable displacement motor and the output shaft, or A hydraulic drive transmission comprising a clutch means for separating and a control pump driven by the high speed and low torque variable displacement motor to generate a separation hydraulic pressure of the clutch means, The gear power transmission mechanism has a four-axis configuration of a primary input shaft, a driven shaft, a secondary input shaft, and an output shaft, and is configured to couple and transmit an engagement gear of a first reduction gear ratio between the secondary input shaft and the output shaft. In addition, the coupling between the driven shaft and the output shaft of the second reduction gear ratio meshing gear of the first reduction gear ratio, and configured to transmit, Attaching the low speed and high torque variable capacitance motor to the primary input shaft, and attaching the high speed and low torque variable capacitance motor and the control pump to the secondary input shaft, And said clutch means is a means that can be connected and disconnected coaxially between said primary input shaft and said driven shaft. 2. The clutch means according to claim 1, wherein the clutch means rotates together with the primary input shaft, the clutch plate connecting the primary input shaft and the driven shaft which are rotatable with each other, and the primary input shaft to provide frictional pressure to the clutch plate. A spring member to be added, disposed between the clutch plate and the spring member, slid in the axial direction along the inner surface of the housing, release of the additional force by the spring member to separate the connection state of the clutch plate, and Free rotation of the driven shaft, and an annular piston for rotating and fixing the primary input shaft with the spring member is configured, And the clutch means has a communication path through which lubricating oil enclosed in the housing space of the clutch plate side and the spring member side located on both sides of the annular piston can be circulated. The said communication path is a through hole formed in the housing wall which faces the outer peripheral part of the said clutch plate, and the through hole formed in the housing wall which faces the outer peripheral part of the said spring member crosses the said annular piston. And a passage connected to the housing outer surface side.