JP4809990B2 - Shift control method for construction vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shift control method for a construction vehicle that changes a hydraulic waveform of a shift clutch based on running resistance.
[0002]
[Prior art]
With recent improvements in the performance of passenger cars, comfortable driving performance is also required in construction vehicles such as dump trucks, and there is a demand for improved transmission feeling.
[0003]
FIG. 5 is a conceptual diagram of a shift control system in a construction vehicle such as a dump truck. In the power train of the construction vehicle, the output of the engine E is a torque converter T / C constituting a transmission T / M, an auxiliary transmission. S, transmitted from the main transmission M to the drive wheels H via a reduction gear (differential or the like) D.
[0004]
A lockup clutch L / C that directly connects the input shaft Ti and the output shaft To is interposed between the input shaft Ti and the output shaft To in the torque converter T / C.
[0005]
The sub-transmission S has a first-stage transmission clutch S1 (Low) and a transmission clutch Sh (High), and the main transmission M has a second-stage transmission clutch M1 (1st) and a transmission clutch M2 ( 2nd), a transmission clutch M3 (3rd), a transmission clutch M4 (4th), and a transmission clutch Mr (Rear).
[0006]
Further, pressure control valves (electromagnetic proportional pressure control valves) Vl, Vh, V1, V2, V3, V4, and Vr are connected to the shift clutches Sl, Sh, M1, M2, M3, M4, and Mr, respectively. Yes.
[0007]
Each of the pressure control valves Vl, Vh, V1, V2, V3, V4, Vr controls the supply pressure of the working fluid to each of the shift clutches Sl, Sh, M1, M2, M3, M4, Mr. The operation is independently controlled by the electric command from C.
[0008]
The controller C is based on the signals from the sensors provided in the accelerator, the brake, etc., the shift lever signal indicating the shift position, the rotational speed information from the sensors provided in each part of the transmission T / M, etc. Then, the state of the transmission T / M is determined, and optimal clutch control and shift position control are performed.
[0009]
FIG. 6 is a time chart (hydraulic waveform) showing a change in clutch hydraulic pressure in the above-described shift control system. A broken line in the figure represents an open clutch pressure (pressure in an open-side shift clutch), and a solid line in the figure. The engagement clutch pressure (the pressure in the engagement side shift clutch) is shown.
[0010]
As is apparent from this time chart, in the shift control method in the above-described shift control system, before the disengagement side shift clutch is disengaged, the engagement side shift clutch is filled with pressure oil to complete the filling, and then the disengagement side After the transmission clutch is disengaged, the hydraulic pressure of the engagement-side transmission clutch is gradually increased, thereby suppressing the occurrence of a transmission shock and improving the transmission feeling.
[0011]
[Problems to be solved by the invention]
By the way, in a construction vehicle such as a dump truck, the running resistance is large depending on various driving conditions such as running on a rugged construction site, running on soft ground or running at extremely low speed, and the weight of the load. Will change.
[0012]
For this reason, in the above-described shift control method, there is a disadvantage that a shift shock occurs due to a change in running resistance when the shift clutch is controlled in accordance with a constant hydraulic waveform preset at each shift stage. .
[0013]
Therefore, a weight sensor (load meter), an angle sensor (tilt meter), etc. are installed in the construction vehicle, and the running resistance is determined based on information from these various sensors, and the hydraulic pressure of the transmission clutch is determined based on the running resistance. There is provided a shift control method for controlling a shift clutch according to a change in running resistance by changing a waveform (control pattern).
[0014]
According to the shift control method for a construction vehicle described above, it is possible to prevent the occurrence of a shift shock due to a change in travel resistance by changing the hydraulic waveform (control pattern) of the shift clutch in accordance with the travel resistance. It becomes.
[0015]
However, in the construction vehicle shift control method described above, various dedicated sensors (vehicle weight sensor, angle sensor, etc.) are required to detect the running resistance of the construction vehicle, and these various sensors are expensive. There was an inconvenience that the cost related to the control system and the cost related to the construction vehicle were increased.
[0016]
In view of the above circumstances, an object of the present invention is to provide a speed change control method for a construction vehicle that can prevent the occurrence of a speed change shock due to running resistance without incurring an inadvertent increase in cost. .
[0017]
[Means for solving the problems and effects]
To achieve the above object, a shift control method for a construction vehicle according to the invention of claim 1 is a shift control method for a construction vehicle that changes a hydraulic waveform of a shift clutch based on running resistance, and is connected to a torque converter. The running resistance of the construction vehicle is determined based on the information related to the lockup control of the lockup clutch, and the command hydraulic waveform corresponding to the determined running resistance is selected from a plurality of preset command hydraulic waveforms and selected. The shift clutch is controlled by a command hydraulic waveform.
[0018]
In the above configuration, the running resistance of the construction vehicle is determined using information related to lockup control of the lockup clutch connected to the torque converter, that is, basic information originally used for control of the construction vehicle. Therefore, a dedicated sensor such as a weight meter is not required to detect the running resistance, and the construction vehicle shift control method according to the present invention causes an inadvertent increase in cost. Therefore, it is possible to prevent the occurrence of a shift shock due to running resistance.
[0019]
The construction vehicle shift control method according to the invention of claim 2 is the construction vehicle shift control method according to the invention of claim 1, wherein the information related to the lockup control is control information of the torque converter lockup speed ratio, The running resistance of the construction vehicle is determined based on the input rotational speed or the output rotational speed of the torque converter when the speed ratio exceeds a predetermined value.
[0020]
In the above configuration, construction is performed using the torque converter speed ratio (ratio of input speed to output speed) and input speed or output speed, that is, basic information originally used for control of construction vehicles. Since the running resistance of the vehicle is determined, there is no need for a dedicated sensor such as a weight meter in order to detect the running resistance. Therefore, according to the shift control method for a construction vehicle according to the present invention, The occurrence of a shift shock due to running resistance can be prevented without inadvertently increasing the cost.
[0021]
The construction vehicle shift control method related to the invention of claim 3 is the construction vehicle shift control method related to the invention of claim 1, wherein the information related to the lockup control is information of the torque converter lockup output rotational speed, The running resistance of the construction vehicle is determined based on the input rotational speed of the torque converter when the output rotational speed exceeds a predetermined value.
[0022]
In the above configuration, the running resistance of the construction vehicle is determined based on the output speed and input speed of the torque converter, that is, the basic information used for controlling the construction vehicle from the beginning. Therefore, a dedicated sensor such as a weight meter is not required, and according to the shift control method for a construction vehicle according to the present invention, it is caused by running resistance without inadvertently increasing the cost. It is possible to prevent the occurrence of shift shock.
[0023]
The construction vehicle shift control method according to the invention of claim 4 is the construction vehicle shift control method according to the invention of claim 1, wherein the information related to the lockup control is control information of the torque converter lockup speed ratio, The running resistance of the construction vehicle is determined based on the time required from when the engagement command is issued to the lockup clutch until the speed ratio of the torque converter reaches a predetermined value.
[0024]
In the above configuration, the time required for the speed ratio of the torque converter to reach a predetermined value from the time when the engagement command is issued to the lockup clutch, that is, basic information used for control of the construction vehicle from the beginning. Since the running resistance of the construction vehicle is determined by using, a dedicated sensor such as a weight meter is not required to detect the running resistance, and therefore the construction vehicle shift control method according to the present invention is used. Accordingly, it is possible to prevent the occurrence of shift shock due to running resistance without inadvertently increasing the cost.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a command hydraulic pressure waveform (fluid gradually increasing waveform) in an engagement-side shift clutch and a command hydraulic pressure waveform (in a release-side shift clutch) when the present invention is applied to a shift control system in a construction vehicle such as a dump truck. 6 is a time chart showing a built-in waveform.
[0026]
By the way, the command hydraulic waveform on the engagement side (fluid gradually increasing waveform) controls the pressure control valve connected to the gear clutch on the engagement side, and the command hydraulic waveform on the open side (built-down waveform) The pressure control valve connected to the speed change clutch is controlled.
[0027]
In addition, the shift control system in a construction vehicle such as a dump truck is basically the same as the conventional shift control system shown in FIG. 5, and all the descriptions related to the shift control system refer to FIG. 5 below. And
[0028]
Here, the time chart shown in FIG. 1 shows that the shift clutch Sl (Low) and the shift clutch Sh (High) of the sub-transmission S are switched. Specifically, the shift clutch Sl (Low) is opened, while the shift clutch A case where a shift from F1 (first speed) to F2 (second speed) is performed by engaging Sh (High) is illustrated.
[0029]
As is apparent from FIG. 1, the command hydraulic pressure waveform (fluid gradually increasing waveform) in the engagement-side shift clutch is first supplied to the shift clutch immediately before the shift clutch is filled by the command (full trigger signal), and then the supply of the working fluid is performed. The amount is reduced to a predetermined flow rate at which an initial filling pressure is generated in the transmission clutch, and then the working fluid is supplied until the filling is completed.
[0030]
After that, when the filling of the transmission clutch is completed, the clutch engagement pressure is increased and held at a predetermined gradual increase rate.
[0031]
Here, in the above-described command hydraulic pressure waveform, the waveform Ah corresponding to a large traveling resistance, the waveform Am corresponding to a medium traveling resistance, and a small amount between the time when filling is completed and the clutch engagement set pressure are set. A waveform Al corresponding to the running resistance is set.
[0032]
The waveform Ah corresponding to a large running resistance is set to a higher hydraulic pressure than the waveform Am corresponding to a medium running resistance, and the waveform Al corresponding to a small running resistance is a waveform corresponding to a medium running resistance. The hydraulic pressure is set lower than Am.
[0033]
Furthermore, a waveform Ah corresponding to a large traveling resistance, a waveform Am corresponding to a medium traveling resistance, and a waveform Al corresponding to a small traveling resistance are set with their respective incremental rates different from each other.
[0034]
These waveforms Ah, Am, Al are selected corresponding to the running resistance of the vehicle determined by the mode described later, and the shift clutch (engagement side) is a command hydraulic waveform including any of the waveforms Ah, Am, Al. It will be controlled by.
[0035]
On the other hand, as is clear from FIG. 1, the command hydraulic pressure waveform (built-down waveform) in the disengagement side shift clutch first discharges the working fluid from the shift clutch according to the command, and from the clutch engagement set pressure to the crossover pressure. The crossover pressure is maintained until the filling of the disengagement side shifting clutch is completed.
[0036]
After that, when the filling of the transmission clutch (engagement side) is completed, the discharge of the working fluid from the transmission clutch (disengagement side) is resumed and the hydraulic fluid is discharged until the hydraulic pressure becomes zero from the crossover pressure. .
[0037]
Here, in the command hydraulic pressure waveform described above, the waveform Bh corresponding to a large travel resistance and the waveform corresponding to a medium travel resistance during the discharge of the working fluid from the time when filling is completed until the hydraulic pressure becomes zero. Bm and a waveform Bl corresponding to a small running resistance are set.
[0038]
The waveform Bh corresponding to a large running resistance has a built-down time (the time required to discharge the working fluid from the time when filling is completed until the hydraulic pressure becomes zero), compared to the waveform Bm corresponding to a medium running resistance. The waveform Bl corresponding to the small running resistance is set longer and the built-down time is set shorter than the waveform Bm corresponding to the medium running resistance. That is, the gradual decrease rate of each waveform Bh, Bm, B1 is They are set differently.
[0039]
These waveforms Bh, Bm, and Bl are selected corresponding to the vehicle running resistance determined by the mode described later, and the shift clutch (disengagement side) is determined by a command hydraulic waveform including any of the waveforms Bh, Bm, and Bl. Will be controlled.
[0040]
Note that the above-described command hydraulic waveform in the engagement-side shift clutch is prepared in advance corresponding to the shift condition based on the driving state, the shift speed, etc., and the command corresponding to the shift condition is controlled when the shift clutch is controlled. A hydraulic waveform is selected and used.
[0041]
Here, in the speed change control method according to the present invention, the running resistance of a construction vehicle such as a dump truck is used to lock up the lock-up clutch L / C connected to the torque converter T / C in the power train (see FIG. 5). Judgment is based on information related to control.
[0042]
Furthermore, as an example of a specific mode for determining the running resistance of the construction vehicle based on information related to the lockup control of the lockup clutch L / C, the speed ratio e of the torque converter T / C has exceeded a predetermined value. The input rotational speed of the torque converter T / C at the time point, in other words, when the condition for engaging (ON) the lockup clutch L / C is satisfied (when the engagement command is issued to the lockup clutch L / C) That is, the running resistance of the construction vehicle is determined based on the rotation speed (= engine rotation speed) of the input shaft Ti.
[0043]
The speed ratio e of the torque converter T / C is a value obtained by dividing the output rotational speed (the rotational speed of the output shaft To) of the torque converter T / C by the input rotational speed (the rotational speed of the input shaft Ti). .
[0044]
Fig. 2 shows the difference in road grade and presence / absence of load when the speed ratio e of the torque converter T / C exceeds a predetermined value (for example, 0.5 to 0.9) during sudden acceleration at F1 (first gear). The relationship between various driving conditions and engine speed (= input speed of torque converter T / C) is shown.
[0045]
As is apparent from FIG. 2, the engine speed is greater than 2000 rpm under the driving condition where the driving resistance is (large) (“loading, climbing”) and the driving condition where the driving resistance is (small) (“empty vehicle”). The engine speed at “flat,” is less than 1500 rpm, and the engine speed at a driving condition (“car, flat”) with a running resistance of “medium” is between 1500 rpm and 2000 rpm.
[0046]
In other words, if the engine speed at the time when the lockup clutch L / C is turned on is greater than 2000 rpm, it can be determined that the running resistance of the vehicle is (large), and similarly the engine speed is from 1500 rpm. If it is small, it can be judged that the running resistance of the vehicle is (small), and if the engine speed is between 1500 rpm and 2000 rpm, it can be judged that the running resistance of the vehicle is (medium). Can do.
[0047]
Note that the engine speed used as the threshold value for determining (large), (medium), and (small) of the running resistance is not limited to the above-mentioned 2000 rpm and 1500 rpm. Degree), the current gear stage (F1, F2,...), And the speed ratio e of the torque converter T / C as a condition for connecting the lockup clutch L / C can be set as appropriate. Needless to say.
[0048]
In the configuration as described above, it is determined that the running resistance of the construction vehicle is (large) based on the input rotational speed of the torque converter T / C when the speed ratio e of the torque converter T / C exceeds a predetermined value. In this case, the engagement side shift clutch is controlled by a command hydraulic pressure waveform (fluid gradually increasing waveform) including the waveform Ah in FIG. 1, while the release side shift clutch is controlled by the command hydraulic pressure waveform including the waveform Bh in FIG. Controlled by waveform (built-down waveform).
[0049]
Here, as described above, the waveform Ah is set to a high hydraulic pressure, and the built-in time of the waveform Bh is set to be long. Occurrence will be suppressed in advance.
[0050]
Further, when it is determined that the running resistance of the construction vehicle is (medium), the engagement-side shift clutch is controlled by a command hydraulic waveform (fluid gradually increasing waveform) including the waveform Am, and the open-side shift clutch has a waveform. It is controlled by a command hydraulic waveform (built-in waveform) including Bm.
[0051]
Further, when it is determined that the running resistance of the construction vehicle is (small), the engagement-side shift clutch is controlled by the command hydraulic waveform (fluid gradually increasing waveform) including the waveform Al, and the open-side shift clutch is the waveform. It is controlled by a command hydraulic waveform (built-in waveform) including B1.
[0052]
Here, as described above, the waveform Al is set to a low hydraulic pressure, and the built-in time of the waveform Bl is set to be short, so that the engagement-side shift clutch is slid even in a situation where the running resistance is small. As a result, the occurrence of a shift shock is suppressed in advance.
[0053]
As described above, according to the configuration described in detail, the speed ratio e of the torque converter T / C and the input rotational speed (engine), which are information related to the lockup control of the lockup clutch L / C connected to the torque converter T / C. Rotational speed), that is, the running resistance of construction vehicles is determined using basic information originally used to control construction vehicles. It is possible to prevent the occurrence of a shift shock due to running resistance without requiring a sensor and without causing an inadvertent increase in cost.
[0054]
On the other hand, in the speed change control method according to the present invention, as another example of a specific mode for determining the running resistance of the construction vehicle based on information related to the lockup control of the lockup clutch L / C, a power train (FIG. ), The input rotational speed of the torque converter T / C, that is, the rotational speed of the input shaft Ti at the time when the rotational speed of the torque converter T / C, that is, the rotational speed of the output shaft To exceeds a predetermined value (= engine It is also possible to determine the running resistance of the construction vehicle based on the number of revolutions).
[0055]
Here, the engine rotational speed used as a threshold for determining (large), (medium), (small) of the running resistance is the rotational speed (predetermined value) of the output shaft To which is the timing for measuring the engine rotational speed. Furthermore, it goes without saying that it can be set as appropriate in accordance with the state of acceleration at the time of shifting, the current shift speed (F1, F2,.
[0056]
Further, in the configuration as described above, the running resistance of the construction vehicle is (large) based on the input rotational speed of the torque converter T / C when the output rotational speed of the torque converter T / C exceeds a predetermined value. If it is determined that there is, the engagement-side shift clutch is controlled by a command hydraulic waveform (fluid gradually increasing waveform) including the waveform Ah in FIG. 1, while the disengagement shift clutch has the waveform Bh in FIG. It is controlled by the included command oil pressure waveform (built-down waveform).
[0057]
Similarly, when it is determined that the running resistance of the construction vehicle is (medium), the engagement-side shift clutch is controlled by a command hydraulic waveform (fluid gradually increasing waveform) including a waveform Am, and the open-side shift clutch is a waveform. It is controlled by a command hydraulic waveform (built-in waveform) including Bm.
[0058]
Further, when it is determined that the running resistance of the construction vehicle is (small), the engagement-side shift clutch is controlled by the command hydraulic waveform (fluid gradually increasing waveform) including the waveform Al, and the open-side shift clutch is the waveform. It is controlled by a command hydraulic waveform (built-in waveform) including B1.
[0059]
According to the configuration described above, the output rotational speed and the input rotational speed (engine rotational speed) of the torque converter T / C, which are information related to lockup control of the lockup clutch L / C connected to the torque converter T / C. In other words, since the running resistance of a construction vehicle is determined from the basic information that is originally used to control a construction vehicle, a dedicated sensor such as a weight meter is required to detect the running resistance. Therefore, it is possible to prevent the occurrence of a shift shock due to the running resistance without inadvertently increasing the cost.
[0060]
On the other hand, in the speed change control method according to the present invention, as still another example of a specific mode for determining the running resistance of the construction vehicle based on information related to the lockup control of the lockup clutch L / C, a power train (see FIG. 5)) from the time when the engagement command is issued to the lockup clutch L / C to the time required for the speed ratio e of the torque converter T / C to reach a predetermined value (for example, “0”). It is also possible to determine the running resistance of the construction vehicle.
[0061]
FIGS. 3 and 4 show the change over time in the input rotation speed and the output rotation speed in the torque converter T / C together with the command hydraulic waveform (fluid gradually increasing waveform) of the lockup clutch L / C.
[0062]
As is apparent from FIG. 3, the output rotational speed Ro of the torque converter T / C increases at a gradually increasing rate from the time when the engagement command is issued to the lockup clutch L / C, and finally the torque It is synchronized with the input rotational speed Ri of the converter T / C.
[0063]
Here, from the time when the engagement command is issued to the lockup clutch L / C, the torque gradually increases in accordance with the command hydraulic waveform of the lockup clutch L / C, and the output rotational speed Ro of the torque converter T / C is increased. Time Tt is required until it matches the input rotational speed Ri (the speed ratio e becomes “0”).
[0064]
On the other hand, when the running resistance of the construction vehicle is (small), the gradually increasing rate of the output rotational speed Ro is large as shown by the chain line in FIG. 4, and the output rotational speed Ro is the input rotational speed in a time shorter than the above-described time Tt. Matches Ri.
[0065]
Further, when the running resistance of the construction vehicle is (large), the rate of increase of the output rotation speed Ro is small as shown by the broken line in FIG. 4, and the output rotation speed Ro is the input rotation speed in a time longer than the above-described time Tt. Matches Ri.
[0066]
Therefore, when the time Tt from when the engagement command is issued to the lockup clutch L / C is set as a threshold value, and the speed ratio e in the time region Tl is shorter than the time Tt, the running resistance of the vehicle is ( Small), and when the speed ratio e of the time region Th is longer than the time Tt, it can be determined that the running resistance of the vehicle is (large).
[0067]
In the above-described embodiment, the time Tt is set as a threshold value for determining (large) or (small) of the running resistance, but is not limited to the above-described determination of the speed ratio e. Needless to say, it can be set appropriately according to various conditions such as the current gear position (F1, F2,...).
[0068]
In the configuration as described above, the running resistance of the construction vehicle is based on the time required from when the engagement command is issued to the lockup clutch L / C until the speed ratio e of the torque converter T / C reaches a predetermined value. When judged, the engagement-side shift clutch is controlled by a command hydraulic waveform (fluid gradually increasing waveform) corresponding to the running resistance, while the open-side shift clutch is controlled by a command hydraulic waveform (built-down waveform) corresponding to the running resistance. Controlled by.
[0069]
In the above-described embodiment, the command hydraulic waveform (fluid gradually increasing waveform and built-down waveform) for the transmission clutch is preset with a waveform corresponding to the running resistance (large) and a waveform corresponding to the running resistance (small). Needless to say.
[0070]
In the above-described embodiment, the running resistance is divided into two regions of (large) and (small). The torque converter T / C is issued after the engagement command is issued to the lockup clutch L / C. Based on the time Tt required for the speed ratio e to reach a predetermined value, the running resistance is set to (large), (medium) by the time region including this time Tt and the time regions provided before and after the time region. ) And (small) can be divided into three areas.
[0071]
According to the above-described configuration, the torque converter from the time when an engagement command is issued to the lockup clutch L / C, which is information related to lockup control of the lockup clutch L / C connected to the torque converter T / C. The time required for the T / C speed ratio e to reach a predetermined value, that is, the running resistance of the construction vehicle is determined based on the basic information originally used for the construction vehicle control. It is possible to prevent the occurrence of a shift shock due to running resistance without incurring an inadvertent increase in cost without requiring a dedicated sensor such as a vehicle weight meter to detect resistance. It becomes possible.
[Brief description of the drawings]
FIG. 1 is a time chart illustrating a command hydraulic pressure waveform to a shift clutch in a shift control method for a construction vehicle according to the present invention.
FIG. 2 is a diagram showing the relationship between running resistance and engine speed when the torque converter is locked up.
FIG. 3 is a diagram showing a change with time of an input rotation speed and an output rotation speed of a torque converter.
FIG. 4 is a diagram showing a change with time of an input rotation speed and an output rotation speed of a torque converter.
FIG. 5 is a conceptual diagram showing a shift control system for a construction vehicle.
FIG. 6 is a time chart showing a state of change in clutch hydraulic pressure in a transmission control system for a construction vehicle.
[Explanation of symbols]
T / C ... torque converter,
Ti ... input shaft To ... output shaft L / C ... lock-up clutch,
Sl, Sh, M1, M2, M3, M4, Mr .... shift clutch,
Ah: Command hydraulic pressure waveform corresponding to running resistance (large),
Am: Command hydraulic pressure waveform corresponding to running resistance (medium),
Al: Command hydraulic pressure waveform corresponding to running resistance (small),
Bh: Command hydraulic pressure waveform corresponding to running resistance (large),
Bm: Command hydraulic pressure waveform corresponding to running resistance (medium),
Bl: Command hydraulic pressure waveform corresponding to running resistance (small).

Claims (1)

A shift control method for a construction vehicle that changes a hydraulic waveform of a shift clutch based on a running resistance,
Torque converter lockup speed ratio control information related to lockup control of a lockup clutch connected to the torque converter, and the torque converter speed ratio is set to a predetermined value from the time when an engagement command is issued to the lockup clutch. Based on the time taken to reach, the running resistance of the construction vehicle is determined,
A command hydraulic waveform corresponding to the determined running resistance is selected from a plurality of preset command hydraulic waveforms,
A shift control method for a construction vehicle, wherein the shift clutch is controlled by the selected command hydraulic waveform.

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