JP2001193830A - Traveling control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle control device capable of automatically shifting the gear of a multi-stage transmission according to load torque and effectively suppressing a speed change of a vehicle at the time of gear shift of the multi- stage transmission. SOLUTION: This running control device for vehicle comprises a continuously variable transmission and a multi-stage transmission provided in series in a running power transmission route ranging from a drive source to a drive wheel and a gear change control mechanism having a signal detection part and a signal control part performing the gear change control of the continuously variable transmission and multi-stage transmission. The signal detection part further comprises a load torque detection means for detecting a load torque to a vehicle, and the control part is controlled, based on the results detected by the load torque detection means, so that, when the vehicle is under a high load torque, the multi-stage transmission is decelerated and the continuously variable transmission is accelerated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling control device for a vehicle in which a continuously variable transmission and a multi-stage transmission are connected in series.

[0002]

2. Description of the Related Art In a vehicle in which a continuously variable transmission and a multi-stage transmission are connected in series, automatically performing a shift operation of the multi-stage transmission in accordance with a change in load torque during traveling of the vehicle involves, for example, As described in JP-A-3-24366, it has been known for some time.

[0003] The traveling control device for a vehicle described in the publication discloses a complicated manual transmission operation of a multi-stage transmission in order to obtain a traveling drive torque corresponding to a load torque that changes depending on a traveling state. In order to prevent this, the shift operation of the multi-stage transmission is automatically performed according to the load torque that changes depending on the vehicle running state.

That is, the traveling control device disclosed in the publication detects the hydraulic circuit pressure of the continuously variable transmission, and when the detected value is equal to or greater than a set value, shifts the multi-stage transmission to a lower speed side. When the detected value is lower than the set value, a high traveling drive torque is obtained, and the multi-stage transmission is shifted to a high speed side so as to be able to travel at a high speed.

[0005] The above-mentioned conventional traveling control device eliminates the need for manual shifting operation of the multi-stage transmission by providing such a configuration, thereby improving the operability of the vehicle. When the transmission is shifted, a large speed difference is generated, which results in poor ride comfort and, in some cases, inconvenience such as engine stall.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems. In a traveling control device in which a continuously variable transmission and a multi-stage transmission are connected in series, the present invention relates to It is an object of the present invention to provide a vehicle control device capable of automatically changing a speed of a multi-stage transmission in response to the change of the speed of the vehicle during the shift of the multi-stage transmission.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a vehicle having a continuously variable transmission and a multi-stage transmission interposed in series in a power transmission path from a driving source to driving wheels. A travel control device that includes a signal detection unit and a control unit, and that includes a shift control mechanism that performs shift control of the continuously variable transmission and the multi-stage transmission, wherein the signal detection unit detects a load torque applied to a vehicle. When the vehicle is in a high load torque state, based on a detection result by the load torque detection means,
A traveling control device for a vehicle that controls the speed of the multi-stage transmission to be reduced and the speed of the continuously variable transmission to be increased.

Preferably, the control unit increases the speed of the multi-stage transmission and decelerates the continuously variable transmission when the vehicle is in a low load torque state based on a result of the detection by the load torque detecting means. You can make it.

The continuously variable transmission has a hydraulic pump and a hydraulic motor connected via a pair of hydraulic lines, and the load torque detecting means detects that the hydraulic pressure of the pair of hydraulic lines is equal to a high pressure side reference value. It is configured to detect whether the vehicle is in a high load torque state, a low load torque state, or an appropriate load torque state by detecting whether the vehicle is above or below the low pressure side reference value. The control unit arithmetically processes a memory unit in which a relationship between the hydraulic pressures of the pair of hydraulic lines and the load torque of the continuously variable transmission is stored, and control signals to the continuously variable transmission and the multi-stage transmission. An arithmetic processing unit, wherein the arithmetic processing unit is configured to output a control signal to the multi-stage transmission and the continuously variable transmission based on a detection signal from the load torque detection unit. That.

Preferably, the signal detector further includes a swash plate angle detecting means for detecting an angle of the swash plate in the continuously variable transmission, and a lever swing for detecting an angle of an operation lever for manually operating the swash plate. Angle detecting means, and the memory unit further stores information on a vehicle speed-swash plate angle relationship between the swash plate angle and the vehicle speed for each gear position of the multi-speed transmission,
The arithmetic processing unit detects a current vehicle speed based on a vehicle speed-swash plate angle relationship of a current engagement shift speed of the multi-stage transmission, using a swash plate angle input from the swash plate angle detection means. ,
Using the detected vehicle speed, it is determined whether or not a shift of the multi-stage transmission is possible based on a vehicle speed-swash plate angle relationship of a speed to be engaged next to the multi-stage transmission. can do.

Preferably, when the arithmetic processing unit determines that the shift of the multi-stage transmission is possible, the arithmetic processing unit further uses the detected vehicle speed to select a shift speed to be engaged next to the multi-stage transmission. Based on the vehicle speed-swash plate angle relationship described above, the swash plate can be controlled so that the vehicle speed does not change during shifting of the multi-stage transmission.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the traveling control device according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic diagram of a transmission path of a vehicle to which the travel control device according to the present embodiment is applied.

The traveling control device according to the present embodiment includes a continuously variable transmission 10 and a multi-stage transmission 3 that are serially interposed in a traveling power transmission path from a driving source 200 to a driving wheel 210.
0 (see FIG. 1), and a shift control mechanism that performs shift control on the continuously variable transmission 10 and the multi-stage transmission 60. Reference numeral 300 in FIG. 1 denotes an emergency clutch that forcibly connects a drive shaft 231 and an output shaft 310, which will be described later, and is used when an output of the continuously variable transmission is directly transmitted to the output shaft 310 in an emergency. Used for Reference numeral 320 denotes a front wheel power take-out shaft operatively connected to the output shaft 310.

First, the continuously variable transmission 10 will be described with reference to FIGS. FIG. 2 is a hydraulic circuit diagram of the continuously variable transmission 10 and the multi-stage transmission 60. As shown in FIGS. 1 and 2, in the present embodiment, a hydraulic pump 11 having a pump shaft 11 a operatively connected to a drive source 100 is used as the continuously variable transmission 10.
And an HST including a hydraulic motor 15 having a motor shaft 15a, and a pair of hydraulic lines 20 connecting the hydraulic pump 11 and the hydraulic motor 15 to form a closed circuit.

The hydraulic pump 11 and the hydraulic motor 15
Is a variable displacement type having at least one swash plate, and the rotation of the motor shaft 15a can be changed steplessly with respect to the rotation of the pump shaft 11a in accordance with the operation of the swash plate. I have. In the present embodiment, the hydraulic pump 11 is a swash plate 11b of a variable displacement type, and the hydraulic motor 15 is a fixed displacement type.

The HST 10 further includes a charging mechanism 30 for supplying pressure oil to the pair of hydraulic lines 20, a maximum operating pressure setting mechanism 40 for setting a maximum operating pressure Pmax in the pair of hydraulic lines, and a swash plate. And a swash plate operation mechanism 50 for performing the above operation.

The charge mechanism 30 includes a bypass line 31 communicating between the pair of hydraulic lines 20, a charge line 32 for supplying pressure oil from a charge pump 110 to the bypass line 31, and a charge line 3.
A check valve 33 interposed in the bypass line 31 for allowing the flow of the pressure oil from the pair 2 to the pair of hydraulic lines 31 and preventing the flow of the pressure oil from the pair of hydraulic lines 20 to the charge line 32. It has. Reference numeral 221 in FIG. 2 denotes a distribution valve that distributes the pressure oil from the charge pump 110.

The maximum operating pressure setting mechanism 40 has one end connected to each of the pair of hydraulic lines 20 and the other end connected to the check valve 33 in the bypass line 31.
A setting line 41 connected between the
And a relief valve 42 interposed between the pair of hydraulic lines 20. When the hydraulic pressure of the pair of hydraulic lines 20 exceeds a predetermined value, pressure oil is discharged from the pair of hydraulic lines 20 via the relief valve 42. I have.

The swash plate operating mechanism 50 includes the swash plate 11b.
A control shaft (not shown) connected to the control shaft, a piston device 51 connected to the control shaft via a suitable link mechanism, and a swash plate operation line 52 for controlling supply of pressure oil to the piston device. It has.

The piston device 51 includes a cylinder 51a.
And a piston 51b which divides the inside of the cylinder 51a into a positive rotation chamber 51a 'and a negative rotation chamber 51a "and is slidable in the cylinder.

The swash plate operation line 52 includes a first pressure oil line 52a to which pressure oil from the charge pump 220 is supplied.
A servo valve 52b connected to the rear end of the first pressure oil line 52a; a positive rotation line 52c communicating the rear side of the servo valve 52b with the positive rotation chamber 51a 'and the negative rotation chamber 51a ", respectively. And a negative rotation line 52d, and a drain line 52e disposed in front of the servo valve 52b.

The servo valve 52b is connected to the first pressure oil line 52a in response to a signal from a control unit described later.
And a forward rotation line 52c and a drain line 52
e, a negative rotation position that communicates with the negative rotation line 52d, a negative rotation position that communicates with the drain line 52e and the positive rotation line 52c, and that communicates with the first pressure oil line 52a and the negative rotation line 52d, A neutral position for closing the positive rotation line 52c and the negative rotation line 52d can be set.

The swash plate operating mechanism 50 has the above-described structure, and thus performs the following operation.
That is, when the servo valve 52b is positioned at the forward rotation position, pressure oil is supplied to the forward rotation chamber 51a 'via the forward rotation line 52c, and from the negative rotation chamber 51a "via the negative rotation line 52d. Accordingly, the piston 51b moves to the right in Fig. 2, whereby the control shaft rotates in one direction and the swash plate 11b rotates in the forward direction. The forward direction is a direction in which the vehicle moves forward.

Conversely, when the servo valve 52b is positioned at the negative rotation position, the positive rotation chamber 5 is connected via the positive rotation line 52c.
1a 'discharges pressure oil, and the negative rotation line 52d
Thus, the pressure oil is supplied to the negative rotation chamber 51a ″ through the shaft. Accordingly, the piston 51b moves to the left in FIG. 2, whereby the control shaft rotates in the other direction, and the swash plate 11b becomes negative. Similarly, the negative direction is a direction in which the vehicle is moved backward.

Further, when the servo valve 52b is located at the neutral position, the positive rotation chamber 51a 'and the negative rotation chamber 51a "are sealed. Therefore, the piston 51b is fixed at that position, and the swash plate 11b is closed. 2 is a relief valve for setting the oil pressure of the first pressure oil line 52a.

Next, the multi-stage transmission 60 will be described. As shown in FIGS. 1 and 2, the multi-stage transmission 60 includes a plurality of power shift devices 70 (in this embodiment, three of 70 a to 70 c) that shift between the drive shaft 231 and the driven shaft 232. ) And a shift operation mechanism 80 for activating one of the plurality of power shift devices.

In the present embodiment, the drive shaft 23
As 1, an intermediate shaft arranged coaxially with the motor shaft 15 a and connected to the motor shaft 15 a so as to be relatively non-rotatable about the axis is used. Further, as the driven shaft 232, a cylindrical shaft disposed coaxially with the pump shaft 11a is used, and the driven shaft 232 is disposed coaxially with the pump shaft 11a and cannot rotate relative to the pump shaft around the axis. Shaft 233 connected to
Through the PTO shaft 23 so as to be relatively rotatable.
3, the size of the entire vehicle is reduced.

Each of the power shift devices 70a to 70c includes a clutch device 71a to 71c supported on one of the drive shaft 231 or the driven shaft 232, and fixed gears 72a to 72c supported on the other shaft so as not to rotate relatively. Have.

The clutch devices 71a to 71c are respectively provided with pushing members 73a to 73c supported by the other shaft so as to be relatively non-rotatable and slidable in the axial direction. There are loosely fitted gears 74a to 74c which are supported so as not to slide and are meshed with the fixed gears 72a to 72c.

The pushing members 73a to 73c and the loose fitting gears 74a to 74c are provided with corresponding clutch plates (not shown), respectively. Further, the clutch devices 71a to 71c include the pushing members 73a to 73a.
An urging member (not shown) for urging the clutch plates 73c and the free-fit gears 74a to 74c in directions away from each other is provided.

On the other hand, as shown in FIG. 2, the shift operation mechanism 80 has a second pressure oil line 81 to which the pressure oil from the charge pump 110 is supplied, and one end connected to the second pressure oil line 81. The other end is connected to the clutch device 71a.
To the first speed line 82a,
The second speed line 82b, the third speed line 82c, the first speed shift valve 83a, the second speed shift valve 83b, and the third speed line 83b interposed between the first speed line to the third speed line 82a to 82c, respectively.
And a speed shift valve 83c.

The first to third speed shift valves 83a to 83c
Are respectively based on a signal from a control unit described later,
An engagement position and a disconnection position for communicating / disconnecting the first to third speed lines 82a to 82c are set.

The multi-speed transmission 40 is provided with such a configuration, and controls the first to third shift valves 83a to 83c to control the first to third speed lines 82a to 82c.
82c, so that the loose fitting gears 74a-74 of the one clutch device 71 to which the pressure oil has been supplied.
The gear ratio corresponding to the gear ratio of the fixed gears 72a to 72c corresponding to the free-fitting gear to the drive shaft 231 and the driven shaft 23
Between the two.

In FIG. 2, reference numeral 81a denotes a relief valve for setting the oil pressure of the second pressure oil line 81. Reference numeral 86a denotes a lubricating oil line branched from the second pressure oil line 81, and reference numeral 86b denotes a relief valve for setting the oil pressure of the lubricating oil line.

The transmission control mechanism 100 will be described below. FIG. 3 shows a block diagram of the speed change control mechanism 100. As shown in FIG. 3, the shift control mechanism 100
It has a signal detection unit 110 and a control unit 150.

The signal detecting section 110 includes a load torque detecting means 111 for detecting a load torque of the HST 10,
A swash plate angle detecting means 112 for detecting a swash plate angle of T10;
ST10 is provided with lever swing angle detecting means 113 for detecting the swing angle of the operation lever 19 for manually operating the swash plate, and rotation detecting means 114 for detecting the rotation speed of the driven shaft of the multi-stage transmission 60.

In the present embodiment, the swash plate angle detecting means 112 and the lever swing angle detecting means 113 respectively swing the swash plate support shaft and the operating lever 19 located on the swing center of the swash plate 11b. A potentiometer provided on the lever control shaft 19a to be moved is used (see FIG. 2).

The rotation detecting means 114 is provided for detecting whether or not the vehicle is actually running and whether or not the vehicle speed is changing rapidly. That is, the continuously variable transmission 1 arranged in series in the transmission path
By detecting the rotation speed of the driven shaft of the transmission arranged at the rear stage of the transmission path among the 0 and multi-stage transmissions 60, the presence or absence of running of the vehicle and the presence or absence of sudden change in vehicle speed are detected. .

In the present embodiment, as shown in FIG. 1, a multi-stage transmission 60
, The rotation detecting means 114 is configured to detect the rotation of the driven shaft 122 of the multi-speed transmission 60.

The load torque detecting means 111 is an HST
Using the proportional relationship between the operating pressure and the HST load torque,
It is configured to detect the HST load torque. FIG. 4 shows the relationship between the HST operating pressure and the HST load torque. As shown in FIG. 4, the HST load torque and the HST operating pressure (the hydraulic pressure of the pair of hydraulic lines 20) are in a proportional relationship.

The load torque detecting means 111 utilizes such a relationship, and detects a case where the HST operating pressure (P) is lower than the low pressure side reference value (Pa) as a low load torque state. The case where the pressure is higher than the high pressure side reference value (Pb) is detected as a high load torque state.

Specifically, the load torque detecting means 111
Is a low pressure side reference value (Pa) detection mechanism 1 as shown in FIG.
11a and a high-pressure side reference value (Pb) detecting mechanism 111b.

The low pressure side reference value detecting mechanism 111a includes a first cylinder 121a and an operating chamber 12 inside the first cylinder.
1a 'and a biasing chamber 121a ", and a first piston 122a slidably slidable in the first cylinder 121a, and a first piston 122a disposed in the biasing chamber 121a". A first urging member 123a that pushes the first urging member toward the working chamber 121a '; a first detecting line 124a having one end connected to the pair of hydraulic lines 20 and the other end communicating with the working chamber 121a'. And operates as follows.

That is, when the pressing force by the pressure oil from the pair of pressure oil lines 20 supplied through the first detection line 124a is larger than the urging force of the first urging member 123a,
That is, the hydraulic pressure of the pair of pressure oil lines 20 is equal to the low pressure side reference value.
When the pressure is higher than (Pa), the first piston 122a is pressed against the biasing chamber 122 against the biasing force of the first biasing member 123a.
a "side and the first detection line 124a
Is smaller than the urging force of the first urging member 123a, that is, the hydraulic pressure of the pair of hydraulic oil lines 20 is lower than the low-pressure side reference value. When the pressure is lower than (Pa), the first piston 122a is pushed toward the working chamber 121a 'by the urging force of the first urging member 123a.

Further, the low pressure side reference value detecting mechanism 111
a is separated from the first piston 122a when the first piston 122a is pushed toward the biasing chamber 121a ″, and the first piston 122a is
When pushed to the a 'side, the first piston 122
a switch means 125a arranged so as to contact
And a Pa detection signal can be output from the first switch means 125a.

That is, the low pressure side reference value detection mechanism 111a
When the oil pressure of the pair of pressure oil lines 20 becomes lower than the low pressure side reference value, the first piston 122a and the first switch means 1
25a is brought into contact with this,
The low pressure side reference value (Pa) can be detected.

On the other hand, the high-pressure side reference value (Pb) detecting mechanism 1
11b is a second cylinder 121b and the second cylinder 1
A second piston 122b slidably slidable in the second cylinder 121b while defining the inside of the second chamber 121b in a working chamber 121b 'and an urging chamber 121b "in a liquid-tight manner;
b ", and the second piston 122b is connected to the working chamber 12
A second biasing member 123b for pushing toward the side 1b ', and a second detection line 124b having one end connected to the pair of hydraulic lines 20 and the other end connected to the working chamber 121b'.
And operates as follows.

That is, when the pressing force by the pressure oil supplied from the pair of pressure oil lines 20 via the second detection line 124b is smaller than the urging force of the second urging member 123b, ie, the pair of pressure oils The oil pressure of the oil line 20 is the high-pressure side reference value
When the pressure is lower than (Pb), the second piston 122b is pushed toward the working chamber 121b 'and the pressing force by the pressure oil supplied from the pair of pressure oil lines 20 via the second detection line 124b. Is larger than the urging force of the second urging member 123b, that is, when the hydraulic pressure of the pair of pressure oil lines 20 is higher than the high pressure side reference value (Pb), the second piston 122b The urging chamber 121b is pushed toward the urging chamber 121b "against the urging force of the member 123b.

Further, the high-pressure side reference value detecting mechanism 111
b is separated from the second piston 122b when the second piston 122b is pushed toward the working chamber 121b ', and the second piston 122b is
When pushed to the b ″ side, the second piston 122
b switch means 125b arranged to abut on
And a Pb detection signal can be output from the second switch means 125b.

When the HST operating pressure (P) is (Pa) ≦
If (P) ≦ (Pb), the low-pressure-side reference value detection mechanism 11
Neither 1a nor the high-pressure side reference value detection mechanism 111b outputs a detection signal. Therefore, the control unit 150, which will be described later, determines when the detection signals are not output from the two detection mechanisms by the HS.
The T operating pressure (P) falls within the range of (Pa) ≦ (P) ≦ (Pb), and it is determined that the state is an appropriate load torque state.

The control unit 150 includes an arithmetic processing unit 151 having a CPU and a memory unit 1 having a ROM and a RAM.
52.

In the memory section 152, H shown in FIG.
Correlation between ST load torque and HST operating pressure (hereinafter, referred to as
A relationship between the vehicle speed and the HST swash plate angle (hereinafter, referred to as a "vehicle speed-swash plate angle relationship") for each shift engagement state of the multi-stage transmission shown in FIG.
Is stored.

Further, the memory section 152 stores data for setting switching conditions at the time of shifting in the multi-speed transmission 60. The switching conditions include the hydraulic pressure of the shift line connected to the currently engaged clutch device in the multi-speed transmission 60 and the hydraulic pressure of the next shift line to be engaged. And the shift time to the clutch device to be engaged with the clutch device. Specifically, the switching condition is stored as a relationship between the hydraulic pressure of the speed change line and time shown in FIG. 6 (hereinafter, referred to as “pressure-time relationship”). The "pressure-time relationship" is:
A plurality can be prepared according to the load torque of the HST. The above relationships may be stored as a look-up table, or may be stored as a function.

Next, the control flow of the control unit 150 will be described mainly with reference to FIGS. FIG.
8 is a control flow performed by the control unit.
9 and 10 show the flow of subroutine A and subroutine B in FIG. 8, respectively.

First, the control unit 150 controls the operation lever angle θ.
x is input (step-1), and it is determined whether or not the operation lever 19 is at the neutral (N) position (step-2). And
If it is determined that the operation lever is at the neutral position, the multi-speed transmission 60 is engaged with the reference
p-3). That is, the control unit 150 outputs a signal for positioning only the second speed shift valve 83b to the engagement position from the output port (see FIGS. 2 and 3).

As described above, by confirming the N position of the operation lever and then engaging the multi-speed transmission 60,
Prevents sudden start of the vehicle. In the present embodiment, a three-stage transmission is used as the multi-stage transmission, and the reference speed is set as the second speed so that both downshifting and upshifting from the reference speed can be performed. I have.

At this point, the control unit 150 inputs the current operation lever angle θx again (step-4). And θx
Is not "0", that is, when the operation lever is tilted in either the forward rotation direction (F direction) or the negative rotation direction (R direction) by the driver (see FIG. 2), (step-6) )
Move to.

On the other hand, when the operation lever angle θx is “0”, that is, when the operation lever is at the N position, the control unit 15
0 inputs the swash plate angle θ (step-50), and
Is determined at the N position (step-51). And
If the swash plate is not at the N position, drive the servo valve 52b to
(step-52), the swash plate angle θ is controlled to be “0”. In this way, the adjustment of the N position between the operation lever 19 and the swash plate 11b is performed by (step-50) to (step-52).

If it is determined in (step-5) that the operation lever is tilted, the control unit 150 recognizes the current engagement speed of the multi-speed transmission from the output port (step 5). step-6). The reason why the engagement gear position of the multi-stage transmission is recognized again in this step is as follows. That is,
At the time of starting the vehicle, the multi-stage transmission is engaged with the reference speed (the second speed in the present embodiment), but after the steps described later, the multi-stage transmission 60 is engaged.
This is because, due to the forced shift, the engagement shift speed of the multi-speed transmission may be other than the second speed.

Thereafter, the control unit 150 sets (step-7) and (s
In tep-8), it is detected whether or not the load torque of the HST 10 is within an appropriate range. That is, the control unit 150 controls the HST1 based on the signal from the load torque detecting unit 111.
0, the hydraulic pressure (P) of the pair of hydraulic lines 20 is equal to the high-pressure side reference value (P
b) It is determined whether it is higher than (step-7) and whether it is lower than the low pressure side reference value (Pa) (step-8).

Hereinafter, the hydraulic pressure (P) of the pair of hydraulic lines is (i)
Pa ≦ P ≦ Pb (appropriate load torque state), (ii) P> Pb
(High-load torque state) and (iii) the case of P <Pa (low-load torque state) will be described separately for each case.

(I) Pa <P <Pb (appropriate load torque state)
In case of proper load torque condition, (step-7) and (step-8)
Then, since each is determined to be "NO", the process proceeds to (step-9). Then, in (Step-9), the rotation speed of the driven shaft 232 of the multi-speed transmission 60 is detected, and in (Step-10), it is determined whether the rotation speed (n) of the driven shaft is “0” or not. Is done.

If it is determined that n = 0 in (step-10), the motor shaft 15a is not rotating because the swash plate 19b of the HST 10 is not inclined enough to start the vehicle. Therefore, input the swash plate angle θ (step-11),
A servo valve 52b is added to add a predetermined angle to the swash plate angle.
Is driven (step-12). In the present embodiment, “1 °” is set as the added predetermined angle. Then, the process returns to the above (step-4).

That is, (step-11) and (step-12) are steps for shifting the vehicle from the stopped state to the running state. At this stage, it is not determined whether the angle of the operation lever 19 matches the angle of the swash plate 11b.

On the other hand, if it is determined in step (step-10) that n ≠ 0, the process proceeds to (step-100). The control unit 150 determines (s
At tep-100), the current operation lever angle θx is input, and the operation lever displacement angle △ θ is calculated (step-101). Note that the displacement angle △ θ of the operation lever is the immediately preceding operation lever angle θ
It is obtained by storing x 'in a RAM and calculating the difference (θx-θx') between θx and θx '.

In the case of △ θx ≠ 0, there is no operation of the operation lever by the driver, so the flow returns to (step-4) without controlling the swash plate, and thereafter, the same flow is repeated. .

When △ θx = 0, the driver
Since the operation lever is being operated, it is necessary to swing the swash plate according to the operation angle of the operation lever.
Therefore, the control unit 150 inputs the current swash plate angle θ
(Step-103), the servo valve 52b is driven so that the swash plate angle becomes θx + △ θ (step-104). In this way,
The HS is adjusted by an amount corresponding to the operation angle of the operation lever by the driver.
The swash plate 11b of T is swung. Hereafter, return to (step-4)
The same flow is repeated.

(Ii) In the case of P> Pb (high-load torque state) When it is determined that the high-load torque state is reached, (step-7)
Move on to (step-70). Then, at (step-70), it is detected whether or not the multi-stage transmission 60 is in a state where downshifting is possible, that is, whether or not the multi-stage transmission 60 is engaged with the lowest speed. As described above, detecting whether or not the multi-stage transmission is engaged at the lowest speed is necessary in the high load torque state because a larger traveling drive torque is required. This is because the gear is shifted down to the low speed side from the combined gear, but if the multi-speed transmission is already engaged with the lowest gear, the gear cannot be downshifted below that. In the present embodiment, the first speed is the lowest speed.

Therefore, when the multi-speed transmission 60 is engaged with the first speed, the flow returns to (step-4) as it is.

On the other hand, when the multi-speed transmission 60 is not engaged with the first speed, the process proceeds to a subroutine A for forcibly downshifting the multi-speed transmission 60.

As shown in FIG. 9, in subroutine A,
First, the current engagement speed of the multi-speed transmission 60 is detected.
(step-A1). Note that, in the present embodiment, the multi-stage transmission 60 has three speeds, and the (step-70)
It is known that the multi-speed transmission 60 is not engaged with the first speed, so it is only necessary to detect whether the output port is at the second speed or not. Which of the gears is engaged can be detected. Therefore, when a multi-speed transmission device having four or more gear stages is used, an appropriate judgment step is provided.

If it is determined in (step-A1) that the vehicle is engaged with the second speed, the gear is shifted down from the second speed to the first speed after (step-A100). Move to the flow.

Here, first, at (step-A100), the current swash plate angle θ is input. Then, based on the input value,
It is determined whether a downshift is possible without changing the vehicle speed (step-A101).

The determination in (step-A101) is based on the “vehicle speed-swash plate angle relationship” (see FIG. 5) stored in the memory unit 152 for each shift of the multi-speed transmission 60 and the current swash plate. This is performed using the angle θ.

That is, from the "vehicle speed-swash plate angle relationship", the fastest vehicle speed V1max at the time of engaging the first speed is obtained. Then, at the time of engaging the second speed, the swash plate angle θα that outputs the vehicle speed corresponding to the highest vehicle speed V1max at the time of engaging the first speed is calculated. That is, when the swash plate angle θ exceeds θα during the engagement of the second speed, if the multi-speed transmission is shifted down from the second speed to the first speed, the vehicle speed changes. .

As described above, in (step-A101), it is determined whether or not the swash plate angle θ exceeds θα obtained from the “vehicle speed-swash plate angle relationship”, whereby the vehicle speed is not changed. , It is determined whether it is possible to downshift from the second gear to the first gear.

If the current swash plate angle θ exceeds θα, the routine returns from subroutine A to (step-4) in FIG. 7 without downshifting the multi-stage transmission.

On the other hand, if the current swash plate angle θ is equal to or smaller than θα, the control unit 150 responds to the current HST load torque of the “pressure-time relationship” stored in the memory unit 152. Based on the "pressure-time relationship", a condition for switching from the second speed to the first speed is calculated (step-A102).

More specifically, as shown in FIG.
To reduce the hydraulic pressure of the second speed line 82b from Pmax to P2. P2 is set within a pressure range in which a torque equal to the torque generated at the time of Pmax can be generated. That is, P2 is set on condition that an engagement torque equal to the engagement torque generated when the hydraulic pressure of the second speed line 82b is Pmax is generated. Thus, the second speed line 82
The reason for reducing the oil pressure of b to P2 is to minimize the time lag in the switching operation to the first speed power shift device. On the other hand, regarding the first speed line 82a,
The hydraulic pressure is increased to such an extent that the speed shift power shift device does not engage. This is to minimize the time lag in the switching operation to the first-speed power shift device. Thereafter, this state is maintained until time t2.

At time t2, the hydraulic pressure of the second speed line 82b is reduced from P2, and the hydraulic pressure of the first speed line 82a is increased to P1 to disengage the second speed power shift device. In addition, the first-speed power shift device is engaged. At this time, on the shaft 72, the engagement torque obtained when the oil pressure of the second speed line 82b is P2 and the engagement torque obtained when the oil pressure of the first speed line 82a is P1 match. If the values of P2 and P1 are set, a change in output torque during shifting of the multi-stage transmission is suppressed, and smooth shifting can be performed. In addition, such P2 and P1 values can be set according to the gear ratio at each shift speed of the multi-speed transmission. Then, after time t2, the hydraulic pressure of the first speed line 82a is gradually increased to Pmax.
To fully engage the first-speed power shift device.

As described above, at the time of shifting of the multi-speed transmission, the hydraulic pressure of the hydraulic line connected to the currently engaged shift clutch is reduced within a range where the engagement torque generated at that time can be generated. The hydraulic pressure coupled to the shift clutch to be engaged next so that the engagement torque and the engagement torque at the time of shifting by the shift clutch to be engaged next match on the basis of the shift output shaft. By configuring so as to increase the hydraulic pressure of the line, it is possible to smoothly shift the multi-stage transmission. The control unit 150 controls the first-speed shift valve 83a based on the aforementioned switching conditions.
And drive control of the second speed shift valve 83b (step-A10
3).

Next, the controller 150 calculates a target angle θ 'of the swash plate 11b (step-A104). That is, the angle to which the swash plate 11b is forcibly swung is calculated. The calculation of the target angle θ ′ is performed as follows.

That is, first, of the swash plate angle θ input in (step-A100) and the “vehicle speed-swash plate angle relationship” stored in the memory 152, the second speed The current vehicle speed V is calculated based on the state data (see FIG. 5). Then, the vehicle speed V and the "vehicle speed-swash plate angle relationship"
Out of the first gear based on the data of the first gear engagement state.
The swash plate angle θ ′ at which the vehicle speed V can be obtained at the time of gear engagement is calculated.

Then, the control unit 150 controls the servo valve 52 so that the swash plate 11b swings toward the target angle θ '.
b is driven (step-A105).

At this time (arbitrary time from time t1 to time t2 in FIG. 6), the control unit 150 determines whether the swash plate angle θ matches θ ′ before the driven shaft 2
The rotation speed (n) of the driven shaft 232 is input (step-A106), and it is determined whether or not the rotation speed (n) of the driven shaft 232 is abnormally varied (st
ep-A107).

This is because during the shifting of the multi-stage transmission 60 (between the time t1 and the time t2 in FIG. 6), the power is not transmitted normally due to some cause.
In the case where the vehicle slips down on a slope or the like, the power shift device for the second speed stage 70b is disconnected before the power angle shift device for the first speed stage 70b is cut off before the swash plate angle θ matches the target angle θ ′. 70a is engaged to prevent the vehicle from slipping down.

Therefore, when it is determined in (step-A107) that the rotational speed (n) of the driven shaft 232 has an abnormal variation,
The control unit 150 immediately proceeds from (step-A107) to (step-A110).
Then, the first-speed power shift device 70b is engaged.

On the other hand, if there is no abnormality relating to the rotation speed (n) of the driven shaft 232, the control unit 150 inputs the swash plate angle θ at that time (step-A108), and the θ becomes θ ′. The servo valve 52b is driven so as to match (step-A10
9).

When it is detected that the swash plate angle θ coincides with the target angle θ ′, at (step-A110) the second
A complete shift from the first-speed power shift device 70b to the first-speed power shift device 70a is performed. That is, (step-A1
The point in time when step 10) is executed corresponds to the time t2 in FIG.

When the shift is completed in this way, the subroutine A returns to (step-4) in FIG.

When the multi-speed transmission 60 is engaged with the third speed, the process shifts from (step-A1) to (step-A200), and from (step-A200) to (step-A220). ), (Ste
The same control as in (p-A100) to (step-A110) is performed.

As described above, in the high load state, the control unit 150 automatically shifts down the multi-stage transmission 60 from the currently engaged gear to increase the traveling drive torque and , In conjunction with it, H
ST10 is automatically operated to the speed increasing side, and the multi-stage transmission 6
Control is performed so that the vehicle speed does not change due to the automatic downshift of 0.

(Iii) In the case of P <Pa (low load torque state) When it is determined that the state is the low load torque state, from (step-8)
Move on to (step-80). Then, in (step-80), it is detected whether or not the multi-speed transmission 60 is in a state where upshifting is possible, that is, whether or not the multi-speed transmission 60 is engaged with the highest speed. That is, it is detected whether or not the multi-speed transmission 60 is engaged with the third speed. Then, the multi-stage transmission 60
Is engaged with the third speed, the (s
It returns to tep-4).

On the other hand, when the multi-speed transmission 60 is not engaged with the third speed, the process proceeds to a subroutine B for forcibly shifting up the multi-speed transmission 60.

As shown in FIG. 10, in the subroutine B, first, the current engagement speed of the multi-speed transmission 60 is detected (step-B1). In the present embodiment, the multi-speed transmission 60 has three speeds, and the (step-
70), it is known that the multi-speed transmission 60 is not engaged with the third speed, so it is only necessary to detect whether or not the output port is at the second speed, and at present, the first speed or the second speed is currently detected. Which of the second speeds is engaged can be detected. Therefore, when a multi-speed transmission device having four or more gear stages is used, an appropriate judgment step is provided.

If it is determined in (step-B1) that the vehicle is engaged with the second speed, the shift-up from the second speed to the third speed after (step-B100) is performed. Move to the flow for

Here, first, the control unit 150 determines the second one based on the “pressure-time relationship” corresponding to the current HST load torque among the “pressure-time relationship” stored in the memory unit 152. The condition for switching from the second gear to the first gear is calculated (step-B100).

Then, the control unit 150 controls the second speed shift valve 83b and the third speed shift valve 8 in accordance with the switching condition.
3c is drive-controlled (step-B101). The specific control procedure is the same as in subroutine A.

Next, the controller 150 calculates the target angle θ 'of the swash plate 11b (step-B102). That is, the angle to which the swash plate 11b is forcibly swung is calculated. The calculation of the target angle θ ′ is the same as in the subroutine A.

The control unit 150 controls the servo valve 52 so that the swash plate 11b swings toward the target angle θ '.
b is driven (step-B103).

At this time (arbitrary time from time t1 to time t2 in FIG. 6), the control unit 150 determines whether the swash plate angles θ and θ ′ coincide with each other before the driven shaft 2
The rotation speed (n) of the driven shaft 232 is input (step-B104), and it is determined whether or not the rotation speed (n) of the driven shaft 232 is abnormally varied (st).
ep-B105).

In the (step-B105), the rotation speed of the driven shaft 232
If it is determined that an abnormal change has occurred in (n), the control unit 150 immediately shifts from (step-B105) to (step-B108) and engages with the third speed power shift device 70c. Perform a match.

On the other hand, when there is no abnormality relating to the rotation speed (n) of the driven shaft 232, the control unit 150 inputs the swash plate angle θ at that time (step-B106), and the θ becomes the θ ′. The servo valve 52b is driven so as to match (step-B10
7).

When it is detected that the swash plate angle θ coincides with the target angle θ ′, at (step-B108) the second
A complete shift from the speed shift power shift device 70b to the third speed power shift device 70c is performed. That is, (step-B1
08) corresponds to time t2 in FIG.

When the shift is completed, the subroutine B returns to (step-4) in FIG.

When the multi-speed transmission 60 is engaged with the third speed, the process shifts from (step-B1) to (step-B200), and from (step-B200) to (step-B208). ), (Ste
The same control as in (p-B100) to (step-B108) is performed.

As described above, in the low load state, the control unit 150 automatically shifts up the multi-stage transmission device 60 from the currently engaged gear position so that high-speed running is possible. With, in conjunction with it, HS
T10 is automatically operated to the deceleration side, and the multi-stage transmission 60
Is controlled so that the vehicle speed does not change due to the automatic upshift of.

FIGS. 11 and 12 are graphs showing the relationship between the HST swash plate angle and the vehicle speed in the traveling control device according to the present embodiment.

FIG. 11 (a) shows a case where the multi-speed transmission 60 is automatically shifted down to the first speed from the state engaged with the second speed, and FIG. Transmission 60
Is automatically downshifted from the second gear to the first gear,
Further, it is a graph in a case where the automatic transmission is shifted up from the first gear to the second gear.

FIG. 12A shows a case where the multi-speed transmission 60 is automatically shifted up from the engaged state to the second speed to the third speed (hereinafter referred to as the second speed). FIG. 12B shows that the multi-speed transmission 60 is automatically upshifted from the second gear to the third gear, and the third gear is further shifted to the third gear.
FIG. 7 is a graph showing a case where a shift is automatically downshifted from the second gear to the second gear (hereinafter, referred to as a second gear → third gear → second gear).

It should be noted that V1max,
V2max and V3max are the maximum vehicle speeds when the multi-speed transmission is engaged with the first speed, the second speed, and the third speed, respectively.

As shown in FIG. 11A, the multi-speed transmission 6
0 is engaged with the second speed, and when it is determined that the load is high, the multi-stage transmission 60
The gear is automatically downshifted to the gear, and HST10
Automatically swings from .theta.1 to .theta.1 'to increase the speed of the HST. As a result, a change in the vehicle speed during shifting of the multi-speed transmission 60 is suppressed.

Further, when it is determined that the vehicle is in the low load state while the vehicle is traveling in the first speed engagement state, the vehicle automatically switches from the first speed to the second speed as shown in FIG. At the same time, the swash plate of the HST is automatically swung from θ2 ′ to θ2, and the HST is decelerated. As a result, the multi-stage transmission 6
The change in the vehicle speed at the time of the shift of 0 is suppressed.

Note that θα in FIG. 11 is the upper limit angle of the HST swash plate that can be shifted down to the first speed without changing the vehicle speed in the second speed engaged state.

Similarly, as shown in FIG. 12 (a), when the multi-speed transmission 60 is engaged with the second speed and it is determined that the load is low, the multi-speed transmission 60 6
0 is automatically shifted up to the third speed, and
The swash plate of ST10 is automatically swung from θ3 to θ3 ',
ST is decelerated. As a result, a change in the vehicle speed during shifting of the multi-speed transmission 60 is suppressed.

Further, when it is determined that the vehicle is in the high load state while the vehicle is traveling in the engagement state of the third speed, the vehicle automatically shifts from the third speed to the second speed as shown in FIG. At the same time, the swash plate of the HST is automatically swung from θ4 to θ4 ', and the speed of the HST is increased. As a result, the multi-stage transmission 6
The change in the vehicle speed at the time of the shift of 0 is suppressed.

Note that θβ in FIG. 12 is the upper limit angle of the swash plate of the HST which can be shifted down to the second speed without changing the vehicle speed in the third speed engaged state.

In the traveling control device according to the present embodiment, the following effects can be obtained in addition to the various effects described above.

That is, a vehicle having a continuously variable transmission and a multi-stage transmission connected in series with each other in a traveling system power transmission path from a driving source to driving wheels, a signal detection unit and a control unit, A transmission control mechanism for performing a shift control of a stepped transmission and a multi-stage transmission, wherein the signal detection unit includes a load torque detection unit that detects a load torque applied to a vehicle, and the control unit includes the load torque detection unit. If the vehicle is in a high load torque state based on the detection result by
Since the multi-stage transmission is configured to be decelerated and the stepless transmission is increased in speed, the multi-stage transmission is automatically shifted down in a high load torque state to obtain a large traveling drive torque. Thus, a change in vehicle speed during downshifting of the multi-stage transmission can be effectively suppressed.

When the vehicle is in a low load torque state, the control unit increases the speed of the multi-stage transmission and decelerates the continuously variable transmission based on the result of the detection by the load torque detecting means. Because it is configured as
In the low-load torque state, the multi-speed transmission can be automatically shifted up to enable high-speed traveling, and the change in vehicle speed during the up-shift of the multi-speed transmission can be effectively suppressed.

Further, the signal detecting section detects a swash plate angle in the continuously variable transmission, and swash plate angle detecting means;
Lever swing angle detecting means for detecting an angle of an operation lever for manually operating the swash plate, wherein a memory unit of the control unit stores the swash plate angle and the vehicle speed for each shift speed of a multi-stage transmission. And a processing unit of the control unit uses a swash plate angle input from the swash plate angle detection means to store a current engagement of the multi-stage transmission. The present vehicle speed is detected based on the vehicle speed-swash plate angle relationship of the combined gear position, and the detected vehicle speed is used to determine the vehicle speed-swash plate angle relationship of the next gear position to be engaged with the multi-speed transmission. , It is configured to determine whether or not the shift of the multi-stage transmission is possible. Therefore, it is possible to effectively prevent a large change in the vehicle speed from occurring during the shift of the multi-stage transmission.

Further, if the arithmetic processing unit determines that the gear shift of the multi-stage transmission is possible, the arithmetic processing unit uses the detected vehicle speed to determine the vehicle speed of the next gear to be engaged after the multi-stage transmission. Based on the swash plate angle relationship, the swash plate is controlled so that the vehicle speed does not change at the time of shifting of the multi-stage transmission, so that it is possible to suppress a change in vehicle speed at the time of shifting of the multi-stage transmission. Become.

[0123]

According to the traveling device for a vehicle according to the present invention,
A travel control device for a vehicle having a continuously variable transmission and a multi-stage transmission, comprising a signal detection unit and a control unit, comprising a shift control mechanism for performing a shift control of the continuously variable transmission and the multi-stage transmission, The signal detection unit has a load torque detection unit that detects a load torque on the vehicle, and the control unit includes:
When the vehicle is in a high load torque state based on the detection result by the load torque detecting means, the multi-stage transmission is decelerated and the stepless transmission is increased in speed. In this case, the downshift of the multi-stage transmission to increase the traveling drive torque can be performed automatically, and the change in vehicle speed during down-shift of the multi-stage transmission can be effectively suppressed.

Further, when the vehicle is in a low load torque state, the control unit increases the speed of the multi-stage transmission based on the detection result by the load torque detection means,
If the continuously variable transmission is configured to be decelerated, the shift-up of the multi-stage transmission for enabling high-speed running can be automatically performed in the case of a low load torque state. A change in vehicle speed at the time of upshifting the transmission can be effectively suppressed.

[Brief description of the drawings]

FIG. 1 is a transmission path diagram of a vehicle to which a preferred embodiment of a travel control device according to the present invention is applied.

FIG. 2 is a hydraulic circuit diagram of the travel control device shown in FIG.

FIG. 3 is a block diagram of a shift control mechanism in the traveling control device shown in FIG. 1;

FIG. 4 is a graph showing a relationship between HST operating pressure and HST load torque.

FIG. 5 is a graph showing a relationship between an HST swash plate angle and a vehicle speed in the vehicle shown in FIG. 1, and shows the relationship for each shift speed of the multi-speed transmission.

FIG. 6 is a graph showing a relationship between a hydraulic pressure of a currently engaged shift line, a hydraulic pressure of a shift line to be next engaged, and time in the multi-stage transmission, and FIG. In FIG.

FIG. 7 is a control flow by the control unit.

8 is a control flow of the control unit, and FIG.
3 shows a control flow in a subsequent stage.

FIG. 9 is a control flow of a subroutine A in FIG. 8;

FIG. 10 is a control flow of a subroutine B in FIG. 8;

FIG. 11 is a graph showing the relationship between HST swash plate angle and vehicle speed. FIG. 11A shows that the multi-stage transmission is the second transmission.
The figure shows a case where the gear is automatically downshifted from the first gear to the first gear. FIG. 11 (b) shows that the multi-speed transmission is automatically downshifted from the second speed to the first speed,
The figure shows a case where the gear is automatically shifted up to the gear.

FIG. 12 is a graph showing the relationship between HST swash plate angle and vehicle speed. FIG. 12A shows that the multi-stage transmission is the second transmission.
The figure shows a case where the automatic transmission is shifted up from the first gear to the third gear. FIG. 12 (b) shows that the multi-speed transmission is automatically upshifted from the second speed to the third speed, and then the second speed is shifted to the second speed.
This shows a case where the gear is automatically downshifted to the speed position.

[Explanation of symbols]

 Reference Signs List 10 continuously variable transmission device 10 pair of hydraulic lines 11 hydraulic pump 15 hydraulic motor 60 multi-stage transmission device 100 transmission control mechanism 110 signal detection unit 111 load torque detection unit 112 swash plate angle detection unit 113 lever swing angle detection unit 150 control unit 151 Arithmetic processing unit 152 Memory unit 200 Drive source 210 Drive wheel

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J552 MA04 MA10 MA11 MA17 NA01 NB01 PA02 PA22 PA32 QA08A QA24A RA03 RA06 RB15 SA01 SA31 SB02 SB09 SB10 SB35 TA01 TB02 TB03 TB07 VA11W VA37W VA52W VA66W VA74W VB01W

Claims (5)

[Claims] 1. A traveling control device for a vehicle having a continuously variable transmission and a multi-stage transmission interposed in series in a traveling system power transmission path from a driving source to a driving wheel, comprising a signal detection unit and a control unit. A shift control mechanism that controls shifts of the continuously variable transmission and the multi-stage transmission; the signal detection unit includes a load torque detection unit that detects a load torque applied to a vehicle; When the vehicle is in a high load torque state based on the detection result by the torque detecting means, the vehicle is controlled to reduce the speed of the multi-stage transmission and increase the speed of the continuously variable transmission. Control device. 2. The control section, when the vehicle is in a low load torque state, increases the speed of the multi-stage transmission and decelerates the continuously variable transmission based on a detection result by the load torque detection means. The vehicle travel control device according to claim 1, wherein the control is performed as follows. 3. The continuously variable transmission includes a hydraulic pump and a hydraulic motor connected via a pair of hydraulic lines, and the load torque detecting unit is configured to control the hydraulic pressure of the pair of hydraulic lines to a high pressure side. It is configured to detect whether the vehicle is in a high load torque state, a low load torque state, or an appropriate load torque state by detecting whether the vehicle is above the reference value and below the low pressure side reference value. The control unit calculates a memory unit in which a relationship between the hydraulic pressure of the pair of hydraulic lines and the load torque of the continuously variable transmission is stored, and a control signal to the continuously variable transmission and the multi-stage transmission. An arithmetic processing unit for processing, wherein the arithmetic processing unit is configured to output a control signal to the multi-stage transmission and the continuously variable transmission based on a detection signal from the load torque detection unit. That The travel control device for a vehicle according to claim 2, wherein: 4. The swash plate angle detecting means for detecting an angle of a swash plate in the continuously variable transmission, and a lever swing for detecting an angle of an operation lever for manually operating the swash plate. An angle detecting means, wherein the memory unit further stores information on a vehicle speed-swash plate angle relationship between the swash plate angle and the vehicle speed for each gear position of the multi-speed transmission, and the arithmetic processing unit Using the swash plate angle input from the swash plate angle detection means, based on the vehicle speed-swash plate angle relationship of the current engagement speed of the multi-stage transmission, to detect the current vehicle speed,
Using the detected vehicle speed, it is determined whether or not a shift of the multi-stage transmission is possible based on a vehicle speed-swash plate angle relationship of a speed to be engaged next to the multi-stage transmission. The travel control device for a vehicle according to claim 3, wherein: 5. The multi-speed transmission, when the arithmetic processing unit determines that a shift can be performed by the multi-speed transmission, further uses the detected vehicle speed to determine a shift speed to be engaged next to the multi-speed transmission. 5. The travel control device for a vehicle according to claim 4, wherein the swash plate is controlled based on a relationship between a vehicle speed and a swash plate angle so that the vehicle speed does not change at the time of shifting of the multi-speed transmission.