液壓機(jī)械無級(jí)傳動(dòng)全功率換段過程排量比調(diào)節(jié)模型

楊樹軍，張 曼，曾盼文，張寅君，張 璐，田 霖

液壓機(jī)械無級(jí)傳動(dòng)全功率換段過程排量比調(diào)節(jié)模型

楊樹軍1，張 曼1，曾盼文2，張寅君1，張 璐1，田 霖1

（1. 燕山大學(xué)車輛與能源學(xué)院，秦皇島 066004；2. 江麓機(jī)電集團(tuán)有限公司，湘潭 411199）

為了解決液壓機(jī)械換段過程中存在的轉(zhuǎn)速波動(dòng)和瞬時(shí)動(dòng)力中斷等問題，該文以兩離合器結(jié)合重疊的五階段全功率動(dòng)力換段方法為基礎(chǔ)，分析了液壓機(jī)械全功率換段過程變排量液壓元件排量比調(diào)節(jié)規(guī)律。以某等差兩段式液壓機(jī)械為研究對(duì)象，建立了液壓機(jī)械全功率換段過程變排量液壓元件排量比調(diào)節(jié)模型，通過仿真分析和全功率換段過程試驗(yàn)，獲得了換段過程液壓回路壓力從當(dāng)前段到目標(biāo)段隨排量比變化的動(dòng)態(tài)響應(yīng)過程。結(jié)果表明，排量比變化量的仿真與試驗(yàn)結(jié)果基本一致，最大偏差為8.93%，驗(yàn)證了模型的正確性；排量比調(diào)節(jié)模型能夠根據(jù)當(dāng)前段狀態(tài)參量和目標(biāo)段壓力預(yù)測出目標(biāo)段排量值；階躍排量比調(diào)節(jié)規(guī)律能有效縮短液壓回路建壓時(shí)間，建壓時(shí)間為0.93 s，壓力波動(dòng)量較小，為0.64 MPa；按階躍調(diào)節(jié)排量比至目標(biāo)值，能在換段過程完成液壓回路高低壓側(cè)壓力平穩(wěn)互換，換段前后輸出轉(zhuǎn)速幾乎無波動(dòng)、轉(zhuǎn)矩連續(xù)傳遞。經(jīng)增速機(jī)后的輸出轉(zhuǎn)矩為100和150 N·m時(shí)，換段時(shí)間分別為1.00和1.10 s，該轉(zhuǎn)矩的最大波動(dòng)量分別為6.80和6.84 N·m，換段過程中功率連續(xù)且平穩(wěn)傳遞。研究結(jié)果可為實(shí)現(xiàn)液壓機(jī)械無級(jí)傳動(dòng)全功率換段控制及后續(xù)研究提供參考。

液壓機(jī)械；傳動(dòng)；控制；無級(jí)傳動(dòng)；全功率換段；排量調(diào)節(jié)

0 引 言

液壓機(jī)械無級(jí)傳動(dòng)（hydro-mechanical variable transmission，HMT）是由液壓功率傳動(dòng)機(jī)構(gòu)和機(jī)械功率傳動(dòng)機(jī)構(gòu)復(fù)合而成的雙功率復(fù)合傳動(dòng)形式。具有實(shí)現(xiàn)大功率無級(jí)調(diào)速，傳動(dòng)效率高等突出優(yōu)點(diǎn)，已經(jīng)在軍用車輛、工程機(jī)械和拖拉機(jī)等大功率車輛上廣泛使用[1-3]，成為了大功率車輛無級(jí)傳動(dòng)系統(tǒng)的主要發(fā)展方向[4-6]。

Ali H Shaker和Berger Guenter對(duì)HMT傳動(dòng)特性和控制方式等問題展開了深入系統(tǒng)的研究[7-8]。文獻(xiàn)[9-10]開展了關(guān)于液壓機(jī)械無級(jí)變速器控制技術(shù)的研究工作。文獻(xiàn)[11]開展了關(guān)于液壓機(jī)械傳動(dòng)特性分析以及建模仿真等方面的研究工作。文獻(xiàn)[12]研制出了裝配在M2步兵車和M3偵察車上的HMPT-500系列液壓機(jī)械傳動(dòng)裝置。其他學(xué)者和科研技術(shù)人員也都相繼在HMT各構(gòu)型和控制領(lǐng)域開展了卓有成效的理論研究和產(chǎn)品研制工作[13]。

國內(nèi)苑士華等帶領(lǐng)的科研團(tuán)隊(duì)對(duì)液壓機(jī)械較早開展了研究，提出了相對(duì)完整的HMT參數(shù)設(shè)計(jì)和理論分析方法[14-16]。張明柱等研究了農(nóng)用拖拉機(jī)多段液壓機(jī)械無級(jí)變速器[17-18]。郭占正等建立了液壓機(jī)械無級(jí)傳動(dòng)模型和液壓路仿真模型[19]。魏超等開展了HMT段內(nèi)速比跟蹤策略研究，可使發(fā)動(dòng)機(jī)工作在最佳區(qū)域[20-21]。王光明等分析了液壓機(jī)械換段品質(zhì)的影響因素[22-23]。朱鎮(zhèn)等仿真分析了分段式液壓機(jī)械變速器換擋策略，通過優(yōu)化參數(shù)和換擋時(shí)序，提高換擋品質(zhì)[24-25]。但以上換段研究均是在常規(guī)換段基礎(chǔ)上進(jìn)行的，換段中離合器的分離與結(jié)合間存在一定的時(shí)間間隔或短時(shí)間的滑摩重疊，液壓傳動(dòng)單元的壓力由負(fù)載被動(dòng)產(chǎn)生，不能從根本上消除動(dòng)力中斷和換段沖擊。胡紀(jì)濱等探究了換段過程中雙制動(dòng)器結(jié)合重疊的可行性[26-27]。楊樹軍等分析了換段過程的影響因素，研究了換段控制方法及功率過渡特性，提出了五階段全功率換段方法[28-30]。全功率換段過程中，兩離合器結(jié)合重疊消除了常規(guī)換段過程的慣性相，通過調(diào)節(jié)排量比能主動(dòng)實(shí)現(xiàn)液壓回路高低壓側(cè)互換達(dá)到目標(biāo)段壓力。然而排量比調(diào)節(jié)的動(dòng)態(tài)過程決定著液壓回路高低壓側(cè)互換的過程及換段時(shí)間，目前關(guān)于全功率換段過程中排量比調(diào)節(jié)規(guī)律的研究未見文獻(xiàn)報(bào)道。

本文建立了換段過程液壓回路容腔模型和變排量液壓元件排量調(diào)節(jié)模型，深入研究了全功率換段中排量調(diào)節(jié)特性對(duì)液壓回路動(dòng)態(tài)建壓過程的影響規(guī)律，獲得了換段過程排量的調(diào)節(jié)值和有效縮短換段時(shí)間的排量比調(diào)節(jié)規(guī)律。

1 液壓機(jī)械全功率換段原理

1.1 液壓機(jī)械工作原理

等差兩段式液壓機(jī)械無級(jí)傳動(dòng)樣機(jī)結(jié)構(gòu)簡圖如圖1所示。HMT工作在液壓段（H段）時(shí)，變排量液壓元件驅(qū)動(dòng)定排量液壓元件，離合器H處于結(jié)合狀態(tài)，行星排1工作；液壓機(jī)械段（HM段）前半段時(shí)，定排量液壓元件驅(qū)動(dòng)變排量液壓元件，離合器L處于結(jié)合狀態(tài)，行星排23工作，匯流機(jī)構(gòu)將液壓流傳動(dòng)機(jī)構(gòu)與機(jī)械流傳動(dòng)機(jī)構(gòu)所傳遞的功率匯流輸出。

1.2 液壓機(jī)械全功率動(dòng)力換段特性

HMT全功率動(dòng)力換段過程如圖2所示[31]。

1.3 液壓機(jī)械全功率換段轉(zhuǎn)矩轉(zhuǎn)移特性

換段過程中，兩離合器結(jié)合重疊，進(jìn)入換段狀態(tài)，HMT各行星排、離合器和定排量液壓元件的轉(zhuǎn)矩存在如下關(guān)系：

求解式（1）可得HMT全功率換段過程的轉(zhuǎn)矩特性，如式（2）。

由式（2）可知，兩離合器結(jié)合重疊的換段過程中，閉式液壓回路高低側(cè)壓差變化，HMT當(dāng)前段到目標(biāo)段離合器的轉(zhuǎn)矩會(huì)發(fā)生改變。根據(jù)文獻(xiàn)[30]，閉式液壓回路的壓力可通過調(diào)節(jié)變排量液壓元件排量比控制，實(shí)現(xiàn)轉(zhuǎn)矩轉(zhuǎn)移和功率過渡。

2 液壓機(jī)械全功率換段排量調(diào)節(jié)特性

2.1 全功率換段過程液壓回路等效模型

兩離合器結(jié)合重疊的換段過程中，定排量液壓元件轉(zhuǎn)速與變排量液壓元件的轉(zhuǎn)速之比為一個(gè)定值，液壓回路低壓側(cè)容腔壓力由補(bǔ)油壓力確定且保持恒定不變，高壓側(cè)容腔壓力的變化由進(jìn)出容腔的油液流量決定，可表示為

圖3 HMT閉式液壓回路等效模型
Fig.3 HMT hydraulic circuit equivalent model

2.2 H段至HM段全功率換段過程排量調(diào)節(jié)模型

H段至HM段換段時(shí)下腔建壓，變排量液壓元件進(jìn)油口和定排量液壓元件出油口的實(shí)際流量分別為

當(dāng)HMT工作在H段至HM段換段后穩(wěn)定階段時(shí)，變排量液壓元件和定排量液壓元件容積效率分別為

由式（2）、式（10）可得H段至HM段全功率換段過程轉(zhuǎn)矩轉(zhuǎn)移機(jī)理表達(dá)式。

H段換至HM段的換段過程中通過調(diào)節(jié)變排量液壓元件的排量比控制壓力動(dòng)態(tài)變化過程，排量比按一定規(guī)律由當(dāng)前值調(diào)節(jié)至目標(biāo)值，使換段過程中閉式液壓回路的壓力從當(dāng)前段狀態(tài)向目標(biāo)段壓力過渡，控制轉(zhuǎn)矩從當(dāng)前段離合器向目標(biāo)段離合器轉(zhuǎn)移。

2.3 HM段至H段全功率換段過程排量調(diào)節(jié)模型

HM段至H段換段時(shí)上腔建壓，變排量液壓元件出油口和定排量液壓元件進(jìn)油口的實(shí)際流量分別為

HMT工作在HM段至H段換段后穩(wěn)定階段時(shí)，變排量液壓元件和定排量液壓元件容積效率分別為

程慧(2013)等采取實(shí)證研究的方法，通過對(duì)證券市場近年數(shù)據(jù)建模研究顯示，研發(fā)支出相關(guān)會(huì)計(jì)規(guī)定的修訂，提升了企業(yè)在年報(bào)對(duì)于研發(fā)支出的發(fā)布要求然而對(duì)于細(xì)節(jié)實(shí)施方面，如研發(fā)項(xiàng)目信息公開的表現(xiàn)形式，明細(xì)增減變動(dòng)，研發(fā)資金的現(xiàn)金流等仍欠缺行業(yè)認(rèn)可和統(tǒng)一的披露發(fā)方法。

將式（17）簡化，得到HM段換至H段閉式液壓回路壓力差與排量比的關(guān)系為

由式（2）、式（18）得HM段至H段全功率換段過程轉(zhuǎn)矩轉(zhuǎn)移機(jī)理表達(dá)式。

HM段換至H段的換段過程中通過調(diào)節(jié)變排量液壓元件的排量比控制壓力動(dòng)態(tài)變化過程，調(diào)節(jié)排量比至目標(biāo)值時(shí)，HMT從當(dāng)前段過渡至目標(biāo)段，從而實(shí)現(xiàn)轉(zhuǎn)矩平穩(wěn)轉(zhuǎn)移。

2.4 全功率換段過程排量調(diào)節(jié)特性仿真分析

為了分析全動(dòng)率換段過程排量比特性，本文建立的HMT全功率換段過程閉式液壓回路容腔模型和排量比調(diào)節(jié)模型的參數(shù)如表1。

表1 液壓回路仿真模型參數(shù) Table 1 Parameters of simulation model for hydraulic circuit

排量比調(diào)節(jié)分別采用階躍和線性2種調(diào)節(jié)，對(duì)應(yīng)的液壓回路壓力響應(yīng)過程如圖4所示。

注：、分別表示液壓回路高低壓側(cè)壓力，MPa。下同。

圖4a是H段換向HM段壓力動(dòng)態(tài)響應(yīng)過程，H段壓力為11.07 MPa，排量比從0.972調(diào)節(jié)為0.804，調(diào)節(jié)后的HM段壓力為9.07 MPa。排量比階躍調(diào)節(jié)時(shí)，建壓所需時(shí)間為0.93 s，壓力波動(dòng)量為0.39 MPa，相對(duì)偏差為4.30%；排量比線性調(diào)節(jié)時(shí)，建壓所需時(shí)間為1.68 s，壓力波動(dòng)量為0.19 MPa，相對(duì)偏差為2.09%。圖4b是HM段換向H段壓力動(dòng)態(tài)響應(yīng)過程，排量比從0.804調(diào)節(jié)為0.972，壓力從HM段9.07 MPa調(diào)節(jié)為H段11.11 MPa。排量比階躍調(diào)節(jié)的建壓時(shí)間為0.85 s，壓力波動(dòng)量為0.64 MPa，相對(duì)偏差5.76%；排量比線性調(diào)節(jié)的建壓時(shí)間為1.63 s，壓力波動(dòng)量為0.46 MPa，相對(duì)偏差為4.14%。

從建壓時(shí)間分析，排量比階躍調(diào)節(jié)明顯優(yōu)于線性調(diào)節(jié)；從液壓回路壓力波動(dòng)量看，線性調(diào)節(jié)優(yōu)于階躍調(diào)節(jié)；與排量比線性調(diào)節(jié)相比，階躍調(diào)節(jié)有效減小了建壓時(shí)間，高壓側(cè)壓力波動(dòng)量無明顯變化，為了減小換段時(shí)間，可采用排量比階躍調(diào)節(jié)。

3 液壓機(jī)械全功率換段過程排量調(diào)節(jié)試驗(yàn)

3.1 試驗(yàn)設(shè)備

為研究HMT全功率換段過程變排量液壓元件排量比調(diào)節(jié)特性，搭建了HMT全功率動(dòng)力換段試驗(yàn)臺(tái)架，試驗(yàn)原理和實(shí)物照片如圖5所示。

試驗(yàn)臺(tái)主體部分為洛陽凱邁機(jī)電的變速箱電封閉傳動(dòng)試驗(yàn)臺(tái)。HMT動(dòng)力源為CJ250變頻電機(jī)（額定功率為250 kW），動(dòng)力輸出端經(jīng)轉(zhuǎn)速轉(zhuǎn)矩儀與HMT樣機(jī)輸入端相連接；HMT輸出端經(jīng)增速機(jī)（增速比1∶3）、T40轉(zhuǎn)速轉(zhuǎn)矩儀（額定轉(zhuǎn)矩為1 000 N·m，轉(zhuǎn)矩精度為0.5%F.S）與加載裝置相連，加載裝置為CJ200電力測功機(jī)（額定功率為200 kW）；試驗(yàn)臺(tái)離合器潤滑控制油液由泵站提供，閉式液壓回路中所用油液與潤滑系統(tǒng)所用油液分開供給，并在定排量液壓元件輸出軸加裝轉(zhuǎn)速傳感器（OD9011-NPN），在液壓回路高低壓側(cè)油路加裝壓力傳感器（HDA3844-A-600，量程0～60 MPa，精度為0.2%F.S）、補(bǔ)油壓力傳感器、殼體溫度傳感器，離合器控制回路加裝壓力傳感器（JYB-K0-HAG，量程2.5 MPa，精度為0.5%F.S）和溫度傳感器（JWB23/2e/A，量程-50～150 ℃，精度為0.2%F.S）。試驗(yàn)臺(tái)測控系統(tǒng)由試驗(yàn)臺(tái)控制柜和HMT控制器組成。HMT控制器輸出兩路開關(guān)量控制離合器電磁閥，輸出2路比例電流（含顫振）驅(qū)動(dòng)變排量液壓元件排量調(diào)節(jié)機(jī)構(gòu)比例閥，并進(jìn)行數(shù)據(jù)采集。比例閥電流從當(dāng)前值階躍調(diào)節(jié)為目標(biāo)值時(shí)，改變伺服閥兩端控制油壓，使伺服缸運(yùn)動(dòng)至目標(biāo)位置，變量泵調(diào)節(jié)至目標(biāo)排量。

a. HMT動(dòng)力換段試驗(yàn)臺(tái)原理圖 a. Schematic diagram of HMT power shifting test bench 1.試驗(yàn)臺(tái)架測控系統(tǒng) 2.排量控制機(jī)構(gòu) 3.控制油源 4.信號(hào)集成單元 5.增速機(jī) 6.轉(zhuǎn)速轉(zhuǎn)矩儀 7.電動(dòng)機(jī) 8.測功機(jī) 9.液壓機(jī)械無級(jí)傳動(dòng) 1.Control system of test bench 2.Displacement control mechanism 3.Control oil sources 4.Signals integration unit 5.Speed increaser 6.Speed and torque meter 7.Motor 8.Dynamometer 9.HMT b. 試驗(yàn)臺(tái)架實(shí)物照片 b. Photograph of test bench

3.2 試驗(yàn)方案

在給定轉(zhuǎn)速和轉(zhuǎn)矩的換段過程中，按調(diào)節(jié)規(guī)律調(diào)節(jié)排量，主動(dòng)控制液壓回路高低壓側(cè)壓力互換，使HMT從當(dāng)前段過渡到目標(biāo)段。按上述方法，進(jìn)行由H段向HM段、HM段向H段往復(fù)換段試驗(yàn)，實(shí)時(shí)采集輸入輸出轉(zhuǎn)速、轉(zhuǎn)矩、定排量液壓元件轉(zhuǎn)速、變排量液壓元件排量比、液壓回路高低壓側(cè)壓力、補(bǔ)油溫度和離合器控制油壓等試驗(yàn)參數(shù)，并與相同條件下的仿真結(jié)果進(jìn)行對(duì)比分析，探究全功率換段的功率轉(zhuǎn)移機(jī)理及換段過程排量比調(diào)節(jié)的影響規(guī)律。

負(fù)載大小決定換段前后液壓回路的工作壓力和全功率換段過程的排量調(diào)節(jié)量，轉(zhuǎn)速影響HMT傳動(dòng)效率，但這2個(gè)參數(shù)都不影響排量調(diào)節(jié)規(guī)律和功率轉(zhuǎn)移機(jī)理。裝備HMT的5 t裝載機(jī)，在典型工作工況（ZZJ/07B01-2017《土方機(jī)械輪胎式裝載機(jī)能效試驗(yàn)及評(píng)價(jià)方法》）中，HMT換段時(shí)的發(fā)動(dòng)機(jī)轉(zhuǎn)速范圍為800～1 200 r/min，液壓回路最高壓力為8～14 MPa，限于試驗(yàn)臺(tái)條件，本文試驗(yàn)時(shí)HMT輸入轉(zhuǎn)速選擇1 000 r/min，測功機(jī)加載轉(zhuǎn)矩選擇100和150 N·m，通過增速機(jī)后，液壓段壓力約為9和11 MPa，屬裝載機(jī)HMT的換段典型工況點(diǎn)，液壓回路試驗(yàn)油溫80 ℃。由于試驗(yàn)設(shè)備的限制，被試HMT和測功機(jī)間設(shè)置了增速機(jī)，轉(zhuǎn)速轉(zhuǎn)矩儀安裝在增速機(jī)之后，故本文所提及的“輸出轉(zhuǎn)矩”均為HMT經(jīng)增速機(jī)后的輸出轉(zhuǎn)矩，即測功機(jī)的加載轉(zhuǎn)矩。

3.3 結(jié)果與分析

輸入轉(zhuǎn)速為1 000 r/min，輸出轉(zhuǎn)矩為100 N·m時(shí)，排量比階躍調(diào)節(jié)化下對(duì)應(yīng)的液壓機(jī)械由H段向HM段和由HM段向H段的換段過程試驗(yàn)與仿真結(jié)果如圖6、圖7所示。

a. 離合器壓力 a. Pressure of clutchb. 變排量液壓元件排量比 b. Displacement ratio of variable-displacement hydraulic component

a. 離合器壓力 a. Pressure of clutchb. 變排量液壓元件排量比 b. Displacement ratio of variable-displacement hydraulic component

輸入轉(zhuǎn)速1 000 r/min、輸出轉(zhuǎn)矩150 N·m，排量比階躍調(diào)節(jié)的換段過程試驗(yàn)結(jié)果如圖8、圖9所示。H、L兩離合器結(jié)合重疊過程仍為2 s。

a. 離合器壓力 a. Pressure of clutchb. 變排量液壓元件排量比 b. Displacement ratio of variable -displacement hydraulic component

a. 離合器壓力 a. Pressure of clutchb. 變排量液壓元件排量比 b. Displacement ratio of variable -displacement hydraulic component

如圖8，試驗(yàn)中排量比從0.985調(diào)至0.802（仿真值為0.972和0.803，試驗(yàn)和仿真結(jié)果偏差為7.65%）時(shí)，液壓回路壓力從H段11.07 MPa調(diào)節(jié)為HM段9.13 MPa，建壓時(shí)間1.05 s，輸出轉(zhuǎn)速無波動(dòng)，轉(zhuǎn)矩波動(dòng)6.70 N·m，為輸出轉(zhuǎn)矩的4.50%；如圖9，排量比0.803調(diào)至0.988（仿真值為0.804和0.973，仿真和試驗(yàn)結(jié)果偏差為8.65%）時(shí)，液壓回路壓力從HM段9.11 MPa調(diào)節(jié)為H段11.11 MPa，建壓時(shí)間1.10 s，轉(zhuǎn)矩波動(dòng)6.84 N·m ，為輸出轉(zhuǎn)矩的4.60%。

圖6～圖9中換段試驗(yàn)與仿真結(jié)果對(duì)比可知，換段過程排量比試驗(yàn)結(jié)果變化量和仿真結(jié)果變化量最大偏差為8.93%，仿真和試驗(yàn)結(jié)果基本一致，證明本文所建立的HMT全功率換段過程排量調(diào)節(jié)模型可以準(zhǔn)確計(jì)算目標(biāo)段排量值，能準(zhǔn)確反映液壓回路高低壓側(cè)壓力互換過程。在兩離合器結(jié)合重疊過程中合理調(diào)節(jié)變排量液壓元件排量，能夠使轉(zhuǎn)矩在離合器間快速轉(zhuǎn)移，負(fù)載為100和150 N·m時(shí)，最大建壓時(shí)間分別為1.00和1.10 s，轉(zhuǎn)矩波動(dòng)量最大分別為6.80和6.84 N·m，分別為輸出轉(zhuǎn)矩的6.80%和4.60%。

4 結(jié) 論

本文以HMT全功率換段為目標(biāo)，開展了換段過程排量變化規(guī)律、液壓回路動(dòng)態(tài)響應(yīng)過程的理論分析和試驗(yàn)研究，得到如下結(jié)論：

1）獲得全功率換段轉(zhuǎn)矩轉(zhuǎn)移機(jī)理表達(dá)式，閉式液壓回路的壓力可以通過調(diào)節(jié)排量比控制，改變閉式液壓回路壓力，使轉(zhuǎn)矩從當(dāng)前段離合器向目標(biāo)段離合器轉(zhuǎn)移。

2）對(duì)比排量比階躍和線性調(diào)節(jié)規(guī)律響應(yīng)特性，階躍調(diào)節(jié)規(guī)律能有效減小建壓時(shí)間，換段時(shí)間為0.93 s，壓力波動(dòng)量為0.64 MPa，與線性調(diào)節(jié)相比，高壓側(cè)壓力波動(dòng)無明顯變化。為有效減小換段時(shí)間，可采用排量比階躍調(diào)節(jié)規(guī)律。

3）在相同工況下，從當(dāng)前段到目標(biāo)段排量調(diào)節(jié)量的仿真與試驗(yàn)結(jié)果基本相同，偏差為8.93%，建壓時(shí)間基本一致，表明本文所建立的排量比調(diào)節(jié)模型能準(zhǔn)確計(jì)算排量比目標(biāo)值，并能準(zhǔn)確反映建壓過程。

4）在當(dāng)前段和目標(biāo)段離合器結(jié)合重疊時(shí)，通過合理調(diào)節(jié)排量比控制液壓回路高低壓側(cè)壓力完成釋壓、建壓過程，能夠使轉(zhuǎn)矩在離合器間快速轉(zhuǎn)移，換段前后輸出轉(zhuǎn)速平穩(wěn)無變化、轉(zhuǎn)矩連續(xù)傳遞。輸出轉(zhuǎn)矩為100和150 N·m時(shí)，建壓時(shí)間分別為1.00和1.10 s，轉(zhuǎn)矩波動(dòng)量最大分別為6.80和6.84 N·m，分別為輸出轉(zhuǎn)矩的6.80%和4.60%，實(shí)現(xiàn)了全功率換段。

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Model of regulating displacement ratio in full power shifting process of hydro-mechanical variable transmission

Yang Shujun1, Zhang Man1, Zeng Panwen2, Zhang Yinjun1, Zhang Lu1, Tian Lin1

(1.,,066004,; 2.,,411199,)

Hydro-mechanical variable transmission (HMT) is a kind of double power flow transmission system constituted by hydraulic branch and mechanical branch in parallel. HMT has the ability to realize high-power CVT and high transmission efficiency, and is suitable for high-power automobiles. In general power shift process, there are load reversal in hydraulic transmission unit, power flow reversal in hydraulic branch, and function interchange in hydraulic components. At the same time, the speed of fixed displacement hydraulic component changes abruptly, and there is a short time power interruption. To solve the problems of speed fluctuation and power interruption in power shift, based on the five-stage full power shift method by overlapping the double clutches, the displacement regulating law of variable displacement hydraulic component is studied in this paper. An arithmetic type two-range HMT is taken as the research object, and the pressure responses to different displacement regulation are analyzed. The torque characteristic equation in full power shift is derived. The cavity model of closed hydraulic circuit is established, in which the closed hydraulic circuit is simplified to two cavities. Considering the influence of the volumetric efficiency of the hydraulic transmission unit, the mathematical model of the displacement ratio regulation of variable displacement hydraulic component is derived. The step change and linear change of displacement ratio are adopted respectively, and the pressure response is obtained by simulation. The results show that the regulation law of displacement ratio has a great influence on the time of pressure building-up and pressure fluctuation. The step change of displacement ratio can effectively reduce the time of pressure building-up, and there is no obvious increase of pressure fluctuation compared with that of the linear change. The power shift time is 0.93 s and pressure fluctuation is 0.64 MPa. In order to reduce the power shift time, the step change of displacement ratio could be adopted. Through the displacement regulation characteristic test of HMT in full power shift process, the pressure response is obtained. The results show that the simulation results of displacement ratio change are in accordance with the test results, and the maximum deviation is 8.93% under the same working conditions. Based on the state parameters of current range and the target range pressure, the mathematical model of the displacement ratio regulation proposed in this paper can predict the displacement ratio target value, and accurately describe the pressure interchange between the high and low pressure circuits. During the double clutches overlapping, the displacement ratio is adjusted to the target value. The pressure interchange between the high and low pressure circuits can be completed in the full power shift process, and the torque is transferred from current clutch to target clutch. The output speed remains unchanged, and the output torque is continuous. When the output torque after speed increaser is 100 and 150 N·m, the power shift time is 1.00 and 1.10 s respectively, it’s the maximum fluctuation is 6.80 and 6.84 N·m respectively. The problems such as speed fluctuation and power interruption in the shift process are solved, this study provides a reference for the realization of HMT full power shift control and subsequent research.

hydro-mechanical; transmission; control; variable transmission; full power shift;displacement regulation

10.11975/j.issn.1002-6819.2019.13.007

U463.2

A

1002-6819(2019)-13-0064-11

2019-01-25

2019-03-03

國家自然基金面上項(xiàng)目(51675462，51175449)；河北省高校科技支撐項(xiàng)目(ZD2016012)

楊樹軍，博士，教授，主要從事車輛新型傳動(dòng)及其控制技術(shù)研究。Email：ysj@ysu.edu.cn

楊樹軍，張 曼，曾盼文，張寅君，張 璐，田 霖. 液壓機(jī)械無級(jí)傳動(dòng)全功率換段過程排量比調(diào)節(jié)模型[J]. 農(nóng)業(yè)工程學(xué)報(bào)，2019，35(13)：64－73. doi：10.11975/j.issn.1002-6819.2019.13.007 http://www.tcsae.org

Yang Shujun, Zhang Man, Zeng Panwen, Zhang Yinjun, Zhang Lu, Tian Lin. Model of regulating displacement ratio in full power shifting process of hydro-mechanical variable transmission[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2019, 35(13): 64－73. (in Chinese with English abstract) doi：10.11975/j.issn.1002-6819.2019.13.007 http://www.tcsae.org