JPH05126233A - Hydromechanical transmission - Google Patents

Abstract

PURPOSE:To obtain a hydromechanical transmission with dimension and weight not so large, however, with a large speed change range. CONSTITUTION:A speed change mechanism 70 for spreading a speed change range is connected to an output shaft 10 and also providing a transmission mechanism control means for switching the speed change mechanism 70 in a condition that clutches 20, 23, 26 are disconnected together. Since no load is applied to the transmission mechanism 70 at switching time normally meshed transmission mechanism and an equal speed meshed transmission mechanism or sliding transmission mechanism, small in size and light in weight, can be used, and the transmission range can be spread by not greatly increasing the dimension and weight of the device main unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical hydraulic transmission.

[0002]

2. Description of the Related Art A transmission has a hydro static transmission (HST) that transmits power by means of hydrostatic pressure, but in general it is more efficient to mechanically transmit power than by hydrostatic pressure. For this reason, a hydro mechanical transmission (HMT) has been developed in which a mechanical differential is added to the HST to reduce the apparent hydraulic horsepower and improve the efficiency. However, this HMT is unstable in the low-speed rotation range and the power transmission efficiency is poor, and it is difficult to control near zero rotation and reverse rotation is possible, but it is unstable and the power transmission efficiency is even worse. There is. Therefore, in order to make up for such a drawback of HMT, the hydro static mode is used in the low speed range.
(HS mode) transmits power, and in the middle and high speed range, hydro-mechanical mode (HM mode) transmits power in a dual mode transmission.
(DMT) is being developed.

An example of such a DMT is shown in FIG.
There is something like. This mechanical hydraulic transmission is connected to an HST4 connected to an input shaft 1 via gears 2 and 3, connected to the HST4 via gears 5 and 6 and an annular gear arm 7, and via gears 8 and 9. The planetary gear mechanism 11 that connects the output shaft 10 to the planetary gear mechanism 11, the power transmission shaft 12 that transmits power to the planetary gear mechanism 11, and the gear 16 that is fitted to the variable unit shaft 15 of the HST 4 and the input via the gear 17. A clutch arm 18 driven in the same rotation direction as the shaft 1, and the clutch arm 18 and the power transmission shaft 12
The clutch 20 for connecting the
A clutch shaft 22 driven in a reverse rotation direction to the input shaft 1 via a gear 21, a clutch 23 connecting the clutch shaft 22 and the power transmission shaft 12, and the gear 6 are the sun gears of the planetary gear mechanism 11. Clutch 26 connected to shaft 25
Is equipped with. The HST4 is a variable hydraulic unit 31.
And a fixed hydraulic unit 32, and a variable hydraulic unit 3
By controlling the angle of the swash plate 33 of No. 1 with the control handle 35 and changing the flow direction and flow rate of the fluid output from the variable hydraulic unit 31 to the fixed hydraulic unit 32, the rotation direction and rotation of the fixed hydraulic unit 32 are changed. It is designed to control speed. That is, by moving the control handle 35 from the neutral position to the maximum forward rotation stroke position 36, the rotational speed of the fixed hydraulic unit 32 in the normal rotation direction is increased, and the control handle 35 is moved from the neutral position to the maximum reverse rotation stroke position 3.
By moving it up to 7, the rotational speed of the fixed hydraulic unit 32 in the reverse direction is increased. The planetary gear mechanism 1
Reference numeral 1 denotes an annular gear 41 connected to the annular gear arm 7, a planet gear 42 meshing with the annular gear 41, and a planet carrier 43 fitted to the power transmission shaft 12 and rotatably supporting the planet gear 42. And the sun gear 4 meshed with the planet gear 42 and fitted on the sun gear shaft 25.
4 is equipped. The clutches 20, 23, 26 are controlled by the control handle 35 pressing the limit switches 51, 52 at the forward rotation maximum stroke position 36 and the reverse rotation maximum stroke position 37, respectively. That is, as shown in FIG. 3, with the forward / reverse selector switch 50 in the forward side 50a, the solenoid 20s is de-energized and the solenoid 26s is not activated until the control handle 35 pushes the limit switch 51 from the neutral position. In the excited state, the clutches 20 and 23 are in the “off” state, and the clutch 26 is in the “on” state. When the control handle 35 pushes the limit switch 51, the solenoid 20s is excited, the solenoid 26s is de-energized, the clutch 20 is in the "on" state, and the clutches 23, 26 are in the "off" state. Press the limit switch 51 again with the control handle 35,
The solenoid 26s is excited again, the solenoid 20s is de-energized, the clutch 20 is "disengaged", and the clutch 2
6 is in the "ON" state. On the other hand, forward / reverse selector switch 5
When 0 enters the reverse side 50b, the control handle 35
From the neutral state until the limit switch 52 is pressed, the solenoid 23s is de-energized, the solenoid 26s is energized, the clutches 20 and 23 are "off", and the clutch 26 is "on". When the control handle 35 pushes the limit switch 52, the solenoid 23s is excited, the solenoid 26s is de-energized, and the clutch 2
3 is in the “on” state, and the clutches 20 and 26 are in the “off” state. When the control handle 35 pushes the limit switch 52 again, the solenoid 26s is excited again, and the solenoid 2
3s is in the non-excitation state, the clutch 23 is in the "off" state, and the clutch 26 is in the "on" state.

This transmission operates as follows. That is, when the input shaft 1 is rotated at a rated speed by a prime mover (not shown), the control handle 35 is in the neutral position, and the forward / reverse selector switch 50 is on the forward side 50a, the clutches 20 and 23 are "disengaged". Since the clutch 26 is in the “on” state and the fixed hydraulic unit 32 does not rotate, the output shaft 10 does not rotate and the vehicle is in a stopped state. From this state, the control handle 35 is moved to the forward rotation maximum stroke position 36.
The fixed hydraulic unit 32 rotates in the positive direction when it starts moving toward the gears 5, 6, and the third clutch 2
6, the sun gear shaft 25 and the gears 8 and 9 are transmitted to the output shaft 10. Set the control handle 35 to the limit switch 51.
When is moved to a position where is pressed, the solenoid 20s is excited, the solenoid 26s is de-energized, the clutch 20 is in the "on" state, and the clutches 23, 26 are in the "off" state. In this HM mode, the engine output is mechanically transmitted to the planet carrier 43 of the planetary gear mechanism 11 via the clutch 20 and the power transmission shaft 12, and the HST 4
It is hydraulically transmitted to the annular gear 41 via. And
The rotation speed of the sun gear 44 is a combined speed of the rotation speed of the planet carrier 43 and the rotation speed of the annular gear 41. When the control handle 35 is moved from this state toward the neutral position, the capacity of the variable hydraulic unit 31 is decreased and the speed of the fixed hydraulic unit 32 is decreased, so that the annular gear 41 is moved.
Of the sun gear 44 increases, and the rotation speed of the output shaft 10 increases. When the control handle 35 returns to the neutral position, the speed of the fixed hydraulic unit 32 becomes zero, and almost all of the power of the prime mover is mechanically transmitted from the clutch 20 to the output shaft via the planetary gear mechanism 11 to maximize the efficiency. can get. Next, the control handle 35
Is moved from the neutral position to the reverse rotation maximum stroke position 37, the stroke of the variable hydraulic unit 31 increases in the reverse direction, the fixed hydraulic unit 32 rotates in the reverse direction, and the rotation speed of the output shaft 10 further increases. It goes. When the speed of the fixed hydraulic unit 32 becomes maximum in the opposite direction,
The vehicle reaches maximum speed.

When the vehicle is moved in the reverse direction, the forward / reverse changeover switch 50 is put in the reverse side 50b and the control handle 35 is moved from the neutral position toward the reverse rotation maximum stroke position 37. In this state, the clutches 20 and 23 are in the “off” state, the clutch 26 is in the “on” state, and the fixed hydraulic unit 32 rotates in the opposite direction, which is proportional to the rotational speed of the fixed hydraulic unit 32. The rotation speed of the output shaft is obtained. The control handle 35 has the reverse rotation maximum stroke position 37.
When the limit switch is reached, the solenoid 23s
Is energized and the solenoids 20s and 26s are de-energized, and the clutch 23 is switched to the "on" state, and the clutches 20 and 26 are switched to the "off" state. When the control handle 35 is moved toward the neutral position in this state, the stroke of the variable hydraulic unit 31 is reduced, the rotational speed of the fixed hydraulic unit 32 is reduced, the rotational speed of the output shaft 10 is increased, and the vehicle is moved backward. The speed of the direction increases. When the control handle 35 is further moved to move from the neutral position to the forward rotation maximum stroke position, the fixed hydraulic unit 32 is moved.
Rotates in the positive direction, and the rotation speed of the output shaft 10 further increases. When the speed of the fixed hydraulic unit 32 becomes maximum in the positive direction, it becomes maximum in the reverse direction of the output shaft 10, and the vehicle reaches the maximum reverse speed.

[0006]

By the way, in the above-mentioned conventional mechanical hydraulic transmission, the swash plate 33 of the variable hydraulic unit 31 is used.
Since gear shifting is performed only by changing the angle of, the gear shift range is small, and there is a problem that it is not suitable for a vehicle that requires high torque at low speed (that is, large traction force) and has a high maximum speed. In order to make it suitable for such a vehicle, there is a method of increasing the capacity of the HST section or a multi-mode transmission with a plurality of mechanical transmission systems. However, the latter requires a very large number of planetary gear mechanisms, clutches, gears, etc., and has a drawback that the switching device becomes complicated and the cost increases. Therefore, conventionally, as shown in FIG. 4, a stepped speed change mechanism 60 is provided on the output side of the DMT having the same small capacity as the DMT shown in FIG. 2, and the speed change mechanism 60 is switched during traveling to thereby change the DMT. I am trying to expand the gear shift range. The speed change mechanism 60 includes an output shaft 6
Large-diameter gear 6 meshing with small-diameter gear 62 fixed to 1
Wet multi-plate clutch 6 connecting 3 to the output shaft 10 of the DMT
4 and a wet multi-plate clutch 67 that connects a small diameter gear 66 meshing with a large diameter gear 65 fixed to the output shaft 61 to the output shaft 10 of the DMT. Wet multi-plate clutch 6
The reason for using 4,67 is to reduce the shock at the time of switching during traveling as much as possible. However, since the torque after the output shaft 10 of the DMT is large, a large-capacity wet multi-plate clutch is required. Therefore, the speed change mechanism 60 becomes large and the size and weight of the entire transmission become large. is there. Therefore, an object of the present invention is to provide a DMT which is not so large in size and weight and has a large shift range.

[0007]

In order to achieve the above object, the present invention connects the input shaft 1 and the output shaft 10 via the first clutches 20 and 23 and the planetary gear mechanism 11, and at the same time, And a fixed hydraulic unit 32 that is rotationally driven by the discharge flow of the variable hydraulic unit 31.
A control gear 6 that is driven by the fixed hydraulic unit 32 and that is connected to the annular gear 41 of the planetary gear mechanism 11, and a second that connects the control gear 6 and the output shaft 10.
A mechanical hydraulic transmission provided with a clutch 26,
A transmission mechanism 70 for expanding the transmission range is connected to the output shaft 10, and a transmission mechanism control means is provided for switching the transmission mechanism 70 with both the first clutch 20, 23 and the second clutch 26 disengaged. Is characterized by.

[0008]

In the above structure, the normal shift operation is performed by controlling the discharge flow rate of the variable hydraulic unit 31 with either the first clutch 20, 23 or the second clutch 26 engaged. When the speed is changed beyond the speed change range controlled by the variable hydraulic unit 31, with the first clutches 20 and 23 and the second clutch 26 both disengaged,
The transmission mechanism 70 is switched by the transmission mechanism control means, and then the first clutch 20, 23 or the second clutch 26 is engaged. As described above, since the transmission mechanism 70 is switched with both the first clutch 20 and 23 and the second clutch 26 disengaged, no load is applied to the transmission mechanism 70 at the time of switching. It is possible to use a smaller and lighter one, such as a constant speed meshing type transmission mechanism or a sliding type transmission mechanism, using a wet multi-plate clutch, and it is possible to reduce the size and weight of the entire device.

[0009]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a block diagram of an embodiment of the present invention.
In FIG. 1, description of the same components as those in FIG. 2 is omitted, and different portions will be described below. This DMT is provided with a two-stage constant mesh type transmission mechanism 70 on the output side of the DMT having the same small capacity as the DMT of FIG. 2, and by switching the transmission mechanism 70, the transmission range of the DMT is expanded.
The speed change mechanism 70 includes a large-diameter gear 73 that meshes with a small-diameter gear 72 fixed to the output shaft 71, and a small-diameter gear 75 that meshes with a large-diameter gear 74 fixed to the output shaft 71. The dog clutch 76 is switchably connected to the output shaft 10 of the DMT. The control device (not shown) for the dog clutch 76 is a control device for the clutches 20, 23, 26.
The clutch 20, 23, 2 receives a signal from (not shown).
The dog clutch 76 can be switched only when all 6 are in the "off" state. Figure 1
Shows a case where a high torque is required at a low speed (a large traction force is required), and the dog clutch 76 is put in the gear 75 side. To "OFF", clutch 26 to "ON", clutches 23 and 26 to "OFF" for forward high speed, clutch 20 to "ON", clutch 20 and 26 to "OFF" for reverse high speed, clutch 23 is set to "ON" and the control handle 35 is operated. Then, in the case of a joint requiring a higher speed during traveling, after disengaging the clutches 20, 23, 26, the dog clutch 76 is switched to the gear 73 side, and then the clutches 20, 23, 2
Insert any of the 6 items.

As described above, since the transmission mechanism 70 is switched while the clutches 20, 23, 26 are disengaged, the transmission mechanism 7
Since 0 is not loaded at the time of switching, the speed change mechanism 7
A small, lightweight constant mesh type transmission mechanism can be used as 0, and the entire device can be made small and lightweight. A wet multi-plate clutch is used as the clutch 20, 23, 26, and the clutch 6 of FIG.
Compared to 4,67, since it is located farther from the wheel to which the shock is transmitted, it is possible to smoothly turn on and off with a small shock.

In this embodiment, the constant mesh type transmission mechanism is used as the transmission mechanism 70, but a constant speed mesh type transmission mechanism can be used for smoother gear shifting. This constant speed meshing type transmission mechanism is also much smaller and lighter in weight and cheaper than the one using the conventional wet multi-plate clutch. In addition, a sliding type transmission mechanism can be used for easier switching. Further, although the two-speed transmission is used as the transmission mechanism 70, the same effect can be obtained even if the transmission mechanism has three or more transmissions. Further, in this embodiment, the clutch 20
Although the above description has been made of the DMT in which the forward and backward traveling HM modes are provided with the power transmission, the same applies to the DMT in which the forward transmission is performed only in the forward travel without the clutch 23. Further, although the DMT in which the clutch 20 or 23 is provided on the input side of the planetary gear mechanism 11 has been described, the same can be said for the DMT in which these are provided on the output side of the planetary gear mechanism 11.

[0012]

As is apparent from the above, in the mechanical hydraulic transmission of the present invention, the input shaft 1 and the output shaft 10 are connected via the first clutch 23 and the planetary gear mechanism 11, and the input shaft 1 is also connected. Variable hydraulic unit 3 driven by rotation
1 and a fixed hydraulic unit 32 that is rotationally driven by the discharge flow of the variable hydraulic unit 31. Further, a control gear that is driven by the fixed hydraulic unit 32 and meshes with a planetary gear 42 of the planetary gear mechanism 11. 6,4
1, a mechanical hydraulic transmission including a second clutch 26 that connects the control gears 6, 41 and the output shaft 10 to each other, and a transmission mechanism 7 for expanding the shift range to the output shaft 10.
Since the transmission mechanism control means for switching the transmission mechanism 70 with the first clutch 23 and the second clutch 26 both disengaged is provided, the constant engagement type transmission mechanism and the constant speed engagement type are connected. It is possible to expand the speed change range by using a small and lightweight speed change mechanism such as a speed change mechanism or a sliding type speed change mechanism, and it is possible to expand the speed change range by increasing the capacity of the hydraulic unit. The transmission efficiency is good, and it can be made small and lightweight.
Compared to a system with multiple mechanical transmission systems to expand the range of shifting, it is smaller and lighter, has fewer parts, and therefore has fewer worn parts for easier maintenance and inspection. It can be made smaller and lighter than the conventional gear shift mechanism that is used to expand the gear shift range.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a conventional mechanical hydraulic transmission.

FIG. 3 is a circuit diagram for performing forward / backward switching and mode switching of the conventional mechanical hydraulic transmission.

FIG. 4 is a schematic configuration diagram of a transmission in which a transmission range using a wet multi-plate clutch is added to the conventional mechanical hydraulic transmission to expand a transmission range.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Input shaft, 6 ... Control gear, 10 ... Output shaft, 11 ... Planetary gear mechanism, 20, 23, 26 ... Clutch, 31 ... Variable hydraulic unit, 32 ... Fixed hydraulic unit, 41 ... Annular gear,
70 ... Transmission mechanism.

Claims (1)

[Claims] 1. An input shaft (1) and an output shaft (10) are connected to a first clutch (20, 23) via a planetary gear mechanism (11) and are rotationally driven by the input shaft (1). A variable hydraulic unit (31) and a fixed hydraulic unit (32) that is rotationally driven by the discharge flow of the variable hydraulic unit (31) are provided, and further, the fixed hydraulic unit (32) drives the planetary gear mechanism. (11) Ring gear (41)
A mechanical hydraulic transmission comprising: a control gear (6) connected to the output gear (6); and a second clutch (26) connecting the control gear (6) and the output shaft (10). ) A transmission mechanism (70) that expands the gear range
And the first clutch (20, 23) and the second clutch (26) are both disengaged.
0) A mechanical-hydraulic transmission characterized in that it is provided with a speed change mechanism control means for switching.